Asian Noodles: Science, Technology, and Processing

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ASIAN NOODLES

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ASIAN NOODLES SCIENCE, TECHNOLOGY, AND PROCESSING

Edited by

Gary G. Hou, Ph.D. Wheat Marketing Center, Inc. Portland, Oregon USA

A JOHN WILEY & SONS, INC., PUBLICATION

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Photo credits: Gary G. Hou, Bon Lee, and Bruce Forster Photography. C 2010 by John Wiley & Sons, Inc. All rights reserved. Copyright


Published by John Wiley & Sons, Inc., Hoboken, New Jersey. Published simultaneously in Canada. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400, fax 978-750-4470, or on the web at www.copyright.com. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, 201-748-6011, fax 201-748-6008, or online at http://www.wiley.com/go/permission. Limit of Liability/Disclaimer of Warranty: While the publisher and author have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives or written sales materials. The advice and strategies contained herein may not be suitable for your situation. You should consult with a professional where appropriate. Neither the publisher nor author shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages. For general information on our other products and services or for technical support, please contact our Customer Care Department within the United States at 877-762-2974, outside the United States at 317-572-3993 or fax 317-572-4002. Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic formats. For more information about Wiley products, visit our web site at www.wiley.com. Library of Congress Cataloging-in-Publication Data: Asian noodles : science, technology, and processing / edited by Gary G. Hou. p. cm. Includes index. ISBN 978-0-470-17922-2 (cloth) 1. Noodles–Asia. 2. Wheat–Milling–Asia. 3. Wheat–Processing–Asia. I. Hou, Gary G. TP435.M3A85 2010 664 .7550951–dc22 2009054244 Printed in the United States of America 10 9 8 7 6 5 4 3 2 1

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In memory of my parents for their unconditional love. In appreciation of my eldest brother and sister-in-law for their love and unwavering support.

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CONTENTS

Preface Acknowledgments Contributors 1. Breeding Noodle Wheat in China

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Zhonghu He, Xianchun Xia, and Yan Zhang

2. Breeding for Dual-Purpose Hard White Wheat in the United States: Noodles and Pan Bread

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Arron H. Carter, Carl A. Walker, and Kimberlee K. Kidwell

3. Wheat Milling and Flour Quality Analysis for Noodles in Japan

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Hideki Okusu, Syunsuke Otsubo, and James Dexter

4. Wheat Milling and Flour Quality Analysis for Noodles in Taiwan

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C. C. Chen and Shu-ying (Sophia) Yang

5. Noodle Processing Technology

99

Gary G. Hou, Syunsuke Otsubo, Hideki Okusu, and Lanbin Shen

6. Instant Noodle Seasonings

141

Kerry Fabrizio, Rajesh Potineni, and Kim Gray

7. Packaging of Noodle Products

155

Qingyue Ling

8. Laboratory Pilot-Scale Asian Noodle Manufacturing and Evaluation Protocols

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Gary G. Hou

9. Objective Evaluation of Noodles

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David W. Hatcher

10. Sensory Evaluation of Noodles

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Bin Xiao Fu and Linda Malcolmson vii

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CONTENTS

11. Effects of Flour Protein and Starch on Noodle Quality

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Byung-Kee Baik

12. Effects of Polyphenol Oxidase on Noodle Color: Mechanisms, Measurement, and Improvement

285

E. Patrick Fuerst, James V. Anderson, and Craig F. Morris

13. Effects of Flour Characteristics on Noodle Texture

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Andrew S. Ross and Graham B. Crosbie

14. Noodle Plant Setup and Resource Management

331

Gary G. Hou, Syunsuke Otsubo, Ver´onica Jim´enez Monta˜no, and Julio Gonz´alez

15. Quality Assurance Programs for Instant Noodle Production

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Sumonrut Kamolchote, Toh Tian Seng, Julio Gonz´alez, and Gary G. Hou

16. Rice and Starch-Based Noodles

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Zhan-Hui Lu and Lilia S. Collado

Index

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PREFACE

While it is still being debated whether or not Marco Polo was the first to introduce noodles into Italy in 1296 on his return to Venice from China (Donadio 2009), at least one case about where noodles may have originated has been closed. The Chinese, the Italians, and the Arabs have all claimed that they were the first ones to invent noodles. However, the discovery of a pot of well-preserved 4000-year-old noodles unearthed in 2005 by Chinese archaeologists in the Lajia archaeological site in northwestern China may have finally settled the dispute (Lu et al. 2005). These easily recognizable noodles are more than 2000 years older than the earliest mention of noodles, which appeared in a Chinese book written during the East Han Dynasty sometime between AD 25 and 220. The noodles were thin (∼0.3 cm in diameter), more than 50 cm in length, and yellow in color. They resemble the La-Mian noodle, a traditional Chinese noodle that is made by repeatedly pulling and stretching the dough by hand. It turned out that these 4000-year-old noodles were made from millet, not from wheat flour as they are made today. Some historical time later, Chinese noodles were introduced into Japan and other Asian countries and beyond, where they were adapted into the local diet and modified, eventually evolving into diverse forms and preparations that have become an essential part of local cuisines. Today, Asian noodles, especially instant ramen noodles, are consumed worldwide. By combining the traditional art of noodle preparation with modern science and processing technology, many noodle products, which used to be produced at small-scale levels, are now being produced in large-scale food manufacturing plants with consistently high quality. Asian noodles and certain Italian pasta products (e.g., spaghetti) are sometimes confusing to consumers because they appear to be quite similar. This may be one of the causes contributing to the ongoing debate about whether these two products are related or have a common origin. Actually, there are some key differences between them in their characteristics and in the raw materials used, the processes involved, and their consumption patterns (Hou 2001). Most Asian noodles are made from common wheat flour (Triticum aestivum) and a salt solution that are mixed together to form a dough that is processed by sheeting. This type of Asian noodle is often eaten in a soup. In contrast, authentic pastas are traditionally made from durum (Triticum durum) semolina and water mixed together to form a dough that is processed by extrusion technology. This type of pasta is often consumed with sauce. Outside of Asia, noodles often are made from wheat flour. Within Asia, however, noodles are thought of as thin strips of dough that can be made from a variety of raw materials, including but not limited to wheat flour, rice flour, buckwheat flour, or ix

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starches derived from mung bean, tapioca, sweet potato, sago, wheat, rice, or corn. Noodles made from wheat flour remain the most popular noodle products in Asia and around the world, followed by rice and starch-based noodles, which are consumed primarily in Asia. The importance of noodles in the Asian diet is significant. Currently, an average of 20–50% of the total wheat flour consumption in many countries occurs in the form of noodles. The percentage of total flour consumed as noodles by country is as follows: Indonesia Korea Vietnam Mainland China Taiwan Malaysia Thailand Japan Philippines

50% 45% 45% 40% 38% 30% 30% 28% 21%

Many of these countries rely heavily on wheat imports because none of them, except for China, grow much wheat. Therefore, the wheat market demand in Asia for noodle flour production is too large to be ignored by the major wheat-exporting countries. In the last 20 years, there has been a growing global interest in Asian noodles. They are very traditional foods, and early research was mainly conducted in countries such as China, Japan, and Korea; however, information and scientific publications were not easily accessible because they were published in the native languages and not translated for a broader audience. Today, however, a wealth of information and technical publications are available in various scientific journals in English. There are many reasons for this interest, including noodle industry expansion, business development, intercultural exchange, migration, and simple changes in dietary habits. One of the key driving forces behind the scenes was the increased investment and focus of major wheat-exporting countries on developing new wheat varieties to compete in the noodle wheat market in Asia and elsewhere. Noodle consumption has not only increased dramatically in Asia over the years but has also received wide acceptance in other parts of the world. For instance, the consumption of instant ramen noodles in 2007 reached nearly 100 billion meals around the world (World Instant Noodle Association 2009), an increase of 66% from 2002. Of the top 15 instant noodle-consuming countries, there are five countries in which noodles are not part of the traditional diet: United States, Russia, India, Brazil, Nigeria, and Mexico. Thus, the noodle product is one of a number of wheat-based foods whose globalization continues to stimulate international trade in the world’s top-ranked grains in terms of harvested area (McKee 2009). For the past 14 years, I have not only witnessed the growth of the noodle industry around the world but have also contributed, to some extent, to its success. When I first joined the Wheat Marketing Center, Inc. in 1995, I was put in charge of conducting the Asian Products Collaborative (APC) project, which was jointly organized by the U.S. Wheat Associates and the Wheat Marketing Center. Throughout the life of this

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project (1995–2008), I worked very closely with nearly 380 collaborators in 70 teams from 9 Asian countries. These collaborators included flour millers, food processors, research scientists, and wheat buyers. Together, we developed standard protocols for 13 types of Asian noodles, 6 types of steamed breads, and several other types of products. Each protocol includes formulation, processing, and quality evaluation methods. After gaining technical expertise through working with these Asian collaborators, I started teaching Asian noodle technology short courses at the Wheat Marketing Center and in institutions overseas to companies in Asia, Africa, Europe, Latin America, and North America. More than 150 noodle processors, flour millers, ingredient suppliers, researchers, and technologists have participated in these courses. In recent years, noodle consumption in Latin America and Africa (particularly Nigeria) has experienced substantial and sustainable growth. Over the years, I have had the opportunity to travel to many countries and have visited numerous noodle manufacturing plants, both large and small, and was able to provide technical assistance to them. Although much more knowledge and information on Asian noodles is available now than ever before, many people in the industry are still not able to access this, partly because many publications are available only in scientific journals and in a handful of scientific books that contain a few chapters on Asian noodles that were published 10 years ago. This has created an urgent need for a book on the subject. Asian Noodles: Science, Technology, and Processing meets this need in a timely manner by providing readers with a comprehensive, up-to-date, single source of information on every aspect of Asian noodles, from wheat breeding to noodle product packaging. There are 16 chapters in all, each written by experts in the subject. The book begins with noodle-wheat breeding in China since noodles were originated in China thousands of years ago. The wheat-breeding community worldwide will be interested in learning about the strategies that Chinese breeders have employed to develop varieties for their own noodle products. This is followed by breeding for dual-purpose hard white wheat in the United States for noodles and pan bread in Chapter 2. The United States started hard white wheat-breeding programs 20 years ago and hoped to offer alternatives to end-users in Asia for producing both noodles and Western pan bread. This chapter discusses the promising selection strategies in breeding dual-purpose hard white wheat in the United States. Chapters 3 and 4 deal with wheat milling and flour quality analysis for noodles in Japan and Taiwan, respectively. Wheat milling is a critical process in noodle flour production, and the milling industry in both Japan and Taiwan has extensive experience and advanced milling technology. Chapter 5 introduces the commercial noodle processing technology of eight types of noodles consumed worldwide. Chapter 6 discusses the composition, processing, and quality evaluation of instant noodle soup seasonings. Packaging of noodle products is covered in Chapter 7. Chapter 8 reports on laboratory pilot-scale noodle manufacturing and evaluation protocols. Objective and sensory evaluation techniques are introduced in Chapters 9 and 10, respectively. The effects of flour composition and characteristics on noodle quality are examined in Chapters 11 and 13 while the effects of polyphenol oxidase on noodle color and its mechanism are

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PREFACE

discussed extensively in Chapter 12. The guidelines for noodle plant setup and resource management are presented in Chapter 14, and quality assurance programs for instant noodle manufacturing are described in Chapter 15. Of course, a volume on Asian noodles would not be complete without a chapter on rice and starch-based noodle products (Chapter 16). This book contains a good mix of theories on wheat breeding and genes (quality markers) as well as many down-to-earth applied noodle manufacturing technologies, from lab-scale noodle processing and evaluation to commercial noodle manufacturing plant setup and quality assurance programs. This compendium is the first of its kind to provide such comprehensive coverage on Asian noodles in a single English volume with up-to-date scientific and technological information. Many chapters contain excellent photos and diagrams, and each chapter is supplemented by an up-to-date bibliography, allowing for follow-up on the information provided. Therefore, the book should serve as a unique reference for all involved in the industry, including wheat breeders, growers, flour millers, noodle processors, quality control personal, scientists/researchers, students, business developers, and suppliers of food machinery, packaging materials, ingredients, spices, and seasonings, as well as informed consumers and newcomers to the noodle business and related industries. I am fully aware that despite the extensive topics covered in this book, it cannot be, nor is it intended to be, all-inclusive. By reviewing the latest research and new developments in Asian noodles and compiling all this information into a single volume, we can lay the foundation for continued advancement in breeding, milling, processing, packaging, plant management, and quality assurance programs that will benefit all of us in the not-too-distant future. Gary G. Hou REFERENCES Donadio, R. 2009. So you think you know pasta. New York Times, October 14, 2009 (http://www.nytimes.com/2009/10/14/dining/14ency.html? r=1). Hou, G. 2001. Oriental noodles. Advances in Food and Nutrition Research 43:141–193. Lu, H., Yang, X., Ye, M., Liu, K., Xia, Z., Ren, X., Cai, L., Wu, N., and Liu, T. 2005. Culinary archaeology: millet noodles in Late Neplithic China. Nature 437:967–968 (October 13, 2005). McKee, D. 2009. Globalization of instant noodles. World Grain 27(3):32–36. World Instant Noodle Association (WINA) 2009. Expanding market. World Instant Noodles Association, Osaka, Japan (http://instantnoodles.org/noodles/expanding-marlet.html).

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ACKNOWLEDGMENTS

I am deeply grateful to all the people who have helped bring this publication into print. My greatest appreciation goes to all the specialists who have contributed to this volume. There are a total of 32 chapter contributors from 11 countries. All have brought new and personal insights to the field of Asian noodle products based on their individual research and industrial experience. I deeply appreciate the help and strong support given to me by Dr. David Shelton, Executive Director of the Wheat Marketing Center, who has made this happen by allowing extensive use of personnel and facilities. This book has benefited immeasurably from the support of many people over many years. I deeply appreciate the help I have received from everyone, including Robert Drynan who first brought me into the field 14 years ago, Mark Kruk whom I worked with and had many intriguing discussions with over many years, and especially all the collaborators from Asia and elsewhere who have generously shared their knowledge and experience with me. I very much appreciate the support and opportunity given to me to learn and to teach on numerous aspects of Asian noodles over the years by the U.S. Wheat Associates, including Dr. John Oades, Rick Callies, Jim Frahm, Matt Weimar, Ron Lu, Mark Samson, Mitch Skalicky, Steven Wirsching, Dr. Won Bang Koh, Alvaro de la Fuente, Ed Wiese, Jim McKenna, Mike Spier, Peter Lloyd, Plutarco Ng, Phua Lock Yang, Roy Chung, Dr. Woojoon Park, Shipu (Andy) Zhao, Gerald Theus, Muyiwa Talabi, and Shu-ying (Sophia) Yang. I am grateful for the guidance and support that Dr. Perry K. W. Ng provided to me when I was pursuing my Ph.D. study under his supervision at the Department of Food Science and Human Nutrition, Michigan State University. Dr. Xiang S. Yin is especially acknowledged for recommending me to Perry Ng. My special thanks go to Pamela Causgrove for her painstaking editing of the manuscript; Susan Perry for her assistance in formatting numerous figures, graphs, and drawings; and Bon Lee for translating some technical literature from Japanese into English. I express my special appreciation to Jonathan Rose, editor at John Wiley & Sons, Inc., for providing me the challenge and wonderful opportunity to write this book. I appreciate the wonderful editing, proofing, typesetting, and production work done by Rosalyn Farkas, production editor at John Wiley & Sons, Inc., and Ronald D’Souza, project manager at Aptara Inc. Last, but not least, I am grateful to my family who has always supported me along the way. G.G.H. xiii

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CONTRIBUTORS

James V. Anderson, Ph.D., U.S. Department of Agriculture – Agricultural Research Service, Plant Science Research Unit, 1605 Albrecht Boulevard, Fargo, ND 58105 USA. Byung-Kee Baik, Ph.D., Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99164 USA. Arron H. Carter, Ph.D., Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99164 USA. C. C. Chen, M.Sc., Chia Fha Enterprise Co. Ltd., 115, Sec. 1, San Min Rd., Ching Shuei Township, Taichung, Taiwan. Lilia S. Collado, Ph.D., School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, PRC. Graham B. Crosbie, Ph.D., Crosbie Grain Quality Consulting, 22a Stratford Street, East Fremantle, WA 6158 Australia. James Dexter, Ph.D., Retired (Canadian Grain Commission), 62 Lemmen Drive, Winnipeg, MB R2K 3J8 Canada. Kerry Fabrizio, M.Sc., Givaudan Flavors Corporation, 1199 Edison Drive, Cincinnati, OH 45216 USA. Bin Xiao Fu, Ph.D., Durum Wheat Research, Grain Research Laboratory, 1404-303 Main Street, Winnipeg MB R3C 3G8 Canada. E. Patrick Fuerst, Ph.D., USDA–ARS Western Wheat Quality Laboratory, Washington State University, Pullman, WA 99164 USA. Julio Gonz´alez, MBA, Ch.E., Grupo Buena, 19 AV 16-30 Zona 10, Guatemala City, Guatemala. Kim Gray, Ph.D., Givaudan Flavors Corporation, 1199 Edison Drive, Cincinnati, OH 45216 USA. David W. Hatcher, Ph.D., Grain Research Laboratory, Canadian Grain Commission, 1404-303 Main Street, Winnipeg, MB R3C 3G8 Canada.

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CONTRIBUTORS

Zhonghu He, Ph.D., CIMMYT China Office, c/o Chinese Academy of Agricultural Sciences, Beijing 100081 China. Gary G. Hou, Ph.D., Wheat Marketing Center, Inc., 1200 NW Naito Parkway, Portland, OR 97209 USA. ˜ MBA, Fabrica de Galletas La Moderna/Bimbo, Ver´onica Jim´enez Montano, Leandro Valle No. 404., Col. Reforma, Toluca, Edo de Mexico. M´exico. C.P. 50010. Sumonrut Kamolchote, M.Sc., Thai President Foods PCL., 601 Moo 11 Suklapiban 8 Rd, Nongkham, Sriracha, Chonburi 20232, Thailand. Kimberlee K. Kidwell, Ph.D., College of Agricultural, Human and Natural Resource Sciences, 423 Hulbert Hall, PO Box 646243, Pullman, WA 99164 USA. Qingyue Ling, Ph.D., Food Innovation Center Experiment Station, Oregon State University, 1207 NW Naito Parkway, Portland, OR 97209 USA. Zhan-Hui Lu, Ph.D., College of Food Science and Nutritional Engineering, China Agricultural University, PO Box 40, China Agricultural University (East Campus), 17 Qinghua East Avenue, Haidian District, Beijing 100083 China. Linda Malcolmson, Ph.D., Canadian International Grains Institute, 1000-303 Main Street, Winnipeg, MB R3C 3G7 Canada. Craig F. Morris, Ph.D., USDA–ARS Western Wheat Quality Laboratory, Washington State University, E202 FSHN East, Pullman, WA 99164 USA. Hideki Okusu, M.Sc., Nippon Flour Mills Co. Ltd., Central Laboratory, 5-1-3 Midori-Gaoka, Atsugi, Kanagawa, Japan 243-0041. Syunsuke Otsubo, B.Sc., Nippon Flour Mills Co. Ltd., Food Processing R&D Laboratory, 5-1-3 Midori-Gaoka, Atsugi, Kanagawa, Japan 243-0041. Rajesh Potineni, Ph.D., Givaudan Flavors Corporation, 1199 Edison Drive, Cincinnati, OH 45216 USA. Andrew S. Ross, Ph.D., Crop and Soil Science, and Food Science & Technology, Oregon State University, Crop Science Building, Corvallis, OR 97331 USA. Toh Tian Seng, MBA, B.Sc., Noodles, Cereals and Nutrition, Nestle R&D Center (Pte) Ltd., 29 Quality Road, Singapore 618802. Lanbin Shen, B.S.E., Guangzhou City Lotte Machinery, Co., Ltd., 121 Wenming Road, Nancun Town, Panyu District, Guangzhou 511442 China. Carl A. Walker, M.Sc., Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99164 USA.

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Xianchun Xia, Ph.D., CIMMYT China Office, c/o Chinese Academy of Agricultural Sciences, Beijing 100081 China. Shu-ying (Sophia) Yang, M.Sc., U.S. Wheat Associates, Chen Shin Building, 3-3 Lane 27, Chung Shan North Road, Section 2, Taipei 104, Taiwan. Yan Zhang, Ph.D., CIMMYT China Office, c/o Chinese Academy of Agricultural Sciences, Beijing 100081 China.

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CHAPTER 1

Breeding Noodle Wheat in China ZHONGHU HE, XIANCHUN XIA, and YAN ZHANG

1.1. INTRODUCTION China is the largest wheat producer and consumer in the world, and wheat ranks as the third leading grain crop in China after rice and maize. Wheat products are the major staple foods consumed in northern China although its consumption in southern China is also increasing rapidly. In 2007, the national wheat area, average yield, and production were 23.7 million ha, 4608 kg/ha, and 109 million metric tons, respectively. However, more than 70% of Chinese wheat is produced in five provinces— Henan, Shandong, Hebei, Anhui, and Jiangsu. The wheat-growing area has been divided into ten major agroecological zones as indicated in Figure 1.1, based on wheat types, varietal reactions to temperature, moisture, biotic and abiotic stresses, and wheat-growing seasons (He et al. 2001). On the basis of sowing dates, autumnsown wheat accounts for more than 90% of production and acreage. Winter and facultative wheats, sown in the Northern China Plain (Zone I) and Yellow and Huai River Valleys (Zone II), contribute around 70% of production. Autumn-sown, spring habit wheat, planted in both the Middle and Low Yangtze Valleys (Zone III) and Southwestern China (Zone IV), contributes around 25% of production. Spring-sown spring wheat is mostly planted in Northeastern and Northwestern China (Zones VI, VII, and VIII) and makes up around 5% of production. From the establishment of the People’s Republic of China in 1949 to the present, wheat continues to play an important role in food production. Great progress has been achieved in wheat production during the last 60 years. Average wheat yield has increased 1.9% annually, and production has increased more than sixfold. Many factors have contributed to the significant increase of average yield, including adoption of improved varieties, extension of high-yielding cultivation technology, increased use of fertilizers and irrigation, expansion of farm mechanization, and improvement of rural policy. Agricultural policy reform in the early 1980s greatly stimulated wheat production, and 123 million metric tons of harvested grain was recorded in 1997. Asian Noodles: Science, Technology, and Processing, Edited by Gary G. Hou C 2010 John Wiley & Sons, Inc. Copyright


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BREEDING NOODLE WHEAT IN CHINA

Harbin

Urumqi

VI

X

Shenyang VII Yinchuan Hohhot

VIII

Xining Lanzhou

I

Taiyuan Shijiazhuang Jinan II

Xian

IX

Beijing Tianjin

Zhengzhou Hefei

Lhasa

IV

Nanjing

Wuhan

Chengdu

III

Shanghai

Hangzhou

Nanchang Changsha

Guiyang

Fuzhou Taibei

Kunming

V Guangzhou Macao Hongkong

Nanning

Haikou

FIGURE 1.1 Chinese wheat production map: I, Northern Winter Wheat Zone; II, Yellow and Huai River Valleys Facultative Wheat Zone; III, Middle and Low Yangtze Valleys Autumn-Sown Spring Wheat Zone; IV, Southwestern Autumn-Sown Spring Wheat Zone; V, Southern Autumn-Sown Spring Wheat Zone; VI, Northeastern Spring Wheat Zone; VII, Northern Spring Wheat Zone; VIII, Northwestern Spring Wheat Zone; IX, Qinghai–Tibetan Plateau Spring–Winter Wheat Zone; X, Xinjiang Winter-Spring Wheat Zone.

Wheat area, however, has declined from 30 million ha to around 23 million ha since 2000, largely due to the policy of increasing crop diversity, elimination of guaranteed pricing policies in south China and spring wheat regions, and lower profitability of wheat production in comparison to cash crops. Around 50% of production is marketed as commercial wheat and stored in governmental grain stations, and the remaining 50% is stored and consumed by individual farmers. The annual wheat consumption is around 100–105 million metric tons. Currently, around 80% of wheat is used for food production, 10% for feed, 5% for seed, and the remaining 5% for industrial use. As listed in Table 1.1, traditional Chinese foods, such as steamed bread and noodles, account for around 85% of food products, and Western-style bread and soft wheat products, such as cookies, cakes, and biscuits, make up the remaining 15% although they are increasing rapidly, particularly in the urban areas. There are many types of noodles consumed across China; however, fresh noodles, instant noodles, and dry white Chinese noodles are the most popular types as presented in Table 1.2.

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INTRODUCTION

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TABLE 1.1 Percentage of Various Wheat Products Consumed in China Classification

Percentage (%)

Steamed bread including flat bread Noodles and dumplings Cookies and cakes Western bread Total

45 40 10 5 100

Data Source: CAAS/CIMMYT wheat quality laboratory.

The international community has a confused concept of Chinese noodles. Yellow alkaline noodles (YANs) are commonly referred to as “Chinese noodles” in English, yet they are consumed mostly in Japan and other southeastern Asian countries, while a different type of yellow alkaline noodle is consumed in parts of northwestern and southwestern China, including Gansu and Sichuan provinces. Most of the previous studies reported in international literature focused on Japanese and Korean style udon noodles and yellow alkaline noodles, but the quality aspects of traditional Chinese noodles remain largely unexplored. Yield improvement has been the top priority for wheat breeding and production, largely due to high population pressure. However, as living standards have improved since the 1980s, market demand for high-quality wheat has increased rapidly. Therefore, quality improvement has become an important objective for wheat breeding programs across China. Genetic improvement for noodle quality is very important to serve domestic market needs although a lot of effort has been focused on pan bread-making quality. The Chinese Academy of Agricultural Science (CAAS) and the International Maize and Wheat Improvement Center (CIMMYT) have worked together on Chinese wheat quality improvement during the last 10 years and have been especially focused on dry white Chinese noodles (DWCNs) and raw Chinese noodles (RCNs), due to popularity and high commercial values. The objective of this chapter is to review the progress achieved in noodle quality improvement, including establishment of standardized laboratory testing, identification of traits and molecular markers associated with noodle quality, and development of noodle quality varieties.

TABLE 1.2 Percentage of Various Noodles Consumed in China Classification Raw Chinese noodles Instant noodles Dry white Chinese noodles Others Total

Percentage (%) 45 25 20 10 100

Data Source: CAAS/CIMMYT wheat quality laboratory.

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BREEDING NOODLE WHEAT IN CHINA

1.2. NOODLE QUALITY TESTING AND CULTIVAR DEVELOPMENT 1.2.1. Laboratory Preparation Chinese noodles have been consumed over several thousand years across various parts of China, but scientific documentation on noodle quality has been very limited in China until quite recently. A standardized laboratory method for assessing noodle quality is crucial in wheat breeding programs targeted at developing noodle quality varieties. Our experience indicates that DWCNs and RCNs show great similarity in preparation and evaluation although drying is needed for DWCNs. Noodles are mainly made from wheat flour, water, and other ingredients such as common salt. In Chinese languages, noodles made from nonwheat flours, such as rice, mung beans, and sweet potatoes, are named Fen (see Chapter 16 for more details); only noodles made from wheat and buckwheat are named Miantiao.

1.2.1.1. Background Information A bright white color is preferred for Chinese white noodles (CWNs), and flour extraction rates have a significant effect on noodle color but not on noodle texture. Flours with extraction rates of 60–70% are commonly used to produce this type of noodles although, occasionally, a 40% extraction rate is employed to produce very high-quality noodle flour. Noodle properties are significantly affected by the amount of added water in dough preparation. High-quality noodles were prepared within a narrow range of water addition that was ±2 percentage points from optimum (Oh et al. 1985, 1986). Therefore, it is crucial to determine the optimum water additions for different types of wheat varieties in noodle testing programs. However, there are different opinions on optimum water additions for laboratory preparation of CWNs. A 44% water absorption (WA), measured by farinograph, was recommended as the optimum water addition in the official method (SB/T10137-1993) released by the Chinese Ministry of Commerce (1993). Optimum water addition varied among varieties; that is, optimum water addition was 50% WA for high WA varieties (WA ≥ 65%), 55% WA for medium WA varieties (55% < WA < 65%), and 60% WA for low WA varieties (WA ≤ 55%) (Liu et al. 2002). Measurement of WA with the farinograph is a labor- and time-consuming activity and is not a practical laboratory procedure for breeding programs. An optimum water addition of 30–35% of the flour weight was recommended (Zhang et al. 1998); the optimum water addition should be determined by targeting a final dough water content of 35% (Lei et al. 2004). Therefore, much more work is needed to determine the optimum water addition for testing different varieties in breeding programs. Salt was the main additive for DWCNs since it leads to avoidance of strand breakage and improves sensory evaluation scores, particularly for noodles made from low-quality flour. However, salt is not commonly added to RCNs in China. In general, a salty taste is not preferred, and the water after cooking noodles is traditionally served as a drink. Salt is often added in laboratory noodle processing procedures, but the amounts vary greatly, ranging from zero to 2%.

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1.2.1.2. Establishment of Noodle Preparation Formula To establish a standardized noodle preparation formula, the effects of flour extraction rate (50%, 60%, 70%), added water (33%, 35%, 37%), including the moisture available in the flour, and salt concentration (0%, 1%, 2%) on color and texture of RCN were investigated using flour samples from five leading Chinese winter wheat varieties in our laboratory (Ye et al. 2009). Analysis of variance indicated that variety, flour extraction rate, level of water addition, salt concentration, and their interactions all had significant effects on the color of raw noodle sheets and textural properties of RCNs. However, variety and water addition were more important sources of variation than flour extraction rate and salt concentration. The brightness (L*) and redness (a*) values of raw noodle sheets were significantly reduced and increased, respectively, as the flour extraction rate was increased from 50% to 70%, and noodle scores were slightly higher at a flour extraction rate of 50%. Noodle sheet brightness (L*) at 2 hours declined as water addition increased, and a significant improvement was observed for noodle appearance, firmness, viscoelasticity, smoothness, and total score as water addition increased from 33% to 37%, as indicated in Table 1.3 (data from three varieties). However, during noodle preparation, 37% water addition gave excessive absorption in all five flour samples, particularly Zhongyou 9507 and Yumai 18. This resulted in slack doughs that were too extensible to maintain the same thickness of the noodle sheet and resulted in increased problems in noodle sheeting and cutting. Water addition at 35% appeared to produce optimum absorption for Jimai 20, Jimai 21, and Wenmai 6, which is slightly more acceptable than for Zhongyou 9507 and Yumai 18. Therefore, 35% water addition was considered optimal for laboratory preparation of CWNs. Brightness of raw noodle sheets and firmness and viscoelasticity of cooked noodles were significantly improved, but noodle flavor significantly deteriorated as salt concentration increased from zero to 2%; 1% salt produced the highest noodle score, as indicated in Table 1.4 (data from three varieties). Thus, the recommended composition for laboratory preparation of RCNs is 60% flour extraction, 35% water addition, and 1% salt concentration.

1.2.1.3. Noodle Preparation A standardized laboratory noodle preparation protocol was established (Zhang et al. 2005a,b, 2007). Noodle dough was prepared by mixing 200 g flour with enough water to achieve 35% water absorption in a Hobart N50 mixer (Hobart, North York, Canada) for 30 seconds using slow mixing speed (speed position 1 of the mixer). This first mixing step produced dough crumbs that were aggregated by hand-kneading and then mixed for 30 seconds at slow speed, followed by mixing at high speed (speed 2) for 2 minutes and then at slow speed for 2 minutes. The final stiff dough obtained was passed through the sheeting rolls of a laboratory noodle machine (Xongying MT40-1, Hebei, China) and sheeted four times using the 4-mm roll gap setting. The sheeted dough was rested in a plastic bag for 30 minutes at room temperature, and then successively sheeted using 3-mm, 2-mm, and 1-mm roll gap settings. The final dough sheet was cut to produce 3-mm wide and 25-cm long, 1.5-mm thick noodle

6 81.4a 79.6c 80.5b

1.2b 1.6a 1.5a

18.4c 21.6a 20.1b

19.7c 22.6a 21.6b 6.4c 7.0b 7.4a

7.2b 7.6a 7.2b

followed by the different letters are significantly different at P = 0.05.

Data Source: Ye et al. (2009).

a Means

33 35 37

Yumai 18

1.4c 1.6a 1.5b

7.1c 7.6b 8.1a

12.8b 13.8a 13.8a

10.8c 12.6b 14.2a

13.2b 14.2a 14.8a

17.0c 18.9b 19.3a

17.1c 20.1b 22.2a

19.5b 21.6a 21.9a

9.8c 11.1b 12.5a

9.3c 10.8b 12.0a

9.5c 10.8b 11.4a

Smoothness

6.7b 7.1a 7.0a

7.4a 7.5a 7.5a

6.9b 7.3a 7.2a

Flavor

61.0c 66.6b 68.6a

61.3c 68.7b 73.2a

68.1c 73.9b 75.9a

Total Score

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82.4a 81.0c 81.6b

20.6c 23.6b 25.4a

Viscoelasticity

33 35 37

0.4b 0.5a 0.4b

Firmness

Wenmai 6

84.9a 83.8b 83.4c

Appearance

33 35 37

b*2 h

Jimai 20

a*2 h

Water (%)

Variety

L*2 h

Effect of Water Addition on Raw Noodle Sheet Color Sensory Parameters of Raw Chinese Noodlesa

TABLE 1.3

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80.0b 80.7a 80.7a

1.4a 1.4a 1.4a

20.5a 19.8b 19.7b

6.7b 7.0ab 7.1a

7.2a 7.5a 7.4a

followed by different letters are significantly different at P = 0.05.

Data Source: Ye et al. (2009).

a Means

0 1 2

21.5a 21.3a 21.0a 13.2b 13.4b 14.0a

13.8a 13.6a 14.2a

13.6b 14.2ab 14.4a

18.4a 18.3a 18.4a

19.2a 19.8a 20.1a

20.4b 21.9a 20.7b

11.0a 11.1a 11.1a

10.7a 10.8a 10.7a

10.6a 10.6a 10.4a

6.8b 7.1a 6.9b

7.6a 7.6a 7.3b

7.2a 7.2a 6.9b

Flavor

Yumai 18

1.7a 1.6b 1.5ab

7.4b 7.7a 7.7a

Smoothness

64.0c 65.4b 66.6a

67.0b 68.5a 67.7ab

71.2c 74.1a 72.6b

Total Score

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81.3b 81.8a 81.8a

24.0a 23.1b 22.6c

Viscoelasticity

0 1 2

0.5a 0.5a 0.5a

Firmness

Wenmai 6

83.7c 84.1b 84.3a

Appearance

0 1 2

b*2 h

Jimai 20

a*2 h

Salt (%)

Variety

L*2 h

Effect of Salt Concentration on Raw Noodle Sheet Color and Sensory Parameters of Chinese White Noodlesa

TABLE 1.4

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strips. Raw noodle strips (150 g) were boiled for 6 minutes in 2 L of boiling water. After boiling, the noodles were rinsed by hand under running tap water for 1 minute. Drying is needed for DWCNs, and the raw fresh noodles were kept in a chamber for 10 hours at 40 ◦ C and 75% relative humidity, and then dried another 10 hours at laboratory room conditions. DWCN strips (150 g) were boiled for 12 minutes in 2 L of boiling water. 1.2.2. Sensory Evaluation of Chinese White Noodles Desirable attributes of cooked Chinese white noodles include white and bright color, smooth appearance, medium level of firmness, good viscoelasticity (resistance to bite and not sticking to teeth), and smooth feel in the mouth, with a pleasant taste and flavor. Chinese white noodles differ from Japanese udon noodles in several aspects. Color is not as white and creamy as udon, indicating a difference in ash content and protein content. Chinese noodles are firmer than udon, indicating a difference in gluten and starch composition. They are more elastic and chewy than udon, also indicating a difference in gluten and starch composition. Although the official method for the sensory evaluation of DWCNs (SB/T101371993, Chinese Ministry of Commerce, 1993) was released in 1993, it needs a lot of improvement. The scoring system (Table 1.5) has three problems. First, most panels have difficulty in evaluating elasticity and stickiness separately since the system definitions of elasticity (elastic and cohesive when chewed) and stickiness (noodles should not stick to teeth when chewed) lead the panels to evaluate similar characteristics. Our unpublished data indicated that the correlation coefficient between elasticity and stickiness ranges from 0.70 to 0.85 in various experiments. Second, the elasticity and stickiness parameters are each assigned 25 points, the highest score given to an individual noodle trait. This seems too high, especially considering the difficulty of

TABLE 1.5

Scoring System for White Salted Noodles in Various Countriesa

Parameter Color Appearance Palate Elasticity Stickiness Firmness Viscoelasticity Smoothness Taste and flavor Total a Dash

Japan (1998)

BRI

New Chinese System

SB/T10137-1993

20 15 — — — 10 25 15 15 100

Minolta — — — — 10 30 10 — 50

15 10 — — — 20 30 15 10 100

10 10 20 25 25 — — 5 5 100

(—) indicates that parameter is not included. Data Source: Zhang et al. (2005b).

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evaluating the two traits separately, as defined above. Third, no reference sample was employed to evaluate the score for a testing sample, and score inconsistency occurred even when the panelists were well trained. Therefore, we adopted the evaluation system used in Japan and other Asian countries for white salted noodles, with major modifications in the score assigned to each noodle trait, as shown in Table 1.5 (Zhang et al. 2005b). In this method, evaluation of elasticity and stickiness was combined into viscoelasticity. The weight given to each noodle trait was modified according to differences in consumer preferences for noodle attributes in China versus consumer preferences in Japan. Color was assigned a higher score (15) than in the previous Chinese method (10) but lower than in the Japanese method (20). The score assigned to appearance (10) was also lower than that in the Japanese method (15), because this parameter is less important for evaluating noodle quality in China. The score given to viscoelasticity (30) was lower than the combined value (25 + 25) assigned to elasticity and stickiness in the previous Chinese method. The score given to smoothness (15) was higher than in the previous method (5), because Chinese consumers believe the sensory mouthfeel, including smoothness and viscoelasticity, is essential for evaluating RCN quality. In addition to panel testing, other approaches were used to measure noodle parameters. The color of cooked noodles was closely associated with measurement by the Minolta CR 310, with r = 0.73. Hardness of texture profile analysis (TPA) using a Texture Analyzer was significantly associated with noodle total score, with r = 0.66 (Lei et al. 2004). To improve consistency among panel members, a new scoring method was developed and presented in Table 1.6. In this method, each attribute was classified into seven classes (i.e., excellent, very good, good, fair, poor, very poor, and unacceptable), and a score was assigned to each class based on comparison with a reference sample at each panel session. A well-known commercial Xuehua flour, with 5% sweet potato starch added to it, showed a relatively good and stable noodle quality and each attribute had a good score. This flour blend was used as a reference sample in our evaluation. Panelists compared six parameters (i.e., color, appearance, firmness, smoothness, viscoelasticity, and taste–flavor) and assigned a score to each. To adapt to standard Chinese noodle-consumption style, noodles were evaluated using hot Chinese chicken soup prepared by dissolving two 10.5-g solid soup tablets (Knorr Co. Ltd.) in 1 L of hot water. 1.2.3. Traits and Molecular Markers for Noodle Quality

1.2.3.1. Characterization of Chinese Wheat for Quality Traits As can be seen in Table 1.7, Chinese wheat varieties and lines, on average, are characterized by acceptable protein content, but accompanied with weak medium gluten strength and poor extensibility, and substantial variation is presented for all quality traits. This is not unexpected since no selection was made on quality performance before the 1990s. Even at present, quality testing is only employed in the leading breeding programs. It is estimated that great progress could be achieved through breeding for DWCN quality given the wide variation of quality characteristics present in Chinese varieties and experimental germplasm.

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TABLE 1.6

Sensory Scoring System for Chinese Noodle Quality

Name

Locality Excellent

Data Very good Good

Sample No. Fair

Poor

Very poor Unacceptable

Color (20)

20

18

16

14

12

10

8

Appearance (10)

10

9

8

7

6

5

4

Firmness (10)

10

9

8

7

6

5

4

Viscoelasticity (30)

30

27

24

21

18

15

12

Smoothness (20)

20

18

16

14

12

10

8

Tasteand flavor (10)

10

9

8

7

6

5

4

100

90

80

70

60

50

40

Total (100) Comprehensive evaluation Comments Data Source: CAAS/CIMMYT wheat quality laboratory.

TABLE 1.7 Mean, Standard Deviation, and Range of Grain Quality Traits for 104 Wheat Varieties Based on Averaged Data from Two Years and Two Locations Trait

Mean

Standard Deviation

Range

Thousand kernel weight (g) Test weight (kg/hL) Hardness Whiteness Flour protein (14% mb) Zeleny sedimentation (mL) Water absorption (%) Development (min) Stability time (min) Mixing tolerance index (BU) Softening (BU) Extensibility (cm) Resistance (BU) Extension area (cm2 ) RVA viscosity (cp) Falling number (seconds)

39.2 78.7 61.3 74.8 11.3 36.3 61.4 3.7 6.6 53.2 95.8 17.5 274.9 84.7 2777 388

4.43 17.23 21.20 4.65 0.78 9.55 3.32 2.21 5.04 26.83 42.66 2.21 111.79 41.03 335.80 47.84

29.5–51.3 73.6–82.3 16–111 54.8–82.2 9.6–13.3 16.9–59.2 53.6–71.4 1.6–15.3 1.9–24.0 6.0–139.0 9.0–208.3 11.0–23.9 110.3–751.5 24.5–233.1 1596–3425 290–516

Data Source: Liu et al. (2003).

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TABLE 1.8 Mean, Standard Deviation, and Range for Cooked Noodle Quality Performance of 104 Wheat Varieties Based on Averaged Data from Two Years and Two Locations Parameter a

Color (10) Appearance (10) Palate (20) Elasticity (25) Stickiness (25) Smoothness (5) Taste (5) Total score (100)

Mean

Standard Deviation

Range

8.4 8.5 15.5 18.3 19.4 4.2 4.3 78.6

0.98 0.85 1.64 2.63 1.84 0.40 0.40 6.59

5.0–9.9 5.0–9.9 10.7–19.5 11.0–24.5 15.0–23.5 3.0–5.0 2.5–5.0 56.0–95.0

a Indicates

full score. Data Source: Liu et al. (2003).

The mean, standard deviation, and range of DWCN quality parameters for 104 varieties and experimental lines, averaged from four growing environments, are presented in Table 1.8. As shown, there is wide variation in all noodle quality parameters, which most likely reflects the large variability in grain quality parameters of test materials. Thus, there is much room for improving the DWCN quality of Chinese wheats.

1.2.3.2. Traits Associated with Noodle Quality A large number of varieties from different parts of China, Mexico, and Australia were used to establish the association between flour traits and noodle quality performance (Chen et al. 2007; He et al. 2004; Liu et al. 2003; Zhang et al. 2005a,b). In general, flour from medium-hard to hard wheat with low ash content, high flour whiteness, medium protein content, medium to strong gluten type, and good starch viscosity is considered suitable for making Chinese noodles. Major traits associated with DWCN quality were identified (i.e., gluten strength and extensibility, starch viscosity, and flour color associated traits), as presented in Table 1.9. The association between SDS–sedimentation value, farinograph stability, and extensograph maximum resistance, extension area, and DWCN score fitted a quadratic regression model, accounting for 31.0%, 39.0%, 47.0%, and 37.0% of the DWCN score, respectively (Table 1.10) (He et al. 2004). The starch peak viscosity contributed positively to DWCN quality, with r = 0.57 (Figure 1.2). Flour ash content and PPO had a negative moderate effect on noodle color (Figure 1.3), while protein content and grain hardness were negatively associated with noodle color, appearance, and smoothness (Zhang et al. 2005b). There was a very high association between flour color grade (FCG) and L* value of flour–water slurry (r = −0.95) (Figure 1.4). Strong associations were also established between milling quality index (MQI) and FCG, L* values of dry flour, flour–water slurry, and white salted noodle sheet (Zhang et al. 2005a). Therefore, FCG can be used to predict noodle sheet color. To summarize,

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TABLE 1.9

Noodle Quality Groups and Their Mean Wheat Quality Characteristics Noodle Qualitya

Quality Parameter Variety (No.) Hardness Whiteness Protein content (%) Zeleny sedimentation (mL) Water absorption (%) Stability (min) Mixing tolerance index (BU) Softening (BU) Extensibility (cm) Extension area (cm2 ) Resistance (BU) Peak viscosity (cP)

Excellent

Acceptable

Poor

14 56.6a 76.4a 11.5a 41.4a 59.9a 10.0a 31a 57a 18.1a 112.8a 471a 3116a

64 60.7a 75.5a 11.3a 37.5a 61.2a 6.8b 52b 94b 17.9ab 86.4b 349b 2794b

26 65.1a 72.4b 11.2a 30.5b 62.7b 4.2c 68c 122c 16.4b 67.2c 311b 2600c

followed by different letters are significantly different (P < 0.05). Data Source: Liu et al. (2003).

a Figures

SDS–sedimentation value or mixing time from mixograph, RVA peak viscosity or flour swelling volume, polyphenol oxidase (PPO) activity, and yellow pigment content can be used to screen for DWCN quality in the early generations of a wheat breeding program.

1.2.3.3. Molecular Markers Associated with Noodle Quality Molecular markers have great potential to improve breeding efficiency if they can be combined with quality testing and conventional breeding technology. In addition to validating molecular makers from other programs around the world, we have started an active molecular marker development program for noodle quality improvement. Our approach is to clone genes, such as Psy 1 genes, on chromosomes 7A and 7B that are associated with yellow pigment and PPO genes at chromosomes 2A and 2D, develop functional markers based on the gene allelic variants, and then validate the TABLE 1.10 Quadratic Regression Model Between DWCN Score and Four Grain Quality Traits Grain Trait SDS–sedimentation value (mL) Stability (min) Maximum resistance (BU) Extension area (cm2 ) Data Source: He et al. (2004).

Equation Y Y Y Y

= 45.59 + 3.2050X − 0.0656X 2 = 71.09 + 1.8220X − 0.0521X 2 = 61.12 + 0.3817X − 0.0015X 2 = −64.81 + 0.0852X − 0.0001X 2

Maximum Point

R2

24.2 17.5 129 508

0.31 0.39 0.47 0.37

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95 90

DWCN score

85 80 75 70 65 60 55 150

200 250 Peak viscosity (RVU)

300

FIGURE 1.2 Association between RVA peak viscosity and DWCN score. (Data source: He et al. 2004.)

markers with Chinese wheat varieties. Therefore, molecular markers developed in our program can be used efficiently in breeding programs. Molecular and biochemical markers, such as Pinb-D1b (grain hardness), PPO 18, PPO 16, and PPO 29 (PPO activity), Psy-7A and Psy-7B (yellow pigment), Glu-A3d and Glu-B3d (gluten quality), and Wx-B1b (starch viscosity), are closely associated with noodle quality as presented in Table 1.11 (Briney et al. 1998;

15

Color

10

5

0 0.4

0.5

0.6

0.7

0.8

0.9

Flour ash (%)

FIGURE 1.3 et al. 2005.)

Association between flour ash content and noodle color. (Data source: Zhang

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L* value of flour–water slurry

80.0 79.5 79.0 78.5 78.0

r = – 0.95

77.5 77.0 0.0

1.0

2.0

3.0

4.0

5.0

Flour color grade

FIGURE 1.4 Relationship between flour color grade and L* value of flour–water slurry. (Data source: Zhang et al. 2005.)

Chen et al. 2007; He et al. 2005, 2007, 2008, 2009; Sun et al. 2005). Use of these molecular markers can greatly improve the selection efficiency in early generations, and they can also be used to confirm the results from conventional quality testing in more advanced stages.

1.3. BREEDING FOR BETTER NOODLE QUALITY A regional quality classification was released in 2002, based on the climate date (temperature/rainfall), soil type/farming system/ use of fertilizers, and quality data collected in China for the last 15 years (He et al. 2002). In general, three regions are recognized. (1) Winter and facultative wheat regions (including Zones I and II)

TABLE 1.11

Molecular Markers for Selection of Desirable Chinese Noodle Qualities

Marker

Type

Trait

Reference

Glu-A3d Glu-B3d Wx-4A PPO 18 PPO 16 PPO 29 Psy-7A Psy-7B Pinb-D1b

Protein Protein STS STS STS STS STS STS STS

Protein quality Protein quality Starch viscosity Bright color Bright color Bright color Bright color Bright color Texture

He et al., 2005 He et al., 2005 Briney et al., 1998 Sun et al., 2005 He et al., 2007 He et al., 2007 He et al., 2008 He et al., 2008 Chen et al., 2007

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(see Figure 1.1) focus on hard white and medium-hard types, targeting for bread, noodle, and steamed bread qualities. (2) Autumn-sown spring wheat regions (including Zones III, IV, and V) focus on red soft wheat; however, red medium-hard types for steamed bread and noodles quality are also recommended. Sprouting tolerance is needed due to the high rainfall environment. (3) Spring-sown spring wheat regions (including Zone VI, VII, and VIII) focus on red hard and medium-hard types, targeting bread, steamed bread, and noodles. Sprouting tolerance is also needed to ensure processing quality. Breeding efforts in quality improvement started in the late 1980s and quality testing laboratories have been established in Beijing, Jinan, Zhengzhou, Yangling, and Harbin. The objectives of wheat quality improvement programs are to combine the high yielding potential and excellent processing quality. As stated previously, Chinese wheat is characterized by broad variation for all quality parameters; it has acceptable protein content but weak gluten strength, thus acceptable quality for manual production but inferior quality for mechanized production. Therefore, improvement in gluten strength was the primary objective for all products, including pan bread, noodles, and steamed bread although color is also important for noodles and steamed bread. Two approaches were employed to improve noodle quality. First, significant effort was put into screening current varieties and advanced lines to identify noodle varieties for production. Second, Chinese varieties with outstanding noodle quality or introductions from the United States, Canada, Australia, and CIMMYT are crossed with high-yielding Chinese wheats to develop new varieties with improved noodle quality. In addition to the final noodle testing, a number of analyses are employed to select for desirable noodle quality at various stages: gluten strength parameters (high molecular weight gluten subunit composition, absence of 1B/1R translocation, SDS or Zeleny sedimentation volume, and farinograph stability time), starch parameters (flour swelling volume and Rapid Visco Analyzer peak viscosity), biochemical and molecular markers for Wx-B1 null, and flour color parameters (PPO activity or yellow pigment). At present, breeding programs that target noodle quality improvement include the Chinese Academy of Agricultural Science (CAAS, Beijing), Shandong Academy of Agricultural Science (Jinan), Shandong Agricultural University (Taian), and Henan Academy of Agricultural Science (Zhengzhou). All four of these programs are located in winter and facultative wheat regions although efforts are also being put toward noodle quality improvement in other regions. Progress on breeding better quality wheat has been reviewed in Chinese Wheat Improvement and Pedigree Analysis (Zhuang 2003). Varieties conferring improved noodle quality, based on the information from breeding programs, uniform quality testing nurseries managed by our own lab, and feedback from milling industries are listed in Table 1.12, and detailed information is presented below. Jing 9428, a soft kernel variety derived from Jing 411/German introduction, was released by the Beijing Seed Company in 2000. It was characterized by soft kernel, medium gluten strength, and very bright white flour and noodle color, thus resulting in outstanding noodle and dumpling quality. Its yield was close to the control variety Jing 411, but with big kernel size (thousand kernel weight 45 g) and red color, it has

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TABLE 1.12

List of Noodle Quality Varieties Released in China

Variety

Pedigree

Jing 9428 Zhongyou 9507 Yannong 15 Jimai 19 Jimai 20 Yumai 34

Jing411/German introduction Reselection of Zhongzuo 8131-1 Baiyoubao/St2422/464 Lumai 13/Linfen 5064 Lumai 14/Shandong 84187 Aifeng 3//Meng 201/Neuzucht/3/ Yumai 2 Yumai 2/Baiquan 3199 Wen 394A/Yumai 2 St2422/464/Xiaoyan 96 Sonora 64/Hongtu

Yumai 47 Yumai 49 Xiaoyan 6 Ningchun 4

Release Year

Adopted Province

2000 2001 1980 2001 2003 1994

Beijing, Hebei Beijing, Shanxi Shandong Shandong, Jiangsu Shandong, Anhui Henan

1997 1998 1981 1981

Henan Henan Shaanxi Zone VIII

good sprouting tolerance. It has been a leading variety in Zone I (including Beijing, Tianjin, northern Hebei, and Shanxi) from 2000 to the present, with annual acreage of 130,000 ha, sharing 20% of the wheat area. Zhongyou 9507, a reselection of outstanding pan bread quality variety Zhongzou 8131-1, was released by the Chinese Academy of Agricultural Science in 2001. It was characterized by high protein content, strong gluten quality, and very bright flour and noodle color, and thus had outstanding pan bread and noodle quality. Its yield was close to control variety Jingdong 8, with big kernel size (thousand kernel weight 45 g), good resistance to stripe rust and powdery mildew, and tolerance to high temperatures. It was released in Beijing, Tianjin, Hebei, Shanxi, and Xinjiang, with annual acreage of 60,000 ha. Its popularity was limited by the susceptibility to preharvest sprouting. It is interesting to observe that Zhongyou 9507 was originally a mixture of hard and soft kernels although the majority of kernels were hard type; then during seed production, the soft kernel became a dominant type. Reselections were made; thus, both hard and soft types were obtained. Xiaoyan 6, a hard kernel variety, derived from St2422/464 crossed with Xiaoyan 96 following a laser treatment, was released by the Northwestern Botany Research Institute in 1980. It was characterized by high yield potential and wide adaptability, resistance to yellow rust, and tolerance to high temperatures. It was a leading variety in central Shaanxi for around 10 years in the 1980s, with an annual sowing area of 400,000 ha. In the late 1980s, it was identified as carrying good noodle and steamed bread qualities since it had medium gluten quality with excellent extensibility and bright white flour color. It also performed with good bread-making quality under a high-protein environment. It was recommended as an excellent quality variety in the 1990s. Xiaoyan 6 was widely used in breeding programs for quality improvement. PH-82-2, a reselection of Xiaoyan 6, was released in Shandong province in the early 1990s. Xiaoyan 54, another reselection of Xiaoyan 6, was released in Shaanxi province in 2000. All three cultivars performed with similar processing quality even though they were sown in different provinces.

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Yannong 15, a soft kernel variety derived from St2422/464 crossed with Baiyoubao, was released by the Yantai Agricultural Research Institute in 1980. It was characterized by high yield potential and good lodging resistance and was identified as carrying good qualities for pan bread, noodles, and steamed bread due to its medium dough strength with excellent extensibility and bright white flour color. It has had an annual acreage of 130,000 ha from the 1980s to the present and was also recommended as a good quality variety in the 1990s. It was widely used to make noodle flour in Shandong province. Jimai 19, a hard kernel variety derived from Lumai 13/Linfen 5064, was released by the Shandong Academy of Agricultural Sciences in 2001. It was characterized by high yield potential (7% better than the control variety) and excellent noodle quality. It has medium gluten strength, and excellent flour and noodle color. It has been a leading variety in Shandong province since 2002 with more than 800,000 ha per year. It was also sown in the provinces of Jiangsu, Anhui, Henan, and Hebei. Jimai 20, a hard kernel variety, was derived from Lumai 14/Shandong 84187 by the Shandong Academy of Agricultural Science in 2003. It was characterized by strong gluten strength and excellent noodle color, thus conferring qualities for pan bread and noodles. It combined high yield potential, outstanding and consistent quality over various environments, and broad adaptation. It is a leading quality variety in the provinces of Shandong, Hebei, Jiangsu, and Anhui, with annual acreage of 1 million ha in 2008. Yumai 34, a hard kernel variety, derived from Aifeng 3//Meng 201/Neuzucht/3/ Yumai 2, was released by the Zhengzhou Agricultural Research Institute in 1994. It was characterized by balanced dough properties and excellent flour and noodle color, thus conferring excellent qualities for pan bread and noodles. Yumai 34 combined high yield potential with 3.2% higher yield than control variety Yumai 18, outstanding and consistent quality over various environments, and broad adaptation. It has been a leading quality variety in Henan province since 1998, with annual acreage of 500,000 ha per year. Yumai 47, a hard kernel variety derived from Yumai 2/Baiquan 3199, was released by the Henan Academy of Agricultural Science in 1997. It was characterized by medium to strong gluten strength, high starch viscosity, and bright white flour, thus conferring good noodle and pan bread qualities. Its yield was close to control variety Yumai 18, and it shows good resistance to powdery mildew. It has been extended as a good quality variety in Henan province from 2000 to the present, with annual acreage of 200,000 ha per year. Yumai 49, a soft kernel variety derived from Wen 394A/Yumai 2, was released by the Xiangyun Agricultural Extension Station in 1998. It was characterized by high yield potential and good qualities for noodles and steamed bread largely due to its bright white product and slightly better gluten strength. It was a leading variety in the late 1990s in Henan province, with annual acreage of 670,000 ha per year. Ningchun 4, a soft kernel variety derived from Sonora 64/Hongtu, was released by the Wheat Seed Production Station of Yongning County in Ningxia in 1981. It was characterized by high yield potential, good resistance to biotic and abiotic stresses, and broad adaptation. It was well known for its excellent noodle quality

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due to medium gluten strength and bright white color. At present, its commercial grain is widely used to produce the well-known Xuehua flour in Ningxia and Inner Mongolia. It has been the leading variety in the Northwestern Spring Wheat Zone covering Gansu, Ningxia, and parts of Inner Mongolia and Xinjiang from 1983 to the present, with the largest annual sowing acreage of 300,000 ha.

1.4. THE FUTURE The improvement in grain yield has always been the top priority for Chinese wheat breeding programs, largely due to high population pressure. However, processing quality has become more and more important since the late 1990s, and farmers are unlikely to accept varieties conferring poor processing quality. Therefore, high grain yield and excellent industrial quality must be combined into new varieties, together with broad adaptation and resistance to various biotic and abiotic stresses. It is quite possible to combine high yield potential with excellent noodle quality, as exemplified by Jimai 19 and Yumai 34, since a medium level of protein content is needed to produce high-quality noodles. Although significant progress has been achieved in developing noodle varieties, there is still a long way to go to improve the overall noodle quality of Chinese varieties. Three approaches were recommended for improving noodle quality in the future. First, noodle quality testing should be included as part of the variety development and release procedure; thus, varieties conferring outstanding noodle quality can be released. At present, only advanced lines with high yield potential are evaluated for end-use quality in most breeding programs. Strong gluten wheat for bread-making quality receives prime consideration in variety release, and it is acceptable if the yield reduction is less than 5% compared to the control variety. To promote noodle quality varieties, we suggest that varieties conferring outstanding noodle quality should be released if the yield performance is equivalent to the control variety. Second, improvement of dough extensibility and starch viscosity is crucial for noodle quality breeding although dough strength and color are also important. Based on the quality data from six environments as presented in Table 1.13, the Australian varieties Hartog and Sunstate, which have excellent dough extensibility, had better noodle quality than the best noodle quality varieties from China. Priority has been given to improve dough strength since the beginning of the quality improvement program, and has thus resulted in improved quality wheat with unbalanced dough properties. Therefore, much more work is needed in the future to improve dough extensibility. It has been determined that starch viscosity is crucial for Chinese noodles; however, the frequency of Wx-B1 null type is very low in Chinese wheat, as presented in Table 1.14. Among the noodle varieties listed in Table 1.13, only Yumai 47 confers Wx-B1 null type. Therefore, integration of desirable genes into current varieties is needed, and both biochemical and molecular markers can play an important role in this area. Third, the possibility of developing soft wheat varieties with medium to strong gluten quality for noodle quality should be explored. This type of germplasm is

11.5 5.2 3.8 7.4 4.7 9.0 9.4 7.0

171 194 214 189 164 165 200 193

8.4 8.9 8.2 8.2 9.9 10.4 9.8 9.3

6.7 6.9 6.9 6.6 6.8 6.7 6.9 7.1

Appearance

a FPC

= flour protein content, Stab = Farinograph stability, Ext = Extensograph extensibility. Data Source: Unpublished data, CAAS/CIMMYT Quality Laboratory, 2005.

11.8 11.9 13.1 12.9 11.0 11.4 11.8 12.4

Color 12.5 12.4 12.3 12.7 12.8 12.9 12.7 13.0

Firmness 18.3 20.6 16.9 18.6 17.3 18.1 21.1 19.9

Viscoelasticity

9.1 9.6 8.5 8.6 9.1 9.3 9.7 9.6

Smoothness

7.0 7.1 6.7 6.8 7.2 7.2 7.2 7.1

Flavor

62.0 65.6 59.5 61.5 63.0 64.2 67.4 66.1

Total Score

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Yumai 34 Yumai 47 Xiaoyan 54 PH82-2-2 Jimai 19 Jimai 20 Hartog Sunstate

Exta (mm)

FPCa (%)

Variety

Staba (min)

Quality Performance of Selected Noodle Varieties, Averaged Data From Six Environments

TABLE 1.13

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TABLE 1.14 Distribution of Wx-B1 Null Genotypes in Different Chinese Wheat Regions Regiona

Variety Number

Number of Wx-B1 Null (%)

Zone I

69

8 (11.6%)

Zone II

131

15 (11.5%)

Zone III

34

5 (14.7%)

Zone IV

26

11 (42.3%)

260

39 (15.0%)

Total

Variety with Wx-B1 Null Fengkang 8, Yuandong 971, Yuandong 8585, Jingnong 8318, Jingdong 6, Jingdong 8, Jinmai 215, Jinmai 218 Ji 5219, Ji 95-6023, Sanghe 030, Zhongyu 5, 85 Zhong 33, Guanfeng 2, Yumai 47, Lu 94 (6) 006, Lu 9436, Yan 239, Yannong 18, Jining 936898, Shaan 160, Shaan 93302, Xinong 8925-13 Ning 98084, Yang 96-152, Yang 97-65, Yangmai 5, Yangmai 9 Chuanmai 107, Chuan 89-114, Chuan 96003, Chuanmai 24, Mianyang 11, Mianyang 20, Mianyang 26, Mianyang 940112, Mianyang 98-17, Yunmai 42, Y10-8

a Zone I = North China Plain Winter Wheat Region, Zone II = Yellow and Huai Valleys Facultative Wheat Region, Zone III = Autumn-Sown Spring Wheat in the Mid- and Lower Yangtze Valley, Zone IV = Southwestern Autumn-Sown Spring Wheat Region.

not uncommon in China, but is not available in countries with a long history of wheat quality improvement. Soft wheat with stronger gluten and exceptionally good brightness received very favorable evaluations by Asian noodle and mill technicians (Morris 1998), and this has been confirmed in China. Our data from two environments, as presented in Table 1.15, indicates that it is possible to develop such a variety type since the noodle quality of Eradu and Gamenya was highly preferred by Chinese consumers. As indicated in Table 1.13, Jing 9428, Yannong 15, Yumai 49, and Ningchun 4 belong to this type. Therefore, development of a variety with soft kernel wheat, medium to strong gluten strength, and good bright color could become an important objective for noodle quality improvement. 1.5. SUMMARY Quality improvement has become a very important breeding objective in China and significant progress in noodle quality improvement has been achieved in the last 10 years. A standardized laboratory preparation and evaluation system for Chinese noodle quality has been established. The recommended composition for laboratory preparation of Chinese noodles is 60% flour extraction, 35% water addition, and 1% salt concentration. A modified scoring system and sensory scoring method were developed and employed, and consistency of noodle quality testing is much improved. The major traits conditioning Chinese noodle quality include gluten strength and

12.3 10.6 13.1 11.6 11.4 11.8 10.9

Eradu Gamenya Zhongyou 9507 Guanfeng 2 Yumai 49 Zheng 81-1 Yangmai 5

17.9 21.1 16.9 20.1 16.8 17.0 16.9

FSVa (mL/g) 57.0 52.4 56.0 56.8 54.1 54.3 55.0

WAa (%) 5.1 5.4 8.7 20.8 6.4 8.7 6.8

Stability (min) 9.2 8.8 8.4 8.0 8.0 8.3 7.9

Firmnessb 12.3 13.1 11.6 12.1 11.2 11.1 11.1

Smoothnessb

b Noodle

a FPC

18.3 18.6 16.6 18.1 15.4 15.8 15.8

Viscoelasticityb

39.8 40.5 36.6 38.2 34.6 35.2 34.8

Total Score

10:9

= flour protein content, FSV = flour swelling volume, WA = farinograph water absorption. texture includes firmness, smoothness, and viscoelasticity, with highest score of 10, 15, and 20, respectively. Data Source: Unpublished data from CAAS/BRI, 2005.

FPCa

Quality Performance of Selected Soft Kernel Varieties, Averaged Data from Two Environments

Cultivar

TABLE 1.15

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extensibility, starch viscosity, yellow pigment, PPO activity, grain hardness, and protein content. SDS–sedimentation value, RVA peak viscosity, yellow pigment content, and PPO activity can be used as selection criteria in early generations. PPO genes at chromosomes 2A and 2D and Psy 1 genes at chromosomes 7A and 7B were cloned and STS markers were developed and validated, that is, Psy-7A and Psy-7B for yellow pigment, and PPO 18, PPO 16, and PPO 29 for PPO activity. Molecular markers for starch viscosity (Wx-B1 null) and grain hardness (Pinb-D1b) were also validated in Chinese wheats. Glu-A3d and Glu-B3d show slightly better noodle quality than the other alleles. Both conventional and molecular approaches have been employed in noodle quality improvement, and ten noodle quality varieties, such as Jimai 19, Jimai 20, Yumai 34, Xiaoyan 6, and Ningchun 4, were developed and extended as leading varieties. A combination of high yield potential with noodle quality is the key for successful varieties development. Three approaches were recommended for noodle quality improvement in the future: i.e. (1) integrating noodle quality testing into variety development and release procedures, (2) improving dough extensibility and starch viscosity, and (3) exploring the possibility of developing soft wheat varieties with medium to strong gluten quality for noodle quality.

REFERENCES Briney, A., Wilson, R., Potter, R. H., Barclay, I., Crosbie, G., Appels, R., and Jones, M. G. K. A. 1998. PCR marker for selection of starch and potential noodle quality in wheat. Mol. Breeding 4: 427–433. Chen, F., He, Z. H., Chen, D. S., Zhang, C. L., Zhang, Y., and Xia, X. C. 2007. Influence of puroindoline alleles on milling performance and qualities of Chinese noodles, steamed bread and pan bread in spring wheats. J. Cereal Sci. 45: 59–66. Chinese Ministry of Commerce. 1993. Noodle flour, SB/T10137-1993. He, Z. H., Rajaram, S., Xin, Z. Y., and Huang, G. Z. (eds). 2001. A History of Wheat Breeding in China. CIMMYT, Mexico, D. F., pp. 1–95. He, Z. H., Lin, Z. J., Wang, L. J., Xiao, Z. M., Wan, F. S., and Zhuang, Q. S. 2002. Classification on Chinese wheat regions based on quality performance. Sci. Agric. Sinica 35(4): 359–364 (in Chinese). He, Z. H., Yang, J., Zhang, Y., Kuail, K. J., and Pena, R. J. 2004. Pan bread and dry white Chinese noodle quality in Chinese winter wheats. Euphytica 139: 257–267. He, Z. H., Liu, L., Xia, X. C., Liu, J. J., and Pena, R. J. 2005. Composition of HMW and LMW glutenin subunits and their effects on dough properties, pan bread, and noodle quality of Chinese bread wheats. Cereal Chem. 82: 345–350. He, X. Y., He, Z. H., Zhang, L. P., Sun, D. J., Morris, C. F., Furerst, E. P., and Xia, X. C. 2007. Allelic variation of polyphenol oxidase (PPO) genes located on chromosomes 2A and 2D and development of functional markers for the PPO genes in common wheat. TAG 115: 47–58. He, X. Y., Zhang, W. L., He, Z. H., Wu, Y. P., Xiao, Y. G., Ma, C. X., and Xia, X. C. 2008. Characterization of phytoene synthase 1 gene (Psy 1) located on common wheat chromosome 7A and development of a functional marker. TAG 116: 213–221.

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He, X. Y., He, Z. H., Ma, W., Appels, R., and Xia, X. C. 2009. Allelic variants of PSY1 genes in Chinese and CIMMYT wheat cultivars and development of functional markers. Mol. Breeding 23: 553–563. Lei, J., Zhang, Y., Wang, D. S., Yan, J., and He, Z. H. 2004. Methods for evaluation of quality characteristics of dry white Chinese noodles. Sci. Agric. Sinica 37: 2000–2005 (in Chinese). Liu, J. J., He, Z. H., Zhao, Z. D., Liu, A. F., Song, J. M., and Pena, R. J. 2002. Investigation on relationship between wheat quality traits and quality parameters of dry white Chinese noodles. Acta Agron Sin 28: 738–742 (in Chinese). Liu, J. J., He, Z. H., Zhao, Z. D., Pena, R. J., and Rajaram, S. 2003. Wheat quality traits and quality parameters of cooked dry white Chinese noodles. Euphytica 131: 147–154. Morris, C. F. 1998. Evaluating the end-use quality of wheat breeding lines for suitability in Asia noodles. In: A. B. Blakeney and L. O’Brien (eds.), Pacific People and Their Food. American Association of Cereal Chemists, St. Paul, MN, USA, pp. 91–100. Oh, N. H., Seib, P. A., Ward, A. B., and Deyoe, C. W. 1985. Noodles IV. Influence of flour protein, extraction rate, and particle size, and starch damage on the quality characteristics of dry noodles. Cereal Chem. 62: 441–446. Oh, N. H., Seib, P. A., Finney, K. F., and Pomeranz, Y. 1986. Noodles V. Determination of optimistic water absorption of flour to prepare oriental noodles. Cereal Chem. 63: 93–96. Sun, D. J., He, Z. H., Xia, X. C., Zhang, L. P., Morris, C., Appels, R., Ma, W., and Wang, H. 2005. A novel STS marker for polyphenol oxidase activities in bread wheat. Mol. Breeding 16: 209–218. Ye, Y. L., Zhang, Y., Yan, J., Zhang, Y., He, Z. H., Huang, S. D., and Quail, K. J. 2009. Effects of flour extraction rate, added water and salt on color and texture of Chinese white noodles. Cereal Chem. 86: 477–485. Zhang, L., Wang, X. Z., and Yue, Y. S. 1998. TOM being a new assessment method for Chinese noodle cooking quality and effects of wheat quality characteristics on it. J. Chinese Cereals Oils Assoc. 13(1): 49–53 (in Chinese). Zhuang, Q. S. (ed.) 2003. Chinese Wheat Improvement and Pedigree Analysis. China Agricultural Press, Beijing, China (in Chinese). Zhang, Y., Kuail, K. J., Mugford, D. C., and He, Z. H. 2005a. Milling quality and white salt noodle color of Chinese winter wheat cultivars. Cereal Chem. 82: 633–638. Zhang, Y., Nagamine, T., He, Z. H., Ge, X. X., Yoshida, H., and Pena, R. J. 2005b. Variation in quality traits in common wheat as related to Chinese fresh white noodle quality. Euphytica 141: 113–120. Zhang, Y., Yan, J., Yoshida, H., Wang, D. S., Chen, D. S., Nagamine, T., Liu, J. J., and He, Z. H. 2007. Standardization of laboratory processing of Chinese white salted noodle and its sensory evaluation system. J. Triticeae Crops 27(1): 158–165 (in Chinese).

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CHAPTER 2

Breeding for Dual-Purpose Hard White Wheat in the United States: Noodles and Pan Bread ARRON H. CARTER, CARL A. WALKER, and KIMBERLEE K. KIDWELL

2.1. INTRODUCTION Hexaploid wheat (Triticum aestivum L.) is the primary food grain consumed directly by humans worldwide, and more land around the globe is devoted to the production of wheat than to any other commercial crop (Briggle and Curtis 1987). Wheat is well adapted to diverse climatic regions, and two growth habit types, winter (requires vernalization to flower) and spring (does not require vernalization), exist. Six market classes, which are distinguished by kernel hardness, grain color, head morphology, and in some cases growth habit, are in commercial production in the United States of America (USA), including soft white (SW), soft red winter (SRW), hard red winter (HRW), hard red spring (HRS), hard white (HW), and durum wheat (USDA-NAAS 2007). The end-use product goals for each wheat market class differ according to flour quality attributes. Flour extracted from hard red wheat (HRW and HRS) typically has strong gluten and is used for bread baking, whereas SW and SRW wheat have weak gluten and are used for making pastries, cookies, cakes, and crackers (Finney et al. 1987). Hard white cultivars are targeted to Pacific Rim consumers for noodles, steam breads, and white pan bread production. The domestic bread-baking industry often uses HW wheat as a replacement for HRW and HRS wheat. Since grain color, head type, hardness, growth habit, and several end-use quality parameters are simply inherited in wheat, these traits can easily be manipulated through plant breeding and selection (Allard 1999). Breeding efforts to develop HW wheat cultivars are relatively new in the United States. A majority of the wheat breeding efforts across the United States have focused on developing red cultivars due to the difficulties of overcoming the problem of preharvest sprouting (PHS) in HW wheat. HW wheat is more prone to PHS than Asian Noodles: Science, Technology, and Processing, Edited by Gary G. Hou C 2010 John Wiley & Sons, Inc. Copyright


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red wheat due to pleiotropic effects of genes controlling red-testa pigmentation on seed dormancy (Anderson et al. 1993). When the genes for red-testa pigmentation are present, PHS is reduced (Imtiaz et al. 2008). Preharvest sprouting damage often has deleterious effects on bread-making qualities, thus increasing the risk of producing white wheat (Groos et al. 2002). Reduced exposure of wheat grain to moisture at physiological maturity is essential to eliminate the risk of PHS. Low annual precipitation levels in the Pacific Northwest provide optimal growing environments for white wheat; whereas in high precipitation areas, such as the Midwest and Southeast regions of the United States, the risk of producing HW is high (Simpson 1990). Sources of moderate tolerance/resistance to PHS are present in white wheat germplasm (Mares 1987; Derera 1989; Wu and Craver 1999); however, breeding for tolerance/resistance to PHS is difficult due to the polygenic nature and low heritability of the trait (Anderson et al. 1993). Resistance to PHS is quantitatively inherited, and expression is greatly affected by environmental factors (Hagemann and Ciha 1987). Establishing field screening nurseries for identifying cultivars with tolerance/resistance to PHS is costly and time consuming as multiple years and locations are required to confirm results (Anderson et al. 1993). Molecular markers associated with PHS tolerance/resistance would be useful breeding tools for cultivar enhancement. Efforts to identify quantitative trait loci (QTL) associated with PHS resistance have been ongoing since DNA markers first became available. Anderson et al. (1993) used RFLP (restriction fragment length polymorphism) markers to identify eight QTL using two different mapping populations. Since then, QTL associated with resistance to PHS have been identified on all chromosomes of hexaploid wheat with the solitary exception of chromosome 1D (Kulwal et al. 2005). Nine QTL associated with PHS resistance were identified in Aegilops tauschii (Imtiaz et al. 2008), and DNA markers associated with these chromosomal regions may be useful for introgressing PHS resistance into adapted HW wheat germplasm using marker-assisted selection. The agronomic performance and end-use quality of HW wheat must equal or exceed that of HRW or HRS wheat for the crop to be a viable option for wheat producers. Grain yields of HW wheat often equal or exceed those of HRW or HRS wheat (Upadhyay et al. 1984; Matus-C´adiz et al. 2003). The bread-making qualities of HW wheat also are comparable to those of HRS wheat (Lang et al. 1998). When milled to a common color standard, flour extraction rates of HW wheat are typically 1–3% higher than those of HRS wheat (Boland and Dhuyvetter 2002). The milling advantage associated with a white seed coat compared to a red seed coat results from the ability to mill closer to the bran layer without leaving visible bran flakes in the flour (McCaig and DePauw 1992). Visible bran flakes discolor flour, and this subsequently affects noodle color (Souza et al. 2004). More HW bran than HRS bran can be included in flour without adversely affecting product color and flavor (McCaig and DePauw 1992). Because of these characteristics, HW wheat is preferred for making Chinese noodles, which are popular in Asian countries (Lang et al. 1998; Seib et al. 2000). HW wheat has gained attention in the United States as the demand for high-quality HW wheat has increased around the world. Based on the milling and end-product quality advantages associated with using HW wheat, the industry

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regards it as the wheat market class of the future to complement or replace hard red wheat in commercial production. Another benefit of growing HW wheat is the range of grain protein contents suitable for making different types of end products. High grain protein levels (12% to >14%) are typically required in HRS wheat to produce an acceptable loaf of bread (Finney et al. 1987). HW wheat, on the other hand, is used for a variety of end products, including white salted noodles (WSNs), yellow alkaline noodles (YANs), and pan bread, each of which can be made with grain ranging from 10.5% to >13.5% in protein content (Hou 2007). HW wheat can be grown in production regions with minimal levels of abiotic stress since low protein HW wheat is marketable. Additionally, given that most producers manipulate grain protein content (GPC) through nitrogen (N) fertilizer application, the lower GPC requirement of HW wheat compared to hard red wheat may lead to reduced input costs. 2.1.1. Market Potential East Asian customers are the major importers of HW wheat on a global scale. They desire HW wheat for noodle manufacturing because of its brighter flour and endproduct color (Hatcher and Kruger 1993). Asian consumers use up to 45% of their wheat imports (about six million metric tons) for noodle production (Miskelly 1996). Additionally, domestic millers and bread bakers have used high protein hard white spring (HWS) wheat as an alternative to HRS wheat (Souza et al. 2004). On average, Australia supplies ten million metric tons to the Asian HW wheat market, but recent crop failures have weakened exports due to limited grain supplies (USDA-FAS 2007). As a result, Asian consumers rely on other wheat-producing regions to meet their annual demands for HW wheat, including Canada and Argentina (USDA-FAS 2007). The United States does not currently produce HW wheat in sufficient quantities to meet export market demands, and only limited amounts of HW wheat are produced for the domestic bread market (Souza et al. 2004). With the benefits of reduced input costs, higher flour yields, and increasing market demands, breeders around the globe are beginning to expand efforts to develop adapted HW wheat cultivars for their regions. 2.1.2. Breeding Targets When developing HW wheat, many essential traits must be taken into consideration before releasing new cultivars for commercial production. To reduce potential production risks, all cultivar release candidates must have superior agronomic performance in the target production region. Production goals for agronomic traits, such as grain yield potential, grain volume, plant height, days to heading, straw strength, and days to grain ripening, will vary based on the length of growing season, amount of annual precipitation, and/or production location. Improved cultivars also must carry all essential pest resistance genes common to each production region to reduce risk and input costs for wheat producers. In addition, essential end-use quality traits, including high flour extraction rates and low flour ash, must be incorporated into new

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HW wheat cultivars to meet the stringent demands of both the milling and baking industries (Souza et al. 2004). 2.1.3. Current Market Standards Two seed traits, grain hardness and grain color, are the major characteristics that distinguish wheat market classes. As determined by the Single Kernel Characterization System (SKCS) Model 4100, a minimum hardness index of 65 is considered to be desirable for HW wheat (Hou 2007). HW wheat grain color can range from white to a dark amber color when grown under diverse environmental conditions, and dark amber grain lots may be graded as hard red even though the red color alleles are not present (Kansas State University 2001). Hard white grain appears to be amber colored when pigments in the endosperm are visible through the clear seed coat (Wang et al. 1999). It is important to segregate hard red from HW wheat since HW wheat tends to have lower grain protein content (Souza et al. 2004). If hard red and HW grain are mixed together, the high GPC typically required for making pan bread is diluted, thereby reducing product quality. Even though distinct segregation categories for GPC exist for hard red wheat, which often result in price premiums (Olmos et al. 2003), segregation categories based on protein content are not currently in place for HW wheat. Segregation of HW wheat based on GPC is important due to the different product targets for flour at different protein contents. Low protein HW wheat produces a softer noodle (Baik et al. 1994a), whereas high protein HW wheat produces a darker, firmer noodle (Konik et al. 1993). High protein HW wheat also is more suitable for making pan bread (Finney et al. 1987). Currently, winter and spring growth habit types of HW wheat are comingled, whereas HRS and HRW wheat are identified as individual market classes. Hard red wheat is segregated by growth-habit type because spring types, on average, are significantly higher in GPC content than winter types, resulting in distinct end-use properties of resulting flours (Entz and Fowler 1991; Fowler 2003). Growth-habit type is simply inherited in wheat and is determined mainly by allelic composition at Vrn loci (Fu et al. 2005). A dominant allele at any Vrn locus results in spring growth habit, whereas recessive alleles across Vrn loci result in winter growthhabit type. Winter types require vernalization for 6–8 weeks at temperatures lower than 4 ◦ C to induce flowering (Fu et al. 2005). Typically, winter wheat (fall-sown) cultivars tend to out-yield spring-wheat cultivars (spring-sown) due to their larger plant size and the ability to generate more photosynthate as a result of an extended growing period in the field (Hurry and Huner 1991). 2.1.4. Dual-Purpose Hard White Wheat Multiple researchers have investigated the ideal combination of starch and protein characteristics necessary to create a HW wheat cultivar with dual-purpose quality; however, this relationship has not been firmly established (Lang et al. 1998; Davies and Berzonsky 2003). A dual-purpose, or dual-use, HW wheat variety could be used to produce both high-quality pan bread and Asian noodles if it had desirable quality

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INTRODUCTION

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attributes for both end-product types. This allows market flexibility, since wheat producers are able to sell their grain to different end-users. There are two main types of Asian noodles: white salted noodles (WSNs) and yellow alkaline noodles (YANs), which are sometimes referred to as Cantonese noodles. WSNs include Chinese raw noodles and Japanese udon noodles. Chinese raw noodles and YANs are characterized by hard and chewy bite, whereas Japanese udon noodles are characterized by smooth, soft, and springy texture (Hou 2001; Ross 2006). Since noodle markets have strict requirements for noodle texture, it is important to produce flour with optimal quality parameters for the targeted end product, which will be discussed later in this section. Color (brightness, intensity) is the most important characteristic of noodles from the consumer’s perspective (Baik et al. 1995). Darkening and discoloration of noodles, especially YANs, has been associated primarily with the activity of polyphenol oxidase (PPO) (Baik et al. 1994a, 1995; Crosbie et al. 1996). PPO also plays a role in the discoloration of flat breads (Faridi 1988), pan bread (McCallum and Walker 1990), and steamed breads (Dexter et al. 1984). Since noodle browning is associated with PPO activity (Marsh and Galliard 1986), HW wheat cultivars with low PPO activity levels are desirable since they have bright noodle color potential. Since color is an important trait for noodle products, all HW wheat designed to be dual-purpose must have low PPO levels. Higher flour protein concentration (a measure of total flour protein) results in firmer and darker noodles (Miskelly and Moss 1985; Konik et al. 1993). Protein quality (as measured by the SDS–sedimentation test) is positively correlated with noodle firmness and, in some studies, had a greater effect on noodle firmness than protein content (Huang and Morrison 1988; Baik et al. 1994b). Bread loaf volume and crumb grain quality also are positively correlated with protein quality and quantity (Finney et al. 1987); therefore, flours suitable for pan bread, YAN, and Chinese raw noodle production should have relatively high protein content and superior protein quality. Starch quality has a major impact on the end-use quality of noodles (Kruger 1996). High starch pasting peak viscosity (also referred to as “pasting”) has been associated with superior udon noodle eating quality (Crosbie 1991; Konik et al. 1992; Batey et al. 1997). Udon noodles are usually produced using soft white wheat; however, Baik et al. (1994a) determined that HW wheat with high peak viscosity and protein content between 9.5% and 11% can produce softer noodles than soft white wheat with relatively lower peak viscosities. Therefore, it may be possible to produce udon noodles with sufficiently soft texture using a HW wheat with high starch pasting properties and low protein content. Multiple researchers concluded that high starch pasting properties or high hot water swelling power, which are related, are negatively correlated with hardness and can therefore result in lower quality YANs (Miskelly and Moss 1985; Konik et al. 1994; Batey et al. 1997; Crosbie et al. 1999; Zhao and Seib 2005; Ross 2006). However, some reports also indicate that high starch pasting or swelling power may increase noodle smoothness and elasticity (Konik et al. 1994; Batey et al. 1997; Akashi et al. 1999; Zhao and Seib 2005; Ross 2006; Tanaka et al. 2006). This presents a conflict where increased starch pasting properties improve some aspects of YAN quality but compromise noodle hardness. The results of a small number of studies

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BREEDING FOR DUAL-PURPOSE HARD WHITE WHEAT IN THE UNITED STATES

TABLE 2.1 Desirable Quality Characteristics of Hard White Wheat Grain and Resulting Flour for Three Distinct End Products Parametera

Chinese Hard Bite Noodle

Pan Bread

Korean Instant Noodle

Wheat quality Test weight (lb/bu) Kernel hardness (SKCS 4100) Protein (%, 12% mb) PPO activity by l-DOPAb

60 minimum 65–90 11–15.0 0–0.2

60 minimum 65 minimum 11.5–14.0 NA

60 minimum 60–85 10–11 0–0.2

Flour quality Protein (%, 14% mb) Ash (%, 14% mb) L* (Minolta Colorimeterc ) Amylograph peak viscosity (B.U.)

10–13.5 0.38–0.45 91 minimum 500–850

10.2–13 NA NA 500 minimum

8.5–9.5 0.38–0.40 91 minimum 800 minimum

72 minimum

NA

NA

10 maximum

NA

NA

NA

900 @ 11% protein

NA

Chinese raw noodle qualityd Chinese raw noodle dough sheet L* 24 he Chinese raw noodle dough sheet L* 0–L* 24 Pan bread quality Loaf volume (cc) a Adapted

from Hou (2007). International Method 22-85. c L* represents the lightness of the color; 0 = black and 100 = white. d Chinese raw noodle formula: flour, 100%; water, 28%; and salt, 1.2%. e L* 24 h represents the lightness of the noodle 24 hours after cooking. b AACC

(Akashi et al. 1999; Zhao and Seib 2005; Ross 2006) indicated that the softening effect of high starch pasting may be overcome by using flour with sufficiently high protein content (10–13%) and superior protein quality. In these situations, high starch pasting properties are beneficial in that YANs are more elastic, resulting in higher quality. This suggests that a dual-purpose HW wheat with moderately high starch pasting properties might be suitable for bread and YAN production at high protein contents, and for WSNs at low protein contents (Table 2.1).

2.2. GENETIC CONSIDERATIONS: SEED TRAITS AND QUALITY TRAITS HW wheat must have excellent end-use quality as well as superior agronomic performance to be commercially viable; therefore, these traits are valued equally during the selection process. Understanding the genetic factors controlling agronomic and end-use quality traits is essential in order to develop superior wheat cultivars. Some

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traits, such as grain color and hardness, are simply inherited as they are controlled by one or few genes (Morris 2002; Kuraparthy et al. 2008). These traits typically have only a few phenotypic classes and thus are easier to select for during the breeding process. Other traits, such as various grain quality traits, are under polygenic control (Payne et al. 1984; Kuchel et al. 2006). Polygenic traits are quantitatively inherited, have various phenotypic classes that are normally distributed, and are challenging to select for during the breeding process (Bernardo 2002). The population mean for quantitative traits will increase or decrease over generations if strong selection pressure is placed on the desired distribution tail (Bernardo 2002). The ability to make significant advances in both end-use quality and agronomic performance requires an understanding of the number of genes controlling each trait (Table 2.2) as well as stringent selection pressure during each generation of advancement (Wicki et al. 1999). Understanding how quality factors are controlled genetically also aids the process of combining various traits from selected parental lines into a single cultivar (Heslop-Harrison 2002). Selecting for quality traits at early and advanced stages of the breeding process ensures that all agronomically superior HW wheat cultivars carry essential end-use quality attributes. 2.2.1. Grain Hardness A wheat kernel is considered either soft or hard based on its texture. A single locus controlling grain hardness, also called grain texture, was identified on chromosome 5DS by Law et al. (1978). Law et al. (1978) designated the locus Hardness, with the soft allele being represented by the dominant designation, Ha, and the hard allele, represented by the recessive allele, ha. These alleles are simply inherited, with the homozygous recessive allele conferring hard kernel texture. Morris (2002) later determined that puroindoline proteins a and b determine the molecular basis of grain hardness. The puroindoline proteins are a primary component of the larger protein named “friabilin,” which is abundant in soft wheat starch (Morris 2002). When both puroindolines are in their wild-type state, the grain texture is soft. If either puroindoline a or b is absent, the resulting grain texture is hard. There also are six known mutations in the puroindoline b genetic sequence, most of which are single nucleotide mutations that result in loss of function, resulting in a hard grain texture (Morris 2002). To date, seven distinct hardness alleles have been identified, designated Pina-D1b and Pinb-D1b through Pinb-D1g (Morris 2002). Different combinations of the puroindoline alleles produce varying degrees of hardness, although further research is required to fully understand impact of kernel texture on end-use quality of HW wheat. 2.2.2. Grain Color Grain color is an important trait to consider during the breeding process since this characteristic further distinguishes market classes of wheat. Seed color is controlled by the three red seed color genes R-A1, R-B1, and R-D1, which are located in orthologous positions on chromosome arms 3AL, 3BL and 3DL, respectively

32 Seven alleles have been identified at the Pina-D1b and Pinb-D1b loci 3 genes—R-A1 , R-B1 , and R-D1 Unknown

Multiple QTL; Gpc-B1

Three high molecular weight glutenin genes—Glu-A1, Glu-B1, and Glu-D1 One major QTL

Grain hardness

Flour extraction rate

Grain protein content

Protein quality

Starch Three genes—Wx-A1, quality—GBSSI Wx-B1, Wx-D1

7A, 4A, and 7D, respectively

2AL

Various chromosomes; 6BS 1A, 1B, and 1D, respectively

Low PPO required to prevent product discoloration over time Partial waxy cultivars are desired for white salted noodles

White wheat yields more flour than red wheat; white bran not visible in flour Higher flour yield results in more end products produced Protein content dictates the flours’ uses in end products Strong elastic dough is used to make bread products

3AL, 3BL, 3DL, respectively Unknown

Hard wheat has higher flour extraction rates

5DS

Impact on End-Use Quality

PCR-based markers are available, but simple assays are available for phenotypic assessment Nonfunctional proteins at any of these three loci reduce levels of amylose and are termed partial waxy or waxy; PCR-based markers are available

Difficult to breed for due to high variability across environments and low genetic control Gluten composition determines which products the flour is capable of producing

Number of genes dictates strength of color; recessive alleles at all loci needed for white seed coat May be predicted based on seed size and test weight

Combinations of different alleles produce varying levels of hardness

Considerations for Breeding

Epstein et al. 2002

Raman et al. 2005

Nieto-Taladrix et al. 1994

Uauy et al. 2006

Lyford et al. 2004

Kuraparthy et al. 2008

Morris 2002

Reference

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PPO activity

Grain color

Known Genetic Factors

Chromosome Location of Known Genes

Genetic Characterization of Desirable End-Use Quality Traits in Hard White Wheat

Trait

TABLE 2.2

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(Kuraparthy et al. 2008). The presence of a dominant allele at any locus confers a red seed coat, whereas the presence of recessive alleles across the three loci confers a white seed coat. Dominate alleles act in an additive fashion at the red seed color loci, in that as the number of dominant alleles present across the three loci increases, the darker red the seed coat becomes. The presence of a single dominant allele at any one of the three loci results in a red seed coat classification; therefore, recessive alleles must be present across these loci for the cultivar to be classified as HW wheat. 2.2.3. Flour Extraction Rates In order to develop a successful HW wheat cultivar for commercial production, enduse quality traits must meet or exceed the standards of the industry. As explained earlier, higher volumes of flours can be extracted from HW wheat compared to hard red wheat (Boland and Dhuyvetter 2002). Flour extraction rate reflects the amount of endosperm removed from the grain during the milling process (Bass 1988). White wheat typically has higher flour extraction rates since processors can mill closer to the bran layer without adversely affecting flour color. Under perfect conditions, maximum flour yield (extraction rate) equates to 85% of the grain kernel (Manley 2000). This level of extraction is often targeted but seldom achieved due to inefficiencies in the milling process (Manley 2000). Flour yield is influenced by genetic factors, which are reflected in differences among cultivars within the same market class when milled to a common extraction rate (Zhang et al. 2005). Little is known about the genes associated with flour extraction rate in wheat. Lyford et al. (2004) report that kernel hardness, seed size, and test weight can be used to predict flour extraction rates. They also report that flour extraction rate varies for grain from the same genotype produced in different environments, indicating environmental factors influence this trait. Variability in flour extraction rate among genotypes, as well as environmental influences on trait expression, continue to challenge the ability of wheat breeders to effectively increase milling capacity of HW wheat cultivars. 2.2.4. Grain Protein Content Grain protein content (GPC) levels in wheat are influenced by genetic factors, nitrogen (N) availability, and environmental conditions (DePauw and Townley-Smith 1988; Gauer et al. 1992). Increasing GPC by applying high rates of N fertilizer can be effective but is inefficient due to high fertilizer cost and increased risk of environmental contamination (Gauer et al. 1992). The most cost effective, desirable approach for improving GPC involves genetic manipulation, which has proved to be challenging. The first limitation is that a majority of the variation associated with GPC results from environmental rather than genetic effects (DePauw and Townley-Smith 1988). Second, a strong negative relationship between GPC and grain yield exists. When breeders select for high GPC, resulting cultivars typically have reduced grain yields (O’Brien and Panozzo 1988). Opportunities to genetically improve GPC in wheat have been identified. A gene for high GPC was identified in wild emmer wheat Triticum turgidum ssp. dicoccoides

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(DIC) accession FA15-3 (Avivi 1978). The gene was initially mapped as a quantitative trait locus (QTL) on chromosome 6BS using recombinant substitution lines (RSLs) of the DIC 6B chromosome in the genetic background of Langdon (Joppa et al. 1997). The same DIC chromosome segment was transferred into the hexaploid wheat variety “Glupro” (Mesfin et al. 1999). The gene was mapped as a single locus designated as Gpc-B1 proximal to the Nucleolar Organizer Region (Olmos et al. 2003). Uauy et al. (2006) reported that the Gpc-B1 allele was associated with accelerated senescence and exhibited a pleiotropic effect on GPC. Kade et al. (2005) observed increased levels of soluble protein and amino acids in the flag leaves at anthesis and increased efficiency in N remobilization in genotypes carrying the DIC Gpc-B1 allele and proposed that these may be the mechanisms by which GPC is increased in wheat. Uauy et al. (2006) reported that incorporation of this gene into hard wheat backgrounds will increase GPC by 10–30 g/kg without reducing grain yields. Conversely, A. Carter et al. (2007) reported that genotype and environmental interactions significantly influence the expression of the DIC Gpc-B1 allele, which may limit its utility for increasing GPC in certain environments. Several researchers are currently working toward improving our understanding of how this gene might be manipulated through breeding efforts to improve GPC in wheat. 2.2.5. Protein Quality GPC is not directly associated with grain protein quality, which complicates the selection process for developing HW wheat cultivars with desirable end-product quality. GPC is easily measured, making it a highly desirable marketing characteristic; however, the protein present in wheat flour must be of acceptable quality for product making to be acceptable to the industry. End-use quality of wheat flour is influenced by both protein content and protein type; however, for a given protein content, quality is largely a function of gluten endosperm storage protein composition (Finney et al. 1987). Gluten proteins confer the unique cohesive and elastic characteristics of wheat dough, and differences between the protein quality of cultivars are mainly caused by different combinations and expression levels of high molecular weight (HMW) glutenin storage protein present in the grain (Payne et al. 1984). Loci coding for HMW glutenin subunits have been characterized and located on chromosome 1 of hexaploid wheat (Nieto-Taladrix et al. 1994). The loci are quantitative in nature although significant epistatic effects between some of the loci involved require they be taken into account during the selection process. Wheat cultivars that produce strongly elastic dough with some extensibility are used to make bread products. Those with highly extensible dough are used primarily for pastries (Finney et al. 1987). Due to the established relationship between gluten strength and end-use quality, incorporating techniques for evaluating gluten quality of early generation lines into selection programs is recommended (Payne et al. 1984). 2.2.6. Polyphenol Oxidase (PPO) Activity Despite the importance of color on noodle product quality, the genes controlling PPO activity have only recently been identified. Using cytogenetic stocks, Jimenez

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and Dubcovsky (1999) mapped the gene(s) for PPO activity to chromosome 2A. More recently, Raman et al. (2005) confirmed chromosome 2AL to be the location of PPO genes using a double haploid population and QTL analysis. Regression analysis revealed a major QTL on chromosome 2AL, which accounted for 80% of the variation for PPO activity (Raman et al. 2005). The simple sequence repeat (SSR) marker Xgwm294b explains over 82% of the line mean phenotypic variation (Raman et al. 2005). Four SSR markers (Xgwm294b, Xgwm312, Xwmc170, and Xwmc198) were validated for PPO linkage and have been proved to correctly predict the PPO activity in more than 92% of wheat lines. 2.2.7. Starch Quality The identification of individual starch attributes that influence starch quality would facilitate improving this trait in wheat cultivars through breeding and selection. Multiple researchers determined that starch pasting values and hot water swelling power are correlated with flour amylose content (Moss 1980; Oda et al. 1980; Miskelly and Moss 1985; Zeng et al. 1997; Zhao and Seib 2005). Amylose is produced in the endosperm by the granule-bound starch synthase I (GBSSI) protein (Chao et al. 1989; Yamamori et al. 1994; Nakamura et al. 1995). Three homoeologous GBSSI protein genes were mapped to chromosomes 4A, 7A, and 7D. Briney et al. (1998) developed a PCR (polymerase chain reaction)-based marker for the GBSSI gene on chromosome 4A. Shortly after, the genes that encode all these proteins were sequenced by Murai et al. (1999), allowing development of PCR-based markers that can be used to select for specific alleles of the GBSSI genes in experimental breeding lines (McLauchlan et al. 2001). Genotypes that do not produce functional proteins from one or two of the three homoeologus genes and thus produce reduced levels of amylose compared to “normal” genotypes are termed “partial waxy” mutants. Genotypes have been developed with nonfunctional alleles of all three genes (producing starch with essentially 100% amylopectin), which are identified as “waxy” mutants (Epstein et al. 2002). Normal, partial waxy, and waxy mutants vary in their starch pasting performance. Epstein et al. (2002) determined that optimal texture for WSNs was achieved using partial waxy mutants, whereas full waxy mutants resulted in poor quality (i.e., overly soft) WSNs. Unfortunately, selection based on these genes alone is not sufficient to allow a breeder to completely control the starch pasting behavior of a cultivar, as demonstrated by Geera et al. (2006), who observed that peak viscosity differed between cultivars with the same GBSSI genotype.

2.3. GENERAL BREEDING METHODS The goal of a breeding program is to create adequate genetic variation among progeny within breeding populations to identify genotypes that carry the desirable traits of the parents and/or transgressive segregants for particular traits of interest. Increasing genetic variation is accomplished by selecting parental lines that are genetically diverse for the trait(s) of interest. Cross-hybridizing genetically distant parents creates

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opportunities for gene recombination, which takes place during crossing-over events during meiosis. This results in the generation of large segregating populations from which superior genotypes can be identified. The primary objective of a breeder is to select progeny with desirable agronomic and end-use quality traits from among segregating populations. Selected lines, if proved superior for desirable traits, are released as new, improved commercial cultivars.

2.3.1. Breeding Methods for HW Wheat A diverse array of breeding strategies can be used for wheat cultivar improvement, ranging from single-seed descent and backcross breeding to the pedigree method and bulk breeding (Sleper and Poehlman 2006). The end goal of the breeder often determines which strategy is most appropriate for the situation. For example, if the intention is to introgress a single disease-resistance gene into a superior cultivar, backcross breeding might be the most effective, efficient approach. If the goal is to maximize variation within segregation populations to combine an array of traits into a single genotype, the pedigree method might be a more desirable choice. Methods vary based on the complexity of targeted trait(s), environmental conditions, and available resources. Each breeding strategy is effective if resulting cultivars developed through the process are genetically superior to the control cultivars to which they are being compared. Regardless of the breeding strategy used, parental selection is essential to the success of cultivar improvement efforts.

2.3.2. Parental Selection When breeding for improved end-use quality, parental selection for use in crossing blocks is the first and most essential step toward success (Allard 1960). Breeders often select parental lines using two approaches: (1) based on performance and adaptability information about the line itself (Bhatt 1973) or (2) based on performance and adaptability information about the parent, as well as offspring derived from that parent (Utz et al. 2001). In the first case, superior performing genotypes are often hybridized to other superior performing genotypes in hopes of recovering progeny that are superior to both parents through transgressive segregation. Another parental selection approach is to hybridize parents with complementary traits in hopes of recovering progeny with superior characteristics of both parents in one genotype (Tanksley and Nelson 1996; Wang et al. 2005). This approach to parental selection is typically used by wheat breeders. Progeny testing also can be used to identify parents with superior combining ability; however, the time requirement often delays the incorporation of new genetic material into breeding schemes. Parental lines should have good-to-superior agronomic and end-use qualities, as well as the essential traits necessary for success in the target production region (Bernardo 2002). For example, if stripe rust resistance is essential for cultivar release in a particular production region, at least one of the parental lines chosen for the cross should carry viable genetic resistance to this disease. If essential genes are not

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present in either parent, the cross will not generate a cultivar suitable for commercial production in that region. End-use quality dictates the marketability of HW wheat, which elevates the priority of end-use quality traits when establishing selection criteria. In addition to superior agronomic performance and essential pest resistances, a successful HW wheat must have superior milling quality and end-product performance. Typically, an adapted genotype that might be lacking in one or two essential end-use quality parameters is crossed to other genotypes that are genetically superior for the targeted traits (Wang et al. 2005). Multiyear agronomic and end-use quality data should be used to identify genotypes carrying complementary traits for use as crossing parents. The number of hybridizations made in a breeding program each year is highly dependent on the resources available to that program. Breeding populations can be created by crossing adapted germplasm from the same production regions, germplasm from the same market class from other production regions, adapted or nonadapted germplasm from different market classes, or adapted germplasm to wild relatives. When a genotype with winter growth habit is crossed to a spring genotype, the winter genotype must be planted 6–8 weeks earlier with exposure to low temperatures to induce flowering. Planting the spring wheat genotype at 1-week intervals for 4–6 weeks ensures that the pollination stages align between the winter and spring parents. If wild relatives or alien species are used as sources of genetic variation, progenitor building is often required before this material is widely used as a crossing parent in a breeding program (Pe˜na and Pfeiffer 2005). The end goal of each cross, regardless of the parental combination used, is to generate progeny from which superior HW wheat germplasm can be selected. Cross performance can be predicted accurately only when information about the genes of interest are known (Wang et al. 2005). This allows breeders to determine when traits will begin to segregate in the population, which will influence when selection for these traits should begin. If parental lines from different market classes are chosen, selection of desired traits should begin early in the breeding process. For example, if a hard red cultivar is being converted into a HW cultivar, early generation selection for seed coat color may hasten the recovery of HW genotypes. If soft white wheat is being converted to HW wheat, selection for kernel hardness early in the breeding process greatly reduces the volume of early generation material maintained in the program.

2.4. SMALL-SCALE GRAIN QUALITY TESTS The following is an example of a modified bulk breeding method used at Washington State University (Pullman, WA) to advance early generation HWS wheat progeny through the cultivar development process (Figure 2.1). Bulked seed (30 g) from several F1 plants is used to establish an F2 field plot. Approximately 100 heads are selected at random from individual F2 plants, and a 40 g subsample of seed is used to establish a single F3 plot in the field the following year. Single heads from 100–150 F3 plants are threshed individually to establish F4 head row families. Following selection for grain appearance, plant height, and general adaptation, seed from

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Parent A x Parent B

F1 Bulk plot

F2 Bulk plot

F3 Bulk plot Visual selection for agronomic appearance, foliar disease resistances, and general adaptation

Individual F4 headrows Selection for grain soundness and color, protein content, protein quality, PPO enzyme activity, and starch quality

F5 Preliminary yield trial, nonreplicated, single location Selection for grain hardness, protein content, protein quality, milling data, starch quality, flour functionality, bread quality, and noodle quality

F6-F9 Multilocation, replicated yield trials

Similar selection criterion as with preliminary yield trials

Identify cultivar release candidates

FIGURE 2.1 Modified bulk breeding method used at Washington State University to develop hard white spring wheat cultivars adapted for production in the Pacific Northwest region of the United States.

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30–50 F4 plants within each selected head row is bulk harvested to obtain F5 seed for early generation, end-use quality assessment. Most tests utilized in the industry to assess HW wheat quality are unsuitable for screening thousands of experimental lines and segregating populations, which is needed in the early stages of the breeding process. To accommodate for this need, several small-scale tests have been developed to provide direct and indirect selection methods for HW wheat end-product quality. To maximize its value as an early-generation breeding tool, a small-scale, end-use quality test must (1) require small amounts of grain since seed supplies of early generation material are limited; (2) be conducive for use on large numbers of samples; (3) be time and cost effective; and (4) produce reliable results. Small-scale tests that meet these criteria are available for the following end-use quality attributes: grain soundness and color, protein content, protein quality, PPO enzyme activity, and starch quality (Bettge et al. 1995; B. P. Carter et al. 1999; Anderson and Morris 2001). Emphasizing selection for end-use quality traits during early stages of the breeding process ensures that HW wheat cultivar releases for commercial production will have essential quality characteristics required by the milling and baking industries (Table 2.3).

TABLE 2.3 Early and Late Generation Selection Parameters Used for Breeding High Quality Hard White Wheat Activity

Selection Parameter

Sample Size (g)

Testing Time/ Sample (min)

Early generation selection (F3 –F5 )

Visual screening Grain soundness Polyphenol oxidase activity SDS–sedimentation Grain protein concentration Hardness Flour swelling volume

5 5 <1 10 15 15 <1

10–15 seconds 10–15 seconds 60 20–25 5–10 5–10 120

Intermediate stages of development (F6 –F9 )

Hardness Grain protein concentration Flour milling—quadrumat SDS–sedimentation Flour swelling volume Mixograph Bread quality Yellow alkaline noodles

5 15 600a 10 <1 10 100 100

5–10 5–10 15 20–25 120 15 35 10

Same as in intermediate stages, plus: Advanced breeding 2000 generations (F10 –F12 ) Flour milling–buehler White salted noodle quality 300

40–50 10

Cultivar release candidates a The

Regional Wheat Quality Council— tests flour samples for multiple end-use quality traits

170 pounds 3–4 months for results

flour resulting from milling 600 g of grain is sufficient to complete all end-use quality tests for intermediate stage breeding.

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2.4.1. Early Generation (F3 –F4 ) Testing for HW Wheat End-Use Quality Parameters Multiple populations of early generation, experimental breeding material are available for selection each year. Large population sizes of early generation material are typically created to maximize variation among segregating progeny for selection purposes. Utilizing early generation testing for end-use quality allows a breeder to cull experimental material that does not have essential quality attributes required for a HW wheat cultivar to be marketable, thereby reducing the volume of material evaluated in replicated field trials. To be effective, small-scale, end-use quality tests must be easy, quick, and reproducible. This section details four tests that are routinely used for early generation, end-use quality assessment in wheat.

2.4.1.1. Grain Soundness Due to the large number of early generation breeding lines, and the limited amount of seed for end-use quality evaluation, agronomic parameters are often the first criteria selected for in breeding programs. Early generation breeding material is grown under field conditions to evaluate agronomic traits such as plant height, disease susceptibility, and grain soundness. Material deemed as being undesirable by the breeder for one or more traits is discarded without further testing. Plant breeders further reduce the number of experimental breeding lines using visual evaluation, although visual evaluation standards differ by breeder and production region. Following visual selection among F4 headrows for general adaptation, resistance to foliar diseases, plant height, and so on, harvested grain samples are evaluated for grain appearance. Visual selection is often used to discard lines with shriveled seed (typically associated with low grain volume), seed color off-types (i.e., red-seeded line among hard white selections), or diseased kernels. Grain traits such as hardness and grain protein content can be evaluated using near-infrared transmittance (NIR) to identify selections that meet the hardness and protein content standards for HW wheat established by the industry (Delwiche 1995). These methods are of great utility to breeding efforts since a large percentage of experimental breeding material can be eliminated before more expensive tests are conducted. 2.4.1.2. Protein Quality Grain protein is a mixture of different protein complexes, one of those being gluten, an essential component of protein quality (B. P. Carter et al. 1999). An established early generation selection method for assessing protein quality in wheat is based primarily on SDS–sedimentation values (B. P. Carter et al. 1999). The SDS–sedimentation test is a small-scale test designed to assess protein quality, which is highly correlated with gluten strength and, ultimately, to bread-baking quality of hard wheat (Matuz 1998). A micro SDS–sedimentation test, as modified by the USDA Western Wheat Quality Laboratory in Pullman, Washington (USDA-ARS 2007), is used to evaluate many of the early generation lines that are selected each year. Whole meal flour is weighed to 0.5 g and placed into a standard glass tube with 4 mL of distilled water added to each sample. This solution is vortexed for an initial 20 seconds, and then vortexed for another 10 seconds after it rests. Next, 12 mL of a lactic acid/sodium dodecylsulfate solution is added to the mixture and caps are screwed

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FIGURE 2.2 Variation in protein quality of early generation hard white spring wheat experimental breeding lines as indicated by results of the micro-scale SDS-sedimentation test. The check cultivars included in this experiment are “Otis” and “Macon.” Samples with large sedimentation values, as identified by the arrow, are predicted to have adequate glutenin strength and quality for bread making, which is desirable for HWW cultivars.

on the glass tubes (Approved Method 56-70, AACC International 2000). The tubes are set in racks and placed on a Zeleny rocker shaker for 40 seconds. The tubes are allowed to rest for 2 minutes and then shaken for another 40 seconds. The tubes are placed upright and allowed to sit for 10 minutes. The height of the sediment interface is immediately recorded and compared to check cultivars. Gluten consists of two major components, glutenin and gliadin. The sediment in the SDS solution results from the swelling of the glutenin strands when hydrated (Eckert et al. 1993). SDS–sedimentation volumes are highly heritable and can be used for selection among early generation progeny (B. P. Carter et al. 1999). The micro SDS–sedimentation procedures have the advantages of requiring small amounts of flour samples and using inexpensive solutions and equipment, and are simple, fast, and reproducible when used to assess gluten strength. Since strong gluten is desired for HW wheat cultivars, progeny with higher SDS-sedimentation values as compared to the controls should be advanced in the breeding program (Figure 2.2).

2.4.1.3. Polyphenol Oxidase (PPO) Activity As explained in Section 2.2.6, PCR-based SSR markers have been identified for a gene controlling PPO activity in wheat. Unfortunately, due to the inconvenience and high costs of PCR, this is not an effective method for screening hundreds of early generation breeding genotypes. In contrast, a cheap and effective method of evaluating PPO enzyme activity has been established. Using five kernels, wheat genotypes can be evaluated for PPO enzyme activity using the l-DOPA (l-dihydroxyphenylalanine) test developed by Anderson and Morris (2001). The darker in color the l-DOPA solution becomes after 1 hour of mixing, the higher the PPO activity. End products made from lines with high PPO activity have a greater probability of darkening and discoloring over time compared to products made from genotypes with low PPO activity

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FIGURE 2.3 Variation in polyphenol oxidase (PPO) enzyme activity among early generation hard white wheat experimental breeding lines. Lines with low PPO activity, as indicated by a lack of color intensity of the solution, are desirable for end-use products due to reduced enzymatic browning over time in noodle products.

levels. Solution color can be analyzed visually using a light, medium, or dark scale compared to standardized controls (Figure 2.3). More precise measurements can be obtained using a light spectrophotometer, but this lengthens the analysis time required per sample. The Asian Products Collaborative Project (Hou 2007) recommends targeting PPO activity levels between 0 and 0.2 for HW wheat cultivars as measured spectrophotometrically. Since low PPO activity is essential for desirable noodle color, progeny with low PPO activity should be advanced in the breeding program.

2.4.1.4. Starch Quality Flour swelling volume (FSV) tests (Approved Method 56-21, AACC International 2000) are performed in order to identify partial waxy type flour, which relates to starch quality as explained in Section 2.2.7. Using 0.45g flour on a dry weight basis, 12.5 mL water is added and the mixture is well dispersed. The samples are placed in a hot water bath at 92.5 ◦ C and are continuously inverted for 30 minutes. A rapid cooling in an ice water bath followed by 5 minutes in 25 ◦ C water is used to bring the samples to room temperature. The samples are then centrifuged at 1000g for 15 minutes. The height of the gel is read in mm and reported in mL/g using the following conversion formula: [(mm × 1.52) − 0.30 mL]/0.45g Normal type wheat, which produces high levels of amylose, has high flour swelling power. Thus, higher gel height values indicate normal starch wheat, whereas lower values indicate partial waxy or waxy types. Although not a perfect indication of starch quality and type, it is a quick method for screening early generation material for starch type, which is associated with noodle-making capabilities. Starch type is indicative of the types of noodle products a cultivar may be most suitable for making, which is discussed in depth in other chapters of this book.

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2.4.1.5. Selection of Early Generation Material for Advancement Early generation quality screening can be performed by personnel within the breeding program or by personnel from a wheat quality lab, depending on resource availability. Since these tests are only indicative of the actual end-use quality characteristics, the tests are often viewed as a means of excluding undesirable material early in the process rather than as a means of identifying genotypes with highly desirable end-use quality characteristics. Genotypes advanced to preliminary yield trials based on promising early generation, end-use quality results are evaluated for yield performance. Grain from genotypes with acceptable agronomic characteristics is evaluated using largerscale tests to more accurately assess end-use quality attributes. HW wheat cultivars that meet current HW wheat quality standards are included in field nurseries with experimental breeding material, and resulting grain is used as the control for end-use quality comparisons among lines. Genotypes that do not meet the end-use quality market standards for HW wheat are eliminated from cultivar release consideration regardless of the agronomic potential of that line since end-use quality dictates marketability of the grain at this point in time. 2.4.2. Preliminary Yield Trials/Single Location (F5 to F6 ) Following selection for early generation, end-use quality potential, F5 seed is used to establish a single location field plot for initial yield evaluations during the following crop year. Due to seed limitations, multilocation, replicated field trial evaluation is not possible. Preliminary grain yield, grain volume, and GPC can be obtained from a single plot, and seed is increased to allow for more expansive agronomic evaluation in the future. During preliminary yield trial evaluation, agronomic data for traits such as plant height, heading date, disease resistances, grain yield, grain volume, and GPC are collected and analyzed. F6 seed from high yielding lines with desirable agronomic attributes is submitted to a regional wheat quality lab for small-scale milling and baking analyses, along with suitable quality checks. The quality traits discussed in the next sections are those analyzed by the USDA-ARS Western Wheat Quality Laboratory in Pullman, Washington (USDA-ARS 2007). The descriptions of these tests, how they are performed, and interpretation of results can be found on their website at http://www.wsu.edu/∼wwql/php/index.php.

2.4.2.1. Hardness To determine hardness, 300 kernels are individually analyzed using a SKCS Model 4100 (Perten Instruments). The mean and standard deviation from a 300-kernel sample are reported for four parameters: hardness, size, moisture, and weight. The machine weighs each kernel prior to dropping it between a rotor and crescent, which crushes it. The crescent has a load cell attachment that senses the size of the kernel, the amount of force needed to crush the kernel, and the moisture content of each kernel. The rotor is ribbed to sweep the crushed kernel past the crescent, preparing the machine for the next kernel. A 15-g subsample of each genotype also can be cyclone milled (UDY Corporation, Fort Collins, CO, USA) using a 0.5-mm screen, and the resulting whole wheat flour sample can be analyzed in a NIR spectrometer calibrated

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to standard Grain Inspection, Packers, and Stockyards Administration (GIPSA) NIR wheat grain hardness values (Approved Method 39-70A, AACC International 2000). Either method provides an estimate of grain hardness, although the SKCS method provides more information about kernel characteristics than the NIR method does.

2.4.2.2. Protein Content Protein concentration is determined by the near-infrared method (NIR) (Approved Method 39-11, AACC International 2000). Whole wheat protein is determined by using the AACC International Approved Method 39-10 (AACC International 2000) and flour protein is determined by using the AACC International Approved Method 39-11(AACC International 2000). These methods and calibrations are set forth by the manufacturer of the NIR spectrophotometer. If more precise measurements are required, 250 mg of the samples can be analyzed using the combustion method (Leco Model FP-428). Minor corrections to the NIR results can be made based on the results from the combustion method. Protein analysis using the combustion method (Approved Method 46-30, AACC International 2000) records the amount of nitrogen freed by pyrolysis and subsequent combustion in pure oxygen, and quantified by thermal conductivity detection. Percent protein is then calculated as Crude protein (%) = %N × 5.70 As explained in Section 2.1.4, protein content often dictates what types of end products a HW wheat cultivar is best suited for. Thus, it is important to obtain accurate GPC values as well as an assessment of the quality of that protein.

2.4.2.3. Milling Data—Quadrumat Grain selections from entries in preliminary yield trials are experimentally milled on a Quadrumat System as modified by Jeffers and Rubenthaler (1979). Milling characteristics of the grain are as important to millers as grain yield is to wheat producers. A minimum grain sample size of 500 g is needed to complete this test, and thus it is performed in later stages of the breeding process when seed quantities are more abundant. Flour yield is defined as the percentage by weight of the total products recovered as straight-grade white flour (USAD-ARS 2007). Large amounts of flour produced from a grain sample indicate larger quantities of products can be manufactured from that grain lot. High break-flour yield (the percentage by weight of the total products recovered as flour off the break rolls) is also a desirable trait. Break flour is economically important because it contains less damaged starch than other flours. It also can be an indication of the ease with which the endosperm can be separated from the bran. Flour ash is the percentage of ash generated from a 4-g sample of flour ignited and heated for 15 hours at 550 ◦ C in a muffle furnace (Approved Method 08-01, AACC International 2000). Since large amounts of ash can discolor the manufactured products, low percentages of ash are advantageous for HW wheat.

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2.4.2.4. Protein Quality HW wheat with strong gluten characteristics, an indication of protein quality, typically produces better end-use products. As a result, protein quality is evaluated using the SDS–sedimentation test following the methods of Mansur et al. (1990). SDS–sedimentation test results are reported as the mean of the volume of sediment (mL) per gram of flour averaged over the number of replicates. Larger volumes of sediment are desired as this indicates better protein quality. Another assessment of suitable protein quality for bread baking involves comparing the pup loaf volume of bread made from experimental breeding lines to a historical regression model that predicts loaf volume based on protein content (USDA-ARS 2007). If the loaf volume of the experimental line is within 25 cc of the historical check, then the protein quality ranking is set to 0. If the loaf volume of the experimental line differs from the predicted loaf volume by more than 25 cc, then the experimental line receives a protein quality ranking of “+1” or “−1.” A “+1” indicates that the experimental genotype has better protein quality than historical checks. Genotypes with protein quality equal to or exceeding historical checks should be selected and advanced in the breeding program. 2.4.2.5. Starch Quality Starch quality has a major impact on the end-use quality of HW wheat, especially on the eating properties of Japanese WSNs (Crosbie 1991; Konik et al. 1992; Kruger 1996). Starch quality is evaluated by measuring a hot-pasting viscosity, as measured by the Rapid Visco Analyzer (RVA). Three and a half (3.5) grams of flour on a 14% moisture basis, added to 25 mL water, is required for this test. The viscosity reported is the peak viscosity in RVA units (centipoise × 10). The temperature profile used to obtain the peak viscosity consists of 2 minutes at 60 ◦ C, then constant-rate heating to 93 ◦ C in 6 minutes with a final hold of 2 minutes at 93 ◦ C. The RVA emulates the Brabender amylograph for testing starch quality. Minimum RVA values would be near 125 with values above 210 desirable for noodle production. 2.4.2.6. Flour Functionality Mixograph tests are often conducted to assess flour functionality and determine gluten strength in HW wheat. Evaluating dough mixing properties is labor intensive and time consuming, and it requires large amounts of grain compared to the sedimentation test. Therefore, mixograph tests are performed late in the breeding process. A mixograph is conducted with 10 g of flour and the appropriate amount of water to provide optimum absorption. Run time is 5–8 minutes, which is sufficient time for most flours to exhibit their mixing time to peak and dough breakdown. For desirable bread-type flour, a mixograph should have high water absorption, moderately long mixing requirements (3–6 minutes), and good dough mixing tolerance. Good dough mixing tolerance indicates that bread dough should be elastic after mixing. Extremely long mixing times are undesirable as they require excessive power and time requirements not economical for a commercial bakery. Mixograph absorption, which is also calculated, is the optimum flour water absorption reported as a percent by weight (Approved Method 54-40A, AACC International 2000).

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2.4.2.7. Bread Quality Since consumer perception of the quality of a loaf of pan bread drives consumption of the product, it is essential to access bread loaf quality during the selection process. Many different parameters can be measured when producing a loaf of bread. Bread quality is determined using an optimum absorption, optimum mixing, 90-minute fermentation straight dough method using 100 g flour, 1.8% dry yeast, 1.5% salt, 6% sugar, 0.3% malt extract, 4% dry milk solids, 75 ppm ascorbic acid, and 3% partially hydrogenated shortening with monoglycerides and diglycerides (Approved Method 10-10B, AACC International 2000). Bake water absorption is the amount of water required to make dough of proper consistency for bread baking when mixed to optimum conditions. This is judged by an experienced baker using the baking method described above (Finney 1945). More water absorption indicates a larger, less expensive end product when using the same amount of flour. Mixing time is measured as the time in minutes required to mix the flour and the other bread dough constituents to the optimum condition as judged by an experienced baker (Finney and Barmore 1945). The lower the mixing time, the fewer resources (power, time, etc.) required to create the dough. The volume of a bread loaf, measured by canola seed displacement (cc), is also determined. In general, bread with high bake water absorption and large loaf volume is most desirable. 2.4.2.8. Yellow Alkaline Noodles (YANs) Color and texture are extremely important to the consumer of YANs. Thus, it is essential that experimental breeding lines are tested for manufacturing of YANs before advancement to multilocation trials. Alkaline noodles are prepared from a formula that contains 100 g flour (14% constant flour moisture basis), 0.5 g Na2 CO3 , 2 g NaCl, and 34 g water. The dough sheet and noodles are prepared with an Ohtake Laboratory Noodle Machine (Ohtake Manufacturing Co., Ltd., Tokyo, Japan). Color measurements are made using a Minolta CR-310 Chroma Meter set to the L*, a*, b* color system. Color readings are taken at 0 h and 24 h. Noodles with a high color reading are desirable, as this corresponds to a brighter noodle color. Noodles that exhibit little color change are superior due to low PPO enzyme activity. 2.4.2.9. Selection of Materials from Preliminary Yield Trials for Advancement After data are gathered from large-scale quality tests, selections are made by comparing results from experimental breeding material with agronomic and end-use quality checks that were included in the trials. Experimental lines that do not meet or exceed the agronomic and end-use quality standards of the checks in the nursery are eliminated from cultivar release consideration. Lines with acceptable agronomic and end-use quality attributes are advanced to multilocation, replicated field trials. This process has been used to release two HWS wheat cultivars, “Macon” and “Otis” from Washington State University’s spring wheat breeding and genetics program (Kidwell et al. 2003, 2006). These two cultivars have excellent agronomic performance in the Pacific Northwest region of the United States, as well as acceptable bread- and noodle-making end-use qualities.

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2.4.3. Multilocation Yield Trials (F7 and Beyond) Advanced lines (F7 ) with superior agronomic and end-use quality potential enter replicated, multilocation yield trial evaluations where detailed notes on field performance, including grain yield, grain volume, plant height, heading date, disease and insect resistance ratings, and various other agronomic characteristics, are recorded. Locations are selected to represent the range of production conditions across the region. Stringent selection pressure for agronomic performance is applied to later generation material since ample data is available to access performance stability across locations. Only high-yielding lines with superior agronomic performance across production conditions are selected for end-use assessment. Quality data collected is the same as for multilocation yield trials as was described for preliminary yield trials except the following tests, which require large volumes of grain, are also conducted.

2.4.3.1. Milling Data—Buhler Experimental Mill Grain samples (2000 g) of experimental breeding line selections from multilocation yield trials are milled on a Buhler MLU-202 pneumatic laboratory mill (Approved Method 26-21, AACC International 2000). The samples are tempered to a predetermined moisture content of 14% for HW wheat. The wheat is allowed to temper for 16–24 hours before milling to permit uniform distribution of the moisture. Additional 0.5% water is added 15–20 minutes prior to milling. The first and second break, and first and second reduction streams, predict long patent flour yield. All six flour streams are then combined to make straight-grade white flour by sifting on a 120 stainless steel wire screen and thoroughly blending. Milling time is determined by the amount of time required in minutes to mill a 2-kg sample with the Buhler experimental mill and obtaining normal separation of bran, shorts, and flour. Time is dependent on adjustments made by an experienced miller after visually observing the milling properties. After milling, a milling score is calculated using the following formula: Milling score = 100 − [(80 − flour yield) + 50 (flour ash − 0.30) + 0.48 (milling time − 12.5) + 0.5 (65 − percent long patent) + 0.5 (16 − first tempering moisture)] Experimental lines with high flour yield, low flour ash, low milling time, and high milling scores are most desirable.

2.4.3.2. White Salted Noodles (WSNs) The quality of WSNs, another important end product of HW wheat, is determined by color and texture, and thus should be tested before cultivar release decisions are made. WSNs are made from a formula that contains 300 g flour, 6.0 g NaCl, and 96 g water (14% constant flour moisture basis) with dough sheet and noodles prepared as in the alkaline noodle test. Often, optimum water absorption is used as opposed to constant absorption. Color measurements are made with a Minolta CR-310 Chroma Meter set to the L*a*b* color system. Color measurements are taken at 0 h and 24 h. Noodle yield is determined by the noodle weight increase, which is the percentage of

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weight increase of cooked noodles relative to raw noodles. A cooked noodle texture score is assigned by a sensory panel, which considers factors such as chewiness, firmness and/or softness, springiness, elasticity, and other bite characteristics. Scores assigned to the experimental cooked noodles can range from 1 to 40. The standard control cooked noodle is assigned a score of 32. Texture measurements can also be determined using instrumental analysis. Instrumental analysis can be used to determine noodle softness and elasticity, as well as brightness, yellowness, and discoloration. Yun et al. (1997) reported significant correlations between instruments and sensory predictions for softness, elasticity, and yellowness. Brightness and discolorations were significantly correlated but did not account for sufficient variation for robust relationships. Although significant correlations were identified, direct use of instrumental assessment requires further refinement as no universal procedures or standards have been published. Depending on the necessity of accuracy, instrumental noodle tests may be applied for quick screening of WSN quality.

2.5. CULTIVAR RELEASE SELECTION/LARGE-SCALE END-USE QUALITY TESTS Experimental HW wheat breeding lines with acceptable agronomic and end-use quality characteristics are selected and advanced to the next generation (F8 +) for field evaluation in replicated trials at multiple locations (10 to 20) representing the range of agronomic production zones targeted for commercial production. Advanced lines with cultivar release potential are evaluated in multiple regional, state, multistate, and USDA agronomic performance trials to assess agronomic performance in diverse environments for at least two years. After the first year, lines that do not perform to expectation are eliminated and are replaced by upcoming lines with promising potential. End-use quality characteristics, including kernel hardness, grain protein content, flour yield, break-flour yield, flour ash, milling score, flour protein content, mixing absorption, mixing type, cookie- or bread-baking quality, noodle color, and RVA values are determined for promising advanced lines using the AACC International Approved Methods (AACC International 2000) as described previously. An optional final quality evaluation on large-scale industry equipment can be performed by submitting cultivars to regional wheat quality councils. In the Pacific Northwest, grain samples of 170 pounds are submitted to the USDA Western Wheat Quality Lab (Pullman, WA), where they are milled using a MIAG mill. Samples of flour are then sent to various mills, bakeries, and laboratories around the United States for evaluation. Samples are evaluated using each company’s internal processes and standards. End-use products are made and compared to accompanying check cultivars for desirable quality attributes. Results are compiled and returned to the various breeders. The mission of the council is to enhance the quality of wheat produced in the region by promoting the development of superior cultivars (Wheat Quality Council 2009). Superior cultivars maintain the market demand for HW wheat

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in the United States and globally since millers and bakers receive the high end-use quality wheat they desire. Based on these product comparisons, cultivar release candidates and new cultivars can be compared to commercially grown cultivars to evaluate end-use quality potential. Most cultivars are best suited for one or two end-use products based on their quality characteristics. Few cultivars are suited for multiple end-use products, in part because protein content and quality dictates product use for HW wheat. Dual-purpose wheat accommodates multiple uses for bread and noodle making. Dual-purpose cultivars have exceptional end-use quality and can be grown in a wide range of environments, resulting in varying protein contents of resulting grain lots based on agricultural production practices. Experimental lines that equal or exceed agronomic and end-use quality standards over multiple sites/years are released for commercial production through the guidelines established by each institution or company.

2.6. SUMMARY The end-use quality of HW wheat drastically affects its marketability to end users. HW wheat must meet the agronomic performance demands of the grain producer while maintaining the high end-use quality standards set forth by the milling and baking industry. This requires that both agronomic and end-use quality screening begins early and simultaneously in the breeding process. Early generation assessment identifies superior agronomic and end-use quality potential prior to multilocation yield trials, thus efficiently utilizing resources in a breeding program. Utilization of stringent selection strategies for agronomic and end-use quality traits in both early and late generation breeding material enhances selection of high-yielding cultivars with desirable end-use quality. End-use products manufactured with HW wheat are diverse, thus HW wheat cultivars should be bred and marketed with specific endproduct targets in mind. Selection strategies similar to those outlined in this chapter allow for efficient development of HW wheat cultivars with end-use quality desirable for Asian noodle and Western pan bread production.

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Anderson, J. V. and Morris, C. F. 2001. An improved whole-seed assay for screening wheat germplasm for polyphenol oxidase activity. Crop Sci. 41:1697–1705. Avivi, L. 1978. High protein content in wild tetraploid Triticum dicoccoides Korn. In: S. Ramunujam (ed.), Proceedings of the 5th International Wheat Genetics Symposium. Indian Society of Genetics and Plant Breeding (ISGPB), New Delhi, India, pp. 372–380. Baik, B.-K., Czuchajowska, Z., and Pomeranz, Y. 1994a. Comparison of polyphenol oxidase in wheats and flours from Australian and U.S. cultivars. J. Cereal Sci. 19:291–296. Baik, B.-K., Czuchajowska, Z., and Pomeranz, Y. 1994b. Role and contribution of starch and protein contents and quality to texture profile analysis of Oriental noodles. Cereal Chem. 71:315–320. Baik, B.-K., Czuchajowska, Z., and Pomeranz, Y. 1995. Discoloration of dough for Oriental noodles. Cereal Chem. 72:198–205. Bass, E. J. 1988. Wheat flour milling. In: Y. Pomeranz (ed.), Wheat Chemistry and Technology. American Association of Cereal Chemists, St. Paul, MN, USA, pp. 1–68. Batey, I. L., Curtin, B. M., and Moore, S. A. 1997. Optimization of Rapid-Visco Analyzer test conditions for predicting Asian noodle quality. Cereal Chem. 74:497–501. Bernardo, R. 2002. Breeding for Quantitative Traits in Plants, Stemma Press, Woodbury, MN, USA. Bettge, A. D., Morris, C. F., and Greenblatt, G. A. 1995. Assessing genotypic softness in single wheat kernels using starch granule-associated friabilin as a biochemical marker. Euphytica 86:65–72. Bhatt, G. M. 1973. Comparison of various methods of selection parents for hybridization in common bread wheat (Triticum aestivum L.). Australian J. Agric. Res. 24:457–464. Boland, M. and Dhuyvetter, K. C. 2002. Economic issues with milling hard white wheat. Kansas State University, Manhattan, KS, USA. Briggle, L. W. and Curtis, B. C. 1987. Worldwide wheat. In: E. G. Heyne (ed.), Wheat and Wheat Improvement, Agronomy Monograph 13. ASA/CSSA/SSSA, Madison, WI, USA, pp. 1–31. Briney, A., Wilson, R., Potter, R. H., Barclay, I., Crosbie, G., Appels, R., and Jones, M. G. K. 1998. A PCR-based marker for selection of starch and potential noodle quality in wheat. Mol. Breeding 4:427–433. Carter, A., Blahnik, A., Koenig, R., Shelton, G., DeMacon, V., and Kidwell, K. 2007. Assessing the impact of early senescence on grain protein content in spring wheat varieties (Triticum aestivum L.). Agronomy Abstracts. American Society of Agronomy, Madison, WI, USA. Carter, B. P., Morris, C. F., and Anderson, J. A. 1999. Optimizing the SDS sedimentation test for end-use quality selection in a soft white and club wheat breeding program. Cereal Chem. 76:907–911. Chao, S., Sharp, P. J., Worland, A. J., Warham, E. J., Koebner, R. M. D., and Gale, M. D. 1989. RFLP-based genetic maps of wheat homoeologous group 7 chromosomes. Theor. Appl. Genetics 78:495–504. Crosbie, G. B. 1991. The relationship between starch swelling properties, paste viscosity and boiled noodle quality in wheat flours. J. Cereal Sci. 13:145–150. Crosbie, G. B., Solah, V. A., Chiu, P., and Lambe, W. J. 1996. Selecting for improved colour stability in noodles. In: C. W. Wrigley (ed.), Proceedings of the 46th Australian Cereal Chemistry Conference. Royal Australian Chemistry Institute, Sydney, North Melbourne, VIC, Australia, pp. 120–122.

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Crosbie, G. B., Ross, A. S., Moro, T., and Chiu, P. C. 1999. Starch and protein quality requirements of Japanese alkaline noodles (Ramen). Cereal Chem. 76:328–334. Davies, J. and Berzonsky, W. A. 2003. Evaluation of spring wheat quality traits and genotypes for production of Cantonese Asian noodles. Crop Sci. 43:1313–1319. Delwiche, S. R. 1995. Single wheat kernel analysis by near-infrared transmittance: protein content. Cereal Chem. 72:11–16. DePauw, R. M. and Townley-Smith, T. F. 1988. Patterns of response for genotypes, grain yield and protein content in seven environments. In: T. E. Miller and R. M. D. Koebner (eds.), Proceedings of the 7th International Wheat Genetics Symposium. Institute of Plant Science Research, Cambridge, UK. Derera, N. F. 1989. Preharvest field sprouting in cereals. N. F. Derera (ed.), CRC Press Inc., Boca Raton, FL, USA, pp. 1–184. Dexter, J. E., Preston, K. R., Matsuo, R. R., and Tipples, K. H. 1984. Development of a high extraction flow for the GRL Pilot Mill to evaluate Canadian wheat potential for the Chinese market. Can. Institute Food Sci. Technol. 14:253–259. Eckert, B., Amend, T., and Belitz, H. D. 1993. The course of the SDS and Zeleny sedimentation tests for gluten quality and related phenomena studies using the light microscope. Z. Lebensm Unters Forsch. 196:122–125. Epstein, J., Morris, C. F., and Huber, K. C. 2002. Instrumental texture of white salted noodles prepared from recombinant inbred lines of wheat differing in the three granule bound starch synthase (waxy) genes. J. Cereal Sci. 35:51–63. Entz, M. H. and Fowler, D. B. 1991. Agronomic performance of winter versus spring wheat. Agronomy J. 83:527–532. Faridi, H. 1988. Flat breads. In: Y. Pomeranz (ed.), Wheat Chemistry and Technology. American Association of Cereal Chemists, St. Paul, MN, USA, pp. 457–506. Finney, K. F. 1945. Methods of estimating and the effect of variety and protein level on the baking absorption of flour. Cereal Chem. 22:149–158. Finney, K. F. and Barmore, M. A. 1945. Optimum vs. fixed mixing time at various potassium bromate levels in experimental bread baking. Cereal Chem. 22:244–254. Finney, K. F., Yamazaki, W. T., Youngs, V. L., and Rubenthaler, G. L. 1987. Quality of hard, soft, and durum wheat. In: E. G. Heyne (ed.), Wheat and Wheat Improvement. ASA/CSSA/SSSA, Madison, WI, USA, pp. 677–748. Fowler, D. B. 2003. Crop nitrogen demand and grain protein concentration of spring and winter wheat. Agronomy J. 95:260–265. Fu, D., Szucs, P., Yan, L., Hulguera, M., Skinner, J. S., von Zitzewitz, J., Hayes, P. M., and Dubcovsky, J. 2005. Large deletions in the first intron in VRN-1 are associated with spring growth habit in barley and wheat. Mol. Genetics Genomics 273:54–65. Gauer, L. E., Grant, C. A., Gehl, D. T., and Bailey, L. D. 1992. Effects of nitrogen fertilization on grain protein content, nitrogen uptake, and nitrogen use efficiency. in six spring wheat (Triticum aestivum L.) cultivars, in relation to estimated moisture supply. Can. J. Plant Sci. 72:235–541. Geera, B. P., Nelson, J. E., Souza, E., and Huber, K. C. 2006. Granule bound starch synthase I (GBSSI) gene effects related to soft wheat flour/starch characteristics and properties. Cereal Chem. 83:544–550. Groos, C., Gay, G., Perretant, M.-R., Gervais, L., Bernard, M., Dedryver, F., and Charmet, G. 2002. Study of the relationship between pre-harvest sprouting and grain color by

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quantitative trait loc analysis in a white × red grain bread–wheat cross. Theor. Appl. Genetics 104:39–47. Hagemann, M. G., and Chia, A. J. 1987. Environmental x genotype effects on seed dormancy and after-ripening in wheat. Agron. J. 79:192–196. Hatcher, D. W. and Kruger, J. E. 1993. Distribution of polyphenol oxidase in flour millstreams of Canadian common wheat classes milled to three extraction rates. Cereal Chem. 70:51–55. Heslop-Harrison, J. S. 2002. Exploiting novel germplasm. Australian J. Agric. Res. 53:873– 879. Hou, G. 2001. Oriental noodles. Adv. Food Nutr. Res. 43:143–193. Hou, G. 2007. Asian Products Collaborative Project Report. Wheat Marketing Center, Portland, OR, USA. Huang, S. and Morrison, W. R. 1988. Aspects of proteins in Chinese and British common (hexaploid) wheats related to quality of white and yellow Chinese noodles. J. Cereal Sci. 8:177–187. Hurry, V. M. and Huner, N. P. A. 1991. Low growth temperature affects a differential inhibition of photosynthesis in spring and winter wheat. Plant Physiol. 96:491–497. Imtiaz, M., Ogbonnaya, F. C., Oman, J., and van Ginkel, M. 2008. Characterization of quantitative trait loci controlling genetic variation for preharvest sprouting in synthetic backcrossderived wheat lines. Genetics 178:1725–1736. Jeffers, H. C. and Rubenthaler, G. L. 1979. Effect of roll temperature on flour yield with the Brabender Quadrumat experimental mills. Cereal Chem. 54:1018–1025. Jimenez, M. and Dubcovsky, J. 1999. Chromosome location of genes affecting polyphenol oxidase activity in seeds of common and durum wheat. Plant Breeding 118:395–398. Joppa, L. R., Du, C., Hart, G. E., and Hareland, G. A. 1997. Mapping a QTL for grain protein in tetraploid wheat (Triticum turgidum L.) using a population of recombinant inbred chromosome lines. Crop Sci. 37:1586–1589. Kade, M. A., Barneix, J., Olmos, S., and Dubcovsky, J. 2005. Nitrogen uptake and remobilization in tetraploid Langdon durum wheat and a recombinant substitution line with the high grain protein gene Gpc-B1. Plant Breeding 124:343–349. Kansas State University. 2001. Hard White Wheat Color Standard. Available at http//www .oznet.edu/pr wrc/newbrief%203.htm (accessed October 19, 2007). Kidwell, K. K., DeMacon, V. L., Shelton, G. B., Burns, J. W., Carter, B. P., Morris, C. F., Chen, X. M., and Bosque-P´erez, N. A. 2003. Registration of “Macon” wheat. Crop Sci. 43:1561–1563. Kidwell, K. K., DeMacon, V. L., Shelton, G. B., Burns, J. W., Carter, B. P., Chen, X. M., Morris, C. F., and Bosque-P´erez, N. A. 2006. Registration of “Otis” wheat. Crop Sci. 46:1386–1387. Konik, C. M., Miskelly, D. M., and Gras, P. W. 1992. Contribution of starch and non-starch parameters to the eating quality of Japanese white salted noodles. J. Sci. Food Agric. 58:403–406. Konik, C. M., Miskelly, D. M., and Gras, P. W. 1993. Starch swelling power, grain hardness, and protein: relationship to sensory properties of Japanese noodles. Starch 45:139–144. Konik, C. M., Mikkelsen, L. M., Moss, R., and Gore, P. J. 1994. Relationships between physical starch properties and yellow alkaline noodle quality. Starch 46:292–299. Kruger, J. E. 1996. Noodle quality—what can we learn from the chemistry of breadmaking? In:

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J. E. Kruger, R. B. Matsuo, and J. W. Dick (eds.), Pasta and Noodle Technology. American Association of Cereal Chemists, St. Paul, MN, USA, pp. 157–167. Kuchel, H., Langridge, P., Mosionek, L., Williams, K., and Jefferies, S. P. 2006. The genetic control of milling yield, dough rheology and baking quality of wheat. Theor. Appl. Genetics 112:1487–1495. Kulwal, P. L., Kumar, N., Gaur, A., Khurana, P., Khurana, J. P., Tyagi, A. K., Balyan, H. S., and Gupta, P. K. 2005. Mapping of a major QTL for pre-harvest sprouting tolerance on chromosome 3A in bread wheat. Thero. Appl. Genetics 111:1052–1059. Kuraparthy, V., Sood, S., and Gill, B. S. 2008. Targeted genomic mapping of a red seed color gene (R-A1) in wheat. Crop Sci. 48:S37–S48. Lang, C. E., Lanning, S. P., Carlson, G. R., Kushnak, G. D., Bruckner, P. L., and Talbert, L. E. 1998. Relationship between baking and noodle quality in hard white spring wheat. Crop Sci. 38:823–827. Law, C. N., Young, C. F., Brown, J. W. S., Snape, J. W., and Worland, J. W. 1978. The study of grain protein control in wheat using whole chromosome substitution lines. In: Seed Protein Improvement by Nuclear Techniques. International Atomic Energy Agency, Vienna, Austria, pp. 483–502. Lyford, C. P., Kidd, W., Rayas-Duarte, P., and Deyoe, C. 2004. Prediction of flour extraction rate in hard red winter wheat using the single kernel characterization. J. Food Quality 28:279–288. Manley, D. J. R. 2000. Technology of Biscuits, Crackers, and Cookies. Woodhead Publishing, Cambridge, UK. Mansur, L. M., Qualset, C. O., Kasarda, D. D., and Morris, R. 1990. Effects of “Cheyenne” chromosomes on milling and baking quality in “Chinese spring” wheat in relation to glutenin and gliadin storage proteins. Crop Sci. 30:593–602. Mares, D. J. 1987. Pre-harvest sprouting tolerance in white-grained wheat. In: S. J. Mares (ed.), Fourth international symposium on preharvest sprouting in cereals. Westview Press, Boulder, CO, USA, pp. 64–74. Marsh, D. R. and Galliard, T. 1986. Measurement of polyphenol oxidase activity in wheatmilling fractions. J. Cereal Sci. 4:241–248. Matus-C´adiz, M. A., Hucl, P., Perron, C. E., and Tyler, R. T. 2003. Genotype × environment interaction for grain color in hard white spring wheat. Crop Sci. 4:219–226. Matuz, J. 1998. Inheritance of SDS sedimentation volume of flour in crosses of winter wheat (Triticum aestivum L.). Cereal Res. Commun. 26:203–210. McCaig, T. N. and DePauw, R. M. 1992. Breeding for preharvest sprouting tolerance in wheat-seed-coat spring wheat. Crop Sci. 32:19–23. McCallum, J. A. and Walker, J. R. L. 1990. O-diphenol oxidase activity, phenolic content and colour of New Zealand wheats, flours and milling streams. J. Cereal Sci. 12:83–96. McLauchlan, A., Ogbonnaya, F. C., Holliingsworth, B., Carter, M., Gale, K. R., Henry, R. J., Holton, T. A., Morell, M. K., Rampling, L. R., Sharp, P. J., Shariflou, M. R., Jones, M. G. K., and Appels, R. 2001. Development of robust PCR-based DNA markers for each homoeo-allele of granule-bound starch synthase and their application in wheat breeding programs. Australian J. Agric. Res. 52:1409–1416. Mesfin, A., Frohberg, R. C., and Anderson, J. A. 1999. RFLP markers associated with high grain protein from Triticum turgidum L. var. dicoccoides introgressed into hard red spring wheat. Crop Sci. 39:508–513.

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Miskelly, D. M. 1996. The use of alkali for noodle processing. In: J. E. Kruger, R. B. Matsuo, and J. W. Dick (eds.), Pasta and Noodle Technology. American Association of Cereal Chemists, St. Paul, MN, USA, pp. 227–273. Miskelly, D. M. and Moss, H. J. 1985. Flour quality requirements for Chinese noodle manufacture. J. Cereal Sci. 3:379–387. Morris, C. F. 2002. Puroindolines: the molecular genetic basis of wheat grain hardness. Plant Mol. Biol. 48:633–647. Moss, H. J. 1980. The pasting properties of some wheat starches free of sprout damage. Cereal Res. Commun. 8:297–302. Murai, J., Taira, T., and Ohta, D. 1999. Isolation and characterization of the three Waxy genes encoding the granule-bound starch synthase in hexaploid wheat. Gene 234:71–79. Nakamura, T., Yamamori, M., Hirano, H., Hidaka, S., and Nagamine, T. 1995. Production of waxy (amylose-free) wheats. Mol. Gen. Genetics 248:253–259. Nieto-Taladrix, M. T., Perretant, M. R., and Rousset, M. 1994. Effect of gliadins and HMW and LMW subunits of glutenin on dough properties in the F6 recombinant inbred lines from a bread wheat cross. Theor. Appl. Genetics 88:81–88. O’Brien, L. and Panozzo, J. F. 1988. Breeding strategies for the simultaneous improvement of grain yield and protein content. In: T. E. Miller and R. M. D. Koebner (ed.), Proceedings of the 7th International Wheat Genetics Symposium. Institute of Plant Science Research, Cambridge, UK. Oda, M., Yasuda, Y., Okazaki, S., Yamauchi Y., and Yokoyama, Y. 1980. A method of flour quality assessment for Japanese noodles. Cereal Chem. 57:253–254. Olmos, S., Distelfeld, A., Chicaiza, O., Schlatter, A. R., Fahima, T., Echenique, V., and Dubcovsky, J. 2003. Precise mapping of a locus affecting grain protein content in durum wheat. Theor. Appl. Genetics 107:1243–1251. Payne, P. I., Holt, L. M., Jackson, E. A., and Law, C. N. 1984. Wheat storage proteins: their genetics and their potential for manipulation in plant breeding. Philos. Trans. R. Soc. London B 304:359–371. Pe˜na, R. J. and Pfeiffer, W. H. 2005. Breeding methodologies and strategies for durum wheat quality improvement. In: Durum Wheat Breeding. The Hawthorne Press, New York, NY, USA, pp. 663–702. Raman, R., Raman, H., Johnstone, K., Lisle, C., Smith, A., Matin, P., and Allen, H. 2005. Genetic and in silico comparative mapping of the polyphenol oxidase gene in bread wheat (Triticum aestivum L.). Functional Integrative Genomics 5:185–200. Ross, A. S. 2006. Instrumental measurement of physical properties of cooked Asian wheat flour noodles. Cereal Chem. 83:42–51. Seib, P. A., Liang, X., Guan, Y. T., Liang, Y. T., and Yang, H. C. 2000. Comparison of Asian noodles from some hard white and hard red wheat flours. Cereal Chem. 77:816–822. Simpson, G. M. 1990. Seed Dormancy in Grasses. Cambridge University Press, Cambridge, UK. Sleper, D. A. and Poehlman, J. M. 2006. Breeding self-pollinated crops. In: Breeding Field Crops, 5th edition. Blackwell Publishing, Ames, IA, USA, pp. 137–154. Souza, E. J., Martin, J. M., Guttieri, M. J., O’Brien, K. M., Habernicht, D. K., Lanning, S. P., McLean, R., Carlson, G. R., and Talbert, L. E. 2004. Influence of genotype, environment, and nitrogen management on spring wheat quality. Crop Sci. 44:425–432.

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Tanaka, Y., Miura, H., Fukushima, M., Ito, M., Nishio, Z., Kim, S.-J., Hashimoto, N., Noda, T., Takigawa, S., Matsuura-Endo, C., and Yamauchi, H. 2006. Physical properties of yellow alkaline noodles from near-isogenic wheat lines with different Wx protein deficiency. Starch 58:186–195. Tanksley, S. D. and Nelson, J. C. 1996. Advanced backcross QTL analysis: a method for the simultaneous discovery and transfer of valuable QTLs form unadapted germplasm into elite breeding lines. Theor. Appl. Genetics 92:191–203. Uauy, C., Brevis, J. C., and Dubcovsky, J. 2006. The high grain protein content gene Gpc-B1 accelerates senescence and has pleiotropic effects on protein content in wheat. J. Exp. Botany 57:2785–2794. Upadhyay, M. P., Paulsen, G. M., Heyne, E. G., Sears, R. G., and Hoseney, R. C. 1984. Development of hard white winter wheats for a hard red winter region. Euphytica 33:865–874. USDA-ARS. 2007. United States Department of Agriculture—Agriculture Research Service, Western Wheat Quality Laboratory Wheat Analysis System. Available at http://www.wsu .edu/∼wwql/php/index.php (accessed October 19, 2007). USDA-FAS. 2007. World Agriculture Production: Current Report. Available at http:// www.pecad.fas.usda.gov/wap current.cfm# (accessed October 25, 2007). USDA-NAAS. 2007. United States Department of Agriculture National Agricultural Statistics Service. Available at http://www.nass.usda.gov/ (accessed October 4, 2007). Utz, H. F., Bohn, M., and Melchinger, A. E. 2001. Predicting progeny means and variances of winter wheat crosses from phenotypic values of their parents. Crop Sci. 41:1470–1478. Wang, D., Dowell, F. E., and Lacey, R. E. 1999. Predicting the number of dominant R alleles in single wheat kernels using visible and near-infrared reflectance spectra. Cereal Chem. 76:6–8. Wang, J., Eagles, H. A., Trethowan, R., and van Ginkel, M. 2005. Using computer simulation of the selection process and known gene information to assist in parental selection in wheat quality breeding. Australian J. Agric. Res. 56:465–473. Wheat Quality Council. 2009. Pacific Northwest Wheat Quality Council. January 27 to 29, Sacramento, CA. Wicki, W., Winzeler, M., Schmid, J. E., Stamp, P., and Messmer, M. 1999. Inheritance of resistance to leaf and glume blotch caused by Septoria nodorum Berk. in winter wheat. Theor. Appl. Genetics 99:1265–1272. Wu, J. and Craver, B. F. 1999. Sprout damage and preharvest sprout resistance in hard white winter wheat. Crop Sci. 39:441–447. Yamamori, M., Nakamura, T., Endo, T. R., and Nagamine, T. 1994. Waxy protein deficiency and chromosomal location of coding genes in common wheat. Theor. Appl. Genetics 89:179–184. Yun, S.-H., Rema, G., and Quail, K. 1997. Instrumental assessments of Japanese white salted noodle quality. J. Sci. Food Agric. 74:81–88. Zeng, M., Morris, C. F., Batey, I. L., and Wrigley, C. W. 1997. Sources of variation for starch gelatinization, pasting, and gelation properties in wheat. Cereal Chem. 74:63–71. Zhang, Y., Quail, K., Mugford, D. C., and He, Z. 2005. Milling quality and white salted noodle color of Chinese winter wheat cultivars. Cereal Chem. 82:633–638. Zhao, L. F. and Seib, P. A. 2005. Alkaline-carbonate noodles for hard winter wheat flours varying in protein, swelling power, and polyphenol oxidase activity. Cereal Chem. 82:504–516.

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CHAPTER 3

Wheat Milling and Flour Quality Analysis for Noodles in Japan HIDEKI OKUSU, SYUNSUKE OTSUBO, and JAMES DEXTER

3.1. INTRODUCTION Japanese noodle flour must be prepared so that it has the characteristics that suit the preferences of Japanese consumers (Oda 1982). Japanese eating habits have been influenced mainly by rice, leading to the so-called “Rice Culture.” That is the reason the preferred properties of cooked noodles are strongly influenced by the nature of cooked rice (although the habit of eating noodles in Japan has a long history of 1000 years or more). Over one million metric tons of noodle flour is consumed annually in Japan. The approximate percentages of noodles by type are (1) instant noodles, 33%; (2) yellow alkaline noodles, 28%; (3) Japanese white salted (udon) noodles, 21%; (4) dried noodles, 11%; and (5) others, including buckwheat (soba) noodles, 6%. The desirable attributes of cooked noodles in Japan are as follows: 1. When in contact with the mouth and tongue, the surface should feel smooth and slippery, never rough or adhering. 2. When chewed, the texture has a good balance between softness, elasticity, and degree of stickiness. 3. The noodles have a bold shape. 4. The noodle surface is lustrous, and the noodles are bright and free of bran specks. Generally, the major noodle brands that have appeared on the market in Japan have the above features. As will be described below, the exact properties preferred for a specific noodle type differ. The majority of wheat used in blends for noodle

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production is imported from Australia, the United States, and Canada. Some domestic soft wheat is used in blends for Japanese white salted noodles and instant noodles.

3.2. WHEAT SELECTION 3.2.1. Wheat Hardness Wheat can roughly be classified according to kernel hardness as either soft or hard. In general, soft wheat is used for Japanese white salted noodles, whereas hard wheat is used for yellow alkaline noodles (Nagao 1995). Wheat hardness is a genetic trait (Giroux and Morris 1998). Soft wheat is predominantly opaque (nonvitreous) in appearance, whereas hard wheat is more translucent (vitreous). This difference in appearance is due to the more open structure of the soft wheat endosperm (Hoseney and Seib 1973). The hardness of wheat has an influence on the milling process (Bass 1988; Sarkar 2003; Dexter and Sarkar 2004; Posner and Hibbs 2004). The particle size of soft wheat flour is finer than hard wheat flour and, generally, soft wheat flour is lower in protein content than hard wheat flour. Soft wheat breaks down more quickly than hard wheat, and the stock is stickier and fluffier, making it more difficult to sift. Thus, soft wheat requires greater sifting capacity and is fed to the mill more slowly to facilitate sifting and to ensure that stock flows freely through the mill. The finer particle size and lower protein of soft wheat flour gives the soft and elastic bite and smooth surface desired for Japanese white salted noodles (Crosbie and Ross 2004). On the other hand, the higher protein content of hard wheat flour gives the springiness and firmness desired for yellow alkaline noodles (Miskelly and Moss 1985). In Japan, most domestic wheat is soft wheat. Unfortunately, until recently Japanese soft wheat had some milling deficiencies. The bran did not separate efficiently during grinding and sifting, resulting in bran contamination in the flour and dark flour color. Therefore, it was used in small proportions in blends with Australian wheat for Japanese white salted noodles and as part of a blend for instant noodles. However, the Japanese wheat breeding program is making progress, and the milling and noodlemaking qualities (texture and color) of domestic wheat have improved in recent years. White salted noodles from purely 100% domestic wheat are now being marketed. 3.2.2. Starch Properties Wheat with high starch paste peak viscosity and high starch swelling properties are preferred for Japanese white salted noodles to impart the desired soft, smooth, and elastic textural properties (Oda et al. 1980; Fu 2008). The pasting characteristics of wheat starch are independent of wheat hardness. Wheat starch pasting temperatures and the rheological properties of wheat starch gel are related to genetic mutations associated with genes that encode isoforms of granule-bound starch synthase enzymes, which influence the amylose content of wheat starch (Baik and Lee 2003a;

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Epstein et al. 2002; Nakamura et al. 1992; Sasaki et al. 2007; Van Hung et al. 2008). There are three genes in all. The presence of one or two mutations reduces wheat starch amylose content to significantly less than the normal 25% (referred to as partially waxy), whereas the presence of all three mutations results in amylose content of less than 5% (referred to as waxy). Lower amylose content in wheat starch is associated with lower pasting onset temperature and lower peak temperature, higher peak viscosity, and lower final viscosity (Baik and Lee 2003b). Partially waxy wheat, with its lower final viscosity, is associated with softer noodle texture, an asset for white salted noodles (Epstein et al. 2002). Partially waxy wheat is undesirable for yellow alkaline noodles because a firm texture is preferred (Ross et al. 1997). It is not possible to give exact specifications for amylograph pasting properties for noodles in Japan, because many commercial flours with a wide range of properties are marketed for a given noodle type to meet the requirements of a very diverse industry. A typical amylograph pasting curve for Japanese white salted noodles is shown in Figure 3.1 in comparison to typical pasting curves for yellow alkaline noodles, dried thin white salted noodles, and instant noodles. The higher peak viscosity

1000 BU

1000 BU

White salted noodle (Udon)

30

45

60

Yellow alkaline noodle

75

90

45

60

75

90

60

75

90

1000 BU

1000 BU

Dry white thin noodle

30

30

45

FIGURE 3.1

60

Instant noodle

75

90

30

45

Typical amylograph curves for some types of noodles consumed in Japan.

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and lower starch pasting temperature of the white salted noodle flour are clearly evident. 3.2.3. Wheat Color Noodles can be made from either red wheat or white wheat. However, white wheat has an advantage over red wheat for making noodles because the bran specks from white wheat are less conspicuous (Ambalamaatil et al. 2002). This is particularly true for fresh noodles, because bran specks become more prevalent with increasing storage time after processing. 3.2.4. Wheat Physical Condition and Protein Content The quality of wheat is affected by genotype and by growing conditions. Therefore, it is necessary to be aware of the condition of the crop each year, and to clearly understand the quality of wheat. According to the results of wheat testing, adjustments can be made to wheat blends and to flour yield expectations. Test weight, a measure of the specific weight of wheat, is a rough index of wheat soundness and kernel plumpness and is used internationally as an indicator of flour yield potential (Hook 1984). Low test weight is associated with lower flour yield. In addition, lower test weight may also be indicative of more damaged kernels (sprouted, diseased, immature, shrunken, frozen, etc.), which are detrimental to the quality of the flour (Dexter and Edwards 1998). The bran becomes more susceptible to shattering to various degrees, depending on the type of damage and the extent of damage. The flour and the noodles become darker and have more specks (Hatcher and Symons 2000a; Hatcher et al. 2003). Flour ash content, which is a marker for bran contamination, increases. Although the water content of noodles is relatively low, the effects of sprout damage on noodle quality can be nearly as serious as for bread quality. The presence of severely sprouted kernels and associated high levels of alpha-amylase activity may have a negative impact on fresh noodle texture (Kruger et al. 1996). Fusarium-damaged kernels are known to cause weaker gluten properties and can impart significant loss of cooked noodle texture (Hatcher et al. 2003). Nevertheless, for production of high quality noodles, wheat with very low levels of damaged kernels is required. Wheat protein content is an important determinant of noodle quality. As flour protein content increases, noodle firmness increases. Thus, the optimal flour protein for Japanese white salted noodles is lower than for yellow alkaline noodles (Miskelly 1998). As protein content increases, flour becomes darker and, accordingly, noodle brightness is reduced (Oh et al. 1985). 3.2.5. Wheat Blending In general, Japanese millers blend several kinds of wheat for noodle flour. Each wheat type has distinct quality attributes that make it best suited for a given noodle product. But, it is very difficult to maintain consistency of quality and supply using a single

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TABLE 3.1

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Typical Wheat Blends Used for Various Types of Noodles in Japan

Noodle Type

Wheat Blenda

White salted noodles (“udon”) Yellow alkaline noodles (“Chinese noodles”) White thin noodles (“Hiyamugi” and “somen”) Instant noodles

ASWNB, Domestic, WW CWRS, DNS, HRW, APH DNS, ASWNB, Domestic CWRS, DNS, HRW, ASWNB, Domestic

a ASWNB = Australian Standard White Noodle Blend, CWRS = Canada Western Red Spring, DNS = Dark Northern Spring, APH = Australian Prime Hard, HRW = Hard Red Winter, WW = Western White Wheat.

wheat type. Australia exports a blend of two wheat classes to Japan and South Korea known as Australia Standard White Noodle Blend (ASWNB). The blend comprises 60% Noodle Wheat and 40% Premium White Wheat. Noodle Wheat is soft wheat that was developed by Australia in cooperation with Japanese milling companies to make a flour with high peak paste viscosity, low final peak viscosity, and creamy color, making it ideal for white salted noodles and related products. Other wheat types used for noodles in Japan include Australian Prime Hard (APH), a high protein hard white wheat; Canada Western Red Spring (CWRS), a high protein hard red spring wheat; and three United States wheat classes, Dark Northern Spring (DNS), a high protein hard red spring wheat; Hard Red Winter (HRW), a medium protein hard red winter wheat; and Western White (WW), a low protein blend of soft white wheat and white club wheat. Table 3.1 shows the wheat blending patterns typically used by Japanese millers for various kinds of noodles. The blends vary according to the general desired attributes for a noodle type and may be altered depending on wheat availability and the personal preference of a given noodle maker. For example, Table 3.2 gives examples of various wheat blend options that produce flour with the desired specifications (ash content 0.37% and protein content 9.4% on a 14% moisture basis) and other quality attributes for preparation of white thin (somen) noodles.

TABLE 3.2 Examplesa of Various Wheat Blending Patterns that Will Give Flour (0.37% Ash and 9.4% Protein, 14% Moisture Basis) Suitable for White Thin Noodles (Somen) Pattern

DNS

HRW

ASWNB

Domestic

#1 #2 #3 #4 #5

40% 30% 20% 30% —

— — — — 30%

40% 20% 50% 70% 40%

20% 50% 30% — 30%

a ASWNB = Australian Standard White Noodle Blend, DNS = Dark Northern Spring, HRW = Hard Red Winter.

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3.3. MILLING 3.3.1. Flour Requirements Japanese millers must satisfy a number of critical elements to achieve satisfactory noodle flour properties. Protein content, which has been discussed earlier, is a primary specification because it is a primary determinant of noodle texture. The most widely used index of flour refinement in Japan is ash content, as determined by AACC International Approved Method 08-01 (AACC International 2000). Ash content is a measure of the mineral content in flour. Ash content is not distributed uniformly in the wheat kernel (MacMasters et al. 1971). There is a gradual increasing mineral content gradient from the center of the kernel to the outer endosperm, so the most highly refined streams from the center of the endosperm have the lowest ash content. Minerals are highly concentrated in the pericarp and the aleurone layers, so streams with the most bran contamination have the highest ash content. Thus, higher flour ash content is associated with less brightness and more visible bran specks. Other key factors for millers to consider are flour particle size and flour starch damage. Generally, noodle flour is sieved over 13XX (aperture 100 µm) or 14XX (aperture 93 µm) nylon cloth. Fine particle size is an asset in manufacturing both white salted noodles (Hatcher et al. 2002) and yellow alkaline noodles (Hatcher et al. 2008). When flour is fine, it hydrates more rapidly and more evenly, the surface of fresh noodles is smoother and less streaky, and cooking quality is better. It is important to avoid excessive starch damage when milling hard wheat (Hatcher et al. 2002, 2008). If starch damage is excessive, dough water absorption increases and the dough fragments more in the mixer agglomerate. As starch damage increases, noodle cooking quality is also affected: cooking loss increases, the noodle surface becomes gummy, and the noodles become less firm.

3.3.2. Wheat Conditioning and Climate Control To mitigate flour starch damage, it is necessary to take steps to soften the wheat prior to milling and to avoid harsh grinding during reduction passages. Wheat conditioning (tempering) to prepare wheat for milling is an important process (Hook et al. 1982). Tempering times in Japan range from 24 to 48 hours. Optimum tempering moisture is different from class to class. The hard wheat classes CWRS, DNS, HRW, and APH are tempered to 16–17%. Medium hard ASWNB is tempered to 15–16%, whereas soft wheat, including domestic wheat, is tempered to 14–15%. In addition to softening the endosperm, thereby controlling starch damage, tempering toughens the bran. Toughened bran is more resistant to breaking down into fine particles, and thus bran contamination in the flour is lessened and flour color improves, and there are less visible bran specks in the flour. In Japanese milling, factory air conditioning is preferable to stabilize the mill environment, particularly in parts of the country where there are distinct seasons. If air conditioning is not installed, or if the weather is too extreme for the air conditioning

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to maintain ideal conditions, it is necessary to decrease the final tempering moisture in the summer because sieving efficiency is less at high temperatures. In the winter, it may be necessary to increase final tempering moisture because sieving efficiency improves at low temperatures and humidity. Too much material passing through sieves is not desirable for preparing noodle flour because more bran specks get into the flour. Thus, in the winter, it may be necessary to use finer sieve cloths to reduce the amount of material passing through the sieves.

3.3.3. The Milling Process A simplified hard wheat milling flow is shown in Figure 3.2. Ground material from the break rolls are segregated by sifting into three categories: bran with some adhering endosperm, large chunks of endosperm with some adhering bran (often referred to as semolina and middlings), and flour. Noodle flour is derived from semolina and middlings going to the reduction process from the first break, the second break, and the third break passages. The break system process is designed such that bran powdering is minimized, the generation of break flour is minimized, and the generation of coarse semolina and middlings is maximized.

FIGURE 3.2 A simplified hard common wheat mill flow. B = break, BD = bran duster, F = flour, GR = grader, P = purifier, SD = shorts duster, SIZ = sizing, M = middlings. (Adapted from Dexter and Sarkar 2004.)

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TABLE 3.3 Typical Break Roll Corrugations for Noodle Flour Milling in Japan Grinding Passage

Corrugations (number per inch)

Corrugations (number per cm)

1st Break 2nd Break 3rd Break—coarse 3rd Break—fine 4th Break—coarse 4th Break—fine 5th Break—coarse 5th Break—fine

8 12 16 20 22 24 24 26

3.1 4.7 6.3 7.9 8.7 9.4 9.4 10.2

The roll corrugations of the first three break rolls are set dull-to-dull (cutting action by the long edges of the sawtooth-like flutes), because the aim is to obtain a maximum yield of coarse semolina and middlings of high purity. When roll orientation is dull-todull, grinding imparts more compression and less shear compared with sharp-to-sharp (cutting action by the short edge of the sawtooth-like flutes) orientation. As a result, the bran remains more intact and comes off as broader flakes (Fang and Campbell 2002). The higher shear associated with sharp-to-sharp orientation breaks the bran down into smaller particles and increases bran contamination in the flour. Therefore, flour from sharp-to-sharp roll orientation contains more visible bran specks, which is highly undesirable for noodles. In addition, bran contamination increases minerals in the flour, and flour ash content increases. Sharp-to-sharp orientation can be used after the fourth break rolls, because middlings from the late break passages are not sent to the beginning of the reduction system where prime noodle flour is made. The corrugations are coarse at the beginning of the break system and become progressively finer with each successive break passage (Table 3.3). The roll spiral (rise over run of corrugations along the roll) is typically about 8–10%. The stock ground by each roll passage is sent to a sifter, which usually has six sections, where the ground material is segregated into several fractions by size. As mentioned earlier, generally, noodle flour passes through 13XX (100 µm) or 14XX (93 µm) nylon sieves. When a miller is concerned about bran specks, particularly when milling for yellow alkaline noodles, the smaller aperture 14XX cloth is preferred. After sieving, each particle size fraction of semolina and middlings from the break system and sizing system is conveyed to a specific purifier. In purifiers, the branny particles are separated from the pure endosperm particles by a combination of sieving and air floatation. Freedom from specks and a bright color are important for noodle flour, making it necessary to set up an extensive purification system. Moreover, the purifiers must be carefully adjusted to assure a high yield of highly refined noodle flour. The reduction process is where the purified semolina and middlings are reduced into flour. Smooth rolls are used. It is important to take care not to set the roll gap

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too narrow, so as not to grind very harshly. As reduction grinding conditions become harsher, flour starch damage increases (Scanlon and Dexter 1986). In addition, as reduction grinding becomes harsher, more bran is released into the flour, adversely affecting flour color and increasing flour ash content (Hatcher et al. 2002, 2008). The starch damage of flour from the reduction system is about twice as high as the flour from the break system. There is a positive correlation between the amount of damaged starch and noodle cooking loss (Hatcher et al. 2002, 2008). Therefore, as discussed earlier, excessive starch damage is to be avoided in noodle flour to prevent high cooking loss and associated gummy surface. In the reduction system, sometimes one section of the sifter is divided into a top group of sieves and a bottom group of sieves. For example, the top group may contain 10 sieves of 14XX and the bottom group may contain 6 sieves of 14XX. The advantage of dividing the sifter is that it provides an opportunity to check the purity of the flour coming from the bottom section before deciding whether to mix the flour from the bottom group of sieves into the stream from the sifter being directed to noodle flour.

3.3.4. Flour Stream Selection To make flour suitable for a given type of noodle, the flour streams are selected for inclusion, by considering color, ash content, protein content, gluten properties, and particle size. Spouts under sifters are selectively connected according to flour grade and directed to a spiral screw conveyor and sifter, where flour streams are combined and stirred to make a uniform product. For yellow alkaline noodle flour, which is derived from hard wheat, the streams selected are mainly from the early reduction streams because those are the streams with the least bran contamination. In contrast, streams from the break system have a greater proportion of bran and aleurone (Symons and Dexter 1996), adversely affecting noodle brightness and imparting more visible bran specks. Break flour from hard wheat is also higher in protein content (Ziegler and Greer 1971), which also contributes to duller noodle color (Kruger et al. 1994). The higher content of aleurone and bran also makes break flour from hard wheat higher in ash content (Symons and Dexter 1996), a primary yellow alkaline noodle flour specification. It is well established that the browning of fresh noodles during storage is related to the oxidation of wheat phenolic compounds by enzymatic browning, principally by polyphenol oxidase, to produce labile quinones, which react with amines and thiols, or undergo self-polymerization, to produce highly colored products (Hatcher and Kruger 1997). The high pH (near 10) associated with the alkaline salts (kansui) in the formula promotes fresh noodle darkening during storage through autooxidation of phenolics. The concentration of kansui and the ratio of sodium to potassium carbonate vary. The alkaline salt composition has a significant effect on noodle color, whereas concentration has a significant impact on noodle texture (Hatcher and Anderson 2007). The concentration of phenolic compounds and the activity of polyphenol oxidase become higher as flour refinement declines and are thus the lowest in the best-quality reduction streams (Hatcher and Kruger 1997). Therefore,

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TABLE 3.4 Properties of Typical Japanese Noodle Floura for Various Types of Noodles

Property Flour yield (%) Ash content (%) Protein content (%) Cooking Appearance

Eating

a On

White Salted Noodles (“Udon”) 45–60 0.34–0.42 7.0–9.0 Low cooking loss Bright white, creamy white

Smooth surface, elasticity, springiness

Yellow Alkaline Noodles (“Chinese Noodles”)

White Thin Noodles (“Hiyamugi” and “Somen”)

Instant Noodles (“Instant Ramen” and “Yakisoba”)

25–40 0.33–0.37 11.0–11.5 Firmness in hot soup Bright yellow, free from specks, clear surface Firm bite, springiness

45–60 0.35–0.42 9.0–11.0 Low cooking loss Bright white

50–70 0.35–0.50 9.0–11.0 Firmness in hot soup Bright yellow

Firm bite, smooth

Firm bite, springiness

a 14% moisture basis.

noodles prepared from highly refined reduction streams exhibit very stable color during storage (Kruger et al. 1994). The yield of yellow alkaline noodle flour is quite low, ranging from 25% to 40%, because, in general, only reduction flours with an ash content of between 0.33% and 0.37% are selected (Table 3.4). The secondary flour produced is used for breadmaking, making it important to select wheat for yellow alkaline noodle production that has good bread-making properties. The removal of the highly refined reduction streams is compensated for during bread-making by the high protein content and strong dough properties of the break flours in the secondary flour (Dexter et al. 1990). White salted noodles (udon, hiyamugi, and somen) are not made with kansui, so color change promoted by alkaline pH is not a factor. In addition, wheat used for white salted noodles is soft or medium hard, rather than hard. Soft wheat endosperm breaks down more quickly than hard wheat, and, as a result, ash and protein do not concentrate as much in break flours of soft wheat compared to hard wheat (Ziegler and Greer 1971). Therefore, most of the reduction flour streams and some of the break flour streams can be combined for making white salted noodle flour. The ash contents of the endosperm of ASWNB, WW, and Japanese domestic wheat are low, so flour ash does not rise as quickly as for hard wheat as flour yield increases. The yield of typical white salted noodle flour ranges from about 45% to 60%, with an ash content of from 0.34% to 0.42% (Table 3.4). Most of the secondary flour from white salted noodle millings is used for traditional chemically leavened Japanese baking products. These products usually have fillings inside. For example, Tai-yaki,

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which has a fish-like shape, is filled with sweet bean cream, and Tako-yaki, which has a round shape, is filled with boiled octopus. There are many variations of instant noodles, so it is not as easy to specifically define flour extraction rate, ash content, and protein content as for other types of noodles. However, usually a blend of hard wheat and ASWNB is used to assure the essential cooking attributes: retaining firmness in hot water and springiness. Dough rheological properties of Japanese flours marketed for a given noodle type exhibit a wide range. Typical farinograph curves for Japanese white salted noodles, yellow alkaline noodles, dry white salted noodles, and instant noodles are shown in Figure 3.3. The flour for the two white salted noodle types exhibit lower water absorptions and weaker mixing curves than the others, because soft wheat of low protein content is included in the wheat mix to achieve the desired texture. The yellow alkaline noodle flour is strong, exhibiting a delayed dough development peak after the initial hydration curve. The combination of higher protein content and strong dough properties for yellow alkaline noodle flour is needed to assure that the noodles remain firm in hot water following cooking. If it is necessary to improve the processing and texture of noodles, starch or vital gluten is added. Starch is used mainly for white salted noodles to improve smoothness and springiness, whereas vital gluten is used mainly for yellow alkaline noodles to improve firmness. In Japan, by general agreement within the industry (not by law), no chemicals, such as peroxide for bleaching, are used. Preferably, once the flour is mixed and homogeneous, it should go through an impact detacher and entoleter in

FIGURE 3.3

Typical farinograph curves for some types of noodles consumed in Japan.

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order to destroy any insect eggs. The final stage of the milling process is to sieve the flour through an aperture of 200 µm or less before it goes to storage. 3.3.5. Air Classification Air classification can be used to further purify noodle flour. Air classification was developed in the United States in about 1960 to classify flour particles by means of air currents (Bass 1988). No matter how carefully wheat is milled, there will always be small amounts of fine bran powder in the flour, which have high polyphenol oxidase activity. Fine particles of about 10 µm, which are bran-rich, can be removed by air classification to reduce the number of visible bran specks and the rate of browning in noodles. Air classification has a high energy requirement, so it is expensive to operate. Thus, to assure that the process is cost effective and achieves the desired improvement in flour, it is important to carefully set the equipment so it is operating as efficiently as possible and is removing the exact targeted particle size. 3.3.6. Flour Tests for Color and Specks As discussed earlier, the decision on which mill streams to use in noodle flour is based on protein content to assure the desired texture, as well as on ash content, color (brightness), and color stability during storage. There is some variability among cargoes, so it is not possible to have a fixed noodle flour mill stream composition. To maintain consistent noodle color, it is necessary to adjust the mill stream composition and the yield of noodle flour from time to time. This is illustrated in Figure 3.4, which shows the variability among ASWNB cargoes for white salted noodle brightness (L*), redness (a*), and yellowness (b*) 4 hours after processing. The noodles were made on a laboratory scale from 60% extraction patent flour prepared on a Buhler test mill. Noodle color (CIE color units L* a* b*) is measured with a Minolta Colorimeter. Needless to say, it is not possible to continuously monitor the noodle-making quality of noodle flour during commercial production. Therefore, it is necessary to conduct tests predictive of noodle quality as a part of production management. These tests include the Pekar slick test (AACC Approved Method 14-10, AACC International 2000) for flour color, measurement of specks by image analysis, and estimation of ash content by near-infrared (NIR) spectroscopy. Particle size of dry flour affects flour color; finer flour appears whiter and brighter (Symons and Dexter 1991). Wet flour tests, such as the Pekar test, eliminate the effect of particle size. In some cases, a solution of the phenolic compound pyrocathecol (commonly referred to as cathecol) is used in the Pekar test. Cathecol is a substrate for polyphenol oxidase, and thus bran specks, which are high in polyphenoloxidase activity, become more visible (Figure 3.5). The Pekar test with cathecol gives good correlations to the number of visible bran specks, brightness (L*), and redness (a*) of fresh noodles. A less widely used alternative to the cathecol solution is an alkaline solution of kansui. There are a number of alternatives for objectively counting specks in flour by image analysis. For example, Branscan (http://www.branscan.com) produces models

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Noodle Brightness L* 85 83 81 79 77 75 2004

2005

2006

2007

Noodle Redness a* 0 -1 -2 -3 -4 -5 2004

2005

2006

2007

Noodle Yellowness b* 30 25 20 15 10 2004

2005

2006

2007

FIGURE 3.4 Variations of Minolta CIE color parameters among ASWNB cargoes for white salted noodles 4 hours after processing.

FIGURE 3.5 Pekar color test for flour slicks immersed in cathecol solution to emphasize polyphenol oxidase activity in flour.

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of Fluoroscan for use either offline in laboratories or online in mills. The online Flouroscan F4000 system gives real-time analysis of measurement of aleurone and bran specks in flour and reports on ash value. Similar devices are being sold by other companies. Noodle flour has very few specks, so it is necessary to increase the measurement frequency or widen the viewing area to accurately estimate the number of specks. Monitoring specks in flour is a valuable quality control measure, but it is preferable to measure specks directly in noodle sheets. Commercial equipment is available to objectively measure bran specks in noodle dough but, alternatively, devices can be developed in-house (e.g., see Hatcher and Symons 2000b) that may be more cost effective. Basic image analysis software can be obtained on the Internet free of charge. For example, the National Institutes of Health (NIH) provides access to “NIH Image,” a public domain image-processing and analysis program for the Macintosh, at http://rsb.info.nih.gov/nih-image, and “Image,” a Java program inspired by NIH Image that runs anywhere is available at http://rsb.info.nih.gov/ij/index.html. A PC version called “Scion Image for Windows” is available from Scion Corporation at http://www.scioncorp.com. An image of flour or a noodle sheet is taken with a camera or scanner and then the particles of specks are analyzed by the image analysis software. A minimum speck size is specified to correspond to specks visible to the human eye. A key aspect for success in using image analysis is to carefully establish imaging parameters to obtain a clear and reproducible image.

3.4. SUMMARY Japanese consumers are discriminating and very demanding. Accordingly, Japanese millers must prepare noodle flour to exacting specifications. Some specifications, such as protein content, dough strength, and starch pasting properties, vary according to noodle type. However, common flour requirements for all noodle types are low flour ash content and absence of bran specks to assure that the noodles are bright and speck-free and that fresh noodles exhibit stable color properties during storage. In order to assure that noodle flours consistently meet the requirements of the Japanese noodle industry, Japanese millers blend several wheat classes. Wheat quality varies from cargo to cargo and from year to year. Therefore, the flour extraction rate and stream selection must be adjusted on a regular basis to account for variability in wheat quality. Noodle flours are finer than bread wheat flours because fine particle size is an asset in both noodle processing and noodle texture. As flour becomes finer, there is a trend toward higher starch damage, which is detrimental to noodle texture. Therefore, to avoid excessive starch damage, care must be taken to avoid harsh grinding. The demanding ash specifications for noodle flour in Japan require that mills use extensive purification to minimize bran contamination in the prime reduction flour streams. These prime reduction streams are universally included in noodle flour, regardless of noodle type. Flour extraction rates must also be kept relatively low.

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Online imaging equipment is used to monitor ash content and bran specks in flour streams. Air classification may also be used to remove small bran-rich particles from noodle flour to reduce the number of visible bran specks. A commonly used quality control test for noodle flour in the mill is to evaluate flour color and appearance by a wet-flour slick test such as the AACC Pekar test and variations. Objective analysis of color and specks in noodle dough can be achieved in quality control laboratories with colorimeters to measure lightness (L*), redness (a*), and yellowness (b*), and by image analysis to quantify visible bran specks. REFERENCES AACC International. 2000. Approved Methods of the AACC International, 10th ed. AACC International, St. Paul, MN, USA. Ambalamaatil, S., Lukow, O. M., Hatcher, D. W., Dexter, J. E., Malcolmson, L. J., and Watts, B. M. 2002. Milling and quality evaluation of Canadian hard white spring wheats. Cereal Foods World 47:319–327. Baik, B.-K. and Lee, M.-R. 2003a. Characteristics of noodles and bread prepared from doublenull partial waxy wheat. Cereal Chem. 80:627–633. Baik, B.-K. and Lee, M.-R. 2003b. Effects of starch amylose content of wheat on textural properties of white salted noodles. Cereal Chem. 80:304–309. Bass, E. J. 1988. Wheat flour milling. In: Y. Pomeranz (ed.), Wheat Chemistry and Technology, 3rd ed. American Association of Cereal Chemists, St. Paul, MN, USA, pp. 1–68. Crosbie, G. B. and Ross, A. B. 2004. Asian wheat flour noodles. In: C. Wrigley, H. Corke, and C. Walker (eds.), Encyclopedia of Grain Science. Elsevier Science, Oxford, UK, pp. 304–312. Dexter, J. E. and Edwards, N. M. 1998. The implications of frequently encountered grading factors on the processing quality of common wheat. Assoc. Operative Millers Bull. June: 7115–7122. Dexter, J. E. and Sarkar, A. K. 2004. Wheat: dry milling. In: C. Wrigley, H. Corke, and C. Walker (eds.), Encyclopedia of Grain Science. Elsevier Science, Oxford, UK, pp. 363–374. Dexter, J. E., Preston, K. R., Kilborn, R. H., and Martin, D. G. 1990. The effect on residual flour quality of removing farina during common wheat milling. Cereal Chem. 67:39–46. Epstein, J., Morris, C. F., and Huber, K. C. 2002. Instrumental texture of white salted noodles prepared from recombinant inbred lines of wheat differing in the three granule bound starch synthase (waxy) genes. J. Cereal Sci. 35:51–63. Fang, C. and Campbell, G. M. 2002. Effect of roll fluting disposition and roll gap on breakage of wheat kernels during first-break roller milling. Cereal Chem. 79:518–522. Fu, B. X. 2008. Asian noodles: history, classification, raw materials, and processing. Food Res. Int. 41:888–902. Giroux, M. J. and Morris, C. F. 1998. Wheat grain hardness results from highly conserved mutations in the friabilin components puroindoline a and b. Proc. Natl. Acad. Sci. USA 95:6262–6266. Hatcher, D. W. and Anderson, M. J. 2007. Influence of alkaline formulation on Oriental noodle color and texture. Cereal Chem. 84:253–259.

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Hatcher, D. W. and Kruger, J. E. 1997. Simple phenolic acids in flours derived from Canadian wheat: relationship to ash content, color, and polyphenol oxidase activity. Cereal Chem. 74:337–343. Hatcher, D. W. and Symons, S. J. 2000a. Influence of sprout damage on oriental noodle appearance as assessed by sprout damage. Cereal Chem. 77:380–387. Hatcher, D. W. and Symons, S. J. 2000b. Assessment of oriental noodle appearance as a function of flour refinement and noodle type by image analysis. Cereal Chem. 77:181–186. Hatcher, D. W., Anderson, M. J., Desjardins, R. G., Edwards, N. M., and Dexter, J. E. 2002. Particle size and starch damage effect on the processing and quality of white salted noodles. Cereal Chem. 79:64–71. Hatcher, D. W., Anderson, M. J., Clear, R. M., Gaba, D. G., and Dexter, J. E. 2003. Fusarium head blight: effect on white salted and yellow alkaline noodle properties. Can. J. Plant Sci. 83:11–21. Hatcher, D. W., Edwards, N. M., and Dexter, J. E. 2008. Impact of flour particle size and starch damage and alkaline reagent on yellow alkaline noodle characteristics. Cereal Chem. 85:425–432. Hook, S. C. W. 1984. Specific weight and wheat quality. J. Sci. Food Agric. 35:1136–1141. Hook, S. C. W., Bone, G. T., and Fearn, T. 1982. The conditioning of wheat. The influence of varying levels of water addition to UK wheats on flour extraction rate, moisture and colour. J. Sci. Food Agric. 33:645–654. Hoseney, R. C. and Seib, P. A. 1973. Structural differences in hard and soft wheat. The Bakers Digest 47(6):26–28, 56. Kruger, J. E., Anderson, M. H., and Dexter, J. E. 1994. Effect of flour refinement on raw Cantonese noodle color and texture. Cereal Chem. 71:177–182. Kruger, J. E., Hatcher, D. W., and Dexter, J. E. 1996. Influence of sprout damage on Oriental noodle quality. In: Proceedings of the 7th International Symposium on Pre-Harvest Sprouting, Hokkaido, Japan, pp. 9–18. MacMasters, M. M., Hinton, J. J. C., and Bradbury, D. 1971. Microscopic structure and composition of the wheat kernel. In: Y. Pomeranz (ed.), Wheat: Chemistry and Technology, 2nd ed. American Association of Cereal Chemists, St. Paul, MN, USA, pp. 51–113. Miskelly, D. M. 1998. Modern noodle-based food raw material needs. In: A. B. Blakeney and L. O’Brien (eds.), Pacific People and Their Foods. AACC, St. Paul, MN, USA, pp. 123–142. Miskelly, D. M. and Moss, H. J. 1985. Flour quality requirements for Chinese noodle manufacture. J. Cereal Sci. 3:379–387. Nagao, S. 1995. Wheat products in East Asia. Cereal Foods World 40:482–487. Nakamura, T., Yamamori, M., Hidaka, S., and Hoshino, T. 1992. Expression of HMW wx protein in Japanese common wheat (Triticum aesthivum L.) cultivars. Jpn. J. Breeding 42:681–685. Oda, M. 1982. Men no hon [in Japanese: Textbook of Noodles], 2nd ed. Shokuhin Sangyo Shinbunsha, Tokyo, Japan. Oda, M., Yasuda, Y., Okazaki, S., Yamaguchi, Y., and Yokoyama, Y. 1980. A method of flour assessment for Japanese noodles. Cereal Chem. 57:253–254. Oh, N. H., Seib, P. A., Ward, A. B., and Deyoe, C. W. 1985. Noodles. VI. Influence of flour protein, extraction rate, particle size, and starch damage on the quality characteristics of raw noodles. Cereal Chem. 62:441–446.

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Posner, E. S. and Hibbs, A. N. 2004. Wheat Flour Milling, 2nd ed. AACC International, St. Paul, MN, USA. Ross, A. S., Quail, K. J., and Crosbie, G. B. 1997. Physicochemical properties of Australian flours influencing the texture of yellow alkaline noodles. Cereal Chem. 74:814–820. Sarkar, A. K. 2003. Grain milling operations. In: A. Chakraverty, A. S. Mujumdan, G. S. Raghavan, and H. S. Ramaswamy (eds.), Handbook of Postharvest Technology: Cereals, Fruits, Vegetables, Tea and Spices. Marcel Dekker, New York, NY, USA, pp. 253–325. Sasaki, T., Yasui, T., Kiribuchi-Otobe, C., Yanagisawa, T., Fujita, M., and Kohyama, K. 2007. Rheological properties of starch gels from wheat mutants with reduced amylose content. Cereal Chem. 84:102–107. Scanlon, M. G. and Dexter, J. E. 1986. Effect of smooth roll grinding conditions on reduction of hard red spring wheat farina. Cereal Chem. 63:431–435. Symons, S. J. and Dexter, J. E. 1991. Computer analysis of fluorescence for the measurement of flour refinement as determined by flour ash content, flour grade color, and tristimulus color measurements. Cereal Chem. 68:454–460. Symons, S. J. and Dexter, J. E. 1996. Aleurone and pericarp fluorescence as estimators of mill stream refinement for various Canadian wheat classes. J. Cereal Sci. 23:73–83. Van Hung, P., Yasui, T., Maeda, T., and Mortia, N. 2008. Physicochemical characteristics of starches of two sets of near-isogenic wheat lines with different amylose content. Starch [St¨arke] 60:34–40. Ziegler, E. and Greer, E. N. 1971. Principles of milling. In: Y. Pomeranz (ed.), Wheat: Chemistry and Technology, 2nd ed. American Association of Cereal Chemists, St. Paul, MN, USA, pp. 115–199.

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CHAPTER 4

Wheat Milling and Flour Quality Analysis for Noodles in Taiwan C. C. CHEN and SHU-YING (SOPHIA) YANG

4.1. INTRODUCTION In Taiwan, noodle flour generally has a lower ash content and whiter color than bread flour because, for all types of noodles, color is preferred to be bright, and the color of fresh (wet) noodles should be stable over a period of storage time. In this chapter, the authors will discuss commercial milling techniques for producing high-quality noodle flours in Asia, with particular reference to Taiwan. The authors will also review current research on milling for noodle flour on laboratory and commercial scales. Consistent flour quality specifications that are associated with the desired noodle attributes are essential for manufacturing noodle products of good and consistent quality (Table 4.1). Most flour mills have a flour quality control and assurance program to ensure that the flour produced will meet customer requirements. Some noodle manufacturers are also equipped with a quality control lab to examine incoming raw materials and to make flour blends for their specific noodle products. This chapter will provide general guidelines and some unique tests used in the flour industry for such purposes. About 45% of wheat imported into Taiwan is used for milling noodle flour. Several types of noodles are commonly produced in Taiwan, including raw noodles (fresh hard-bite white salted noodles), dry noodles, wet alkaline noodles, and instant noodles. Flour quality required for making these different types of noodles varies. In Taiwan, noodle products can be divided into three groups: (1) fresh noodles, (2) dry noodles, and (3) instant noodles. Fresh noodles usually have a short shelf life because of high moisture content. Modern sterilizing processing and new packaging techniques, such as vacuum packaging, can extend the shelf life. Dry noodles and

Asian Noodles: Science, Technology, and Processing, Edited by Gary G. Hou C 2010 John Wiley & Sons, Inc. Copyright


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TABLE 4.1

Basic Flour Specifications for Making Noodles in Taiwan

Noodle Type

Ash (14% mb) (%)

Protein (14% mb) (%)

Wet Gluten (14% mb) (%)

Amylograph Peak Viscosity (BU)

Udon noodles Yellow alkaline noodles White salted noodles Dried noodles Thin noodles Fried instant noodles

0.33–0.42 0.40–0.45 0.38–0.40 0.40–0.45 0.40–0.50 0.45–0.50

9.0–9.5 11.5–12.0 11.0–11.5 11.5–12.0 12.0–12.5 12.0–12.5

29 34 31 30 32 35

800–1000 600–650 ≥ 600 ≥ 600 ≥ 650 ≥ 550

instant noodles have a much longer shelf life because of lower moisture content, but fried instant noodles tend to become rancid over time because of high fat absorption. Fresh and dry noodles are produced mostly by hand or semiautomatically by machine. Instant noodles, on the other hand, are often mass produced on an automatic noodle line. Millers are mostly concerned about the different types of flour used for the different production processes. Production of noodle flour is not as difficult as, for instance, the production of bread flour. The flour requirement for noodle production is mainly a question of price. High-quality fresh, dry, or instant noodles are made from high-quality flour and vice versa. In general, fresh or dry noodles are produced from low ash flour of medium to high protein; however, if some natural colorants or flavorings such as spinach, shrimp, or beef powders are added into the noodles, the noodles may be produced from higher ash flour.

4.2. MILLING FOR NOODLE FLOUR White flour with low ash content is used for making noodles in Taiwan in order to stabilize noodles so as to maintain their quality and color. Many factors, including wheat quality and flour milling techniques, affect the extraction of low ash flour. It is important to look at the flour ash content when comparing flour yields; therefore, cumulative ash curves of different wheat samples are often compared to determine the milling performance. The following factors are considered to affect flour yield and noodle flour quality. 4.2.1. Wheat Quality Characteristics The intrinsic properties and physical condition of wheat have a tremendous influence on flour yield, and nearly every wheat type has a different yield potential. One of the most significant indicators for millers to consider is the test weight (TW), expressed as kilogram per hectoliter (hectoliter weight) or as pounds per bushel (bushel weight) (Approved Method 55-10, AACC International 2000). TW is a measurement of wheat density. Plump, sound kernels give a higher TW than thinner kernels and damaged

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kernels. Therefore, higher TW is a rough indicator of higher flour yield because, in general, as TW increases, the proportion of endosperm in wheat kernels increases. The thickness of the bran layers also influences the flour yield because thicker bran layers reduce the proportion of endosperm and lower the flour yield. Endosperm texture is one of the most important quality characteristics of wheat, and it largely determines how a particular wheat cultivar is processed. The endosperm texture, or the relative hardness or softness of a grain, can be defined as a measure of the resistance to deformation. This definition is at the basis of the measurement of hardness by the Single Kernel Characterization System (SKCS), which measures the force required to crush individual grains of a sample between two surfaces, taking into account the weight, diameter, and moisture of the grain (Osborne et al. 2001). Using the SKCS, the hardness scores for hard wheat are over 50, and the scores for soft wheat are less than 50 (Approved Method 55-31, AACC International 2000). More indirect definitions of grain texture refer to the manner in which grain breaks down to a meal or flour and how that meal or flour behaves during processing. For example, the particle size index (PSI) is determined by grinding the grain and determining the percentage of the total weight that passes through a sieve (Approved Method 55-30, AACC International 2000). The average particle size for soft wheat flour is smaller than hard wheat flour, so the proportion that passes through the sieve is higher when the wheat is softer. The hardness of wheat can also be assessed by other means such as near-infrared (NIR) spectroscopy (Williams 1979; Approved Method 39-70A, AACC International 2000). For a given wheat type, the ash content of the wheat is related to the amount of bran (Hirsch 1997). Therefore, ash content is a widely used index of flour refinement. Wheat with higher ash content in the endosperm is undesirable because a lower flour yield will be achieved at a given ash content. Impurities in wheat are removed before milling, so flour yield on an incoming dirty-wheat basis are lower than on a clean-wheat basis. Mills should calculate the yield on both dirty-wheat weight and clean-wheat weight to get the most accurate indication of milling value. Another important factor is wheat moisture. More water can be added for tempering if wheat is drier, giving a higher yield of flour on a dry-weight basis. In summary, sound, dry, and plump kernels with a high TW give a higher flour yield. 4.2.2. Wheat Cleaning Wheat cleaning is related to the flour yield and ash content. The wheat that goes to the mill must be clean of all impurities because impurities increase the ash content of the flour, adversely affect flour color, and reduce the flour yield. 4.2.3. Wheat Tempering Proper tempering results in the correct amount of evenly distributed moisture in the kernels; otherwise, the flour yield will suffer. Optimum temper moisture varies depending on wheat hardness and the climate in the mill. Temper moisture for soft wheat is lower because soft wheat stock does not flow as easily and does not sieve as efficiently as hard wheat at the same moisture level. The wheat tempering moisture is

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adjusted so that the resultant flour moisture is below the legal maximum level (Anon. 2001). If the tempering moisture is too low, the bran tends to shatter more, the bran yield declines, and the straight-grade flour yield increases; however, the flour has higher ash and more specks. As a result, the low ash flour production yield decreases. 4.2.4. Milling The mill flow and the grinding techniques have a tremendous impact on flour yield and flour quality. Figures 4.1 and 4.2 show a typical commercial flour mill chart (Hirsch 1997).

FIGURE 4.1 Flour production plant (wheat cleaning and milling). (From Hirsch 1997; used by permission.)

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FIGURE 4.2

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Flour production plant (flour silo). (From Hirsch 1997; used by permission.)

The flour milling process involves sequential steps, including selection of wheat, tempering, milling, and flour blending. The flour mill mechanically separates the bran from the endosperm and reduces the endosperm into fine flour particles. The flour milling process comprises two major systems: the break and the reduction systems. In the break system, the grain is opened up and the endosperm is separated from the bran. This is achieved by grinding between five or six pairs of spirally fluted (corrugated) rolls driven at different speeds. The rolls are set progressively closer together and are more finely fluted. The products released at each stage are classified by sieving to separate the coarse branny material and release fragments of endosperm. In the reduction system, coarse chunks of endosperm are gradually reduced in particle size into flour by successive grinding between smooth rolls and sieving.

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It should be emphasized that flow sheets and any grinding conditions have to be adjusted according to the wheat quality, required end product, climate, and other factors. It is uncommon for the flow sheet and the roller settings to stay unchanged for a month or even for a week. A good head miller makes necessary adjustments whenever they are required. The ash content of the flour and the ash curve of the streams should be the guidelines for modifications and adjustments of the flow sheet and roller settings. The kernels should be opened like an orange at the first and second breaks. The third and fourth breaks should scrape the rest of the flour from the bran. The size of the bran particles should be kept as large as possible because if the bran is broken, bran dust will go into the flour, increasing the ash content and reducing the flour yield at a given ash content. In addition, bran dust in flour reduces flour brightness and results in visible bran specks, which detract from noodle appearance. The major purpose of reduction rolls is to produce flour. For making noodle flour, the reduction process is “gradual” with roll gaps that are set more open for coarse middlings than for fine middlings. To minimize bran contamination in the flour, the endosperm particles conveyed to reduction rolls should be as free from adhering bran as possible. Purifiers, which classify endosperm particles on the basis of particle size and density, are critical to assuring this goal is reached. Purifier settings must be carefully set to assure good performance, which is essential for producing highly refined flour suitable for noodles (Hirsch 1997). The first three reductions should receive only purified clean stocks. The rest of the reductions gradually reduce the ground middlings, and each successive passage produces flour of gradually higher ash content, as shown in Figure 4.3 (Hirsch 1997). Flour milling is not just a science; it is also an art and is therefore dependent on the experience and craftsmanship of the miller. Millers can be judged by their achievements, and one of the most important achievements is how efficiently bran is separated from flour and the yield of the flour at a given ash content.

0.65

Extract yield (%)

0.60 0.55 0.50 0.45 0.40 0.35

HRW DNS

0.30 0.25

0

20

40

60

80

100

Ash (%)

FIGURE 4.3 Ash curve: extraction yield (%) versus ash content (%) for DNS/14.5% and HRW/13.5%. (From Hirsch 1997; used by permission.)

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In Taiwan, noodle flour is often milled from Hard Red Spring (HRS) and Hard Red Winter (HRW) wheat. White flour that is low in ash content and as free as possible from bran specks is preferred for making noodles in Taiwan. To achieve the desired flour purity, a low flour extraction rate of 55–60% is commonly obtained from HRS and HRW wheat. How do flour mills select proper flour streams for noodle flour in Taiwan? How do flour mills use clear flour produced from milling noodle flour? These two questions concern important factors in determining whether a flour mill can be profitable. A common way to produce high-quality noodle flour in Taiwan is to mill HRS wheat with 14.5% protein or HRW wheat with 13.0% protein and split the flour into three portions: Flour 1: Low ash with low but strong protein (0.36–0.40% ash and 11% protein @ 14% mb); for example, C1A, C1B, C2-1b, and C3-1a. Flour 2: Higher ash with higher protein content (0.45–0.50% ash and 12.5% protein @ 14% mb); for example, 2B, 3B, 4B, C6, and C7. Flour 3: All flour streams that do not fit into flour 1 and 2 categories will be added to bread flour in small quantities; for example, C4, C5, 4B, and DIV2-2. This split milling system requires a mill with three flour screw conveyors and a flour mixing plant. The typical flour streams data are shown in Tables 4.2 and 4.3 (Hirsch 1997).

4.3. FLOUR MILL QUALITY CONTROL AND ASSURANCE PROGRAMS Flour mills that produce noodle flour often have a well-equipped quality control/ assurance laboratory. The functions of the laboratory serve the following purposes: (1) evaluation of arriving wheat, (2) control of the milling process, (3) evaluation of finished flour products, and (4) technical services to customers and handling of complaints. 4.3.1. Evaluation of Arriving Wheat An important task for quality control on arrival of wheat is “sampling.” The samples must be representative of the whole lot. If not, any further testing does not give meaningful results. An automatic sampler is installed at the wheat receiving plant. The sampler takes samples out of a stream at adjustable intervals, and assuming the sampler is of approved design and properly installed, the samples may be presumed representative of the average of a wheat lot. If tests cannot be carried out before unloading, the arriving wheat is stored in temporary silos, and only after the evaluation is completed will the lot be transferred to storage silos. The evaluation of the arriving wheat should be based on the following three criteria.

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TABLE 4.2 Mill Stream Analysis Result of 14.5% Protein (“As Is” Moisture Basis) Dark Northern Spring (DNS) Wheat Mill Stream

Moisture (%)

Protein (%, as-is mb)

Wet Gluten (%, as-is mb)

Ash (%, as-is mb)

Extraction Rate (%, as-is mb)

1B

a b

15.1 15.0

15.2 15.1

41.5 40.3

0.58 0.57

1.48 1.63

2B

a b

15.0 15.0

16.4 16.3

43.5 42.5

0.49 0.49

1.20 1.02

3B

a b

14.7 14.7

17.5 17.5

46.0 46.0

0.60 0.60

2.23 2.24

4B

a b

14.6 14.6

18.8 18.9

49.5 49.9

0.63 0.62

0.77 0.88

DIV 1

a b

14.8 14.9

14.6 14.7

40.1 41.1

0.51 0.47

4.47 4.72

DIV 2

a b

14.6 14.7

15.3 15.5

41.9 43.8

0.56 0.56

1.57 0.38

DIV 3

a b

12.8 12.2

13.7 14.0

36.7 38.8

0.60 0.67

2.93 0.06

14.8

16.9

42.9

0.96

1.75

DIV 4 C1A

1a

14.5

12.4

33.8

0.32

8.90

C1A

2a

14.4

12.5

34.2

0.32

1.32

C1A

1b

14.5

12.6

34.9

0.32

7.67

C1A

2b

14.4

12.5

33.6

0.33

3.83

C1B

1

14.4

12.7

35.3

0.40

4.09

C1B

2

14.1

12.6

34.9

0.40

0.70

C2

1a 2a 1b 2b

13.5 12.5 14.0 13.3

11.3 11.2 12.5 12.4

31.4 29.8 36.3 35.6

0.32 0.59 0.34 0.46

12.12 0.43 12.80 0.29

C3

1a 2a

13.5 13.0

12.8 12.9

37.1 NIL

0.46 0.81

7.10 0.23

14.1

13.9

36.3

0.70

1.50

C4 C5

1 2

13.3 12.6

13.1 13.0

35.2 34.4

0.62 0.92

3.07 0.14

C6

1 2

13.0 12.4

14.9 14.6

38.0 37.8

0.75 0.92

1.88 0.12

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TABLE 4.2

(Continued )

Mill Stream

Moisture (%)

Protein (%, as-is mb)

Wet Gluten (%, as-is mb)

Ash (%, as-is mb)

Extraction Rate (%, as-is mb)

C7

1 2

13.5 13.3

14.0 13.9

35.5 34.6

0.91 0.90

1.06 0.21

C8

1 2

13.6 13.5

15.6 15.3

40.4 39.1

0.86 0.87

1.91 0.39

C9

1 2 3

12.8 13.0 12.5

14.6 15.4 16.3

34.5 NIL NIL

0.63 0.83 1.32

1.86 0.66 0.41

Source: Hirsch (1997); used by permission.

TABLE 4.3 Mill Stream Analysis Result of 13.0% Protein (“As Is” Moisture Basis) Hard Red Winter (HRW) Wheat Mill Stream

Moisture (%)

Protein (%, as-is mb)

Wet Gluten (%, as-is mb)

Ash (%, as-is mb)

Extraction Rate (%)

1B

a b

14.7 14.7

13.6 13.8

38.4 40.5

0.52 0.51

1.77 1.81

2B

a b

14.6 14.5

14.4 14.3

40.7 39.0

0.41 0.42

1.26 1.31

3B

a b

14.4 14.4

15.4 15.4

43.3 43.1

0.52 0.49

2.16 2.50

4B

a b

14.0 14.0

16.5 16.4

45.5 43.5

0.57 0.55

0.86 0.94

DIV 1

a b

14.4 14.4

12.7 12.8

35.7 34.8

0.41 0.43

5.09 5.41

DIV 2

a b

14.2 14.2

14.1 14.4

37.5 40.5

0.51 0.51

2.21 0.50

DIV 3

a b

12.8 12.5

12.6 12.9

36.4 37.5

0.59 0.72

4.66 0.06

14.2

14.4

38.7

0.75

2.07

DIV 4 C1A

1a

13.9

10.8

30.7

0.30

9.83

C1A

2a

13.7

10.7

30.1

0.30

1.40

C1A

1b

13.9

10.9

30.8

0.29

8.37

C1A

2b

13.9

10.7

30.4

0.30

2.23

C1B

1

14.0

11.0

30.9

0.34

4.65 (Continued )

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TABLE 4.3

(Continued )

Mill Stream

Moisture (%)

Protein (%, as-is mb)

Wet Gluten (%, as-is mb)

Ash (%, as-is mb)

Extraction Rate (%)

C1B

2

13.9

10.9

31.5

0.35

0.81

C2

1a 2a 1b 2b

13.0 12.4 13.1 12.5

10.1 10.3 11.2 11.6

27.8 28.0 32.5 33.2

0.32 0.44 0.33 0.51

10.90 0.31 11.32 0.25

C3

1a 2a

12.6 12.4

11.1 11.5

32.0 33.2

0.44 0.72

6.02 0.23

13.1

11.8

29.6

0.68

1.34

C4 C5

1 2

12.0 11.5

11.0 11.7

29.7 NIL

0.58 0.93

2.43 0.11

C6

1 2

12.3 12.1

12.8 12.9

34.2 34.5

0.64 0.71

1.91 0.13

C7

1 2

12.7 12.5

12.1 12.2

30.7 31.1

0.84 0.82

1.00 0.34

C8

1 2

12.8 12.6

14.1 14.0

35.8 35.5

0.85 0.85

1.57 0.52

C9

1 2 3

11.8 11.9 11.8

13.6 13.2 14.2

32.4 NIL NIL

0.83 0.98 1.28

1.01 0.43 0.31

Source: Hirsch (1997), used by permission.

4.3.1.1. Is the Wheat Suitable for Storage? The moisture content, infestation, and nonmillable materials (defects such as shrunken and broken kernels, heat, or frost-damaged kernels, sprouted kernels, etc.) are the main concerns in determining wheat storage capability. Wheat kernels are living organisms that respire and produce moisture and carbon dioxide (CO2 ). Therefore, wheat moisture is the most important factor to consider. Excessive wheat moisture favors development of fungi and yeasts, which cause musty and sour odors that carry over into the flour and processed products. Excessive wheat moisture also can lead to heating during storage that may injure the quality of the gluten. In general practice, wheat is safe to store for a long period of time if the moisture content is below 12%; however, if the wheat moisture is over 14%, it is not suitable for storage. But these figures should not be considered absolute because other factors, such as storage humidity, temperature, and microorganisms in the wheat, also greatly influence the storage capability. Infestation by insects is another import factor and should be avoided by all means. Fumigation equipment should be installed at all wheat storage facilities. The nonmillable materials contain high levels of microorganisms and must be removed

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before milling. Imported wheat is graded according to international standards and all items concerning its grading and testing evaluation are reported in the export certificate.

4.3.1.2. What Is the Milling Capability of the Wheat? The moisture content, proportion of vitreous kernels, kernel size, and nonmillable materials are the factors influencing the milling capability. Wheat moisture not only affects wheat storage, it also influences the flour yield because wheat that is too dry or too wet reduces the noodle flour extraction yield. Therefore, it is very important to properly select wheat materials and carefully control wheat tempering conditions prior to milling. 4.3.1.3. What Are the End Uses of the Flours? Noodle products require specific flour quality parameters and specific wheat for milling. In order to produce optimum products, it is essential to have the right flour for each end product, and this can only be achieved if the wheat is segregated based on protein/gluten content and kernel hardness. For the evaluation of wheat storage capability, milling capability, and flour quality, the following tests are usually performed in flour mills: r Moisture content—to determine storage and milling capability. r Class/protein—to determine wheat class and protein content; for example, Dark Northern Spring (DNS)/14.5%, Hard Red Winter (HRW)/13.5%, Western White (WW)/9–10.5%. r Falling number (FN)—to detect sprouted wheat (300-second minimum). r Test weight—to provide information about the soundness and plumpness of the wheat kernels related to milling potential. r 1000 kernel weight—to give information about the size of the wheat kernels. r Vitreous kernels test—to provide information about the expected flour milling and quality. r Test milling—to produce flour from small wheat samples; the flour is evaluated for end-use functionality. Many flour mills use test mills to evaluate a wheat sample before grinding on the commercial mill. Test milling performance gives a good indication of millability in commercial milling. Millers rely on test milling results to anticipate changes in milling potential from shipment to shipment and to make necessary adjustments in commercial milling. 4.3.2. Milling Control Moisture, color, protein, and gluten tests are performed regularly for the purpose of flour milling production control. Moisture control of tempered wheat is important

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because continuous, accurate, and even moisture distribution of kernels at the first break rolls is essential for smooth running of the mill. Any irregularity in the first break moisture influences the flour produced and, therefore, the end products. The flour color grade or the Pekar test (Approved Method 14-10, AACC International 2000) can detect any irregularity in the milling process. Variations in the first break moisture, incidents of chokes, uneven wheat qualities, irregular production flow, broken sieves, and incorrect roll settings can readily be recognized by color grade. Protein/gluten testing is important, particularly if split flours (patent, clear) are produced. The protein content often shifts from patent flour to clear flour and has to be properly controlled. A gluten content test is sometimes used for milling production control because it is a quick test; however, mills with near-infrared (NIR) online equipment do not use the gluten test any more for production control because the online equipment gives continuous results for protein. Most modern mills have this online equipment, which, at adjustable intervals, takes samples automatically and is calibrated to estimate several major flour quality parameters such as protein, ash, and moisture. The results are recorded on graphs and give the millers a clear picture of the current status of mill production performance. Other tests, such as break release (proportion of ground product through a sieve of defined aperture) control, extraction control, and flour stream analysis (protein, wet gluten, ash, color, damaged starch, etc.), are handled by the head miller and mill staff onsite.

4.3.3. Flour Evaluation Evaluation of finished noodle flour in flour mill quality control laboratories includes generic tests and noodle making. The general flour tests include moisture, protein, wet gluten, ash, color, falling number, granulation, farinograph, and extensograph. For most test procedures, the AACC International (2000) Approved Methods are followed.

4.3.3.1. Moisture The percentage of moisture that a product contains can be measured by determining the amount of water under specific drying conditions. Since drying conditions affect results of moisture determinations, the conditions should be specified. If a standard procedure is employed, no modifications likely to affect results should be introduced. Moisture content is important for several reasons. Efficient flour milling requires knowledge of wheat moisture before milling and distribution of water in various parts of the kernel after conditioning and during milling. The amount of water that grain contains is economically significant and may result in certain advantages or disadvantages at various stages of marketing. Moisture content is of the utmost importance in safe storage of grains. Grain that contains moisture in excess of the critical level is subjected to rapid deterioration from mold growth, insect damage, and heat. And finally, many flour quality parameters, such as protein and ash content, are reported based on a constant moisture basis (usually 14%).

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4.3.3.2. Protein The protein determination, while not included as a grading factor for wheat, is accepted as a marketing factor. The relationship between crude protein content and bread-making potential is so well established that today protein content is generally accepted as a reliable indicator of the physiochemical properties of wheat flour to maintain protein’s position as the primary commercial market criterion of quality, supplementary to grade standards. For noodle flour, protein content is associated with the color of processed noodles and cooked noodle texture (Hirsch 1997). 4.3.3.3. Ash The purpose of flour milling is to separate endosperm from bran and germ and, subsequently, to reduce endosperm particles to flour. The efficiency of separation can be judged by several empirical, indirect methods. Since the mineral content of the bran is about 20 times that of the endosperm, the ash test is associated with the purity of the flour or thoroughness of the separations of bran and germ from the endosperm. The ash test has assumed greater importance in commercial milling than any other test for the control of the milling operation. For noodle flour, ash content is one of the main flour specifications required by noodle manufacturers. Lower ash flour is more desirable for making noodles because it is indicative of low bran contamination and associated with less noodle discoloration in products such as fresh white noodles and yellow alkaline noodles. 4.3.3.4. Flour Color Although flour color has considerable commercial importance, it has proved somewhat difficult at times to evaluate this property with precision and to record it permanently. Flour color is dependent mainly on the following four factors (Hirsch 1997): 1. 2. 3. 4.

Flour grade (degree of refinement) Degree of yellowness in the flour Flour granularity Presence of extraneous impurities in the wheat prior to milling

The flour grade is determined by the relative proportion of ground bran powder and hence the bran pigment present in flour. It is estimated by measuring the dullness or the brightness of flour. Flour also contains yellow pigment due to the presence of carotenoids, mainly the hydroxylated carotenopid lutein (Humphries et al. 2004). However, the degree of yellowness exhibited by commercial flours depends not only on the quantity of carotenoids but also on the extent to which these substances have been artificially bleached in the mill. Granularity also affects the color of dry flour; the finer a flour is ground, the brighter and whiter it appears because more light is reflected as particles become finer. A common test for flour color used in mills is the Pekar test. This test involves packing a flour sample beside a standard flour on a plate with a flour slick, immersing

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the slicked flours under water, and comparing the colors when wet and after drying. The test has the advantage of simplicity and there is no need for expensive equipment, but it is open to criticism because it is very subjective. Results are influenced by the manipulation of the operator, and the apparent color is also affected by the moisture content of the flour; the lower the moisture, the better the color appears. A laboratory method by which flour color can be expressed on a numerical scale is the Flour Color Grade, as first proposed by Kent-Jones and Martin (1950). This method involves preparing a flour slurry and measuring relative reflectance at 530 nm. Because the measurement is in the green region of the spectrum, it is independent of yellow pigment content and is thus a direct reading of the extent of bran contamination in the flour. Modern instruments use an empirical scale ranging from −5 (brightest) to +18 (dullest) (Kent-Jones et al. 1956). Another instrument that has gained attention in the flour industry is the Minolta Colorimeter. The results are commonly reported as CIE color units: L* (whiteness), a* (redness), and b* (yellowness). This device measures not only the color of flour powder but also the color of finished products such as noodle sheets and steamed bread skins.

4.3.3.5. Falling Number The falling number test (Approved Method 56-81B, AACC International 2000) is used to estimate the degree of sprout damage in wheat, caused by unfavorable wet weather conditions during harvest. As wheat germinates, α-amylase enzymes, which digest starch into sugars to supply nutrients to the developing embryo, are synthesized. Once flour is wetted, the α-amylase in the flour becomes active and breaks down the starch. If the α-amylase activity is high due to severe sprouting, it may cause the crumb of baked breads to be gummy and give boiled noodles a mushy texture. Ground wheat (or flour) is stirred into a hot aqueous paste, and the time it takes to stir and allow the stirrer to fall through the paste in seconds is the falling number. As the activity of the α-amylase increases, the starch paste becomes less viscous, and the falling number decreases. 4.3.3.6. Granulation A flour sample is sifted in a laboratory sifter with different sieve apertures (90–100–112–130 µm). The coarser sieves are at the top. The OVERS remaining on each sieve and the THROUGHS passing through the last sieve are weighed and expressed in percentage of total flour weight. The procedure should be standardized so results can be compared. Flour granulation is an important factor in determining noodle processing quality as well as noodle water absorption and noodle surface brightness. 4.3.3.7. Gluten Content Gluten content is measured by hand washing (AACCI Approved Method 38-10) or by a mechanical gluten washer (AACCI Approved Method 38-12A). Mechanical washing gives more consistent results than the hand-washing method. Wet gluten and protein content are related. A ratio of 1 part protein to 3 parts wet gluten is generally

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accepted, but the ratio depends on wheat quality and flour grade. Gluten of the last clear flour sometimes disappears during washing because it is too weak and cannot form a viscoelastic mass. Gluten content and quality are very important to noodle bite and cooking tolerance.

4.3.3.8. Farinograph The farinograph (AACCI Approved Method 54-21) is widely used to measure the physical dough factors that determine the suitability of flour for various end-product applications. The farinograph measures and records the resistance (consistency) of dough to mixing. Resistance is measured as torque by an arbitrary scale in Brabender units. Dough is mixed in a bowl by two Z-shaped blades that counterrotate. On older models, the resistance of the dough to mixing is recorded by a pen, which makes a graph on the farinograph paper. More modern instruments record curves electronically and automatically generate values for mixing parameters. Little resistance is registered when the machine is started, but as the dough develops, the resistance increases. The following terms are used to describe dough properties from the appearance of the mixing curve (“farinogram”). Absorption Absorption is the percentage of water (ratio of water to weight of flour) required to center the curve on the 500 Brabender unit (BU) line when the dough reaches maximum consistency. The more water a flour absorbs at a definite consistency of the dough, the greater the fresh noodle yield per bag of flour. Initial Development Initial development is the time required for the mixing curve to reach the 500-BU line from the beginning of the curve. It measures the rate of dough development and is sometimes called the arrival time. Mixing Time Mixing time is the time required for the curve to reach peak (maximum) consistency. Longer mixing times are usually associated with stronger wheat. Stability Time Stability time is the time that the curve remains on the 500-BU line and is measured from the arrival time to the departure time. Longer stability is indicative of greater tolerance to processing irregularities and the ability to withstand longer fermentation time. Mixing Tolerance Index The Mixing Tolerance Index (MIT) is an indication of how fast dough will break down after it has reached its full development time. It is measured in Brabender units (BU) and is defined as the drop in consistency from the peak height of the curve to the height of the curve 5 minutes after the peak. Higher values are associated with weaker dough. Valorimeter The valorimeter is an empirical single-figure quality score value based on dough development time and tolerance to mixing 12 minutes after peak time (AACCI Approved Method 54-21). The value is derived by means of a special

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template supplied by the manufacturers of the farinograph. A higher figure indicates stronger flour and a lower figure indicates weaker flour.

Degree of Softening The degree of softening is a measurement of the difference (decline) in BU between the center of the curve at the end of the dough development time and the center of the curve at a definite time after this point. The time is usually 12 minutes. 4.3.3.9. Extensograph The extensograph (AACCI Approved Method 54-10) measures the rheological properties of dough in an extension test. Dough is mixed in a large farinograph bowl, rounded, and placed in a sample holder. After specified periods of time, it is stretched to its breaking point. The standard procedure involves stretching the dough with a hook after a 45-minute rest and again at 90 minutes and 135 minutes, reforming the dough after each intermediate stretching time. The instrument measures the resistance to extension (elasticity) and extensibility. Older models use a pen to draw a curve on paper and more modern instruments record curves electronically and automatically generate rheological parameters. Results are provided in the form of “extensograms.” The extensograms detail the measuring parameters related to resistance to extension, energy of deformation, and distance the dough can be stretched before failure. Energy The energy required to stretch the dough is measured in square centimeters. In older models, the area under the curve is measured by means of a Planimeter and recorded in square centimeters (cm2 ). The energy value supplies information on the dough strength or on the blending value of flour. The larger the energy factor, the greater the dough strength of a flour. A value of less than 50 cm2 is not satisfactory for good quality noodles. Resistance to Extension The resistance to extension is obtained from the height of the extensograph measured 50 mm from the origin of the curve (resistance at constant deformation) or at the point of the curve where maximum height is reached (maximum resistance) and is stated in extensograph units. This is an indication of oxidation possibility. With oxidation agents, the value goes up. In Taiwan, some oxidizing agents are added into noodle flour. Extensibility Extensibility is measured in millimeters (mm) and corresponds to the length of the curve. With oxidation, the extensibility is reduced and the resistance is increased. The Ratio (R/E) The ratio of resistance (either at constant deformation or at maximum height) to length is important in evaluating the balance between elasticity and extensibility. The smaller the ratio, the greater the tendency of the dough to flow. A lower value, together with low area number, is a clear indication of weak gluten and poor quality. A high ratio of more than 5 indicates a “short” dough (difficult to sheet).

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4.4. MILLING TEST There is no satisfactory physical–chemical test, other than an experimental milling test, to predict milling quality. Many attempts to standardize and evaluate experimental milling procedures have met with varying success. The speed and ease of operation of the Buhler experimental mill have led to its extensive use in flour mill labs. A 60% extraction patent flour is often prepared from the Buhler experimental mill and analyzed for noodle quality to predict the quality attributes of commercially milled noodle flour.

4.5. FLOUR SPECIFICATIONS The suitability of wheat for the production of Asian noodles is affected by such factors as (1) wheat milling properties, which are affected by soundness, cleanliness, kernel size, kernel structure, and moisture content (Nagao 1981; Simmonds 1989; Hou 2001); (2) kernel hardness, which affects flour particle size, starch damage (farinograph water absorption), and extraction rate (Toyokawa et al. 1989; Hou 2001); (3) protein quantity and quality (as related to water absorption, processing, and endproduct characteristics) (Nagao et al. 1977; Oh et al. 1985); (4) starch composition (amylose to amylopectin ratio, and related starch swelling power and gelatinization attributes such as temperature of initial rise, peak viscosity, and setback) (Toyokawa et al. 1989; Crosbie 1991; Konik et al. 1992); and (5) noodle color and discoloration during processing and storage (Miskelly 1984). The enzyme polyphenol oxidase is thought to play a predominant role in this undesirable discoloration, although autooxidation of endogenous phenolic compounds can occur (Pierpoint 1969; Francis and Clydesdale 1975; Miskelly 1984; Hatcher and Kruger 1993; Baik et al. 1995). Various types of noodles are produced from specific quality flour (see Table 4.1). The udon white salted noodles are typically made from low protein flour, but the manufacturers prefer flour with high protein content and strong gluten for yellow alkaline noodles and Chinese white salted noodles to emphasize chewy texture. Several scholars have provided evidence that starch with high viscosity is beneficial to the eating quality of udon noodles (Nagamine et al. 2003). Udon noodles must have excellent purity of color (bright and speck-free) as well as harmonized stickiness and smoothness when chewed, qualities which are mainly derived from high starch viscosity and medium gluten protein elasticity (Nagamine et al. 2003). Similar to udon noodles, the Chinese white salted noodles are made from flour, sodium chloride, and water. Color is a key quality trait in Chinese white salted noodles to provide visual attractiveness to consumers. It also provides some indication of quality of the flour and, in some cases, the age of the product. Asian customers prefer bright and white noodles that, when stored fresh, retain a stable color for 1 or 2 days. To meet this requirement, flour mills usually supply low ash flour to noodle manufactures. U.S. hard white (HW) wheat is considered a suitable raw material for milling white salted noodle flour in Taiwan. According to our studies, the color of white salted noodles made with U.S. HW wheat flour showed a lower correlation with

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flour ash while HRS and HRW wheat flour ash had higher correlations with the noodle color. The U.S. HW wheat flour ash content did not show a significant correlation with E (r = 0.003, p > 0.05, N = 12) (E = [(L*)2 + (a*) 2 + (b*) 2 ]1/2 (Good 2002). The HW wheat noodles had both good bite and color stability because of good flour protein quality and quantity and low polyphenol oxidase (browning enzyme) content. The flour protein content was highly positively correlated with the cooked noodle tension force, tension distance, hardness, and springiness values measured with the TA.XT2 Texture Analyzer (r = 0.96, 0.85, 0.90, and 0.89, respectively; p < 0.05, N = 15). The flour protein content was also highly correlated with the dried noodle cutting force (r = 0.85, p < 0.05, N = 15) (unpublished data). Yellow alkaline noodles are made from flour, sodium chloride, water, and alkaline salts such as sodium and potassium carbonates. Yellow alkaline noodles represent a major use of U.S. hard wheat flour in Taiwan. The addition of alkaline salts results in a concomitant increase in the intensity of the yellow due to endogenous flavonoids undergoing a chromophoric shift; that is, turning yellow in the presence of alkali (Asenstorfer et al. 2006). The color of alkaline noodles is also due partly to xanthophylls (Hatcher et al. 2008). The noodle manufacturers often add pigments, such as gardenia pigment and carotene, to give the desired color. The consumption of fried instant noodles is growing fast in Asian countries and they are gaining popularity in Western countries (Shin and Kim 2003; Yu and Ngadi 2004). Fried instant noodles are made by a continuous steaming and frying process that gelatinizes the starch and quickly dehydrates the noodles. The resulting product has a porous, spongy structure and excellent flavors (Rho et al. 1986; Wu et al. 1998). Table 4.4 lists the quality ranges of commercial instant noodle flours in Taiwan. After soaking the fried noodles in 95 ◦ C water for 3 minutes, the flour protein content was positively correlated with fried instant noodle tension force, tension distance, and hardness and springiness (r = 0.96, 0.85, 0.90 and 0.89, p < 0.05, N = 15, HRW + DNS flours) (unpublished data). The flour ash content significantly affected the appearance of instant noodles as measured by the L*, a*, and b* values (r = −0.62, 0.83, and −0.73, p < 0.05, N = 15, HRW + DNS flours). Similarly, the flour ash content correlated significantly with the ground noodle cake powder color (r = −0.60, 0.81, and −0.72, respectively, for L*, a*, and b* values; p < 0.05, N = 15). The cooked noodle hardness showed significantly negative correlations with flour amylograph peak viscosity, gel breakdown, and setback viscosity (r = −0.81, −0.80, and −0.80, respectively; p < 0.05, N = 15) (unpublished data).

4.6. NEW QUALITY INDICATOR FOR FLOUR GRADING Commercial flours are blends of different mill streams. In Asia, flour is often blended based on the ash content of flour streams. Nonetheless, commercial flour quality still varies from time to time even when formulated by a well-trained expert, which suggests that using ash content as the sole indicator of flour grading is, in reality, randomly biased from the inherent flour quality. Suspecting that ash content may not be a relevantly good indicator for formulation, we reviewed the quality parameters of

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Survey of Commercial Instant Noodle Flour Quality in Taiwan

Quality Parameter Protein (%, 14% mb) Ash (%, 14% mb) Wet gluten (%, 14% mb) Dried gluten (%, 14% mb) Damaged starch (%, 14% mb) L* a* b* Farinograph water absorption (%, 14% mb) Farinograph stability time (min) Farinograph development time (min) Amylograph peak viscosity (BU) Amylograph gel breakdown viscosity (BU) Amylograph setback viscosity (BU)

Minimum

Maximum

Average

11.36 0.36 32.1 10.7 5.63 88.99 −1.55 6.77 63.1 8.0 22.0 525 332 720

14.58 0.75 42.7 14.8 7.95 92.77 −0.47 9.45 65.5 15.5 16.5 931 702 1437

12.68 0.52 36.6 12.5 6.84 91.19 −0.93 8.17 64.6 12.5 18.3 733 514 1070

Source: Unpublished data.

flours associated in situ with 20 flour mi1l streams, which included ash content, crude fat content, fatty acid composition, and some lipid peroxidative enzyme activities, including lipoxygenase, hydroperoxide lyase, and peroxidase. In preliminary examinations, we found that ash content was not a very reliable flour quality indicator and has limited practical value. To search for a more relevant parameter, we conducted further confirmatory tests by preparing reconstituted flour blends having constant ash and/or constant crude fat contents, by which we discovered that crude fat content could be a more relevant and more reliable parameter for flour quality grading and evaluation and it is suggested that it be used as a novel indicator for flour grading (Lin et al. 2010). Wheat flour contains a variety of biochemical enzymes. In searching for an indicator that would be pertinently associated with flour grading, we examined the ash and crude fat contents, fatty acid composition, and activities of some lipid peroxidative enzymes including lipoxygenase, hydroperoxide lyase, and peroxidase that are normally present in situ in different mill streams (Rani et al. 2001). The distribution of α-amylase, protease, lipoxygenase, polyphenol oxidase, and peroxidase in wheat roller flour mill streams was studied (Lin et al. 2010). Break flours had relatively less α-amylase and protease activity than reduction flours both on flour weight and a protein basis. Among the different flour streams, the fifth and sixth reduction passages had the highest α-amylase activity, while the fourth reduction passage had the highest protease activity. The lipoxygenase activity was concentrated mostly in the last break and the reduction streams, whereas polyphenol oxidase activity was highest in the break flour streams. Peroxidase activity was distributed unevenly among different mill streams. The lipoxygenase, polyphenol oxidase, and peroxidase were highly concentrated in different bran fractions. The milling by-product had the most enzyme activity and the farina the least. The highest ash content was in stream 4B,

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followed by streams C7, lB, and C6; whereas the highest crude fat content was in stream C7, followed by streams C6 and 4B. Practically, the ash and the crude fat contents in 20 different mill streams in situ in the mill factory were poorly correlated (R2 = 0.55). With regard to peroxidation, lipoxygenase activity was highest in stream C7, and moderate in streams C4–C6 and lB–4B. Hydroperoxide lyase and peroxidase activities were highest in streams 4B and 3B, respectively. Significantly stronger correlations between lipoxygenase activity and crude fat (R2 = 0.95) compared to ash contents (R2 = 0.75) was also confirmed in selected streams by confirmatory tests (R2 = 0.84 vs. R2 = 0.11). Similar results were found for hydroperoxide lyase and peroxidase activities. The correlation coefficients were 0.91 versus 0.40 for hydroperoxiderase; and 0.72 versus 0.02 for peroxidase with crude fat and ash contents, respectively. Moreover, sensory evaluation by the confirmatory tests also revealed the crude fat showed a closer correlation with off-odor with the crude fat than with the ash content. Conclusively, the crude fat content is suggested to replace the ash content as a novel quality control index for flour milling and noodles processing (Lin et al. 2010). Table 4.5 lists the compositional distribution of some representative free fatty acids in different mill streams. Apparently in all streams, palmitic acids (C16:0) ranging from 12.7% to 22.8% were the most prominent saturated fatty acids, while linoleic acids (C18:2), having a range of 55.6–70.2% in all mill streams, were the major component in the unsaturated fatty acid group. These results were consistent with Prabhasankar’s study (Prabhasankar and Rao 1999). In agreement with this, the higher proportion contributed by mill streams C6 and C7, the more readily the flour would deteriorate or develop an off-odor, although the content of linoleinic acid (C18:3) was the highest in stream 2B, and streams 1B, 3B, C3A1
, C3A1, C6 and C7 comprised only moderate contents of linoleinic acid (Lin et al. 2010).

4.7. SUMMARY The production of a good noodle flour starts with good control on wheat quality, including sound grains, high test weight, large kernels, low ash, good gluten quality, white color, and low enzyme activity. Optimizing the wheat tempering operation minimizes bran contamination in flour, which improves color stability of fresh noodle products. Good milling management on roll passages, sifters, and purifiers is essential to produce the highest possible extraction of low-ash noodle flour. A recent study indicated that the crude fat content may be a more reliable quality indicator than ash to select flour streams for noodle flour production.

ACKNOWLEDGMENTS The authors wish to thank Dr. Jim Dexter of Grain Research Laboratory, Canadian Grain Commission, Winnipeg, Canada, and Dr. Gary Hou of Wheat Marketing Center, Portland, Oregon, USA, for their critical review of this manuscript.

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TABLE 4.5 Fatty Acid Compositions (%) of Mill Streams for (DNS: HRW = 50:50) Wheat Samplea Mill Streamb

C16:0

C18:0

C18:1

C18:2

C18:3

1B 2B 3B 4B C1A1
C1A1 d C1Al C1B1
C1B1 C2A1
C2A1 C2B1
C2B1 C3A1
C3Al C4 C5 C6 C7 DIV1A


18.92 20.32 20.11 19.28 19.75 21.01 20.84 17.91 20.47 18.07 19.79 17.47 22.78 21.21 21.21 12.66 20.02 19.80 20.32 20.05

1.17 1.17 1.51 0.98 1.13 1.06 1.13 1.01 1.12 1.19 1.55 1.26 2.09 1.14 1.14 1.14 1.12 1.08 0.97 1.15

15.39 15.29 18.54 17.73 12.55 12.18 10.92 10.84 12.52 10.83 11.16 15.75 19.44 12.88 12.88 16.50 10.86 15.53 15.07 1384

64.38 62.71 59.66 61.96 66.43 65.58 67.03 70.18 65.79 69.82 67.41 65.40 55.59 64.65 64.65 69.63 67.92 63.42 63.53 64.86

0.13 0.51 0.18 0.06 0.14 0.07 0.08 0.06 0.09 0.09 0.08 0.11 0.10 0.13 0.13 0.06 0.09 0.17 0.11 0.09

a Sample preparation as described by Dahmer et al. (1989) and Liu (1994). Fatty acid analysis: an FID-type gas chromatography (Angilent 6890, Wilmington, DE, USA). b Mill stream designations:

1B · · · 4B: Flour streams in the break mill system. C1A l
to DIV1A
: Flour streams in the reduction mill system. lB: The flour stream obtained from the first break roller. 2B, 3B, and 4B: The flour streams obtained from the second, third, and fourth break rollers, respectively. C1A1
: C1 denotes the flour obtained from the first smooth rollers; A1
denotes the flour sieved out from the upper outlet of the system A1. C1A1 d: C1 denotes the flour obtained from the first smooth rollers; Al ddenotes the flour sieved out from the middle outlet of the system A1. C1Al: C1 denotes the flour obtained from the first smooth rollers; A1 denotes the flours sieved out from the lower outlet of the system A1. C1B1
: C1 denotes the flour obtained from the first smooth rollers; B1
denotes the flours sieved out from the upper outlet of the system B1. C1B1: C1 denotes the flour obtained from the first smooth rollers; B1 denotes the flours sieved out from the lower outlet of the system B1. C2A1
: C2 denotes the flour obtained from the second smooth rollers; A1
denotes the flours sieved out from the upper outlet of the system A1. C2A1: C2 denotes the flour obtained from the second smooth rollers; A1 denotes the flours sieved out from the lower outlet of the system A1. C2B1
: C2 denotes the flour obtained from the second smooth rollers; B1
denotes the flours sieved out from the upper outlet of the system B1. C2B1: C2 denotes the flour obtained from the second smooth rollers; B1 denotes the flours sieved out from the lower outlet of the system B1. C3A1
: C3 denotes the flour obtained from the third smooth rollers; A1
denotes the flours sieved out from the upper outlet of the system Al. C3Al: C3 denotes the flour obtained from the third smooth rollers; A1 denotes the flour sieved out from the lower outlet of the system Al. C4, C5, C6, and C7: These denote the flours obtained from the fourth, the fifth, the sixth, and the seventh smooth rollers, respectively. DIV1A
: The flour obtained from the second sieve of the first break roller and the second reduction millers. Source: Lin et al. (2010).

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REFERENCES AACC International. 2000. Approved Methods of the AACC, 10th ed. American Association of Cereal Chemists, St. Paul, MN, USA. Anon. 1999. The Special Project Reports of the Industrial Development Bureau. Ministry of Economic Affairs, Taipei, Taiwan. Anon. 2001. Chinese National Standard: CNS 550. Bureau of Standards, Metrology & Inspection, Ministry of Economic Affairs, Taipei, Taiwan. Asenstorfer, R. E., Wang, Y., and Mares, D. J. 2006. Chemical structure of flavonoid compounds in wheat (Triticum aestivum L.) flour that contribute to the yellow colour of Asian alkaline noodles. J. Cereal Sci. 43:108–119. Baik, B. K., Czuchajowska, Z., and Pomeranz, Y. 1995. Discoloration of dough for oriental noodles. Cereal Chem. 72:198–205. Crosbie, G. B. 1991. The relationship between starch swelling properties, paste viscosity and boiled noodle quality in wheat flours. J. Cereal Sci. 13:145–150. Dahmer, M. L., Fleming, P. D., Collins, G. B., and Hildebrand, D. F. 1989. A rapid screening technique for determining the lipid companion of soybean seeds. J. Am. Oil Chemists Soc. 66(4):543–548. Francis, F. J. and Clydesdale, F. M. 1975. Food Colorimetry: Theory and Applications. Avi Publishing, Westport, CO, USA. Good, H. 2002. Measurement of color in cereal products. Cereal Foods World 47(1):5–6. Hatcher, D. W. and Kruger, J. E. 1993. Distribution of polyphenol oxidase in flour millstreams of Canadian common wheat classes milled to three extraction rates. Cereal Chem. 70: 51–55. Hatcher, D. W., Dexter, J. E., and Fu, B. X. 2008. Investigation of amber durum wheat for production of yellow alkaline noodles. J. Cereal Sci. 48:848–856. Hirsch, W. 1997. China’s Flour Milling Industry into the 21st Century. Genesis Printing & Arts Co. Ltd., Hong Kong, China. Hou, G. 2001. Oriental noodles. Adv. Food Nutr. Res. 43:142–188. Humphries, J. M., Graham, R. D., and Mares, D. J. 2004. Application of reflectance colour measurement to the estimation of carotene and lutein content in wheat and triticale. J. Cereal Sci. 40:151–159. Kent-Jones, D. W. and Martin, W. 1950. A photo-electric method of determining the colour of flour as affected by grade, by measurements of reflecting power. Analyst 75:127–132. Kent-Jones, D. W., Amos, A. J., Martin, W., Scott, R. A., and Elias, D. G. 1956. A modern reflectometer for flour and near white substances. Chem. Ind. (December 22):1490–1493. Konik, C. M., Miskelly, D. M., and Gras, P. W. 1992. Contribution of starch and non-starch parameters to the eating quality of Japanese white salted noodles. J. Sci. Food Agric. 58:403–406. Liu, K. S. 1994. Preparation of fatty methyl esters for gas-chromatographic analysis of lipids in biological materials. J. Am. Oil Chemists Soc. 71(11):1179–1187. Lin, L. Y., Peng, C. C., Wu, T. H., Yu, T. H., Chen, C. C., Wang, H. E., and Peng, R. Y. 2010. Four blending based on crude fat is more crucial than ash content in view of prolonged quality assurance. J. Food Processing Preservation 34:104–126. Miskelly, D. M. 1984. Flour components affecting pasta and noodle color. J. Sci. Food Agric. 35:463–471.

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Nagamine, T., Ikeda, T. M., Yanagisawa, T., Yanaka, M., and Ishikawa, N. 2003. The effects of hardness allele pinb-D1b on the flour quality of wheat for Japanese white salty noodles. J. Cereal Sci. 37:337–342. Nagao, S. 1981. Soft wheat uses in the Orient. In: W. T. Yamazaki and C. T. Greenwood (eds.), Soft Wheat: Production, Breeding, Milling, and Uses. American Association of Cereal Chemists, St. Paul, MN, USA, pp. 267–304. Nagao, S., Ishibashi, S., Sato, T., Kenbe, T., Kanbe, Y., and Otsubo, H. 1977. Quality characteristics of soft wheat and their utilization in Japan. III. Effects of crop year and protein content on product quality. Cereal Chem. 54:330–336. Oh, N. H., Seib, P. A., Ward, A. B., and Deyoe, C. W. 1985. Noodles VI. Functional properties of wheat flour components in Oriental dry noodles. Cereal Foods World 30:176–178. Osborne, B., Turnbull, K. M., Anderssen, R. S., Rahman, S., Sharp, P. J., and Appels, R. 2001. The hardness locus in Australian wheat lines. Australian J. Agric. Res. 52:1275–1286. Pierpoint, W. S. 1969. O-Quinones formed in plant extracts—their reaction with amino acids and peptides. Biochem. J. 112:609–616. Prabhasankar, P. and Rao, H. P. 1999. Lipids in wheat flour streams. J. Cereal Sci. 30:315–319. Rani, K. U., Prasada, U. J. S., Leelavathi, K., and Haridas, R. P. 2001. Distribution of enzymes in wheat flour mill streams. J. Cereal Sci. 34:233–242. Rho, K. L., Seib, O. K., and Chung, D. S. 1986. Retardation of rancidity in deep-fried instant noodles (Ramyon). J. Am. Oil Chemists Soc. 63:251–256. Simmonds, D. H. 1989. Wheat and wheat quality in Australia, pp. 25–28. Australian Wheat Board, CSIRO, Australia. Shin, S. N. and Kim, S. K. 2003. Properties of instant noodle flours produced in Korea. Cereal Foods World 48:310–314. Toyokawa, H., Rubenthalcr, G. L., Powers, J. R., and Schanus, E. G. 1989. Japanese noodles qualities. II. Starch components. Cereal Chem. 66:382–386. Wu, T. P., Kuo, W. Y., and Chen, M. C. 1998. Modern noodle based foods product range and production methods. In: A. B. Blakeney and L. O’Brien (eds.), Pacific People and Their Foods. American Association of Cereal Chemists, St. Paul, MN, USA, pp. 37–89. Williams, P. C. 1979. Screening wheat for protein and hardness by near infrared reflectance spectroscopy. Cereal Chem. 56:169–172. Yu, L. J. and Ngadi, M. O. 2004. Textural and other quality properties of instant fried noodles as affected by some ingredients. Cereal Chem. 81:772–776.

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CHAPTER 5

Noodle Processing Technology GARY G. HOU, SYUNSUKE OTSUBO, HIDEKI OKUSU, and LANBIN SHEN

5.1. INTRODUCTION Asian noodles are traditionally made by hand through repeated stretching or sheeting with rolling pins and hand-cut into strands with a knife. Currently, the hand-stretching technique is used primarily to make high-quality dried noodles with good mouthfeel and flavor in China and Japan, and some Chinese restaurants make them for artistic show, but the production quantity is very limited. Many specialty noodle restaurants and some homes in Asia use this method to prepare freshly made noodles, such as Chinese salted noodles, Japanese udon noodles, soba noodles (containing buckwheat flour), and chukamen noodles. Today, most noodle products are mass produced by industrial noodle machines for retail and food service markets. This industrial noodle-making method is called the “roll pressure stretching” technique. It was originally developed in 1883 by the Masaki Menki Co., Japan, and the technology has been improving ever since. Although various specialized versions of noodle equipment have been developed, most of them are variations of the roll pressure stretching method. One of the other noodle-making methods is “extrusion,” which is the same method that is used in making Italian pasta products. Asian noodle processing includes basic (primary) processing and secondary processing units (Hou 2001; Fu 2008). The basic processing unit for machine-made noodles includes mixing raw materials, resting the crumbly dough, sheeting the dough into two dough sheets, compounding the two dough sheets into one, gradually reducing the dough sheet into a specified thickness by roll pressure stretching, and slitting into noodle strands. In the secondary noodle processing unit, noodle strands are further processed according to noodle type. This chapter provides a comprehensive description of processing technology and quality attributes of eight major noodle types in the market.

Asian Noodles: Science, Technology, and Processing, Edited by Gary G. Hou C 2010 John Wiley & Sons, Inc. Copyright


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5.2. BASIC PROCESSING OVERVIEW 5.2.1. Mixing Formula Ingredients The aim of mixing is to hydrate flour uniformly with salt or alkaline salt solution to form crumbly dough. Most ingredients, such as sodium chloride, alkaline salt (kansui), and gums, are predissolved in water and stored in tanks. Wheat flour and other dry ingredients, such as starch or vital gluten, are dry-blended in the mixer before the salt/alkaline solution is added. Dry-blending is often done by mixing at a high speed (90–120 rpm) for 2 minutes to achieve a relative homogeneous mixture.

5.2.1.1. Dough Mixer There are two commonly used dough mixers in the noodle industry: the horizontal mixer and the vertical mixer. Both mixers are capable of providing good mixing action, but the horizontal mixer seems to have better mixing results, so it is more commonly used than the vertical one in commercial noodle production. Mixing results in the formation of small dough crumbs. In addition, there are several other specially designed mixers: the low-speed mixer, the continuous super-high-speed mixer, and the vacuum mixer. The low-speed mixer is used exclusively for mixing a high-water dough formula (more than 40% of flour weight) with a paddle and operates at 10 rpm. This method of dough preparation combines high water absorption and slow mixing with a paddle and yields results similar to the hand-kneading action of dough. Gluten is well developed in the noodle dough, but caution is required not to overdevelop the gluten because it will form big dough chunks in the mixer and cause stickiness to machine rollers during sheeting. The super-high-speed mixer operates at a speed of 1500 rpm and the salt/alkaline solution is sprayed at the flying flour particles in the mixer as it is running. This very high-speed mixing creates a much larger contact area between the flour particle surface and water, so flour can be hydrated instantly and evenly. More water may be added in the dough because the gluten is little developed during high-speed mixing. In many cases, a normal mixer is installed after the high-speed mixing to develop some gluten structure prior to dough sheeting. The vacuum mixer is becoming more popular in modern commercial noodle production as it allows more water (36–40% of flour weight) in the noodle formula and facilitates gluten development during sheeting, promotes starch gelatinization during steaming, and shortens noodle cooking time (Wu et al. 1998). In their study, Wu and co-workers found that if the mixing moisture level was lower (less than 36%), it was difficult to obtain optimal results and more mixing energy was required. However, if the mixing moisture was too high (higher than 40%), the dough pieces tended to form large lumps, causing difficulty in subsequent sheeting and in controlling the final dough sheet thickness. When extra water is added during vacuum mixing, the gluten development is improved during mixing and sheeting. A well-developed gluten network gives the noodles a continuous internal structure and improves their biting texture. For making instant noodles, starch gelatinizes better and swells to a greater extent during steaming when the noodle moisture is higher. Well-gelatinized

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starch imparts to the noodles a shorter cooking time, less surface stickiness, a slower retrogradation rate during refrigeration, and more viscoelastic texture after cooking. One theory holds that the vacuum mixing is effective in dough formation because of water incorporation into lost air pockets (Oda 1991). Vacuum higher than 600 mm Hg gives a more pronounced effect, but 400–600 mm Hg is commonly used. Lower vacuum is used for noodle products that require a softer bite, such as udon noodles.

5.2.1.2. Mixing Moisture Level The optimum water addition in noodle dough is important for ease of processing, finished noodle color, and textural characteristics. Insufficient water addition causes a streaky dough sheet and sometimes flaking on the surface. The resultant noodle strands are weak and break easily when hung for air-drying because of the presence of noncohesive zones, and the cooked noodle texture tends to be softer because the gluten is less developed. On the other hand, excessive water forms larger-sized dough crumbs during mixing and causes problems in dough sheeting due to overdevelopment of the gluten. Even so, the water absorption level in noodle dough is not as sensitive to processing as it is in bread dough. Variation in noodle dough water absorption among different flours is generally within 2–3%, and this is usually determined by doughhandling properties. Guidelines for determining optimum noodle dough absorption using subjective and instrumental methods are described in Chapter 8. Complicating the matter is the fact that flour mixing moisture level strongly affects uncooked noodle brightness (Kruger et al. 1994; Baik et al. 1995; Morris et al. 2000); thus, for noodle color comparison, the mixing moisture level should be kept constant for all flours. Other than the type of mixer used, the optimum mixing moisture level of noodle dough is also affected by flour quality (protein content and quality, damaged starch, flour granulation, and pentosans), ingredients added, and the temperature and humidity of the processing environment. In contrast to bread making, water absorption in noodle flour has a negative relationship with flour protein content (Park and Baik 2002; Zhao and Seib 2005). High-protein flour hydrates faster and easily forms largesized dough crumbs that are often uneven in hydration, that is, wet outside and dry inside (Azudin 1998), and thus requires less mixing time. If the mixing time remains constant for ease of commercial production, the amount of water added to highprotein flour needs to be reduced to avoid excessive gluten development in mixing and problems in dough sheeting. Small crumb size is preferred to assure even formation and development of gluten during subsequent sheeting, resulting in smoothness and uniformity of the noodle dough sheet. Flour with highly damaged starch often requires more water because damaged starch granules compete with the gluten protein for the limited amount of water available in noodle dough. Pentosans have the same effect as the damaged starch because they also compete with other components for water. Flour particle size and their distribution affect the time that water penetrates into the flour. Larger particle flours require a longer time for water to incorporate and they tend to form larger dough lumps. It is desirable to have relatively fine and evenly distributed particle size flours to achieve optimum dough mixing.

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Addition of salt and alkaline salt in a noodle formula tends to toughen the dough and allows for the addition of more water without causing difficulty in processing. However, under normal mixing conditions, the mixing moisture level is relatively low (28–35%); thus, gluten development in noodle dough during mixing is minimized. Lower water absorption helps to slow down fresh noodle discoloration and reduces the amount of water to be taken out during the final drying or frying process.

5.2.1.3. Mixing Water Temperature Water temperature affects mixing time and noodle quality. If water temperature is too low (<18 ◦ C), it slows down flour hydration speed and gluten development and requires a longer mixing time. If water temperature is too high (>30 ◦ C), excessive heat generated during mixing could denature the protein and gelatinize the starch, resulting in sticky dough. High dough temperature can also increase enzyme activity and deteriorate noodle quality. It is recommended that the water temperature be adjusted to achieve a final dough temperature of 25–30 ◦ C. 5.2.2. Dough Resting After mixing, the dough pieces are usually rested for 10–30 minutes before compounding. Dough resting helps water penetrate into dough particles evenly, resulting in a smoother and less streaky dough after sheeting. Another reason for resting the dough is to relax the intense gluten structure formed during mixing and to improve dough-sheet formation. In commercial production, the dough is rested in a receiving container while being stirred slowly (5–10 rpm). The stirring helps to dissipate heat inside the dough mass, prevent formation of large dough lumps, and feed dough crumbs into the sheeting rolls in a continuous process. 5.2.3. Dough Sheet Forming and Compounding The rested, crumbly dough pieces are transferred to the hopper of a compounding unit, which consists of two pairs of horizontal rolls (30 cm in diameter) located below the hopper, rotating inwardly in opposite directions. The dough crumbs are divided into two portions, each passing through a pair of sheeting rolls to form a noodle dough sheet. At this stage, the surface of the sheets is rough and sheet strength is weak. Larger diameter rolls with more strength may be used for less water formulation noodles as well as to accommodate larger lumps of dough for high water formulation noodles. The two sheets are then combined (compounded) and passed through a second set of same sized sheeting rolls to form a smoother and stronger sheet. The roll gap is adjusted so that the dough thickness reduction is between 30% and 50%. There are at least two goals to achieve by combing two separate sheets into one (Ross and Hatcher 2005). First, it evens out potential differences in density that could occur in a single sheet, including filling in gaps and holes, and it provides a far more homogeneous sheet. Second, it increases the mechanical work going into the dough, accelerating gluten development.

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5.2.4. Dough Sheet Resting The compounding rolls exert a strong force on the combined dough sheet; therefore, the sheet is often rested for as short as a few minutes to as long as a few hours to mellow tensed gluten structure in order to ease subsequent sheeting steps. In commercial operations, a balance needs to be struck between the amount of dough darkening one is prepared to accept and optimum relaxation of the dough. There are different ways to rest the dough sheet, depending on production facilities and noodle types. In batch production, the dough sheet is often stored and covered by winding on wooden or plastic spools. In continuous production, the dough sheet is rested on a multilayer conveyor belt located in a temperature-controlled and relativehumidity-controlled cabinet. This stage of dough resting has at least four functions: (1) to help moisture distribute more evenly, (2) to enhance disulfide bond formation, (3) to form bonds between gluten and lipids, and (4) to relax the gluten for easy reduction in the subsequent sheeting operation. The typical aging time is about 15–30 minutes. Whether a dough sheet is allowed to rest or not has a significant impact on the degree of starch gelatinization during steaming. According to Wu et al. (1998), a wellrested dough has a higher degree of starch gelatinization than an unrested dough, as examined by differential scanning calorimetry. The lack of evenly distributed water may prevent starch from being fully gelatinized during steaming. Meanwhile, the unrelaxed gluten may suppress starch swelling. 5.2.5. Noodle Sheet Reduction Further dough sheeting is done on a series of four to six pairs of rolls with decreasing roll gaps. There are two main effects at this step: reducing the dough sheet to final noodle thickness and developing the gluten network. Roll diameter, sheeting speed, and the degree of dough sheet thickness reduction should carefully be considered to achieve an optimum dough reduction. Table 5.1 lists the optimum commercial TABLE 5.1

Typical Commercial Noodle Machine Settings

Steps

Sheet Roll Linear Rolling Dough Sheet Thickness Diameter Velocity Speed Thickness Reduction Power Rolls (mm) (m/min) (rpm) (mm) Ratio (%) (kilowatts)

Sheet forming Compounding

#1, #2 #3

240 300

3.8 7.6

5 8

#4 #5 #6 #7 #8

240 180 150 120 90

11.3 17.0 21.1 26.4 28.2

15 30 45 70 100

Reduction and sheeting Source: Ye (2006).

4 4 2.4 1.7 1.3 1.1 1.0

100 50 40 29 24 15 9

3.7

5.5

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TABLE 5.2 Reference Values of Dough Sheet Reduction for the Five Reduction-Rolls Noodle Machine

Rolls Dough sheet reduction ratio (%)

Dough Sheet Forming Rolls

Compounding Roll

#1 and #2

#3

#4

#5

#6

#7

100

50

38–43

30–33

20–25

10–15

Reduction Rolls

Source: Ye (2006).

processing parameters to produce a 1.0-mm thick noodle sheet on the five reductionroll noodle machine (Ye 2006). The gluten alignment in the dough sheet is developed in the direction of the rolls by this sheeting process. This contrasts to the multidirectional gluten development that happens with the hand-kneaded noodle method. Repeated sheeting can increase the density of the noodles by pressing out gas, thus improving the physical integrity of raw and dry noodles. However, gluten structure tearing, dough sheet tearing, and/or dough sheet surface peeling may occur when the roll gap reduction ratio is too large and extreme pressure is applied on the dough sheet. To achieve an optimum gluten development and smooth noodle sheet surface, the reduction ratio of the dough sheet gradually decreases from the compounding roll to the final calibration roll. The reason for limiting the amount of reduction during one sheeting step is that damage to the gluten structure may occur, and the dough may simply tear, rendering the sample unusable. Because the gluten structure holds the dough together (Moss et al. 1987), tearing is a macroscopic indicator of damage to the gluten structure. Tables 5.2 and 5.3 show the reference values of dough sheet reduction ratios for two different types of rolling machine (Ye 2006). The roll speeds of the series of sheeting rolls are synchronized with light sensors installed between rolling stations to prevent dough from stretching or slacking that may result in sheet tearing. More reduction roll setup is often recommended for a fast-speed operation and for products that require less pressure-stretching during TABLE 5.3 Reference Values of Dough Sheet Reduction for the Six Reduction-Rolls Noodle Machine Dough Sheet Forming Rolls

Compounding Roll

#1 and #2

#3

#4

#5

#6

#7

#8

100

50

38–43

28–35

23–26

11–23

9–10

Rolls Dough sheet reduction ratio (%) Source: Ye (2006).

Reduction Rolls

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sheeting, such as dry noodles. The last set of rolls with a slitter has little pressurestretching ability; therefore, tearing or flaking problems may occur when trying to achieve extreme thickness reduction at this stage. Most noodle machines are equipped with smooth rolls, and noodles produced from them have relatively poorer biting texture compared to hand-made noodles. This shortcoming of machine-made noodles can be overcome by the use of waved rolls in multiroll sheeting to simulate the motions of manual sheeting. Because the dough is sheeted in multiple directions, the gluten network is well developed and more uniform, resulting in an improved biting quality and a lower cooking loss (Zhou and Guo 1996). Since the temperature has impact on the gluten properties and enzyme activities, it is important to control the dough temperature as well as the temperature in the processing room to maintain good processing performance, proper gluten development, and minimized enzyme activity in the dough sheet. 5.2.6. Slitting and Waving Noodle slitting is done by a cutting machine, which is equipped with a pair of calibration rolls (the last set of reduction rolls), a slitter, and a cutter or a waver. The final dough sheet thickness is set on the calibration rolls according the noodle type and measured using a thickness dial gauge. Once the dough sheet is reduced to the desired thickness, the sheet is then slit into noodle strands of desired width with a slitter along the direction of sheeting. The width of noodle strands determines the size of noodle slitter to be used (noodle width, mm = 30/slitter number). Noodle strands are cut into a desirable length by rotary cutting blades. The shape of a noodle strand cross section can be rectangular, square, or round, depending on the type of slitters used. In most cases, noodle strands are slit so that the cross section becomes a rectangular shape with the upper and bottom dough sheet surface sides being longer than the two slit sides. Since the dough sheet surfaces are smooth, the noodle strands have less of a tendency to break down during cooking; thus, they have a smooth mouthfeel. As the width of the slit noodle strands gets smaller, the cross section becomes closer to a square shape. A round-shaped slitter with oval or round cross-section configuration may be used to intensify the noodle springiness because a round shape is the strongest physical structure. The roundshape surface does not absorb water easily because its surface is smoother than the slit-side surface of rectangular or square type noodles. Round-shaped noodles give more springiness and textural tolerance after cooking. Thin-bladed slitters, which give sharper cuts than regular slitters, may be used for softer dough sheets to provide cleaner cuts without squashing the noodle strands, so cooked noodles are felt as smoother on the surface. In the case of making instant noodles, noodle strands emerging from the slitter are fed into an attached waver and are hindered by metal blocks (weights), resulting in unique noodle waves. Waving noodles not only shortens the noodle strand length by two-thirds and reduces the length of the steamer as well as the steaming time, but it can also make steaming more effective and uniform because steam can freely

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run through spaces among noodle strands created by the waving process. Another advantage of waving noodles includes a variety of different textures created by waved and nonwaved areas in a serving portion, providing for better soup integration than straight noodles for a more enjoyable eating experience. After steam cooking, the waved noodle strands are cut into serving sizes and molded into a block or cup shape before deep-frying or air-drying. 5.2.7. Noodle Aging Raw chukamen noodle texture becomes harder and less cohesive after aging for one or more days in refrigerators (Oda 1991). This aging effect is due to the decrease of air pockets in the noodles and an alkali reaction. Three days of aging produces a product with enhanced noodle transparency, hardness, and springiness.

5.3. PROCESSING TECHNOLOGY AND QUALITY CHARACTERISTICS OF MAJOR NOODLE TYPES 5.3.1. Fresh Raw Noodles Fresh raw noodles are initial forms of noodles without secondary processing steps. The moisture content of fresh raw noodles is in the range of 32–38%. Many noodle types fit into this category and they include Chinese raw noodles (white salted), raw Japanese white salted noodles, and raw yellow alkaline noodles. Fresh alkaline noodles are known as Cantonese noodles in Southeast Asia and called chukamen in Japan. Their typical formulas are shown in Table 5.4 (Hou 2007). Potato or tapioca starch (native or modified) is often added at 5–15% of flour weight to Japanese udon noodles to improve springiness and smoothness of cooked noodles. Also, 1–2% of alcohol is commonly added to chukamen noodles to serve as a preservative.

5.3.1.1. Processing Technology Fresh raw noodle production involves all of the steps in the basic noodle processing unit as described previously. Figure 5.1 illustrates the typical commercial fresh raw TABLE 5.4 Ingredient

Typical Noodle Formulations of Three Noodle Types Chinese Raw Noodles

Japanese White Salted Noodles

Yellow Alkaline Noodles

100 28–32 1–2

100 32–40 2–5

100 28–34 1–1.5 0.5 0.5

Flour (%) Water (%) Salt (%) K2 CO3 (%) Na2 CO3 (%) Source: Hou (2007).

Dough Sheet Combining Machine

Feeder

Continuous Rolling Machine

Fresh raw noodle processing line.

Aging Chamber

FIGURE 5.1

Slitter & Cutter

Flour Duster

Sterilizing Tunnel

Packer

8:9

Alkali Liquid Mixing Tank

Mixer

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Flour + salt or alkaline salt solution ↓ Mix (10–15 min) ↓ Dough resting (15–30 min) ↓ Dough sheet forming and compounding ↓ Dough sheet aging (15–30 min) ↓ Sheeting and reduction to desired thickness ↓ Dusting both sides of dough sheet surface with starch ↓ Noodle slitting and cutting to desired width and length ↓ (Sterilization) ↓ Weighing ↓ Packaging ↓ Storing in refrigerator ↓ Fresh raw noodles

FIGURE 5.2

Processing procedures of fresh raw noodles.

noodle processing line and Figure 5.2 outlines the fresh raw noodle production steps. Fresh noodles are produced after the sheeted dough is cut into strands of desired length and width. Both sides of the dough sheet surface are dusted with starch before slitting and cutting to prevent noodle strands from sticking together during handling, transportation, and storage. Alternatively, the starch dusting step can be done on noodle strands after the slitting and cutting have been completed. Sometimes, fresh noodles pass through a tunnel installed with UV lights to sterilize them before weighing and packaging. A predetermined weight of noodles is cut and portioned for automatic packaging or placed into trays in bulk for retail outlets.

5.3.1.2. Quality Characteristics The most important quality characteristics of fresh raw noodles are desirable color and smooth surface. Japanese udon noodles are perhaps the most intensively studied. They are white or creamy-white in appearance and have a soft and elastic texture coupled with a smooth surface after boiling. The criteria for judging cooked udon noodle quality are cooked noodle texture (eating quality), followed by color, surface appearance, and taste (Nagao 1996). The flour used is primarily milled from semisoft wheat and has a low protein level (8.5–9.5%), low ash content (0.36–0.40%), low damaged starch, and good color grade (Crosbie et al. 1990; Nagao 1996). Chinese fresh white salted noodles are very popular in Mainland China and Taiwan, but they have been less studied. Good quality Chinese raw noodles are generally

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characterized by bright and white color, clean appearance, and firm and chewy texture (Hou 2001). For yellow alkaline noodles, a desirable quality attribute includes a bright and even light yellow color. They should be free of any darkening or discoloration, have a firm clean bite as well as a chewy and elastic texture with some degree of springiness and a satisfactory al dente reaction on biting (Miskelly and Moss 1985). Hard wheat flour of medium to high protein content (10.5–12%) and low ash content (0.45% or less) is recommended for these fresh noodles (Hou 2007). Fresh raw noodles have a limited shelf life of one to several days, depending on the packaging materials and storage conditions. They are often stored under refrigeration to minimize discoloration caused by the activity of polyphenol oxidase (PPO) and microbial growth. 5.3.2. Wonton Wraps Wonton is a type of Chinese dumpling made with a thin 10-cm square lye-water pastry wrapper typically made of flour, water, eggs, salt, and kansui. It is filled with savory minced meat, vegetables, or combinations of both. Compared to other Chinese dumpling products, traditional wonton wraps are thinner and have a rectangular shape. Many other Chinese dumplings are wrapped in a round and thicker dough sheet. Wontons are commonly boiled and served in soup or sometimes deep-fried. Several different shapes are common, depending on the region and cooking method (http://en.wikipedia.org/wiki/Wonton).

5.3.2.1. Processing Technology Wonton wraps are thin, square dough sheets that are made by mixing and sheeting dough prepared from flour, water, and other ingredients (Table 5.5). Some variations in formulation occur, depending on regions and taste, but the basic formula includes flour, water, and salt. Eggs not only increase protein content but also enhance bite texture and provide yellow color to the finished product. Kansui salt imparts a yellow color to wonton wraps in addition to giving them the characteristic alkaline taste preferred by some consumers. Potato starch improves the surface smoothness of

TABLE 5.5

Typical Formula for Making Wonton Wraps

Ingredient Flour (medium to high gluten strength) Water Fresh eggs Salt Chemical leavening (optional) Kansui (K2 CO3 : Na2 CO3 = 1 : 1) Potato starch (optional) Fat (optional) Alcohol (optional)

Percentage (%) 100 25–40 0–20 1 1 0.5–0.8 10 0.5–1 1

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boiled wonton wraps or the crispiness for fried wonton wraps by increasing their volume during deep-frying. Fat (0.5–1%) is often added in the formula to prevent quick drying of the dough sheet during processing and the wonton wraps after opening the package. Alcohol (1%) is usually added to serve as a preservative. A diagram of a commercial processing line and the procedures for producing wonton wraps are shown in Figures 5.3 and 5.4, respectively. Similar to noodle processing, flour is mixed with eggs and other solutions to form slightly wetter and more glutendeveloped dough than dough for noodles. A longer mixing time and more water are required since some gluten development in dough mixing is desirable for wonton wraps because they require multidirectional gluten alignment to exhibit stretchability and extensibility from all directions. Developing the gluten network by pressing and stretching on the noodle line could only produce one-directional gluten alignment; thus, the wonton wraps do not have similar stretching strength from all directions. After the dough is rested for 10–30 minutes, two dough sheets are formed and combined to form a single sheet on the combining machine. This single sheet is often dusted with flour or starch and rolled on wooden, plastic, or metal spools and rested for 20–60 minutes, or even longer, to relax intense gluten and to help water distribute more evenly. The dough sheet is then further compressed and stretched gradually on the noodle line to the desired thickness of 0.5–1.0 mm. The dough sheet surface is heavily dusted with corn starch before being rolled on spools or directly folded to a certain length and stacked together. This stage of starch-dusting on the dough sheet surface is very important because it prevents wonton wraps from sticking together during storage and helps to separate them easily when they are peeled off one by one at some time in the future to wrap fillings for wontons. Finally, the stacked dough sheets are cut into 8–10-cm square and 0.5–1.0-mm thick wonton wraps. These wraps are stacked together and packed in a cubic-block shape. Unless they are made for immediate use, the wonton wraps are typically quickly frozen and stored in freezers where they can last for over 6 months. When ready to use, the packed frozen wraps are taken out and thawed in the refrigerator or at room temperature for about 30 minutes. Wonton wraps can also be stored in refrigerators, but the product shelf life is only a few days. Because the wonton wrappers are usually quite thin, they dry out within a few hours after opening the package, making them brittle and unusable.

5.3.2.2. Quality Characteristics There are a number of ways to use wonton wraps. In addition to making wontons, they can be used to make small dumplings, pot stickers, egg rolls, and other wrapped foods. Wonton wraps can be steamed, fried, or boiled, and they are usually very sturdy, which means that they withstand reheating very well. Wonton wraps can also be used plain; twisted and fried wonton skins, for example, are a popular snack in some parts of the world. Traditional wonton wraps are made with eggs and lye water, so they should be bright yellow, transparent, and smooth and have cooking tolerance (do not break up during boiling) (Huang 1999). They require good stretchability, strength, and rollability to meet wrapping requirements and do not break up after fillings are inserted. For making frozen wontons, the wonton skin must be resistant to cracking problems during frozen storage. Upon boiling, desirable wonton wraps are characterized by

FIGURE 5.3

Dough Sheet Combining Machine

Feeder

Wonton wraps processing line.

Continuous Rolling Machine

Aging Station

Cutter

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Flour + alkaline salt solution ↓ Mix (10–15 min) ↓ Dough resting (10–30 min) ↓ Dough sheet forming and compounding ↓ Dough sheet aging (20–60 min) ↓ Sheeting and reduction (0.5–1.0 mm thickness) ↓ Starch dusting ↓ Cutting into squares (8–10 cm each side) ↓ Weighing ↓ Packaging ↓ Quick freezing ↓ Stored in freezers

FIGURE 5.4

Processing procedures of wonton wraps.

a chewy and elastic texture, smooth surface, and bright color. When fried, wonton wraps are usually very crispy, have uniform and small bubbles on the surface, and display a uniform brown color. These desirable features for wonton wraps are largely dependent on the flour quality used in production. Hard wheat flour of medium to high dough strength and low ash content is recommended for such products. However, some quality issues remain for some wonton products, such as skin cracking of frozen wontons and lack of crispiness and small uniform bubbles for fried wonton skins. Frying freshly made wonton wraps tends to produce larger and nonuniform oily pockets on skins, perhaps due to uneven water distribution. Storing the fresh wonton wraps overnight or longer in a refrigerator will minimize this problem. 5.3.3. Dried Noodles Dried noodles are raw noodles that have been hung to dry, either in the sun or in a special controlled temperature and humidity drying chamber, to about 10–12% moisture. Many of the Chinese, Japanese, and Korean white salted noodles are in dried form. Dried noodles are very popular because of the extended shelf life and ease of storage.

5.3.3.1. Processing Technology Today, most dried noodles are typically produced from drying fresh raw noodles by hanging them on rods in a drying chamber with controlled temperature and relative humidity (Figures 5.5 and 5.6). Air-drying usually involves multistage processes

Dough Sheet Combining Machine

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Cutting & Hanging Bar Device

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Dried noodle stick processing line.

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Unloading Bar Device

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Flour + salt or alkaline salt solution ↓ Mix (10–15 min) ↓ Dough resting (15–30 min) ↓ Dough sheet forming and compounding ↓ Sheeting and reduction ↓ Noodle slitting, cutting and hanging ↓ Predrying (15–25 °C, 60% RH, 30–60 min) ↓ Drying (40 °C, 70–80% RH, 6 h) ↓ Cooling (to room temperature) ↓ Cutting to desired length ↓ Packaging ↓ Dried noodles

FIGURE 5.6

Processing procedures for dried noodle sticks.

since too-rapid drying causes noodle checking, similar to spaghetti drying. There are commonly three stages in the drying process. The first stage is called “pre drying,” where low temperature (15–25 ◦ C) dry air (60% relative humidity) is applied for 30–60 minutes to reduce the noodle moisture content from 32–42% to 27–28%. Dehumidifiers and air-conditioning equipment are used to produce the low temperature and low humidity air. This predrying process is very important to minimize noodle-strand stretching derived from its own weight by quickly drying and hardening noodle surfaces. Slight noodle-strand deformation is not a main concern because it will become straight in the next phase of drying. The second stage is the main drying process to achieve the noodle moisture content of 1–2% above the target moisture content by applying warm and humid air. Typically, air at 40 ◦ C and 70–80% relative humidity is used to increase noodle interior moisture migration to outside surfaces while reducing surface drying speed. This process takes about 6 hours. Noodle surface checking problems can occur when the drying process is too fast because the drying speed of the noodle interior is slower than that of the surface. On the other hand, other problems, such as noodle stretching, discoloration due to enzyme activation at warm temperatures, and foreign odor formation, occur when the main drying process is too long because of improper drying conditions. To conserve energy in the main drying process, a combination of exhaust and outside air is used after temperature and relative humidity have been adjusted. To circulate air in the drying chamber, fans should be properly situated and installed and the air velocity set to blow at 1 m/s in the parallel direction of hung noodle strands.

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Drying problems can be indicated by noodle tip flaring, noodle stretching, and noodle twisting. Temperature, relative humidity, exhaust rate, air velocity, and/or air circulation may be adjusted to produce properly dried noodles. In the final stage, noodles are further dried and the temperature is gradually reduced to close to room temperature by using cool air. Dried noodles are set to cool at 0.5 ◦ C/min to minimize checking problems that result if cooling is too fast. Caution is warranted in the cold winter season when temperature deviation between the drying chamber and the room temperature is more than 15 ◦ C. Incomplete cooling may also cause noodle checking in the package due to uncontrolled drying by decreasing product temperature in the package. If the dried noodles are not cooled enough before packaging, moisture condensation occurs and this promotes mold growth and reduces shelf life. Drying capacity is determined by the temperature, humidity, air velocity, and exhaust rate of air in the drying chamber. Each parameter is calculated and adjusted based on the finished product specifications and production quantity. Even air circulation in the drying chamber is critical to overall drying performance, and this is better achieved by moving mechanical noodle hangers rather than the still type. The final drying parameter adjustments are performed by producing test batches since differences in environment and production facilities exist among noodle plants. Other drying methods include low- and high-temperature drying. The lowtemperature drying method takes 2 days and produces whiter color noodles with good flavor and similar textural characteristics compared to raw noodles. The hightemperature drying method takes only 2–3 hours and often employs tunnel equipment, but the cooked noodle texture tends to be a bit harder. In general, dried noodles always have a harder texture than fresh raw noodles upon cooking regardless of drying conditions. While some people like hard-bite noodles, others prefer dried noodles with a soft noodle texture and short cooking time, similar to fresh raw noodles. Adding some salt to the dried-noodle formula could yield softer noodle texture and shorten cooking time, because salt can prevent noodles from drying too fast. Softer noodle texture could also be produced by adding extra water in the dough; however, higher moisture leads to noodle stretching during drying and prolongs drying time. A larger drying capacity chamber can be useful in this case. There is a new development toward production of semidried noodles that contain about 25% moisture. The water activity and pH must be adjusted and oxygen scavenger agents should be included in the package to maintain the product during the established shelf life.

5.3.3.2. Quality Characteristics Most dried noodles are small- to medium-sized white salted noodles, varying shape from flat, thick noodles to round, hair-thin noodles. For example, Japanese dried white salted noodles range from the thick udon type to the very thin somen type. Desirable appearance of dried white salted noodles includes bright and white or bright and creamy white color, free from specks and checking on the surface, and free from

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deformation in shape. There are also a few dried yellow alkaline noodles or egg noodles on the market, and the preferred color is bright yellow. In Japan and Korea, dried soba (buckwheat) noodles are popular. Typically, soba noodles are made from 60–70% high protein wheat flour and 30–40% buckwheat flour because buckwheat flour does not have gluten and strong flour gluten is needed to bind the mixture together to form the noodle structure. Soba noodles are brown or grey colored and are usually served cold in summer and warm in winter. They are characterized by a firm and slightly elastic eating texture and unique soba flavor (Nagao 1995). Flour used for producing dried noodles varies, depending on noodle type and quality preferences of consumers; however, the dough must have sufficient physical strength to support the long noodle strands as they dry. The noodles should have a uniform shape and cleanly cut sides. Since dull, grey, or brown noodles are considered inferior, highly purified flours are generally used to give the desired color and brightness to noodles. Similar to dried spaghetti, dried noodles generally require a longer cooking time, especially for flat and thick noodle types. The drying process reduces the sizes of air cells in the noodles; as a result, it takes a longer time to rehydrate the noodles due to the slow migration of water from the surface to the core area. The noodle surface tends to become mushy and sticky during prolonged cooking in boiling water while the noodle core area may still be undercooked. Dried noodle cooking time is affected by many factors such as flour type, ingredients added, noodle size, drying conditions, and moisture content. If the moisture content is too low, the cooking time will be longer because of slower moisture migration and less heat transfer. Certain additives, such as modified potato or tapioca starch or hydrocolloids, can be useful in shortening cooking time because the modified potato or tapioca starch reduces starch gelatinization time and the hydrocolloids absorb water faster and speed water migration during cooking. During storage, dried noodle quality changes. One common occurrence is the development of rancidity because of lipid autooxidation. Improper drying conditions (high temperature and a long time), inappropriate packaging materials, and improper handling and storage conditions are the main causes of rancidity. Noodle texture tends to become harder when the dried noodles age. This change makes a positive improvement to thin noodles, such as somen type, but could create problems for thick udon-type noodles. 5.3.4. Boiled Noodles Boiled noodles are precooked noodles that are cooked in boiling water immediately after fresh noodles have been made. These include parboiled, standard fully boiled, semi-LL, and LL noodles. LL means “long life.” The parboiled noodles often refer to wet alkaline noodles (such as hokkien noodles) and are very popular in Southeast Asia. The standard fully boiled noodles had been a major boiled noodle product in Japan, but they are being replaced by semi-LL noodles. Both the standard boiled noodles and semi-LL noodles are delivered in cold chain. LL noodles have gained

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wide acceptance in Asia because they have much longer shelf life and can be stored at room temperature. Since the process steps from dough mixing to noodle boiling are the same for all boiled noodles, we will focus on parboiled noodles and LL noodles in this section.

5.3.4.1. Parboiled Alkaline Noodles Parboiled alkaline noodles are called “hokkien noodles” in Southeast Asia and “wet noodles” in Taiwan. They are widely consumed in these regions because of their unique alkaline flavor and ease of preparation for consumption. This type of noodle is often stored at room temperature and consumed within 24 hours due to high moisture content. Processing Technology Parboiled alkaline noodles are made from flour (100%), water (32–35%), salt (1–2%), and alkaline salts (0.5–1%). The amount of water is determined by the type of flour, dough mixer, and noodle machine. Alkaline salts (kansui) are a mixture of sodium carbonate and potassium carbonate (typically 4:6) or sodium hydroxide in some cases. The alkaline salts affect the unique flavor and texture of the resulting noodles and, by detaching flavones from the polysaccharides, allows the yellow color to become manifest. The yellow color becomes intense as the dough pH increases. Flour commonly used for making parboiled alkaline noodles is milled from hard or semihard wheat, with protein content in the range of 10–12.5% (14% moisture basis) and mellow gluten quality, and ash content of less than 0.50% (14% moisture basis) (Hou 2007). In Malaysia, flour protein of 10–11% is commonly used, while in Taiwan flour protein of 11.5–12.5% is often required to give a firmer noodle bite. The commercial noodle processing line and procedures of parboiled alkaline noodles are shown in Figures 5.7 and 5.8. In automated plants, uncut fresh raw alkaline noodles (1.2–1.8-mm thickness and 1.5–1.7-mm width) pass through a boiling water bath for 45–60 seconds to achieve 70–80% starch gelatinization. After boiling, the noodles are steeped immediately in tap water for 1–2 minutes or showered with tap water, and excess water is drained from the noodle surface by blowing air from fans installed on the noodle line. The noodle strands are cut to a certain length with a rotary blade, and vegetable oil (∼2% of noodle weight) is sprayed or dripped onto noodle strands and well mixed to prevent noodles from sticking together. Noodles are then packed in plastic bags for storage or delivered to retail outlets. In traditional batch production, fresh noodles are cut to the desired length first before boiling in a large kettle. Quality Characteristics Because of the short boiling time, parboiled wet noodles have a fine uncooked white core in the center, surrounded by cooked or gelatinized dough. This can be seen by squeezing the noodle strands between two clear glass plates. The white core will disappear as the parboiled noodles are stored overnight because the moisture from outer layers migrates to the core area. Therefore, they can be quickly recooked by boiling or stir-frying prior to consumption. The desirable parboiled wet noodle quality characteristics include a bright and yellow appearance free of any darkening or discoloration over time, a firm bite,

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FIGURE 5.7

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Cooling Water Shower

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Hokkien noodle processing line.

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Blower

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Flour + alkaline salt solution ↓ Mix (10–15 min) ↓ Dough resting (10–30 min) ↓ Dough sheet forming and compounding ↓ Dough sheet aging (0–40 min) ↓ Sheeting and reduction (1.2–1.8 mm thickness) ↓ Noodle slitting (1.5–1.7 mm width) ↓ Boiling for 45–60 s ↓ Cool water rinsing for 1–2 min ↓ Water draining by blowing fans ↓ Cutting to desired length with a rotary blade ↓ Adding 2% vegetable oil ↓ Blending ↓ Weighing ↓ Packaging ↓ Hokkien noodles

FIGURE 5.8

Processing procedures of hokkien noodles.

and a chewy and elastic texture with some degree of springiness. Parboiled noodles have a moisture content of 55–60% and thus a relatively short shelf life of 2–3 days stored under room conditions. They do not discolor upon storage because the boiling denatures the polyphenol oxidase (PPO) enzyme, but they have to be protected from airborne contaminants because their surface provides an ideal substrate for bacterial and moldy growth. Their shelf life can be extended by hygienic manufacturing practices and refrigeration or freezing of the products. The water absorption of parboiled noodles is considered important to manufacturers because it directly affects the noodle yield. However, one should not overboil the noodles for the sole purpose of increasing noodle yield, because overcooking noodles in boiling water will make the finished product too sticky and the noodle texture too soft.

5.3.4.2. Long-Life (LL) Noodles LL (long-life) noodles are fully boiled noodles and are pasteurized with heat. Fresh noodles are cooked for 10–15 minutes, rinsed and cooled in running water, steeped

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in dilute acidic water before packing, and further steam-pasteurized for more than 30 minutes. This type of noodle usually has a shelf life of 5–8 months. After steeping in boiling water for about 1 minute, the noodles are ready for consumption. LL noodles, particularly LL udon noodles, have been developed and manufactured in many countries because of their long shelf life and ease of preparation for serving. This prolonged shelf life increases the profitability for manufacturers and retailers, as well as being more environmentally friendly due to less waste of the product.

Processing Technology Most LL noodles are udon noodles; although a small portion of LL noodles are chukamen type noodles. LL udon noodles are typically made from 100% flour, 32–34% water, and 2–4% salt. The protein content of udon noodle flour is 8.5–9.5% (14% moisture basis) and the ash content is 0.40% or less (14% moisture basis). The formula of chukamen noodles contains 100% flour, 32–34% water, 1% salt, and 0.8–1% kansui (K2 CO3 : Na2 CO3 = 6 : 4). The basic flour specifications for chukamen noodles are 10.5–12% protein and 0.33–0.38% ash (14% moisture basis) from specially selected mill streams. The general process steps for LL noodles include boiling, cooling, acidifying, packaging, heat pasteurization, cooling, and pinhole checking (Figure 5.9). The important step in preparing LL noodles is to cook fresh noodles to the targeted noodle cooking yield and not to compromise physical noodle appearance. For example, it takes more than 20 minutes to boil udon noodles; therefore, the longer the boiling time, the more difficult the process control becomes. Several steps can be taken to assure optimal cooking (Hou 2001): (1) the weight of cooking water is at least 10 times that of the uncooked noodles; (2) the size of the boiling pot is properly chosen; (3) the pH of the boiling water is 5.0–5.5; (4) the cooking time is precisely controlled to give optimal results to the product; and (5) the cooking water temperature is carefully maintained at 98–100 ◦ C throughout the boiling process. For cooking noodles in the lab setup, the amount of boiling water required is at least 10 times the amount of raw noodles, but in the commercial boiling process, more than 20 times the amount of noodles is needed in order to maintain water temperature. Too-little water or too-low water temperature can cause more noodle damage during boiling. It is important to keep the noodle strands from sticking together by allowing the raw noodle strands to move freely in the boiling bath and maintaining gentle boiling so as not to damage the noodle surfaces. Also, water quality must be controlled for udon noodles by pH adjustment. Boiling damage can be avoided by adjusting boiling water pH to 5.0 with an organic acid. The boiling water pH adjustment is not necessary for soba and chukamen noodles because their boiling times are much shorter than udon noodles. After boiling, the cooked noodles are immediately rinsed in chilled water to avoid further cooking, which causes inferior noodle texture. The target product temperature at the end of cooling is 10 ◦ C or less. It is preferable to use chilled running water to reduce microbial reproduction. Adjusting the product pH by soaking boiled noodles in an organic acid solution extends product shelf life. The lower the pH, the better the results; but the product taste may be jeopardized at pH 5 or lower. Organic acids, such as lactic acid, tartaric

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Flour + salt or alkaline salt solution ↓ Mix (10–15 min, 20–30 °C) ↓ Dough resting (15–30 min) ↓ Dough sheet forming and compounding ↓ Dough sheet aging (15–40 min) ↓ Sheeting and reduction ↓ Noodle slitting and cutting ↓ Boiling ↓ Washing and cooling pH balance control (pH 4.0) ↓ Packaging into pillow type ↓ Steam sterilization (95–98 °C; 30–40 min) ↓ Cooling ↓ Pinhole checking ↓ External packaging ↓ Final product

FIGURE 5.9

Processing procedures of LL noodles.

acid, citric acid, acetic acid, and their salts, are commonly used to control the pH of the boiled noodles. It may be more important to control both the pH and the total titratable acidity (TTA) of the product due to the importance of acid retention on the noodles. Many weak organic acids, such as acetic or lactic acids, are dissolved in water, but they do not dissociate completely into hydrogen ions (H+ ) and other ions. Thus, the pH of these acid solutions is only a measure of those ions that do dissociate, and not the total acid present in the solution. Acidity and sourness vary, depending on different agents; for example, acetic acid has a high preservation effect, but it has a strong odor. The pH control acids may be used in dough, noodle boiling water, and/or boiled noodle soaking solution. However, caution is warranted if the acids are incorporated into noodle dough because they can weaken gluten strength (Shiau and Yeh 2001). The use of alcohol, glycine, lysozyme, or protamine together with organic acids will enhance the preservative effect. Acid-soaked boiled noodles are packaged in plastic bags and steam pasteurized for 30–40 minutes at a minimum temperature of 95 ◦ C for LL noodles. LL noodle products typically require more than 6 months of shelf life at room temperature, so pH adjustment is necessary in conjunction with heat pasteurization in order to

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control heat-stable bacteria. Long shelf life is achieved by soaking boiled noodles in an organic acid solution of pH 3.8–4 and steam-pasteurizing them at 95 ◦ C for over 40 minutes after packaging. Steam-pasteurized noodles are quickly cooled to room temperature and are stored and checked for possible package leaking (pinholes in the package bags). This is usually done by storing the bagged noodles for 1 week and visually checking for noodle spoilage due to package bag breakage. Alternatively, the bagged noodles are steeped in a colored water pool (cf. blue colored water) and visually checked for color leakage into the bags. This method can also be used for noodle cooling. If continuous and automatic checking for package leaking is required, an automatic package leak detector can be installed. The basic principle is to load packaged samples into a vacuum chamber and to detect pressure changes as a way to determine any leakage of the package bags.

Quality Characteristics LL noodles are similar to instant noodles because they are served by soaking in hot water for 3 minutes or cooking for 1 minute in boiling water. LL noodle quality tends to degrade over time because of the lower pH environment and severe pasteurization conditions (high temperature and long time). If properly processed with special formulation and under tightly controlled conditions, LL noodles could retain some characteristic attributes similar to fresh noodles. Heat-stable starches and acid-stable ingredients may be used in noodle formulations to cope with the harsh processing conditions. It is more difficult to produce LL chukamen noodles by using acids to lower noodle pH value, because chukamen noodles are made with kansui salt. Lowering chukamen noodle pH will neutralize alkaline salts and cause loss of original chukamen flavor and yellow color. 5.3.5. Frozen Noodles Freezing is a food preservation method that can potentially deliver a high degree of safety, nutritional value, sensory quality, and convenience (Berry et al. 2008). In addition to its value as a preservation method, freezing can supply a pleasurable eating experience. For example, the texture of boiled noodles deteriorates very fast after cooking. By applying quick-freezing technology, the fresh quality of boiled noodles can be preserved and extended for up to 1 year if they are properly stored in a freezer. Noodles of this type are sold mostly from a central factory to noodle restaurants, where they are thawed in a specially designed boiling pot and immediately served to guests, thus saving time and labor costs.

5.3.5.1. Processing Technology Quick-freezing technology can be applied to many noodle types, but frozen raw noodles and frozen boiled noodles are the two most commonly produced. Frozen raw noodles are traditionally produced by quickly freezing fresh raw noodles to −15 ◦ C before packaging and then the products are stored in a freezer. However, in modern mass production, raw noodles are packed first before being quickly frozen (Figure 5.10). For producing frozen boiled noodles, the process includes boiling fresh

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Flour + salt or alkaline salt solution ↓ Mix (10–15 min, 20–30 °C dough crumbs temp.) ↓ Dough resting (15–30 min) ↓ Dough sheet forming and compounding ↓ Dough sheet aging (15–40 min) ↓ Sheeting and reduction ↓ Starch dusting ↓ Noodle slitting and cutting ↓ Packaging (100–150 g per portion) ↓ Quick-freezing (10–20 min; center temp. < –15 °C) ↓ Storing in freezer (–20 °C) ↓ Final product

FIGURE 5.10

Processing procedures of frozen raw noodles.

raw noodles, washing and immersing the boiled noodles in water chilled to <5 ◦ C, fitting them into block-shaped baskets, and quickly freezing them to −15 ◦ C before transferring them to a freezer for storage (Figure 5.11). Quick freezing is necessary to produce good quality frozen noodles. The freezer must have enough capacity to drop product temperature from 0 ◦ C to −5 ◦ C quickly to minimize ice crystal size and to bring product core temperature to −15 ◦ C. Freezing technology includes air (gas) freezing, contact freezing, brine freezing, and cryogenic freezing. There are advantages and disadvantages for each freezing mechanism; therefore, choose the best one to fit your company and product concepts (Magnussen et al. 2008). To retain the best boiled-noodle quality, it is important to keep the time from the end of boiling to the end of freezing as short as possible. Another important processing step is cooling. The cooling process delays swelling of the boiled noodles; therefore, the capacity of cooling water becomes an important factor. It is difficult to produce frozen noodles that are thin in size due to their fast swelling. The boiling time to cook noodles for freezing is the total boiling time of fresh noodles minus the cooking time of frozen boiled noodles for serving. This shorter boiling time reduces the noodle-swelling effect and prevents the frozen boiled noodles from being overcooked before serving.

5.3.5.2. Quality Characteristics After thawing, frozen raw noodles should retain quality characteristics similar to fresh raw noodles. Frozen boiled noodles require a very short time (less than 2 minutes) to

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Flour + salt or alkaline salt solution ↓ Mix (10–15 min, 20–30 °C) ↓ Dough resting (15–30 min) ↓ Dough sheet forming and compounding ↓ Dough sheet aging (15–40 min) ↓ Sheeting and reduction ↓ Noodle slitting and cutting ↓ Boiling (over 98 °C; 55–70% moisture) ↓ Washing and cooling (product temp.: < 5 °C) ↓ Packing in trays (200–250 g) ↓ Quick-freezing (20–30 min, center temp.: < –15 °C) ↓ Removing from the baskets ↓ Packaging ↓ Storing in freezer (–20 °C) ↓ Final product

FIGURE 5.11

Processing procedures of frozen boiled noodles.

thaw and cook in boiling water, which allows restaurants to serve tasty noodles conveniently and efficiently without the need to provide special equipment and training to employees in noodle preparation. However, frozen raw noodles are produced less because they tend to dehydrate during frozen storage. The three main factors that affect product quality of any given frozen food are initial quality of the original foodstuff, processing and packaging of the product, and temperature and duration of storage (Zaritzky 2008). Even if noodles are adequately frozen, physical–chemical and biochemical changes during storage can lead to degradation in their quality. Quality of frozen noodles is highly dependent on storage temperature, and there is a need for a constant and systematic control on maintaining the required temperature throughout the frozen noodle distribution in the cold chain, from production to final consumption. Storage and transport conditions have great influence on the quality of frozen foods (Zaritzky 2008). The main physical changes during storage of frozen foods are moisture migration and ice recrystallization. Both phenomena are related to the stability of frozen water inside and on the surface of the product. The most important chemical changes that can occur during freezing and frozen storage are enzymatic reactions, protein denaturation, lipid oxidation, degradation of pigments and vitamins, and flavor deterioration (Zaritzky 2006).

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5.3.6. Steamed Noodles In this section, steamed noodles refer to noodles that are steamed for a longer period of time (typically more than 4 minutes) and focus on two main types: low-moisture steamed noodles and high-moisture steamed noodles. Instant noodles are not included in this section, although they are also steamed, but only for 1.5–2 minutes. Instant noodles are discussed separately. Low-moisture steamed noodles contain less than 35% moisture and are produced by steaming fresh raw noodles for over 10 minutes with dry steam before cooling and packaging. High-moisture steamed noodles are mainly “yakisoba” type noodles and are produced by steaming for 4–6 minutes, steeping in warm or hot water, cooling and rinsing in chilled water, draining excess water, and finally mixing with some vegetable oil. Their moisture content is 55–65%.

5.3.6.1. Processing Technology of Low-Moisture Steamed Noodles Low-moisture steamed noodles are produced by steaming fresh raw noodles in dry steam, so the primary noodle processing units are the same as fresh raw noodles, but an additional tunnel steaming unit and a noodle loosener are required in a fully automated production plant (Figure 5.12). The outline of low-moisture steamed noodle processing is shown in Figure 5.13. Fresh noodles are cooked for 10–15 minutes on a net conveyor passing through a tunnel steamer. To achieve optimum steaming results, raw noodle strands are loosely placed on the steel mesh conveyor belt in order for steam to pass between the strands. To minimize noodle strands from sticking together, oil could be sprayed onto noodles prior to entering the steaming tunnel. After steaming, noodle strands are delivered in portions to a rotating drum-shaped noodle loosener to separate them before being weighed and packaged. Steamed noodles produced by this process have a moisture content of less than 35%, so they are easy to handle because of their dry surface and they have a longer shelf life. 5.3.6.2. Processing Technology of High-Moisture Steamed Noodles High-moisture steamed noodles, such as yakisoba noodles in Japan, are often produced by steaming noodles for 4–6 minutes and the noodles are showered with water at intervals while passing through a tunnel steamer. If additional water absorption of noodles is needed, steamed noodles are soaked in warm water (65–70 ◦ C) for ∼2 minutes or boiled for less than 1 minute. Noodles are then rinsed in chilled water, drained for excess water, and mixed with 1–2% vegetable oil before packaging. High-moisture steamed noodles contain about 60% moisture. Some high-moisture steamed noodles are pasteurized with steam after packaging. The noodle shelf life is extended to about 2 weeks. The pasteurization is done at 90 ◦ C for 30 minutes and the bagged noodles are cooled immediately to less than 30 ◦ C. It is especially important to drop noodle temperature to below 40 ◦ C as quickly as possible. Steam pasteurization also increases starch gelatinization of noodles and increases noodle springiness. Steamed noodle texture depends largely on the steaming process. The efficiency of steaming is very important for setting the operating conditions. Since the raw noodle moisture before steaming is less than 35% and after steaming is about 40%, the

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Mixer

FIGURE 5.12

Continuous Rolling Machine

Steamer

Low-moisture steamed noodle processing line.

Slitter & Cutter

Basket Packing Packer Loosener Conveyor Elevator

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Flour + salt or alkaline salt solution ↓ Mix (10–15 min) ↓ Dough resting (15–30 min) ↓ Dough sheet forming and compounding ↓ Dough sheet aging (15–40 min) ↓ Sheeting and reduction to desired thickness ↓ Starch dusting ↓ Noodle slitting and cutting to desired width and length ↓ Steaming for 10–15 min ↓ Noodle strand loosening ↓ Weighing ↓ Packaging ↓ Steamed noodles

FIGURE 5.13

Processing procedures of low-moisture steamed noodles.

starch gelatinization is incomplete after steaming and the noodle texture tends to be hard. The noodles become brown in color and too hard in texture when dry-steaming and very long steaming times are used. There are some traditional noodle products manufactured in this way. One example is special brown steamed noodles marketed in the Philippines. The noodles are produced by steaming for over 1 hour. It is possible to increase the specific heat of noodles by spraying water on the noodles during the steaming process to produce a soft noodle texture, because a higher specific heat raises the hydration of noodles by more condensed water. Increased noodle moisture promotes starch gelatinization and produces firm (not hard) and springy noodle texture. Since noodle quality changes with water spray location, quantity, and water temperature, it is important to establish these conditions according to the product concept. Low-pressure wet steam gives the best results while high-pressure dry steam is not recommended. A similar noodle placement configuration can be used for batch steamers.

5.3.6.3. Quality Characteristics Steamed noodles are mostly alkaline noodles, but the level of alkaline salt is often lower than for fresh alkaline noodles. Bright yellow color is generally preferred for steamed noodles, but in some areas, traditional brown-looking steamed noodles are very popular because noodles are steamed for up to 1 hour to achieve unique texture and flavor characteristics.

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Low-moisture steamed noodles generally require short cooking in boiling water before being served in hot soup or stir-fried with meat and vegetables. High-moisture steamed noodles are typically stir-fried without boiling in water. Steamed noodles have distinct quality characteristics compared to other noodle types because their texture is firmer, chewier, and springier. Steamed noodles also have more texture stability in hot soup than raw noodles. The shelf life of steamed noodles is longer than raw noodles or regular boiled noodles because hot steam sterilizes noodles and the moisture content is less than that of regular boiled noodles. The low-moisture steamed noodles can be stored at room temperature for several days, while the high-moisture steamed noodles are usually stored under refrigeration and can last for up to 2 weeks. Yakisoba noodles have become a popular noodle product in North America, and they are available in plastic packages in many grocery stores and are served in many restaurants.

5.3.7. Instant Noodles Instant noodles, as the name indicates, are noodles that are ready to serve with easy preparation. There are two main types of instant noodles: steamed and deep-fried and steamed and air-dried. Because instant noodles are precooked, they need only 3–4 minutes of boiling or rehydration with boiling water to prepare for serving. The frying process removes the water from the noodle strands, resulting in a porous structure that rehydrates quickly when hot water is added. Instant noodles are either flavored with seasonings or are plain in taste, accompanied by a separate sachet of soup base. They are usually packed and sold in a polyethylene bag and have good storage properties, particularly if packed to exclude oxygen and light. Instant noodles may also be packed in a styrofoam cup or bowl with a peelable aluminum cover along with a dried soup base, such as vegetables, shrimp, or meat, and can be eaten by pouring hot water into the cup and letting the noodles soak for a few minutes. Readers are advised to consult Chapter 7 to learn about the benefits of different packaging materials for noodle products.

5.3.7.1. Processing Technology of Steamed and Fried Instant Noodles For making steamed and fried instant noodles, the wavy noodle strands are sprayed with water before being conveyed to a steaming tunnel to cook at 98–100 ◦ C for 2–3 minutes. The steaming time varies according to the noodle size and plant elevation compared to sea level, but it can be estimated by squeezing a noodle strand between two pieces of clear glass plate. If the white noodle core disappears, the noodle strands are likely well cooked. Steam temperature, steam pressure, and steaming time are the key process factors affecting product quality. After steaming, noodle strands are either cut by a rotating blade and folded in half to form a double layer of noodle blocks and showered with water or seasoned water before loading into square-shaped frying baskets for bag-type noodles, or the noodle strands are stretched, showered with water, cut into desired portions, and loaded into cup-shaped or bowl-shaped frying baskets for cup/bowl-type noodles (Figures 5.14 and 5.15).

Solution Metering Tank

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Flour + salt or alkaline salt solution ↓ Mix (10–15 min, 20–30 °C) ↓ Dough resting (5–10 min) ↓ Dough sheet forming and compounding ↓ Sheeting and reduction ↓ Noodle slitting and waving ↓ (Spraying water) ↓ Steaming (over 98 °C; 2–3 min) ↓ Cooling with fans ↓ ↓ Cutting and folding in half (70–120 g) ↓ Showering with water or seasoning water ↓ Loading into square-shaped frying baskets ↓ Draining excessive water with fans ↓ Deep-frying (140–160 °C, 1–2 min) ↓ Removing from baskets ↓ Draining oil ↓ Cooling ↓ Placing seasoning sachets on noodle block ↓ Packaging into polyethylene film bag ↓ Bag-type instant fried products

FIGURE 5.15

↓ Stretching noodle strands ↓ Showering with water ↓ Cutting into desired portion of weight ↓ Loading into cup-shape frying basket ↓ Deep-frying (140–160 °C, 1–2 min) ↓ Removing from baskets ↓ Draining oil ↓ Cooling ↓ Filling the styrofoam cup ↓ Placing seasoning powders or sachet bags ↓ Sealing cup with a cover using heat ↓ Wrapping cup with thin polyethylene film ↓ Shrinking cup film inside a heat tunnel ↓ Wraping with paperboard sleeve box ↓ Cup-type instant fried noodles

Processing procedures of steamed and fried instant noodles.

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As mentioned in the production of steamed noodles, the purpose of steaming is to allow starch to swell and gelatinize to a greater extent, which is needed for a fast rehydration rate of the finished product before serving. Steaming also denatures the protein and helps to fix the noodle waves. The protein denaturation process usually occurs prior to starch gelatinization because of relatively low moisture in noodles (∼40% moisture). Starch does not begin to gelatinize until it reaches 84 ◦ C even when the moisture is more than 70% (Wu et al. 1998). The starch gelatinization temperature of noodles is therefore even higher than 84 ◦ C. This suggests that noodles are only partially gelatinized under normal steaming conditions. Because the gelatinized starch plays a key role in determining the rehydration rate and viscoelastic texture of the finished noodles, it is a challenge to promote the degree of starch gelatinization during steaming. After steaming, noodle blocks are fed into frying baskets that are mounted on the traveling chain of a tunnel fryer. The baskets filled with noodle blocks are immersed in 140–160 ◦ C hot oil and fried for 1–2 minutes. Water vaporizes quickly from the surface of the noodles upon dipping into the hot oil. Dehydration of the exterior surface drives water to migrate from the interior to the exterior of the noodle strands, resulting in a porous spongy structure by steam. Eventually, some of the water in noodles is replaced by oil. The moisture content of the finished noodle products is in the range of 3–7%. Many tiny holes created in the frying process serve as channels for water to get in upon rehydration in hot water. Because the surfaces of fried noodle strands absorb oil during frying, they can easily be separated in hot water. It usually takes 3–4 minutes to cook or soak fried instant noodles in hot water before consumption. There are two important points to consider during instant fried noodle production. The first consideration is to prevent frying oil rancidity because fried noodles contain about 20% fat. Oil quality must be chosen with extreme care. Replace the frying oil more frequently, control the frying temperature so it is not too high, and filter the frying oil continuously to keep oil fresh (refer to Chapter 15 for more quality control details). The second consideration is to prevent noodle surface swelling during frying. This can be achieved by controlling the oil temperature so it is not too high and by sprinkling the seasoning solution on noodles prior to frying. Oil absorption is a result of noodle-making conditions (water absorption, flour protein, ingredients, etc.) and frying conditions (oil temperature and frying time) (Anon. 1998).

5.3.7.2. Processing Technology of Steamed and Air-Dried Noodles For the manufacture of steamed and air-dried instant noodles, wavy noodle strands are first steamed for 2–3 minutes at 98–100 ◦ C, then dried for 35–45 minutes using hot-blast air at 70–85 ◦ C (Figures 5.16 and 5.17). This drying temperature is much higher than the temperature used for regular dried noodles described previously, and the drying time is much shorter. The moisture content of the finished product is less than 12%. The degree of starch gelatinization for this type of noodles is usually between 80% and 85%, which is lower than that of fried instant noodles (85–90%). Prolonging the steaming time can increase starch gelatinization—thus, shortening the rehydration

132 FIGURE 5.16

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Flour + salt or alkaline salt solution ↓ Mix (10–15 min, 20–30 °C) ↓ Dough resting (5–10 min) ↓ Dough sheet forming and compounding ↓ Sheeting and reduction ↓ Noodle slitting and waving ↓ (Spraying water) ↓ Steaming (over 98 °C; 2–3 min) ↓ Cooling with fans ↓ Cutting and folding in half ↓ Hot-blast air drying (70–85 °C, 35–45 min) ↓ Cooling with fans ↓ Placing seasoning sachets on noodle block ↓ Packaging into polyethylene film bag ↓ Bag-type steamed and air-dried instant noodles

FIGURE 5.17

Processing procedures of steamed and air-dried instant noodles.

time and improving noodle eating quality. The dried noodles are cooled prior to packaging and often included with a seasoning sachet. This type of nonfried instant noodle is also called the “nonexpanded type” because the noodles have a tight structure and rehydrate slowly in hot water. Because the starch is not fully gelatinized during steaming, the noodles will have a better texture if cooked in boiling water rather than soaked in hot water. One of the key technical challenges in making nonfried instant noodles is to prevent noodle strands from sticking together, which causes uneven drying. In severe cases, the dried noodle strands may not separate easily during cooking, resulting in uneven rehydration and poor texture. Attempts have been made to solve this problem by spraying oil on the surface of the noodles after steaming, but it slows down the drying process by interfering with the water evaporation. Other approaches (Wu et al. 1998) include (1) making noodles round to minimize the surface area; (2) forming a nonsticky film on the noodle surface by adding an emulsifier or a small amount of mung bean starch; (3) applying two-stage steaming (initial steaming, spraying an emulsifier to prevent the starch from swelling excessively during the second steaming stage, and resteaming); (4) cooling steamed noodles quickly to remove excess water and allowing soluble starch on the surface to form a film; and (5) cooling the steamed

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noodles quickly (10 ◦ C or below) and washing away soluble starchy material from the noodle surface. The basic quality requirement for instant noodles is short rehydration time (less than 3–4 minutes) in hot water. However, the nonexpanded air-dried noodles require a longer rehydration time because of the lack of a porous structure. To overcome this shortcoming, Wu et al. (1998) proposed a concept of “expanded-type air-dried instant noodles.” The major characteristic of the expanded air-dried instant noodles is their porous, honeycomb-like internal structure created by high-temperature expansion, which allows for the rapid entry of water and shortens the rehydration time. In principle, only noodles with a dense and well-developed gluten network structure will have a good chewy texture. Therefore, creation of a porous internal structure could undermine the noodle texture. It is necessary to control the manufacturing process to achieve this balance. The mechanism and controlling steps in making this type of product are described by Wu and co-workers (1998).

5.3.7.3. Processing Technology of Chaomein Noodles Chaomein noodles are very popular noodle products in Latin America and they have a similar manufacturing process to the steamed and air-dried instant noodles, except that the steaming time is much longer. In commercial production of chaomein noodles, both batch-type and automatic processing procedures are employed. In traditional batch-type production, preformed fresh noodle blocks are steamed for 1–3 hours in a closed-door, stand-still steamer or retort steamer, and dried in a stand-still drying cabinet for 6–18 hours. In some factories, the steamed noodles are baked in a continuous conveyor oven for 40–60 minutes. In continuous production, fresh raw noodles are steamed in a conveyor tunnel for 15–30 minutes, molded into the desired form, and dried in a continuous drying chamber (such as a pasta dryer) for 45–60 minutes. Chaomein noodles can also be considered nonfried instant noodles. Although some chaomein noodles are packed and served in the same way as the instant noodles, most chaomein noodles are prepared in restaurants or at home by stir-fry cooking. Most manufacturers use very basic ingredients for making chaomein noodles: medium- to high-protein flour, water, and salt. Even salt is considered an optional ingredient. Because the traditional batch-type processing technology requires more labor and a longer time and consumes too much energy, more and more noodle manufacturers in Latin America are moving toward processing automation by upgrading noodle machinery. This will not only reduce production costs but also improve productivity and product-quality consistency. 5.3.7.4. Quality Characteristics Quality requirements of instant noodles vary, depending on regions and consumer groups. For good consumer acceptance, instant noodles should have a bright and yellow color and be free of rancidity. When cooked in boiling water, the Chinesetype instant noodles should have a strong bite and firm nonsticky surface, while the Korean- and Japanese-type instant noodles are characterized by a soft and elastic texture and very smooth surface.

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Nonfried instant noodles (including chaomein noodles) have a longer shelf life because little fat rancidity is involved due to the low fat content; however, they tend to have a longer cooking time and harder noodle texture than the fried instant noodles due to denser structure. In developed countries, nonfried instant noodles are gaining popularity because of consumers’ greater awareness of healthy foods. However, slow output of the process and lack of a pleasant shortening taste and mouthfeel make the products less popular in Asia compared with fried instant noodles. In recent years, many new and improved instant-noodle products have been developed to meet consumers’ demand for healthy and nutritious foods. Some of these products include whole-wheat instant noodles, high-fiber instant noodles, lowcarbohydrate instant noodles, and various nutrient-fortified instant noodles with vitamins, minerals, and/or proteins. There is another type of instant noodle that has received increasing acceptance, fresh type long-life (LL) noodle. A packaged LL noodle bag is placed inside a plastic bowl along with seasoning sachets. For consumption, remove both the LL noodles and seasonings from the bags, place them in the plastic bowl, and add boiling water to soak for a few minutes. The production details of LL noodles are described in Section 5.3.4.2. 5.3.8. Freeze-Dried Noodles

5.3.8.1. Equipment and Processing Technology Most drying processes involve the evaporation of liquid water to water vapor, but freeze drying instead occurs as a result of sublimation of ice crystals directly to water vapor. Figure 5.18 outlines the schematic steps of manufacturing freeze-dried noodles. The basic steps in freeze drying noodles are briefly described as follows: 1. Boil fresh raw noodles to achieve 65–80% moisture. Boiling is a quick way to fully hydrate and gelatinize starch. Boiling noodles before freeze drying improves the rehydration rate of the product. Without boiling, the core of the freeze-dried noodle strand tends to be stiff and the rehydration rate is slow. If fresh raw noodles are steamed instead of boiled, neither noodle hydration nor starch gelatinization is sufficient. 2. Wash and cool boiled noodles in chilled water (<10 ◦ C). 3. Place the boiled noodles in designated round or square-shaped trays. 4. Quickly freeze noodles (usually on trays), which results in the formation of ice crystals within and between noodle strands and the non-ice phase becoming freeze concentrated. This process typically takes 20–50 minutes, depending on the freezing capacity. 5. Frozen noodles are then exposed to a headspace with a partial pressure of water vapor well below the equilibrium vapor pressure of ice at the temperature of the materials. This causes the sublimation of the ice crystals (primary sublimation) and also desorption of noncrystalline water present within the food matrix (secondary drying). The vacuum drying time could require 1–2 days to achieve the final moisture of less than 5% in the finished product. 6. The freeze-dried noodles are packed for storage and shipping.

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Flour + salt or alkaline salt solution ↓ Mix (10–15 min, 20–30 °C) ↓ Dough resting (15–30 min) ↓ Dough sheet forming and compounding ↓ Dough sheet aging (15–40 min, 95% RH) ↓ Sheeting and reduction ↓ Noodle slitting and cutting ↓ Boiling (98–100 °C) to 65–70% moisture ↓ Washing and cooling (< 10 °C) ↓ Tray stuffing ↓ Quick freezing (~20 minutes) to < –20 °C ↓ Vacuum drying (under 4.6 mm Hg (6.12 hPa), 1–2 days) to < 5% moisture ↓ Packaging (with soup sachet) ↓ Final product

FIGURE 5.18

Processing procedures of freeze-dried noodles.

The main elements of a freeze dryer include (Stapley 2008) (1) a vacuum-tight chamber, (2) a vacuum pump to remove air and other noncondensable gases, (3) a condenser to remove water and maintain a low partial pressure of water vapor in the freeze drying chamber, and (4) some means to supply heat. In conventional freeze drying, a vacuum is maintained in the freeze-drying chamber, typically via the use of a vacuum pump. The primary function of the vacuum pump is to remove air (and other noncondensable gases desorbed from the food) from the chamber. The presence of the gases slows down the rate of transfer of water vapor from the food to the condenser. The very low partial pressure of water vapor in the headspace is generally achieved by placing a condenser unit in close proximity to the food. The temperature of the condenser surface should be significantly lower than that of the drying material (typically −60 ◦ C). Another important function of the condenser is to effectively remove water from the drying chamber. Because sublimation is an endothermic process, heat must be applied to the frozen food to continue the sublimation process. However, the temperature of the food must always be maintained below its “collapse” temperature (which is related to the glass transition temperature) so that the ice crystals do not melt and the frozen food matrix maintains its rigidity in order to obtain a properly freeze-dried food. The collapse temperature is not constant, but rises as the moisture content in the food matrix is reduced.

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5.3.8.2. Quality Characteristics The overall quality of freeze-dried products is usually superior to that of other dried foods. If the process is performed correctly, the resulting freeze-dried noodles will have the following attributes: 1. A rigid structure at ambient temperature. The collapse temperature of sufficiently dried food is far above ambient temperature, so the dried food will maintain its physical integrity throughout its shelf life. 2. An excellent rehydration property. If the sample has consistently been maintained below the collapse temperature throughout drying, the ice crystals will leave behind voids (which the crystals once occupied) as they sublime. This results in a highly porous structure with excellent rehydration properties as the water is sucked into the pores by capillary action on wetting. The presence of pores also accelerates the sublimation process by providing easy routes for water vapor to escape from the solid. 3. Minimal quality changes. Freeze-dried products are maintained at much lower temperatures than other drying processes. Reactions associated with the much higher temperatures that occur in other drying processes (such as the Maillard browning reaction and enzymatic reaction), therefore, are minimized in freeze drying. 4. Maximum retention of volatile flavor and aroma compounds. Freeze drying retains a maximum level of volatile flavor and aroma compounds in comparison to high-temperature drying processes. This process is especially applicable to soba noodles (buckwheat) to retain the rich, characteristic soba flavor. Freeze drying is the premier drying technique for preserving product quality; however, every processing technique incurs quality losses and freeze drying is no exception. There are three possible quality issues associated with this process (Stapley 2008): (1) physical damage of cell walls due to the formation of large ice crystals during freezing; (2) the ability to be rehydrated back to the original fresh form; and (3) quality losses from losses of volatile flavor and aroma compounds during the drying process. It is important to realize, however, that the raw material quality (boiled noodles) feeds through to the freeze-dried product and is an important aspect.

5.3.8.3. Limitations Although freeze-dried noodles present high value by having good color, texture, and freshness, they are only tailored for niche markets on a commercial basis due to high production costs. The drying chamber must be designed for vacuum operation. The condenser presents a heavy refrigeration burden as it typically operates in the range between −40 and −60 ◦ C, and it must extract the same amount of heat in condensation from the condenser coils as that which is provided by heating to sublime the ice from the foods. The food must also first be frozen, which also incurs an energy cost. And finally, freeze drying is a slow process, taking many hours, and

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this requires large-scale equipment in order to produce acceptable throughput for bulk food manufacture. Consequently, both the capital and operating costs of freeze dryers are higher. The freeze dried products are more convenient to store or carry than the equivalent fresh or frozen products, and this in many instances compensates for any reduction in quality.

5.4. SUMMARY This chapter describes the processing technology and quality characteristics of eight major noodle types in the world market. Modern noodle processing technology includes primary and secondary processing units. Most Asian noodles have similar primary processing units, but the secondary processing units differ and, therefore, create various types of noodle products. The primary processing unit includes steps of dough mixing, resting, sheeting and compounding, thickness reduction, and slitting and cutting into noodle strands. These raw noodle strands can be processed further in the secondary processing unit to manufacture specific noodle styles for different market needs for the purpose of extended shelf life, convenience, taste, and other improved quality attributes. Each step of noodle manufacture plays an important role in the finished-product quality and safety.

ACKNOWLEDGMENTS The authors wish to thank Mr. Bon Lee for translating some Japanese literature into English.

REFERENCES Anon. 1998. Shin Sokuseki-men Nyumon (in Japanese). Japan Convenience Foods Industry Association (ed.), Shokuhin Sangyou Shinbun Sha, Tokyo, Japan. Azudin, M. N. 1998. Screening of Australian wheat for the production of instant noodles. In: A. B. Blakeney and L. O’Brien (eds.) Pacific People and Their Foods. American Association of Cereal Chemists, St. Paul, MN, USA, pp. 101–121. Baik, B.-K., Czuchajowska, Z., and Pomeranz, Y. 1995. Discoloration of dough for oriental noodles. Cereal Chem. 72:198–205. Berry, M., Fletcher, J., McClure, P., and Wilkinson, J. 2008. Effects of freezing on nutritional and microbiological properties of foods. In: Judith A. Evans (ed.), Frozen Food Science and Technology. Blackwell Publishing Ltd., London, UK, pp. 26–50. Crosbie, G., Miskelly, D., and Dewan, T. 1990. Wheat quality for the Japanese flour milling and noodle industries. W. Australian J. Agric. 31:83–88.

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Fu, B. X. 2008. Asian noodles: history, classification, raw materials, and processing. Food Res. Int. 41(9):888–902. Hou, G. 2001. Oriental noodles. Adv. Food Nutr. Res. 43:141–193. Hou, G. 2007. Asian Products Collaborative Project Report. Wheat Marketing Center, Portland, OR, USA. Huang, S. 1999. Wheat products: 2. Breads, cakes, cookies, pastries, and dumplings. In: Catharian Y. W. Ang, KeShun Liu, and Yao-Wen Huang (eds.), Asian Foods: Science & Technology. Technomic Publishing Company, Lancaster, PA, USA, pp. 71–109. Kruger, J. E., Anderson, M. H., and Dexter, J. E. 1994. Effect of flour refinement on raw Cantonese noodle color and texture. Cereal Chem. 71:177–182. Magnussen, O. M., Hemmingsen, A. K. T., Hardarsson, V., Nordtvedt, T. S., and Eikevik, T. M. 2008. Freezing of fish. In: Judith A. Evans (ed.), Frozen Food Science and Technology. Blackwell Publishing Ltd., London, UK, pp. 151–164. Miskelly, D. M. and Moss, H. J. 1985. Flour quality requirements for Chinese noodle manufacture. J. Cereal Sci. 3:379–387. Morris, C. F., Jeffers, H. C., and Engle, D. A. 2000. Effects of processing, formula and measurement variables on alkaline noodle color—toward an optimized laboratory system. Cereal Chem. 77:77–85. Moss, R., Gore, P. J., and Murray, I. C. 1987. The influence of ingredients and processing variables on the quality and microstructure of hokkien, Cantonese, and instant noodles. Food Microstruct. 6:63–74. Nagao, S. 1995. Wheat usage in east Asia. In: H. Faridi and J. M. Faubion (eds.), Wheat End Uses Around the World. American Association of Cereal Chemists, St. Paul, MN, USA, pp. 167–189. Nagao, S. 1996. Processing technology of noodle products in Japan. In: J. E. Kruger, R. B. Matsuo, and J. W. Dick (eds.), Pasta and Noodle Technology. American Association of Cereal Chemists, St. Paul, MN, USA, pp. 169–194. Oda, M. 1991. Shin Men no Hon (in Japanese), 1st ed. Shokuhin Sangyou Shinbun Sha, Tokyo, Japan. Park, C. S. and Baik, B.-K. 2002. Flour characteristics related to optimum water absorption of noodle dough for making white salted noodles. Cereal Chem. 79(6):867–873. Ross, A. S. and Hatcher, D. W. 2005. Guidelines for the laboratory manufacture of Asian wheat flour noodles. Cereal Foods World 50(6):296–304. Shiau, S.-Y. and Yeh, A.-I. 2001. Effects of alkali and acid on dough rheological properties and characteristics of extruded noodles. J. Cereal Sci. 33:27–37. Stapley, A. 2008. Freeze drying. In: Judith A. Evans (ed.), Frozen Food Science and Technology. Blackwell Publishing Ltd., London, UK, pp. 248–275. Wu, T. P., Kuo, W. Y., and Chend, M. C. 1998. Modern noodle based foods—product range and production methods. In: A. B. Blakeney and L. O’Brien (eds.), Pacific People and Their Foods. American Association of Cereal Chemists, St. Paul, MN, USA, pp. 37–89. Ye, Min. 2006. Rice and Flour Product Processing Technology (in Chinese). Chemical Industrial Press, Beijing, China. Zaritzky, N. E. 2006. Physical–chemical principles in freezing. In: D. W. Sun (ed.), Handbook of Frozen Food Processing and Packaging. CRC/Taylor & Francis Group, Boca Raton, FL, USA, pp. 3–33.

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Zaritzky, N. E. 2008. Frozen storage. In: Judith A. Evans (ed.), Frozen Food Science and Technology. Blackwell Publishing Ltd., London, UK, pp. 224–247. Zhao, L. F. and Seib, P. A. 2005. Alkaline-carbonate noodles from hard red winter wheat flours varying in protein, swelling power, and polyphenol oxidase. Cereal Chem. 82:504–516. Zhou, H. and Guo, D. 1996. Study of the effects of a corrugated roll sheeting on noodle properties. In: Discussion of the Assembly of Collected Works of the First Asian Cooked Wheaten Food Industry Development (in Chinese). Chinese Institute of Food Science and Technology, Beijing, China, pp. 83–88.

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CHAPTER 6

Instant Noodle Seasonings KERRY FABRIZIO, RAJESH POTINENI, and KIM GRAY

6.1. INTRODUCTION Asian cuisine has long been a staple of diets across the globe. Due to the current economic conditions, noodle houses and noodle cuisine have become one of the top flavor trends for 2009 in North America (Morago 2008). Noodles are quick, nourishing, and inexpensive, making them a fundamental food both in the home and when dining out. Flavor & the Menu magazine (Anon. 2009) reported that Asian noodles were the top “ethno-cuisine” trend, landing noodles a top 10 spot for 2009 trends. The majority of Asian style noodles are consumed as soup. As such, the industry of ramen noodle soup has exploded over the past 50 years, since the handy packaged version was developed in 1958 by Momofuku Ando (Anon. 2007). These instant ramen noodles have become synonymous with convenience foods, and consumers have come to expect a certain consistency in the product, both in flavor and texture. One of the key components for the success of these instant noodles is the spice seasonings that provide a consistent flavor balance. Spice seasonings are defined as blends of salt, herbs, and/or spices used to enhance or improve the flavor of food (Hirasa and Takemasa 1998). Preference for a certain food can be dictated by the type of seasoning and amount used. In the case of instant ramen noodles, the flavor profile of the finished soup is driven by the region of consumption, with seafood/shrimp, chicken, and beef being the most popular flavors. In this chapter, the basic components of the seasoning, as well as the processing and quality, will be discussed to provide noodle producers with the foundation to produce their own seasonings and flexibility in manufacturing seasonings. 6.2. SEASONING COMPONENTS Although the overall flavor profile of a ramen-style soup can be vastly different, depending on the region, the foundation ingredients of the ramen soup are essentially Asian Noodles: Science, Technology, and Processing, Edited by Gary G. Hou C 2010 John Wiley & Sons, Inc. Copyright


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TABLE 6.1

Generalized Ramen Soup Ingredients

Salt: sodium chloride, potassium chloride Sweeteners: sucrose, corn syrup solids, dextrose Flavor enhancers: monosodium glutamate, disodium inosinate, disodium guanylate Fillers: dextrose, maltodextrin, whey, starches Body ingredients: hydrolyzed vegetable or animal proteins, soy sauce, yeasts Functional: oils/fats, flavored oils, starches and gums, acids, anticaking agents Garnishes: dried vegetables, herbs, meats, seafood Herbs and spices: including onion and garlic Flavors: artificial and/or natural flavors Coloring: artificial and/or natural (caramel, turmeric, paprika)

the same (Table 6.1). The majority of seasonings are delivered via a seasoning sachet that is added to the soup by the consumer during cooking. One method to boost the overall flavor perception is to spray a slurry seasoning onto the fried noodle cake prior to packaging. This method does not deliver the best flavor impact and it is not used very often due to the additional equipment required.

6.2.1. Salt Salt, or sodium chloride, serves many functions, depending on the type of food such as flavor enhancer, preservative, binder, texture enhancer, color aid, and control agent (Brown 2004a). When used in noodle seasoning, the primary function of salt is flavor enhancement. Salt is very effective and relatively inexpensive, which makes it a very popular flavoring agent. Salt comes in many forms: sea salt, rock salt, table salt, kosher salt, and flavored salts (Brown 2004). The most commonly used variety is table salt, which is refined from rock salt and fortified with iodine. Depending on the flavor profile, a seasoning blend for noodles could contain 50% or more salt. The biggest trend in food currently is sodium reduction. Despite the fact that sodium replacement tools are generally more expensive than salt, the health benefits far outweigh the increase in cost. Furthermore, noodle companies are under pressure to reduce the sodium levels in the seasonings being used. When tasting salt in a product, there are three parts of the sensory perception profile to consider: initial salt hit, middle/body, and lingering saltiness. One inexpensive method to replace salt is the use of potassium chloride (KCl). KCl is a good all-around tool that provides the initial impact of salt very well. A very large majority of the population is sensitive to off notes of KCl, which are often described as metallic, bitter, and lingering, depending on the usage. For that reason, when KCl is used, a masking agent is often used in conjunction. Because KCl has taste disadvantages, many suppliers and flavor houses are working on alternative salt replacers. Furthermore, in some parts of the world, KCl has a negative connotation and the general public does not want to see it on the label statement of the products they purchase. As stated earlier, the taste of salt is quite

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complicated and therefore the approach has been to mimic the taste of salt in the upfront hit, middle/body, and linger using a combination of techniques. 6.2.2. Sweeteners Sugar, or sucrose, is a natural sweetener harvested from sugar beets or sugar cane, with sugar cane being the primary source. Sugar can serve a multitude of functions in foods, such as sweetener, flavor enhancer, browning agent, substrate for fermentation, preservative, masker for acidic, bitter, or salty flavors, or texture enhancer, just to name a few (Brown 2004b). Flavor enhancer and taste masker are the key functions of sugar in noodle seasonings. The amount of sugar added to a formula is dependent on the flavor profile and form used, with a range of 0–10%. High fructose corn syrup solids can also be used as a sweetener. Sodium is not the only ingredient getting attention for being less than healthy. Recently, food producers have been pushed by consumers to reduce high-calorie sweeteners from processed foods, including noodle seasonings. Artificial sweeteners are often used to maintain virtually the same flavor profile. In the United States, saccharin, aspartame, sucralose, and neotame are available. Rebaudioside-A is the only natural, noncaloric sweetener approved for use in food products. Regulations vary per country and therefore require reviewing prior to formulating. 6.2.3. Flavor Enhancers One of the most common amino acids used as a flavor enhancer is also the salt of glutamic acid or monosodium glutamate (MSG). Glutamate is a nonessential amino acid that serves several functions in the body: an amino group for the synthesis of other amino acids, an energy source for various tissues, and a glutathione synthesis substrate (Freeman 2006). Traditionally, MSG is naturally occurring in many foods including meat, fish, poultry, and vegetables, with vegetables containing proportionally more free glutamate. For commercial purposes, MSG is produced from molasses, sugar cane, and sugar beet fermentation, or starch hydrolysis (Food Standards Australia New Zealand 2003). In the late 1960s, MSG garnered bad publicity with what became known as Chinese restaurant syndrome. Symptoms varied but frequently included headaches, numbness/tingling, flushing, muscle tightness, and overall weakness. This syndrome has been studied extensively over the years with no consistent data to suggest that MSG alone is causing the problem (Freeman 2006). Despite the negative press, MSG continues to be an important ingredient in all types of foods, with soup seasonings being no exception. One of the reasons MSG is used so frequently is to provide the basic taste known as umami. Umami (translated from Japanese to mean “delicious” or “savory”) is the fifth basic taste along with salt, sweet, sour, and bitter and is described as providing a savory character to foods. The Japanese believe that umami is crucial to enhance the flavors rather than providing an actual flavor profile (Freeman 2006).

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The use of MSG in a seasoning is necessary to provide valuable flavor enhancement at very little cost. The actual usage varies significantly, depending on overall flavor profile, but the suggested level is 6.0–8.0% in the seasoning formulation. MSG is also used frequently in conjunction with disodium inosinate, also known as inosine 5 -monophosphate (IMP) and disodium guanylate, or 5 -guanosine monophosphate (GMP), which seem to provide a synergistic flavor enhancement effect (L¨oliger 2000). To maximize the synergistic effect, IMP and GMP usage is approximately 0.02–0.04% of the finished product. As the negative publicity against MSG has increased, food companies have found that they can replace MSG successfully with the use of IMP and GMP, although the cost is significantly higher. To provide the best umami impact, however, all three flavor enhancers are used in conjunction. When used separately, IMP imparts a beefy character while GMP is said to be mushroom-like (L¨oliger 2000). 6.2.4. Fillers Depending on the flavor profile, fillers are often needed to ensure a consistent usage level to the finished product. The most popular fillers are dextrose, maltodextrin, whey, and/or starches. Some fillers can provide mouthfeel, thicken the product, or add nutritional value in the form of protein. Dextrose can also be used as it is less sweet than sucrose (about 0.75 times the sweetness of sucrose). Dextrose is the name given to glucose that has been produced from corn. When dextrose is used, there is a dextrose equivalent (DE) value associated with it. If all the starch present has been converted to glucose, the DE value is 100 and is more commonly associated with corn syrups and corn syrup solids (Brown 2004). The sweetness is proportional to the DE value, with a low DE being not very sweet. Often low DE dextrose and maltodextrin serve as bulking agents, with the usage in a seasoning formulation having a range of 0–50%. 6.2.5. Body Ingredients Body ingredients are a group of ingredients, such as hydrolyzed vegetable or animal proteins, soy sauce, and/or yeast, which provide mouthfeel and body to the finished product. These components usually contain nondeclarable glutamates or glutamic acid that provides umami to the finished product. Hydrolyzed vegetable proteins (HVPs) are processed from a variety of different vegetable protein sources including soy, wheat, and corn. The process includes hydrolysis with hydrochloric acid followed by neutralization with sodium hydroxide (Aaslyng et al. 1998). The end result produces a compound that is comprised of different amino acids and, depending on the substrate used, glutamic acid (as found in MSG) and up to 60% salt (Tainter and Grenis 1993a). Due to the high amounts of glutamic acid, HVP is a good secondary source of umami character. HVP is also good for adding a meaty, salty character without adding significant cost. Yeast extracts or autolyzed yeast extracts (AYEs) are also used to provide a meaty character to the overall profile. Many types of AYEs are available and each

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provides a different flavor aspect, depending on the processing. Commercially, yeast is grown and sodium chloride is added to the solution to make it hypertonic. This triggers autolysis and causes the internal enzymes to break down the cell structure. The solution is heated to stop the enzymatic reaction and the cell structures are filtered off. The resulting commercial product can either be a thick paste or a dried powder that varies in color from light to dark, depending on the flavor profile. AYEs contain large amounts of free glutamic acid, also found in MSG. AYEs can be used in conjunction with MSG or serve as a replacement. However, AYEs can no longer be considered a “natural flavor” and must be labeled as such (Tainter and Grenis 1993b). One could not discuss Asian noodle seasoning without a section on soy sauce. Soy sauce has been an integral part of Asian cuisine since it was originally developed over 2500 years ago (Raghavan 2007a). Traditionally, soy sauce has been made using a fermentation method that utilizes both molds and yeasts and takes over a year to complete the process. This method makes for a unique end result that contains over 300 chemicals (i.e., amino acids, alcohols, organic acids, esters, sugars, and salt) (Raghavan 2007b). Due to the length of time required, a more commercial method was developed that begins with hydrolyzed soy protein rather than soybeans (McGee 1984; L¨oliger 2000). The result is a cheaper product that is less complicated in composition and lighter in color. This requires the soy sauce to be colored with caramel coloring. Regardless of the method, soy sauce provides important umami characteristics to the seasoning. When used in noodle seasonings, the soy sauce is generally spray-dried and mixed into the dried seasoning.

6.2.6. Functional Ingredients Fat or oils can be added to the complete soup in two ways: an oil packet that is added by the consumer at the time of consumption or blended in the seasoning sachet. Flavored oils, such as chili or garlic oils, are often delivered using a separate oil packet. The advantage is the perception of a higher-quality product, but the cost associated with the extra packaging materials and handling can be a disadvantage. Even when an oil sachet is used, oil or fat will need to be added to the seasoning for reasons that will be discussed in the manufacturing section (see Section 6.3). When adding the fat directly to the seasoning blend, a cheaper, more hydrogenated fat can be used. In this case, the fat is used as a plating material for the granulated ingredients that helps keep the seasoning blended consistently. In addition to being used as a processing aid (see Section 6.3), fat or lipids are an integral part of the soup as they provide mouthfeel and richness (Nawar 1996). Lipids provide an interesting character to completed ramen soup. Once added to the noodles and hot water, the fat melts and provides a layer on the surface of the soup. This layer serves as a barrier to trap heat and volatile flavors under the surface. When stirred, the aromas are released into the air, creating a sensory response.

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6.2.7. Garnishes The garnishes used will vary greatly, depending on the flavor profile. The most commonly used garnishes are vegetables such as scallions, carrots, chives, green onions, mushrooms, leek, celery, and cabbage. Dried meats are also used as garnishes, with salted shrimp being the most popular. Like oil/fat, the garnish can be delivered either directly in the seasoning or in a separate sachet packet. If added directly to the seasoning packet, care needs to be taken to prevent the destruction of the particle size during blending. This requires that the garnish be added at the very end of sequencing and mixed just until incorporated. Even using the most precautions, the size of the particles will be reduced under commercial conditions, during both blending and packaging. One way to get the desired particle size at the consumer level is to start with a bigger piece, but this can also add cost. The other method for reducing the amount of particle breaking is to pack the garnish in separate sachet packets. Since there is very little mixing involved, the particles tend to maintain their original integrity, but as with the separate oil packets, the cost is increased. 6.2.8. Flavor Ingredients Additional flavorings (natural and natural/artificial flavor blends) may be used in the seasonings to enhance or complement the flavor experience during the consumption of noodles (Tainter et al. 1993a,b). These flavoring materials may be used either in liquid, paste, or spray-dry form and are generated by one of the four ways listed below: 1. 2. 3. 4.

Extracted essential oils from herbs and spices or other natural sources Complex blends of natural and/or synthetic flavor compounds Generation of flavors via fermentation Generation of flavors via thermal reaction chemistry

Essential oils, such as garlic, clove, onion, and other citrus oils used in the seasonings, are extracted either using techniques such as solvent extraction/distillation or by pressing (Raghavan 2007c). This method almost always results in liquid form. Flavors can also be generated by linking analytical techniques to flavor creation. Using analytical techniques, such as gas chromatography (GC) in combination with mass spectroscopy (GC/MS) and olfactometry (GCO), the key volatile compounds can be identified. These key compounds can then be reconstituted to form complex flavors that can be used in the seasoning blends (Church 1999). Reconstituted flavors are not only herb and spice profiles but also meat profiles such as shrimp, beef, and pork. However, one of the disadvantages with this blending process is that it may not provide the complete flavor profile desired. Complex meaty profiles can be generated using thermal reaction chemistry. Flavor precursors are blended and cooked under various process conditions (ingredient concentration, temperature, pH etc.), providing desired flavors using complex Maillard reaction chemistry. These precursors may include proteins, amino acids,

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meat extracts, hydrosylates, yeast products, sugars, carbohydrates, fats, and nucleotides. Most of the meaty profiles, such as chicken, bacon, and shrimp used in seasoning powders, are generated through thermal reaction chemistry. In the case of soy and cheese profiles, enzymatic modified cheese (EMC) extracts generated via fermentation are commonly used (Church 1999). Although the flavorings are generated by various methods, the key for a commercially successful seasoning blend lies in the art of formulating the blend of ingredients in the right ratio that will provide a desired profile for the customer during consumption of noodles (Church 1999). Traditionally, this blending process can be divided into three parts and blended in this order: (1) base notes (hydrolyzed vegetable proteins, fermented foods, and autolyzed yeast), (2) mid notes (process flavors, natural flavors, EMCs, and spice extracts), and (3) top notes (intense volatile flavor compounds to impart sweet, savory, and citrus notes). 6.2.9. Onion and Garlic After salt and MSG, two of the most common flavor components of ramen seasoning are onion and garlic. When dried, they can be added in a variety of forms (i.e., powder, granulated, ground, flaked, sliced, minced, chopped, or toasted/roasted) with the amount varying, depending on the flavor profile (Raghavan 2007b). Garlic cloves are known for their very pungent flavor; however, the impact is subdued upon cooking. Dried garlic, however, remains strong and pungent in both aroma and taste, even after cooking (Raghavan 2007b). Garlic is unique in that the flavor delivered is different, depending on how the clove is processed. The flavor variation is not as obvious as it can be when the dried form is used. Onion, one of the oldest known vegetables, comes in several different varieties: shallots, red, white, green, leek, and yellow. Yellow onions are by far the most commonly used variety in both fresh and dried formats. As with garlic, the form used dictates the flavor impact on the seasoning, with powders providing the most impact and the chopped form providing a more subtle flavor.

6.3. MANUFACTURING The process to produce the noodle soup seasoning is vital to the consistency and outcome of the final product. Several areas encompass the manufacturing, quality of ingredients, blending, and packaging. 6.3.1. Spice Quality The main governing bodies that regulate and set the international standards of quality for spices are the American Spice Trade Association (ASTA) and U.S. Federal Specifications: spices, ground and whole, and spice blends. Major spice exporting countries, such as India and Malaysia, have their own export specifications that

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classify a quality grade based on moisture content and amount of foreign material (Hirasa and Takemasa 1998). Spice-based seasonings are usually contaminated with insects, bacteria, and/or molds. Several methods have proved to be successful in eliminating and preventing microbial and insect contamination. These methods include irradiation, chemical fumigation, sterilizing with ethylene oxide, and heat treatment. The method used is often regulated by the region where the spices will be consumed. Fumigation with ethylene oxide has been banned in Europe and Japan as the residue has been shown to cause health issues. Ethylene oxide has also been shown to alter the flavor profile of the spices (Raghavan 2007c). One sterilization method that has met with mixed reviews is irradiation. Highly effective at reducing contamination with usage level limits of 30 kGy/s for spices and an average dose of 10 kGy, irradiation does not alter the profile of the spices being irradiated (Hirasa and Takemasa 1998; FDA 2008). This is due to the very low moisture content in most spices. Spices that contain high amounts of essential oils, like black pepper, are irradiated at levels between 2 and 9 kGy to prevent the degradation of the flavor components. Color-rich spices, such as paprika, have been shown to be more stable after treatment with irradiation (Urbain 1986). Despite the positive results with the use of irradiation, Japan has banned this method. The use of steam sterilization has had to be adapted to accommodate the low moisture content found in most spices. For this reason, saturated or supersaturated steam is the most effective method. Kikkoman has designed a method called the “air-steam sterilization system” in which superheated steam is employed. The effect is very quick, even on thermophilic bacteria, and it keeps the spices from clumping or sticking together. The disadvantages to this method are the discoloration of spices, especially ones containing chlorophyll, which tend to turn brown, and the sterilization effect, which can vary greatly within a lot due to inconsistency in surface texture (Hirasa and Takemasa 1998). 6.3.2. Blending The principles behind the commercial blending of a seasoning are the same regardless of the flavor profile. The seasoning formula is written based on 100%, with ingredients in descending order (Table 6.2). Ingredients such as salt, sugar, maltodextrin, and dextrose are knows as carriers and are used in a process called “plating” when spice extractives or oils/fats are used (Raghavan 2007a). The first step in the process is to plate any liquids being used onto the carrier. A liquid colorant would be added at this stage. Next, all ground spices, herbs, and other flavoring ingredients are added and mixed well. Caking of the noodle seasoning can be an issue in many of the formulations. Several of the ingredients commonly found in noodle seasonings are hydroscopic, or water loving, such as yeasts and HVPs. The caking issue of a seasoning can also be seasonal: the more humid the outside environment, the more intervention is needed. With storage conditions over a 12-month period, without the use of an anticaking

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TABLE 6.2

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Typical Formulation and Processing Sequence

Seasoning packet Sugar Salt Garlic powder Yeast extract Maltodextrin Onion powder Sunflower oil Hydrolyzed vegetable protein Monosodium glutamate Parsley flakes Silicon dioxide Chicken flavor Black pepper (spice) Disodium inosinate Disodium guanylate Total

40.00% 35.00% 5.00% 5.00% 4.55% 4.00% 2.00% 1.75% 1.00% 0.60% 0.50% 0.25% 0.15% 0.10% 0.10% 100.00%

Processing 1. Mix sugar and salt in blender. 2. Slowly add sunflower oil and blend well. 3. Add remaining ingredients, excluding silicon dioxide and parsley; blend well. 4. Add silicon dioxide and blend until uniform. 5. Add parsley flakes; mix just until blended. 6. Sift. 7. Package. Oil packet Soybean oil Garlic Chili Shallot Tocopherol (antioxidant) Total

95.40% 2.00% 1.50% 1.00% 0.10% 100.00%

Garnish packet Diced garlic Sliced green onion Total

50.00% 50.00% 100.00%

agent, the seasoning would become a solid mass. Anticaking or flow agents can be added to prevent or limit the amount of caking. Anticaking ingredients are chemicals and are limited in their use, depending on the local governing bodies. The well-mixed seasoning is then sifted to remove any large particles that did not incorporate into the blend. If there are any large particulates, such as parsley, freeze-dried vegetables, or meat, they would be added at the very last step and mixed

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5000 lb ribbon blender

Rotary valve

Conical mill or sifter

Inline metal detector

Vibratory pan and Pack-off scale

FIGURE 6.1

Industrial ribbon blender. (Image courtesy of Givaudan.)

just until blended. This is to prevent degradation of the particle size. The majority of commercial blending is done with what is known as a “ribbon blender” (Figure 6.1). Figure 6.2 shows the inner workings of the ribbon blender. Quality control is an essential aspect of the processing of seasoning blends from start to finish. To ensure a consistent product, several areas are monitored to ensure that the product flavor and appearance do not vary. In most cases, these two areas

FIGURE 6.2

Inside view of industrial ribbon blender. (Image courtesy of Givaudan.)

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TABLE 6.3 Microbiological Requirements for Seasoning Blends Salmonella Escherichia coli Aerobic plate count (APC) Yeast and mold

Negative/25 g sample <10 colonies/g sample <10000 colonies/g sample <250 colonies/g sample

are reviewed once the product has been made and compared to control or previously run samples. The salt levels of a product are a quick and easy way to measure whether ingredients were added at the correct levels. This information is almost always included on the Certificate of Analysis (COA) that accompanies any commercially made product. The COA usually includes these other attributes: appearance, flavor, moisture, particle size, microbiological restrictions for aerobic plate count (also known as total plate count), Salmonella, Escherichia coli, yeast, molds, and coliforms. See Table 6.3 for typical microbiological requirements. When reviewing the product for proper appearance, a Hunter colorimeter, sieve analysis, or the human eye can be used. As with flavor, the appearance of the product is compared to previously run product or control samples. The ribbon blender uses high shear, so the blending time is crucial in the final-product appearance. If mixed too long, any larger particles will be ground down, and if the mix time is not long enough, the product color and consistency can be affected. 6.3.3. Packaging Selection of packaging is dependent on factors such as the food composition, preservation from microbial growth, and physiochemical changes (light, humidity, and temperature) as well as protection from aroma losses leading to a better shelf life of the product (Varriano-Martson and Stoner 1996). Different commercial noodle manufacturers pack their seasonings in different combinations. Depending on the cost aspects and the manufacturing facilities available, the seasoning ingredients can be packed together or separate. In either case, the most common packaging style is the laminates type (Vermeiren et al. 2003). In case of noodle seasonings, the types of ingredients to be packaged can be divided into four categories: 1. Spices: Aroma loss and oxidation of flavor are the most common issues for spices. These ingredients require packaging materials that are excellent gas barriers with good aroma retention. Laminates, such as cellophane/polyethylene or PET/aluminum foil/polypropylene, are commonly used for such purposes (Brown and Williams 2003). 2. Powders: Powders, such as sugars, MSG, and HVPs, contain low moisture (1–5%) and hence have a tendency to absorb moisture and can turn hygroscopic

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and clumpy. Packaging material with good water vapor impermeability, such as LDPE, HD-LDPE, and PP pouches, is used (Brown and Williams 2003). 3. Fats/Oils: The presence of fat or oil as part of the spice seasonings may lead to fat migration through the packaging during storage; hence, a good greaseresistant material such as polyester films, cellophane, and polypropylene is used (Vermeiren et al. 2003). 4. Sauces: For the same reasons that fat/oils are packaged separately, sauces are also separated. The packaging materials currently used for this ingredient are also polyester films, cellophane, and polypropylene. These materials are used to prevent the migration of fat and moisture, which increases the shelf life of the product.

6.4. SUMMARY The flavor profiles may change with the trends, but the basic ingredients used to make Asian noodles taste great will remain the same. Understanding the fundamentals of these ingredients and the seasoning manufacturing process will enable noodle processors to formulate their own seasonings or have better control over the process.

REFERENCES Aaslyng, M. D., Martens, M., Poll, L., Nielsen, P. M., Flyge, H., and Larsen, L. M. 1998. Chemical and sensory characterizations of hydrolyzed vegetable protein, a savory flavoring. J. Agric. Food Chem. 46:481–489. Anon. 2007. Obituary: Momofuku Ando. The Economist, January 18. Anon. 2009. Top Ethno—Cuisine Trend: NoodleMania. Flavor & the Menu (http://flavoronline.com/edition.asp?mainky=1017#ART1248). Brown, A. 2004a. Food preparation basics. In: J. Lee (ed.), Understanding Food Principles and Preparation. Wadsworth/Thomson Learning, Belmont, CA, USA, pp. 119–136. Brown, A. 2004b. Sweeteners. In: J. Lee (ed.), Understanding Food Principles and Preparation. Wadsworth/Thomson Learning, Belmont, CA, USA, pp. 166–180. Brown, H. and Williams, J. 2003. Packaged product quality and shelf life. In: R. Coles, D. McDowell and M. Kirwan (eds.), Food Packaging Technology. CRC Press, Boca Raton, FL, USA, pp. 65–94. Church, D. C. F. 1999. Savory flavors for snacks and crisps. In: P. R. Ashurst (ed.), Food Flavorings, 3rd ed. Aspen Publishers, Gaithersburg, MD, USA, pp. 267–282. FDA. 2008. Irradiation in the production, processing and handling of food. 21 CFR. Part 179. Federal Register, Vol. 3, No. 2b, 1 April 2008. Food Standards Australia New Zealand. 2003. Monosodium glutamate: a safety assessment. Technical Report Series No. 20. Freeman, M. 2006. Reconsidering the effects of monosodium glutamate: a literature review. J. Am. Acad. Nurse Prac. 18:482–486.

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Hirasa, K. and Takemasa, M. 1998. Spice qualities and specifications. In: Spice Science and Technology. Marcel Dekker, New York, NY, USA, pp. 29–52. L¨oliger, Jurg. 2000. The use and utility of glutamates as flavoring agents in foods. J. Nutr. 130:915S–920S. McGee, H. 1984. Legumes. In: On Food and Cooking, the Science and Lore of the Kitchen. Collier Books/Macmillan Publishing, New York, NY, USA, pp. 252–253. Morago, G. 2008. Food trends 2009: a simply happy new year. Houston Chronicle, December 18. Nawar, W. W. 1996. Lipids. In: O. R. Fennema (ed.), Food Chemistry, 3rd ed. Marcel Dekker, New York, NY, USA, pp. 225–320. Raghavan, S. 2007a. A to Z spices. In: Spices, Seasonings, and Flavorings. CRC Press, Boca Raton, FL, USA, pp. 63–185. Raghavan, S. 2007b. Commercial spice blend and seasoning formulations. In: Spices, Seasonings, and Flavorings. CRC Press, Boca Raton, FL, USA, pp. 295–303. Raghavan, S. 2007c. Spice labeling, standards, regulations, and quality specifications. In: Spices, Seasonings, and Flavorings. CRC Press, Boca Raton, FL, USA, pp. 55–61. Tainter, D. R. and Grenis, A. T. 1993a. Seasoning blend duplications and tricks of the trade. In: Y. H. Hui (ed.), Spices and Seasonings. John Wiley & Sons, Hoboken, NJ, USA, pp. 193–206. Tainter, D. R. and Grenis, A. T. 1993b. Snack seasonings. In: Y. H. Hui (ed.), Spices and Seasonings. John Wiley & Sons, Hoboken, NJ, USA, pp. 167–180. Urbain, W. M. 1986. Cereal grains, legumes, baked goods, and dry food substances. In: B. S. Schweigert (ed.), Food Irradiation. Academic Press, Orlando, FL, USA, pp. 217–236. Varriano-Martson, E. and Stoner, F. 1996. Pasta packaging. In: J. E. Kruger, R. B. Matsuo, and J. W. Dick (eds.), Pasta and Noodle Technology. American Association of Cereal Chemists, St. Paul, MN, USA, pp. 75–93. Vermeiren, L., Heirlingers, L., Devlieghere, F., and Debevere, J. 2003. Oxygen, ethylene and other scavengers. In: R. Ahvenainen (ed.), Novel Food Packaging Technologies. CRC Press, Boca Raton, FL, USA, pp. 20–49.

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CHAPTER 7

Packaging of Noodle Products QINGYUE LING

7.1. INTRODUCTION To ensure the quality of noodle products, it is essential to understand how they are manufactured effectively and efficiently, as described in the previous chapters of this book. This, however, only guarantees noodle quality at the manufacturing facility, not necessarily the quality when they are delivered into the hands of consumers or when they are consumed, because the manufactured noodles have to be transported from the manufacturing facility to grocery stores through different transportation means (trucks, airplanes, and ships) and various food distribution channels (wholesale, retail, and food services). Food distribution channels could be a very sophisticated distribution system, such as Wal-Mart, or a simple one such as a local farmers market. The former requires very tight control on its distribution and storage environment for temperature and humidity, while the latter requires very limited or no control on its distribution environment. The former often ships their food products over a long distance internationally, while the latter distributes their products over a short distance locally. The former requires welldesigned and tested packaging containers and the latter may require only minimum packaging. In those different distribution channels, the extreme temperature and humidity conditions could cause paramount physical, chemical, biological, and microbiological changes in the noodle products, and thus cause significant impact on the quality and shelf life of the noodle products. Furthermore, intensive vibration and shock in shipping and handling, contamination from dust and other materials, and physical damage by animals or insects can significantly damage the quality integrity of the noodle products. A proper packaging system provides not only the required physical protection that maintains the integrity of a food product but also the needed microenvironment that minimizes quality degradation. Asian Noodles: Science, Technology, and Processing, Edited by Gary G. Hou C 2010 John Wiley & Sons, Inc. Copyright


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This chapter provides a good understanding of the packaging of Asian noodles. First, the basic functions and components of noodle packaging and the key factors that affect noodle packaging are discussed. Next, the common packaging materials and containers used for Asian noodles are described, followed by the innovative packaging technologies.

7.2. FUNCTIONS OF NOODLE PACKAGING It is important to understand the functions of noodle packaging to effectively select, design, and utilize noodle packaging systems. The functions of noodle packaging can generally be described as (1) to provide containment, (2) to protect quality of noodles, (3) to provide convenience, (4) to enhance marketability, and (5) to provide traceability. 7.2.1. Containment Containment is the basic function of food packaging. Noodle products have to be contained in specific sized and shaped packaging containers for easy and efficient handling and service. For instance, fresh noodles have many thin strands and tend to stick together if handled by bare hands without packaged bags or containers. Instant noodles can be carried around easily if they are packaged in a plastic cup or bowl, without the risk of breaking into small pieces. The packaging container can also be used to heat and serve the instant noodles. The containment function of the instant noodles packaging cup or bowl also provides portion control for the right amount of noodles to be stored and served. Finally, the proper packaging container prevents food pollution of the environment from faulty packaging or underpackaging. 7.2.2. Protection

7.2.2.1. Physical Integrity A noodle product has to maintain its physical integrity during shipping and handling for its desired shape, size, and appearance because it directly affects the quality and marketing value of the product. For example, instant fried noodles are fried and dehydrated, and they are low in moisture content and crispy in texture. They are vulnerable to intensive vibration and shock and can be broken into smaller pieces during shipping. For fresh noodles, excessive weight or compression on the noodle packages could alter the shape and size of the noodles inside the packages and degrade the quality of the fresh noodles. Proper packaging design can reduce the impact of vibration and shock and protect the integrity of the noodles. Proper cushioning can be provided inside the noodle packaging bags by using gas flushing such as nitrogen or CO2 gas. It is also important to understand the effects of distribution environment on the physical strength of food packages, that is, the physical strength changes as environment conditions change. For example, much greater compression strength may be

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required for a paperboard container stored in a high-humidity condition because its compression strength decreases as humidity increases. Improper design or selection of the corrugated containers may lead to collapse of the container, thus resulting in damage of the noodle products inside. Other physical damage to noodle packages may include damage caused by insects and animals in long-term storage. Thicker plastic, metal, or glass containers may be required to avoid such kinds of package damage (Malin 1980).

7.2.2.2. Sensory Quality It is obvious that physical damage to noodle packages will likely lead to quality degradation of the noodle products. There are many cases, however, where the noodles inside a package go bad without obvious physical damage to the packages. Examples are spoiled fresh noodles with mold and a sour or rancid taste in instant fried noodles due to oxidation after long-term storage. Most of these quality deteriorations are caused by either an improper microenvironment inside the package and/or improper storage conditions. The former could be caused by poor barrier properties of the packaging containers. Water vapor and oxygen permeability of a packaging material are two of the most important barrier properties of a packaging material for noodle products. Excessive amounts of oxygen inside a package can cause oxidation of the noodle, producing off-flavor and bad aroma. Excessive moisture content inside the package can cause dried noodles to lose their crispness and produce mold. An inadequate odor barrier could lead to absorption of undesired odor into the package and alter the flavor of the dried noodles. The latter could involve extreme or large variations of storage temperature and humidity surrounding the noodle packages. This will have a profound impact on the microenvironment inside the packages and, consequently, result in quality degradation. In recent years, many packaging technologies have been developed to minimize quality deterioration of packaged foods. These include new packaging materials with high oxygen and water vapor barriers, oxygen scavengers, and odor and moisture absorber pads. Further discussion on different packaging technologies can be found in Section 7.6. 7.2.2.3. Food Safety Most noodle packages are sealed in airtight packaging containers that provide a controlled microenvironment for noodles. This type of packaging isolates the noodles from outside contamination and provides a safer environment. Improper design and selection of packaging materials and containers could produce favorable conditions for microorganisms, such as yeast and mold, to grow, especially for fresh noodles, which have a high moisture content and a high level of water activity. If properly designed, the microenvironment inside a noodle package can be created to slow down the growth of these microorganisms with extended shelf life. For example, vacuum packaging is used to remove oxygen from the packages of fresh noodles, boiled noodles, and steamed noodles; modified atmospheric packaging is used to replace

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oxygen in the headspace of the noodle package with inner gases such as nitrogen and carbon dioxide. 7.2.3. Convenience Tremendous changes have taken place in the lifestyles of our modern society, including a faster pace of living, more single-parent and working-parent families, and more outdoor activities and sport events. These, in turn, bring about changes in our eating behavior. More people demand convenience in serving their food. Ready-to-cook (RTC), ready-to-eat (RTE), and ready-to-go (RTG) food products have become more and more popular. Instant noodles are the best example of how packaging can bring convenience to consumers. This type of packaging not only makes the noodles easy to handle and to store but also easy to prepare, cook, and serve. Further discussion is given in Section 7.5. 7.2.4. Marketability Noodle package appearance, including shape, size, graphic design, and nutritional labeling, has a large impact on its marketability. A well-designed noodle package can attract consumer attention and set it off from competitors’ products through unique appearance and favored graphic design. Correct serving-size and accurate nutritional information could also help consumers quickly make the desired purchasing decision. 7.2.5. Traceability In a noodle production system, the noodle product information has to be tracked throughout its distribution system, from processing plant to wholesale and retail stores. In the processing plant, noodle product name, weight, production date, expiration date, and other production information have to be monitored and recorded for inventory and management purposes. They can either be printed on or stored in food packages in the data formats of bar codes, magnetic data strips, and radiofrequency identification (RFID). The data can then be scanned and read by various data readers in different stages of the distribution system for traceability. In addition to inventory, the product information can be used to trace the origin and the date of production as well as where the product has been distributed in the case of food contamination, poisoning, pathogen outbreaks, and other food security situations.

7.3. COMPONENTS OF NOODLE PACKAGING Like most food packages, noodle packaging is usually composed of three components: (1) primary package, (2) secondary package, and (3) tertiary package. Depending on the specific noodle product and the way it is served, there could be at least one or two or all three components used in a noodle packaging system.

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A primary package is defined as a package that is directly in contact with the noodle product. It is mainly used to form a sealed microenvironment to protect and isolate the noodle content from an unwanted environment (e.g., high humidity, oxygen, microbial) and other contamination from dust and undesired human contact. One example of this would be the inner pouch used to vacuum-pack raw or parboiled noodles. It is important to select the proper primary packaging material to make sure no foreign odors and flavors are being introduced from the primary packaging material into the noodles. A secondary package is the package that contains one or more primary packages. It is often used to provide physical and environmental protection to the primary packages. A secondary package can also be used to provide convenience in handling. Another function of the secondary package is to provide noodle product information such as lot number, production and expiration dates, and nutritional labels. It is also often used as a product display box. A tertiary package incorporates the secondary package in the final shipping and distribution. The purpose is to consolidate secondary packages and to assist in storage and handling and to provide an additional layer of protection for the packaged noodles against physical damage and weather conditions. Examples are corrugated boxes, pallets, and stretch plastic films.

7.4. KEY FACTORS IN NOODLE PACKAGING There are many factors that determine the quality of a noodle product, such as initial quality of the noodle, processing technology used, packaging system, distribution system, and storage conditions. In this section, only the key properties of noodles, packaging materials, and environmental conditions that affect packaging and storage will be discussed. 7.4.1. Properties of Noodles Water activity, pH, and fat content are three of the most important properties of noodles. They control rates of quality deterioration and growth of microorganisms (Troller and Christian 1978). According to Hocking and Christian (1995), water activity and pH, alone or in combination, often determine if a food product is subject to microorganism spoilage. Fat content in dried or fried noodles, on the other hand, directly affects the lipid oxidation process and development of rancidity with oxidized off-flavors. By properly controlling these three properties of the product along with the proper packaging system and environment, minimum quality deterioration and extended shelf life can be achieved.

7.4.1.1. Water Activity Water activity, aw , is defined as the ratio of vapor pressure in a medium to the water vapor pressure of pure water: aw = Pfood /Pwater

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TABLE 7.1 Range of aw 1.00–0.95

0.95–0.91

0.91–0.87 0.87–0.80

0.80–0.75 0.75–0.65

0.65–0.60

0.60–0.50 0.50–0.40 0.40–0.30 0.30–0.20

Water Activity and Growth of Microorganisms in Food Microorganisms Generally Inhibited by Lowest aw in This Range Pseudomonas, Escherichia, Proteus, Shigella, Klebsiella, Bacillus, Clostridium perfringens, some yeasts Salmonella, Vibrio parahaemolyticus, Clostridium botulinum, Serratia, Lactobacillus, Pediococcus, some molds, yeasts (Rhodotorula, Pichia) Many yeasts (Candida, Torulopsis, Hansenula), Micrococcus Most molds (mycotoxigenic penicillia), Staphylococcus aureus, most Saccharomyces (bailii) spp., Debaryomyces Most halophilic bacteria, mycotoxigenic aspergilli Xerophilic molds (Aspergillus chevalieri, A. candidus, Wallemia sebi), Saccharomyces bisporus Osmophilic yeasts (Saccharomyces rouxii), few molds (Aspergillus echinulatus, Monascus bisporus) No microbial proliferation No microbial proliferation No microbial proliferation No microbial proliferation

Foods Generally Within This Range Highly perishable (fresh) foods and canned fruits, vegetables, meat, fish, and milk, wet noodles Some cheeses (Cheddar, Swiss, Muenster, Provolone), cured meat (ham) Fermented sausage (salami), sponge cakes, dry cheeses, margarine Most fruit juice concentrates, sweetened condensed milk, syrups

Jam, marmalade, marzipan, glac´e fruits Jelly, molasses, raw cane sugar, some dried fruits, nuts Dried fruits containing 15–20% moisture, some toffees and caramels, honey Dry pasta/noodles, spices Whole egg powder Cookies, crackers, bread crusts Whole-milk powder, freeze-dried vegetables, cereals

Source: Adapted from Beuchat (1981).

Water activity is used to describe the availability of water to participate in physical, chemical, and biochemical reactions. The growth of various microorganisms stops at a given level of water activity. Table 7.1 lists the range of water activity aw at which various microorganisms are inhibited. Table 7.1 indicates that most pathogenic bacteria in food, including Clostridium perfringens, Bacillus cereus, and Clostridium botulinum, can be inhibited at a water activity level less than 0.95 to 0.91 with the exception of Staphylococcus (Chirife 1994). Most yeasts and molds can be stopped at a lower water activity range of 0.91 to 0.75. No microbial proliferation can happen when water activity is lower than 0.60. Average water activity levels for Asian noodles on the current U.S. market are listed in Table 7.2. The average water activity for the instant noodles is from 0.342 to 0.497, which is lower than the 0.575 water activity of the dried noodles. The water activity of the precooked noodles is close to 1.0.

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TABLE 7.2

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Water Activity of Some Retail Asian Noodlesa

Noodle Samples 1 2 3 4 Average

Dried Noodle Sticks

Preboiled Wet Noodles

Instant Noodles in Bags

Instant Noodles in Cups

0.568 0.550 0.573 0.614 0.575

0.999 0.998 0.999 0.997 0.998

0.168 0.437 0.626 0.140 0.342

0.500 0.504 0.504 0.481 0.497

a This

water activity has been measured directly from noodle samples purchased from an Asian grocery store and the values reflect actual variation of storage time on the store shelf.

Although water activity in dried and instant noodles is less than 0.60 and microbial spoilage is not likely to occur, chemical reactions and enzymatic changes including rancidity may occur at considerably lower water activity (Chirife and Buera 1996). Typical deteriorative changes of dried foods include enzyme-catalyzed changes, nonenzymatic browning, and oxidation (Eskin and Robinson 2000). Detailed analysis on the effects of those changes on food quality can be found in Taub and Singh (1998) and Linssen and Roozen (1994).

7.4.1.2. pH Values The pH of noodles varies according to type of noodle: white salted noodles and yellow alkaline noodles. The former has a pH range of 6.5–7.0 and the latter 9.0–11.0 (Miskelly and Gore 1991). Their level in alkaline noodles is directly related to the amount of alkali added as well as the type of alkali used. 7.4.1.3. Fat Content The fat content in Asian noodles depends on the type of wheat used, specific ingredients, and processing method. Table 7.3 lists average total fat content for several types of Asian noodles. Generally, instant cup noodles have the highest total fat content of 20–37%, while dried, uncooked noodles have the lowest total fat content of 0.4–2%. Bag-type TABLE 7.3

Fat Content (Total Fat) of Selected Asian Noodles

Noodle Samples

Dried Noodle Sticks

Preboiled Wet Noodles

Instant Noodles in Bags

Instant Noodles in Cups

1 2 3 4 Average

2% 0.4% 2% 1% 1.35%

5% 4% 5% 6% 5.0%

17% 15% 12% 14% 14.5%

37% 30% 28% 20% 28.8%

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instant noodles have a fat content range of 12–17%, while cooked and wet noodles vary around 5%. Noodles with high fat content are vulnerable to oxidation and development of rancidity. Better oxygen-barrier packaging material is a must for packaging them. For some products, removal of oxygen from the noodle packaging container may be necessary to achieve the extended shelf life. The most commonly used methods include nitrogen gas flushing, vacuum packaging, and oxygen scavengers. 7.4.2. Properties of Packaging Materials Proper packaging materials provide the needed protection for noodles from physical, biochemical, and environmental damage. The effectiveness of packaging materials largely depends on their properties under specific physical and environmental conditions. The main properties discussed here include the barrier properties for gases and water vapor as well as the mechanical properties.

7.4.2.1. Barrier Properties For dried noodles, the gain of moisture leads water activity to approach the region of either physical or biological defects. More harmful than water is oxygen inside the packaged noodles. It can cause lipid oxidation and produce rancidity, especially at favorable light and temperature conditions. Another problem related to packaging materials for noodles is off-flavor. The flavor change is generally caused by the interactions between packaging materials and the noodles. These include migration, permeation, and absorption (Jasse et al. 1994). The barrier properties of packaging materials are described by gas/water-vapor permeability, which is defined as the rate at which a gas or water vapor will pass through a membrane. It is usually presented as the gas/water vapor transmission rate (TR). For example, oxygen permeability of a packaging material is expressed as O2 TR and measured in volume per surface area per time unit [cm3 /(m2 · day)]; water-vapor permeability is expressed as WVTR and measured in mass per surface area per time unit [g/(m2 · day)]. Permeability of a packaging material is affected by the structure and properties of the material, which depend on their physical and chemical structure, method of preparation, and processing conditions. For polymers, these include free volume, crystallinity, tacticity, cross-linking and grafting, orientation, and polymer blends (Robertson 2006a). By carefully engineering those parameters, various polymers can be manufactured with a wide range of gas and vapor permeability to meet the requirements of various food products. In addition to the packaging material itself, temperature and humidity are the critical environmental factors that affect the permeability of a packaging material. More discussion is given in the Section 7.4.3. 7.4.2.2. Mechanical Properties Although barrier properties could provide noodles with the needed protection from chemical, biochemical, and microbiological damage, the mechanical properties of a

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packaging material and containers provide physical protection for the products during handling and distribution. Depending on the type of packaging materials, the important mechanical properties mainly include tensile strength, tear strength, burst strength, impact strength, compression strength, and elasticity. Tensile strength is usually used to describe the strength of rigid materials such as wood and metals. It is defined as the maximum tensile strength that a material can sustain under a tensile load. It equals the maximum load divided by the cross-sectional area of the test specimen of the material. Generally, the greater the tensile strength, the tougher the material is. Tear strength is used to describe the force required for a material to be torn apart. It is the measure of the energy absorbed by a testing material in propagating a tear that has been initiated by a small cut in the sample with a blade. Proper tear strength is required for almost all primary packaging materials. If it is too low, the package can be opened by accident or through mishandling. If it is too high, however, the package will be difficult to open and not user-friendly. Burst strength is used to describe the strength of paper, polymer, foil, corrugated board, and other fiber materials. It measures the material resistance to penetration, puncture, and shock or the capacity of a material to absorb energy. The greater the burst strength, the greater the resistance of the material to penetration or puncture by sharp or pointed objects. Instant noodles are crispy in texture and could contain tiny sharp corners when they break into smaller pieces inside the package due to improper shipping and handling. Those sharp corners could punch through the plastic packaging bags and destroy the barrier function of the packaging containers. Therefore, selection of plastic packaging bags with high burst strength is highly recommended for instant noodles. Impact strength is a measure of the material’s ability to withstand shock, and it is used to predict the resistance of a material to breakage from dropping or other quick shocks. It can be quantified on an impact tester, also known as the Izod test (ASTM D 3420). For packages that contain dried noodle products, impact strength is critical to maintain the integrity of the products. Compression strength is another important mechanical property for noodle packaging containers, especially for secondary and tertiary packages. It measures the capability of a packaging container to withhold vertical load or weight without failure. Many packaging material or container failures in shipping and handling are caused by lack of compression strength. Compression strength depends not only on the packaging material but also on the dimension and configuration of the packaging container as well as loading patterns on the pallet. Environmental factors such as temperature and humidity may have a profound impact on compression strength. 7.4.3. Environmental Factors In addition to the properties of foods and packaging materials, the environmental conditions under which a food package is distributed and stored have paramount impact on the quality and shelf life of the product. These important environmental factors include temperature, relative humidity, atmospheric pressure, light, and

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shipping or transport conditions such as shock and vibration. Proper control of these environmental factors will minimize quality deterioration and extend shelf life.

7.4.3.1. Temperature Ambient or storage temperature of a noodle package varies widely with climate and storage conditions. It is not uncommon for outdoor ambient temperature to drop to −40 ◦ C in the winter and rise to 40 ◦ C in the summer. Even the indoor temperature and/or storage temperature in many distribution centers, retail, and wholesale stores can vary significantly due to poor temperature control by inadequate management and equipment. The barrier properties of water vapor and gases (oxygen and carbon dioxide) through packaging materials vary as storage temperature changes. This change could significantly alter the actual barrier properties of the packaging bags and containers and, consequently, the quality of packaged noodle products. However, the barrier properties of the commonly used packaging materials and containers for noodles are mostly available at ambient temperatures. The barrier properties at different storage temperatures for a particular packaging material are not readily available. To obtain those barrier properties at a specific storage temperature, the packaging film or container samples have to be sent to a testing lab. 7.4.3.2. Relative Humidity For dried noodles, it is critical to keep the relative humidity level as low as possible to avoid moisture intake by the products. Moisture transfer into the dried noodles can result in a number of undesired changes, such as loss of crispness, microbial spoilage due to increased water activity, rancid taste, and other enzymatic changes. To eliminate or minimize the impact of high relative humidity, packaging materials, such as glass, ceramic, and metal, are the best choices. If plastic materials are used, high water-vapor-barrier polymers, such as polyvinylidene chloride (PVdC), high-density polyethylene (HDPE), and polypropylene (PP) are recommended. For paper-based corrugated secondary packaging containers, a paraffin wax coating and a plastic laminated layer can provide additional barrier properties. Relative humidity can also have a significant impact on the mechanical strength of a food package, especially on compression strength. Collapse of corrugated packaging containers under unit load in a warehouse environment could be caused by the reduced compression strength of the packaging containers exposed to a high level of relative humidity since the corrugated containers absorb water from the ambient air. Therefore, relative humidity in the distribution and storage environment has to be taken into consideration in packaging design for dried noodles. 7.4.3.3. Atmospheric Pressure Atmospheric pressure can vary significantly under different distribution and storage conditions. For example, food packages air-shipped through UPS and FedEx may experience altitudes as high as 19,000 ft. Those packages that are ground-shipped over mountain passes may experience altitudes as high as 12,000 ft. The Federal

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Aviation Administration (FAA) has observed an increase in the number of package failures of hazardous materials in commercial and cargo aircraft over the past three years (Singh and Burgess 2001). Singh et al. (2002) have found that approximately 50% of packages experienced leak failure during simulated low pressure of 17.57 in. Hg (pressure equivalent of 14,000 ft) and vibration tests.

7.4.3.4. Light Light has a significant impact on quality and shelf life of noodles during storage, transport, and sales display. Light could induce lipid oxidation, loss of vitamins, degradation of free amino acids, and formation of unpleasant volatile compounds as well as color changes (Bosset et al. 1994). The factors that influence these photodegradation changes include intrinsic and extrinsic factors. The former has been discussed briefly in the last section. The latter mainly includes spectrum and intensity of the light source and the conditions of light exposure. Sunlight is usually the light source when the product is stored or distributed outdoors. Fluorescent tubes are common light sources when stored indoors. The sunlight spectrum is broad, homogeneous, and rich in energy. Therefore, it is good practice to avoid exposing the packaged noodles directly to sunlight; if possible, no sunlight at all should be allowed. Fluorescent tubes can be categorized as “cold white” or “warm white” fluorescent tubes. The former are rich in all color components of visible light with high energy, and the latter are rich in yellow, orange, and red components and poor in violet, blue, and green components with low energy. Therefore, the “cold white” fluorescent tubes are inappropriate for illumination of store display cabinets and storage rooms. Metal is the best packaging material for complete blockage of sunlight. Darkcolored glass is also good. For papers, thick and dark-colored paperboard is relatively effective. For polymers, multilayers with aluminum foil and metallized coatings are often used to minimize light transmittance for instant noodle bags.

7.5. PACKAGING MATERIALS AND CONTAINERS FOR ASIAN NOODLES Asian noodles are one of the most consumed food items and usually are not high in price. They are usually packaged in cost-effective materials such as paper or/and plastic polymers. 7.5.1. Paper and Paperboard Papers for noodle packaging can generally be categorized into two groups: fine papers and coarse papers. The former are thinner, softer, and whiter in color than the latter. They are mainly used as primary packaging materials for wrapping of raw and fresh noodles. The coarser papers are used often for packaging dehydrated noodles because they are thicker, tougher, and darker in color.

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The main types of packaging papers include kraft papers, bleached papers, greaseproof papers, and waxed papers. Kraft papers are the most common packaging papers. They are heavy-duty coarse papers with a light brown color. They can be bleached or colored. Bleached papers are brighter in color and have excellent printability. Greaseproof papers are hydrated (heavily beaten) to have resistance to water and grease. They are often used for packaging wet noodles and fried noodles. Waxed papers are made out of a high-grade sulfite paper. The basic sheet is coated with paraffin wax. Depending on whether or not hot rolls are used, they can either be “dry-wax” papers with hot rolls or “wet-wax” papers without hot rolls. Wet-wax papers provide more protection from moisture than dry-wax papers. Waxed papers are good and cost-effective primary packaging materials for both wet and dried noodles. Although most of these papers can provide certain levels of water and gas barrier protection as well as the required strength of primary packages, they are not strong enough to provide the needed mechanical strength of secondary packages. Paperboards are usually much thicker or consist of multiple layers of different paper materials, providing much greater mechanical strength than coarse papers. The important types of paperboard are corrugated board and solid paperboard. They are often used for secondary packaging boxes. Corrugated board is constructed of two paper components: linerboard and corrugated medium. The linerboard is the outside planar sheet and it adheres to the flute tips. The medium is the fluted center portion of the board. Different combinations of liner and medium produce a range of different corrugated board with a wide range of compression strength and stiffness. Due to the unique construction of the corrugated board, it can produce the same level of mechanical strength as other paperboard with minimum weight. Solid paperboard is constructed of two to five bonded plies consisting of two outer liners and fillers. Its greater thickness provides much stronger strength and stiffness. For a given thickness, solid paperboard is heavier than corrugated board. It is usually two to three times the cost of corrugated board. However, due to its high durability, solid paperboard containers can be reused 10–15 times (Robertson 2006c).

7.5.2. Polymers Polymers or plastic packaging materials have increasingly replaced traditional materials, such as metal, glass, or paper, in many food packaging applications because of their light weight and superior functionality (Hanlon 1998b; Piringer and Brandsch 2000). The major advantages of polymers include flexibility of various packaging shapes and sizes compared to metal and glass, and the wide range of mechanical and barrier properties compared to paper and paperboard. More importantly, most polymers are low in cost compared to other packaging materials. Finally, polymers require less energy for manufacturing and transportation (Hanlon et al. 1998a). The most limiting factors for use of polymers as food packaging are their relatively poor barrier properties (permeability of water vapor, gases, and light) compared to metal and glass. However, those barrier properties have been greatly improved by

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167

Barrier Properties of the Major Polymers

Material Polyethylene LD HD Oriented polypropylene (OPP) Polyester (PET) Oriented polyester Oriented polystyrene (OPS) Polyvinyl chloride (PVC)

Water Vapor Transmission Rate [g/(m2 · day) at 38 ◦ C and 90% RH]

Gas Permeability [cm3 /(m2 · day) at 1 atm] for 25-µm Film at 25 ◦ C Oxygen

Carbon Dioxide

Nitrogen

18 7–10 6–7

7800 2600 2000

42,000 7600 8000

2800 650 400

400–600 25–30 100–125

800–1500 50–130 5000

7000–25,000 180–390 18,000

600–1200 15–18 800

15–40

500–30,000

1500–46,000

300–10,000

Source: Adapted from Table 4.1 of Parry (1993).

laminating polymers with aluminum foil and several different polymer films together, along with other processing technologies. There are five types of polymers frequently used in food packaging: polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), and polyethylene terephthalate (PET or polyester). High-density polyethylene is used in applications such as milk containers, and detergent bottles, bags, and industrial wrapping. Low-density polyethylene (LDPE) is used for film, bags, coatings, and containers. Polypropylene is employed in film, crates, and microwavable containers. Polystyrene finds use in jewel cases, trays, and foam insulation, while PET is used in bottles, film, and other food packaging applications. Table 7.4 gives the barrier properties against gas and water vapor for those common polymers. More detailed barrier properties and chemical compatibility of these major polymers can be found in Parry (1993). 7.5.3. Coated and Laminated Materials To meet the requirements of various food packaging applications, coating and lamination technologies have been developed rapidly over the last 40 years. Coating and laminating technologies can fully utilize the advantages of each packaging material, such as metal, paper, or polymers, and combine them together to create a packaging material with better barrier and mechanical properties. The most common and effective coating materials with high barriers to water vapor and oxygen are polyvinylidene chloride (PVdC) and ethylene alcohol (EVOH). They can be either single-side or double-side coated to substrate materials such as paper, nylon, PE, PVC,

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TABLE 7.5

Barrier Properties of Laminated Films and Copolymers

Material PVdC coated polyester PVdC–PVC copolymer EVOH PVdC coated oriented polypropylene

Water Vapor Transmission Rate [g/m2 · day) at 38 ◦ C and 90% RH]

Oxygen

Carbon Dioxide

Nitrogen

1–2 1.5–5.0 16–18 4–5

9–15 8–25 3–5 10–20

20–30 50–150 — 35–50

— 2–2.6 — 8–13

Gas Permeability [cm3 /(m2 · day) at 1 atm] for 25-µm Film at 25 ◦ C

Source: Adapted from Table 4.1 of Parry (1993).

and LLDPE (linear LDPE). Table 7.5 lists the barrier properties of those materials. In addition to polymer coatings, aluminum metallization is also an effective coating to provide high barrier properties to packaging materials, especially to provide high barrier properties against light. Laminated materials are made by bonding two or more layers of webs of different packaging materials together. The purpose is to create a new structure that contains the required barrier and mechanical properties. For example, aluminum foils can be laminated with papers or polymers to provide excellent barrier properties against light. Polyethylene can be laminated to provide excellent sealing capability. Paper can be laminated on the top of aluminum foil to provide excellent printability. 7.5.4. Packaging Containers for Asian Noodles The actual packaging materials and containers for Asian noodles vary with the types of noodles, method of serving, and storage conditions. They can generally be described in two categories: (1) wet noodles and (2) dried noodles.

7.5.4.1. Wet Noodles Wet noodles contain high moisture content. They are either fresh noodles stored under refrigeration or the shelf-stable wet noodles stored at 68–72 ◦ F room temperature or at frozen condition (0 ◦ F or below), depending on how they are processed and packaged. Fresh Noodles Fresh noodles refer to noodles that are raw or minimally cooked and are consumed immediately or within a few days. People enjoy fresh noodles because of their distinguished fresh texture and taste. However, raw noodles have a very short shelf life of a few days and could not stay fresh on the shelves of a retail grocery store. To extend the shelf life and maintain their freshness, raw noodles are minimally precooked and packaged in plastic film bags. They are usually found in the refrigeration section of a retail grocery store. Figure 7.1 shows fresh noodles that are vacuum-packaged and sealed with a polypropylene (PP) bag. The thickness of the bags ranges from 4 to 6 mil (1 mil = 0.001 inch) to provide good burst strength.

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FIGURE 7.1

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Packaged fresh noodles.

The amount of vacuum applied to the bag has to be controlled to the proper level to remove the oxygen inside the package but not damage the integrity of the noodles. Figure 7.2 shows a steamed noodle package with seasonings. It consists of two inner bags and one outer bag. One inner bag contains the wet noodles and the other contains seasonings for the noodles. The noodle bag is made of PP and serves as the primary packaging to contain the wet noodles. It is vacuum-sealed to eliminate

FIGURE 7.2

Steamed noodles with seasonings.

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FIGURE 7.3

Shelf-stable wet noodle package.

the oxygen inside the noodle bag for extended shelf life. The seasoning bag is made of multilayer polymer film coated with aluminum foil. The outer bag is made of multiple layers of polymers of PP and PE. While the core layer PP provides good barrier properties against oxygen and water vapor, the two surface layers of LDPE films provide good heat sealability and printability.

Shelf-Stable Wet Noodles Shelf-stable wet noodles are preboiled and steamed to eliminate all microbial organisms and enzymatic activities in the noodles and preservatives are usually added to achieve an extended shelf life of 6–12 months. Figure 7.3 shows an example of a shelf-stable wet noodle package. This package is stored under room temperature and no refrigeration is required. It consists of one outer bag and three inner bags for noodles, seasonings, and vegetables, respectively. The outer bag is a multilayer laminated bag made of PE, PP, and aluminum coating with very good oxygen and water barrier properties as well as light barrier properties. The three inner bags are usually hot-filled to eliminate possible microbial activity in the inner bags. They are made of PP film with a high melting temperature of 140 ◦ C (Parry 1993). This film also has a good water vapor barrier and fat resistance. Frozen Noodles Figures 7.4 and 7.5 show an example of packaged frozen noodles. The frozen noodles are stored and distributed at 0 ◦ F or below to achieve an extended shelf life of 9 months to 1 year. The low storage temperature significantly slows down enzymatic and microbial activities; thus, there is no need to add preservatives for extended shelf life. To minimize freezer burn or loss of moisture caused by temperature variation in the freezer, the noodles are often vacuum-packaged to remove the air and oxygen inside the noodle package.

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FIGURE 7.4

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The outer packaging bag.

The outer bag in Figure 7.4 is made of PP that not only provides strong physical protection to the noodles but also offers excellent printability for graphic display of noodle information. The inner bags in Figure 7.5 are also made of PP, which provides strong sealing integrity and is ideal for vacuum packaging. The double PP film bags significantly increase the barrier properties of the film bags against water vapor and oxygen and minimize moisture loss from the noodle and outside oxygen permeation into the bags.

FIGURE 7.5

The noodle and seasoning bags.

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7.5.4.2. Dried Noodles Dried noodles are noodles that have been dehydrated to a low moisture content of less than 12% to achieve extended shelf life. They are often packaged in watertight and airtight bags and containers. The shelf life of the dried noodles varies anywhere from several months to 2 years, depending on the ingredients used and how they are processed, packaged, and stored. They are categorized as dried noodle sticks and instant noodles. The former are mainly air-dried raw noodles while the latter are either deep-fried or air-dried steamed noodles. Dried Noodle Sticks Dried noodle sticks are packaged in various packaging materials and containers depending on the expected shelf life and the market in which they are sold. Dried noodle sticks are very tolerant of storage conditions due to their low water activity level with an average value of 0.575 (Table 7.2) and the very low average fat content of 1.35% (Table 7.3). Therefore, the main barrier property of the packaging material is WVTR (water vapor transmission rate) or water vapor permeability. Packaging materials for dried noodle sticks range from food wrapping paper, to cardboard, to plastic films. Figure 7.6 shows three types of Japanese dried noodle sticks. They are first packed in bundles for portion control and then packaged in PP plastic films with good WVTR and good heat sealability. Dried noodle sticks are raw and have to be cooked in boiling water for a significant amount of time to obtain the desirable moisture and soft texture. Instant Noodles Instant noodles, as their name indicates, are made for fast serving. They are often packaged in a heat-resistant and/or microwavable cup or bowl for quick heating and convenient serving. Figure 7.7 shows instant noodles packaged in a styrofoam cup and mixed with dried vegetables, spices, and flavor powder.

FIGURE 7.6

Packaged dried noodle sticks.

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FIGURE 7.7

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Instant cup noodles.

The cup is thermally sealed with a peelable plastic film cover. The whole cup is then wrapped and sealed with a thin polyethylene film to provide a water-resistant protection layer. A paperboard formed sleeve box is used to provide extra strength and protection to the wrapped and sealed cup. It also serves as a surface for printing nutritional and product information. Figure 7.8 presents a bowl packaging example for instant noodles. The bowl design makes it more serving friendly. The noodles are first wrapped and sealed in an LDPE

FIGURE 7.8

Instant bowl noodles.

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bag and the spices and flavors are packaged separately in an aluminum foil bag. They are then packaged inside the bowl and sealed with a lid. Both the bowl and the lid are made of polystyrene (PS). The whole bowl is finally airtight wrapped with a thin LDPE film. The noodles inside this bowl packaging are effectively protected by the two layers of LDPE film bags from water vapor and oxygen permeation. Although the packaging materials and containers described above are very important for Asian noodle packaging, the packaging technologies or the methods for packaging them into the containers are equally important. The following section will discuss several of the most common and effective packaging technologies that have been used or could be used for packaging Asian noodles for extended shelf life.

7.6. PACKAGING TECHNOLOGIES FOR ASIAN NOODLES Modified atmosphere packaging (MAP), active packaging, and intelligent packaging are three of the major packaging technologies that have been used in the food packaging industry to achieve extended shelf life for various food products. While MAP and active packaging have been commercially available in certain food categories for extended shelf life since the 1950s (King 1955; Day 2001; Han 2005a,b), the widespread industrial adoptions and applications of the two technologies occurred in the 1980s (Han 2005a) and 1990s (Han 2005b). Intelligent packaging is a relatively new technology and is still under research and development for various food applications. This section briefly describes those technologies and their applications for Asian noodles. More detailed information can be found in Han (2005a,b) and Farber and Dodds (1995).

7.6.1. Modified Atmosphere Packaging (MAP) “Modified atmosphere” refers to the addition or removal of gases and/or water vapor from a food package or container to change the levels of gases and/or water vapor and to obtain gas and water vapor compositions inside the package that are different from that of normal or ambient air (Floros 1990). The purpose of this alteration is to modify the microatmosphere inside the package and to minimize the quality deterioration in the products caused by chemical and enzymatic or microbiological reactions facilitated by gases and water vapor in the package (Han 2005e). A MAP system typically consists of three independent elements: (1) packaging machine (2) packaging material, which requires certain barrier properties for gases, and (3) a type of gas or gas mixture and its concentration. The atmosphere inside a noodle package can be modified passively and actively. In passive MAP, such modification is mainly realized through the permeation from the packaging materials and the container, that is, the permeability or barrier properties of the packaging container are the determining factors. For example, plastic bags with high water-vapor barrier are used to protect dried noodle sticks from absorption of moisture in high-humidity storage conditions.

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In active MAP, however, the atmosphere inside a package is altered actively by either removing both gases and water vapor from the inside headspace or adding them into the package. The former requires no equipment but proper temperature and humidity conditions, while the latter has to be implemented with additional MAP equipment. On the other hand, the active MAP can instantly change the atmosphere of the package to the desired level while the passive MAP may take several days to achieve the same atmosphere condition. Vacuum-packaged fresh noodles and nitrogen-flushing-packaged potato chips are good examples of active MAP.

7.6.1.1. Vacuum Packaging Vacuum packaging reduces the amount of air in a package and hermetically seals the package so that a near-perfect vacuum remains inside. A common variation of the process is vacuum skin packaging in which a highly flexible plastic barrier allows the package to mold itself to the contours of the food being packaged. By removing air from the packaging, oxygen concentration inside the package is significantly reduced to prevent the growth of microorganisms such as bacteria, mold, and yeast. For fresh raw and wet noodles, the moisture content or water activity level is very high and they are not thermally processed; the microorganisms can grow very fast at proper storage temperature if enough oxygen is present inside the package. Vacuuming eliminates most of the oxygen from the package and slows down the growth of microorganisms, thus extending the shelf life of the fresh noodles. For frozen noodles, vacuuming can remove air from the package and minimize surface frosting and freezer burn caused by variation of the storage temperature, resulting in extended shelf life. For dried noodles, especially instant noodles with high fat content, removing oxygen inside the package by vacuuming can reduce the amount of noodle rancidity caused by oxidation of the fat if good oxygen barrier packaging bags are used to prevent oxygen from outside entering into the package. 7.6.1.2. Gas-Flush Packaging Gas flushing is a process in which a continuous stream of a gas or a mixture of gases is injected into a package under a specific pressure to force out air inside the package before the package is sealed. The gases used for MAP usually are CO2 , N2 , and O2 . CO2 inhibits the growth of most bacteria and molds; N2 is used to exclude air and, in particular, oxygen and prevents the collapse of packs for high-moisture and fat-containing foods; and O2 helps to maintain fresh, natural color (e.g., in red meats) and respiration (in fruits and vegetables), and it also inhibits the growth of anaerobic organics (in some types of fish and in vegetables). The specific combination of these gases is determined by the type of product and packaging containers or bags. Depending on the amount of gas flushed into a package, nitrogen gas is good for both fresh and dried noodles, while carbon dioxide gas may be better for dried noodles since high moisture content in the wet noodles may react with carbon dioxide to form carbonic acid, which may cause undesired changes to the flavor of the fresh wet noodles. Gas flushing would also reduce the risk of caking of dried noodles by

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preventing the absorption of moisture from the air. For instant noodles that are high in fats and oils, gas flushing would significantly reduce rancidity. In a commercial production line, the gas-flushing process is incorporated into vertical or horizontal filling machines. Typically, residual oxygen levels in a gasflushed package are 2–5%, which may not be acceptable for packaging foods that are very oxygen sensitive. In this case, an oxygen scavenger may be used. It should be noted that a modified atmosphere slows down reactions that cause product deterioration but does not fully block them. Also, MAP is not a miracle technique. A product of poor quality at the outset will still be of poor quality, no matter which gas mixture is used. In addition, a modified atmosphere must always go along with strict adherence to the cooling chain for most of the products. More detailed information about the principles, practices, and applications can be found in Farber and Dodds (1995). 7.6.2. Active Packaging Active packaging is a packaging technology that incorporates certain additives into packaging films/materials or within packaging containers to modify the packaged microenvironment for the benefit of extending shelf life of the packaged food. The main difference between active packaging and MAP is that it performs certain desired functions other than merely providing a barrier to the external environment (Han 2005b). These special active functions include antimicrobial activity, oxygen scavenging/emitting ability, carbon dioxide absorption and emitting activity, ethylene scavenging/emitting activity, and moisture absorbing activity. The most active packaging research and development activities in recent years have been focused in three areas: (1) antimicrobial packaging, (2) antioxidative packaging, and (3) oxygen-scavenging packaging.

7.6.2.1. Antimicrobial Packaging Antimicrobial packaging is a packaging system that can inhabit the growth of microorganisms in the packaged food to extend its shelf life and to enhance its safety for human consumption. The antimicrobial function can be realized by three means: (1) coating or constructing antimicrobial agents into the packaging materials, (2) including antimicrobial agents inside the package space, and (3) adding antimicrobial agents into the formulation of the packaged food. There are basically three types of antimicrobial agents for antimicrobial packaging: (1) chemical antimicrobial agents, (2) natural antimicrobial agents, and (3) probiotics. The most chemical antimicrobial agents used are organic acids such as acetic acid, benzoic acid, citric acid, and sorbic acid. They can either be used alone or mixed together. Mixtures of those organic acids have a wider antimicrobial spectrum and stronger activity than a single acid (Han 2005b). Natural antimicrobial agents include herb extracts, spices, enzymes, and bacteriocins. The most widely studied natural antimicrobial agent is nisin because it is a hydrophobic protein produced by a safe food-grade bacteria, Lactococcus lactis. Apart from antimicrobial function, those natural agents also possess antioxidative

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activity. However, their concentration level has to be managed carefully when used as antimicrobial agents since they tend to have strong flavors. Currently, only several types of antimicrobial agents are used for noodles and pasta products: organic acids and their salts, ethanol, and volatile essential oils (Han 2005c).

7.6.2.2. Antioxidative Packaging Antioxidative packaging is a packaging system that has antioxidants incorporated into its packaging materials to control the oxidation of fatty components and pigments of the packaged food. Synthetic antioxidants used for antioxidative packaging include butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA). They have been shown to protect cereals from oxidation when incorporated into HDPE liners (Miltz et al. 1988). Recent research has been focused on using natural antioxidants such as α-tocopherol and ascorbic acid. The amount of oxidation was significantly lower for the oatmeal packaged using LDPE films with the antioxidant α-tocopherol level above 360 ppm (Summers 1992). This indicates the possible application of antioxidative packaging for instant noodles for extended shelf life. Minimally processed fresh noodles that are sensitive to both microbial spoilage and oxidative deterioration may be packaged in polymetric materials containing both antimicrobial and antioxidant additives. However, more research is required to find more cost-effective antimicrobial and antioxidative packaging technologies before they can be used for commercial-scale noodle production. 7.6.2.3. Oxygen-Scavenging Packaging Oxygen-scavenging packaging refers to the packaging system that eliminates oxygen inside a food package by oxygen-absorbing sachets and/or by packaging materials imbedded with oxygen scavengers. The removal of oxygen inside a food package slows down not only microbial activity but also oxidative reaction in food with high fat content. Although the MAP technology previously discussed can remove most oxygen from a food package, additional MAP equipment is required for such packaging operations. Also, most commercial packaging machines are not able to remove 100% of the oxygen and still leave 2–5% residual oxygen inside the package. For some oxygen-sensitive food, this may not be good enough. Moreover, the MAP technology can only remove oxygen from the package one time in production and it cannot remove the oxygen that permeates into the package during storage. Oxygen-scavenging packaging will overcome the above limitation of MAP. Oxygen scavengers used for food packaging can be categorized as (1) metal-based (iron, zinc, manganese), such as AgelessTM sachets, cards, labels, and closure liners by Mitsubishi Gas Chemical Company (Tokyo, Japan); and FreshMaxTM and FreshCardTM by Multisorb Technologies (New York, USA); (2) sulfur compound-based; and (3) oxidase enzyme-based, such as OxybanTM . Oxygen-scavenging sachets are good for solid or semisolid food packages but not for liquid foods such as beverages. As a result, oxygen-scavenger imbedded packaging materials were developed for various food products. Some examples are Oxyguard by Toyo Seikan (Tokyo, Japan); AmosorbTM 1000, 2000, and 3000 by

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Amoco Chemicals (Chicago, USA); and OxbarTM by Carnaud MetalBox Company (West Yorkshire, UK).

7.6.3. Intelligent Packaging Intelligent packaging refers to a package that can sense environmental changes and, in turn, inform the user of these changes (Han 2005d). A packaging system such as this is able to sense and provide information about the functions and properties of the packaged foods, and/or contains an external or internal indicator for the active product history and quality determination. Based on the above definition, intelligent packaging can be categorized into two groups by its sensing function: (1) quality indicators and (2) product information indicators. The quality indicators are used to sense quality changes of a food product during storage and transportation. The most commonly used quality indicators are freshness indicators and microbial indicators. The compounds detected include gas composition (CO2 , O2 , and ethylene), H2 S, volatile amine, microbial toxin, and pathogens. In addition, time and temperature histories are also used as indicators for quality changes. One example of the freshness indicator is FreshTag® (COX Technologies, Belmont, NC, USA) for seafood. FreshTags are color indicators that sense the production of gases known as “volatile amines.” These compounds produce the familiar “fishy odor” that is common to all seafood. Another example is the ripeSense® indicator (Ripesense Limited, New Zealand) currently being tested in New Zealand and the United States. It shows consumers whether a tray of pears is ready to eat or not based on a color change on the label, which is triggered by the aroma components excreted by the fruits (www.ripesense.com). Product information indicators are used to display or carry product information during storage and transportation throughout the food distribution system. Traditionally, bar code and printed product labels are two of the common indicators for product information. Recently, radio frequency identification (RFID) technology has been developed as a more effective product information indicator. RFID utilizes radiofrequency to transmit product information from product case or pallet to a computer information system. An electronic code that carries product information is stored in a microchip imbedded in the product or product label that is applied onto the product package. As the product moves through the supply chain, this electronic code can be automatically read at specific times and points or locations, enabling much greater visibility of the supply chain with minimum human intervention. Furthermore, RFID-enabled labels can interact with various sensors to obtain more dynamic or “real-time” product information such as time–temperature and quality changes as the product is being stored or distributed throughout the supply chain. It is predicated that RFID will revolutionize how food is being distributed through its supply chain in the coming years, and inevitably, the Asian noodle industry will also benefit by its application in noodle packaging.

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7.7. SUMMARY Packaging for Asian noodles is one of the essential steps to deliver high-quality noodle products into the hands of consumers. This chapter helps readers to understand the functions and basic components of noodle packaging; it also gives readers a basic understanding of the key factors in Asian noodle packaging and how they affect the quality of noodles, including properties of noodles, properties of packaging materials, and environmental factors such as temperature, humidity, light, and atmospheric pressure. Most commonly used packaging materials for Asian noodles are then discussed, including paper-based materials, plastic polymers, and laminated materials. In addition, different types of Asian noodle packaging containers are described for packaging wet noodles, dried noodles, and instant noodles. Finally, to extend shelf life of Asian noodles, three innovative packaging technologies for noodle products are introduced: (1) modified atmospheric packaging (MAP), (2) active packaging, and (3) intelligent packaging.

REFERENCES Beuchat, L. R. 1981. Microbial stability as affected by water activity. Cereal Food World 26:345. Bosset, J. O., Gallmann, P. U., and Sieber, R. 1994. Influence of light transmittance of packaging materials on the shelf life of milk and dairy. In: M. Mathlouthi (ed.), Packaging and Preservation. Blackie Academic & Professional, an imprint of Chapman & Hall, London, UK, Chap. 13. Chirife, J. 1994. Specific solute effects with special reference to Staphylococcus aureus. J. Food Eng. 22:409–416. Chirife, J. and Buera, M. P. 1996. Water activity, water glass dynamics, and the control of microbiological growth in foods. Crit. Rev. Food Sci. Nutr. l36:465–471. Day, B. P. F. 2001. Active packaging—a fresh approach. J. Brand Technol. 1(1):32–41. Eskin, N. A. and Robinson, D. S. 2000. Packaging considerations. In: Food Shelf Life Stability: Chemical, Biological, and Microbiological Changes. CRC Press LLC, Boca Raton, FL, USA, Chap. 9. Floros, J. D. 1990. Controlled and modified atmospheres in food packaging and storage. Chem. Eng. Prog. 86:25–32. Farber, J. M. and Dodds, K. L. 1995. Principles of Modified Atmosphere and Sous Vide Product Packaging. Technomic Publishing Co., Lancaster, PA, USA. Han, J. H. 2005a. Introduction to active food packaging technologies. In: Innovations in Food Packaging. Elsevier/Academic Press, San Diego, CA, USA, Chap. 5, pp. 63–79. Han, J. H. 2005b. Antimicrobial packaging. In: Innovations in Food Packaging. Elsevier/ Academic Press, San Diego, CA, USA, Chap. 6. Han, J. H. 2005c. Packaging containing natural antimicrobial or antioxidative agents. In: Innovations in Food Packaging. Elsevier/Academic Press, San Diego, CA, USA, Chap. 7.

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Han, J. H. 2005d. Intelligent packaging. In: Innovations in Food Packaging. Elsevier/Academic Press, San Diego, CA, USA, Chap. 9. Han, J. H. 2005e. Introduction to modified atmosphere packaging. In: Innovations in Food Packaging. Elsevier/Academic Press, San Diego, CA, USA, Chap. 10, pp. 159–172. Hanlon, J. F., Kelsey, R. J., and Forcinio, H. E. 1998a. Coatings and laminations of flexible materials. In: Handbook of Packaging Engineering, 3rd ed. Technomic Publishing Company, Lancaster, PA, USA, Chap. 4, pp. 105–128. Hanlon, J. F., Kelsey, R. J., and Forcinio, H. E. 1998b. Plastics. In: Handbook of Packaging Engineering, 3rd ed. Technomic Publishing Company, Lancaster, PA, USA, Chap. 8, pp. 207–298. Hocking, A. D. and Christian, J. H. B. 1995. Microbial ecology interactions in the processing of foods. In: G. V. Barbosa-Canovas and J. Welti-Chanes (eds.), Food Preservation by Moisture Control. Technomic, Lancaster, PA, USA, pp. 553–574. Hotchkiss, J. H. 1994. Prediction of the effects of modified atmosphere packaging on food safety. 27th Annual Convention, Australian Institute of Food Science and Technology, May 9–13, 1994, Canberra, Australia, Abstract No. 9. Jasse, B., Seuvre, A. M., and Mathlothi, M. 1994. Permeability and structure in polymeric packaging materials. In: M. Mathlouthi (ed.), Packaging and Preservation. Blackie Academic & Professional, an imprint of Chapman & Hall, London, UK, Chap. 1. King, J. 1955. Food Manuf. 30:441. Labuza, T. P. 1982. Dried foods. In: Shelf Life Dating of Foods. Food & Nutrition Press, Westport, CT, USA, Chap. 18, pp. 387–420. Linssen, J. P. H., and Roozen, J. P. 1994. Food flavor and packaging interactions. In: M. Mathlouthi (ed.), Packaging and Preservation. Blackie Academic & Professional, an imprint of Chapman & Hall, London, UK, Chap. 3. Malin, J. D. 1980. Metal containers and closures. In: S. J. Palling (ed.), Developments in Food Packaging 1. Applied Science Publishers Ltd., Essex, UK, Chap. 1. Mascia, L. 1982. In: Thermoplastics: Materials Engineering. Applied Science Publishers Ltd., Essex, UK, p. 193. Miltz, J., Hoojia, P., Han, J. K., Giacin, J. R., Harte, B. R., and Gary, I. J. 1988. Loss of antioxidants from high-density polyethylene: its effect on oatmeal cereal oxidation. In: Food and Packaging Interactions. American Chemistry Society, Washington DC, USA, pp. 83–93. Miskelly, D. M. and Gore, P. J. 1991. The importance of Asian noodles to the Australian wheat industry. In: C. Wrigley and D. Martin, (eds.), Proceeding of Cereals International 91. Royal Australian Chemical Institute, Melbourne, Australia, pp. 271–275. Parry, R. T. 1993. Films for MAP of foods. In: Principles and Applications of Modified Atmosphere Packaging of Food. Blackie Academic & Professional, London, UK, Chap. 4, pp. 63–100. Piringer, O. G. and Brandsch J. 2000. Characteristics of plastic materials. In: Plastic Packaging Material for Food. Wiley, Weinheim, Germany, Chap. 2, pp. 9–45. Robertson, G. L. 2006a. Optical and mechanical properties of thermoplastic polymers. In: Food Packaging: Principles and Practice. Marcel Dekker, New York, NY, USA, Chap. 3, pp. 43–54. Robertson, G. L. 2006b. Permeability of thermoplastic polymers. In: Food Packaging: Principles and Practice. Marcel Dekker, New York, NY, USA, Chap. 4, pp. 55–78.

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Robertson, G. L. 2006c. Paper and paper-based packaging materials. In: Food Packaging: Principles and Practice. Marcel Dekker, New York, NY, USA, Chap. 6, pp. 103–120. Singh, S. P. and Burgess, G. 2001. Effects of vibration, low pressure and temperature on packages. Annual Report, Consortium of Distribution Packaging Research, Michigan State University, East Lansing, MI, USA. Singh, S. P., Burgess, G. J., and Singh, J. 2002. Effects of high altitude on packaging integrity. In: Dimensions ’02. Conference Proceedings: The International Conference on Transport Packaging. Disneyland Resort, Anaheim, CA, USA. Summers, L. 1992. Intelligent Packaging. Center for Exploitation of Science and Technology, London, UK. Taub, I. A. and Singh, R. P. 1998. Food Storage Stability. CRC Press LLC, Boca Raton, FL, USA. Troller, J. A. and Christian, J. H. B. 1978. Water Activity and Food. Academic Press, New York, NY, USA.

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CHAPTER 8

Laboratory Pilot-Scale Asian Noodle Manufacturing and Evaluation Protocols GARY G. HOU

8.1. INTRODUCTION Asian noodles have been recognized as an important wheat product by a wide range of food professionals, including research scientists, breeders, ingredient suppliers, flour millers, and food manufacturers. Whether a study focuses on the varietal selection in breeding, components of raw materials, formulation, ingredient application, process control, new product development, or other research issues, each line of investigation normally requires valid, reliable, and small-scale laboratory testing methods (Ross and Hatcher 2005). The most important goal of any small-scale test is to achieve reproducible preparation and manufacture of the noodles themselves. Despite the many articles that have reported various small-scale testing and evaluation of noodles (Miskelly 1984; Anon. 1985; Miskelly and Moss 1985; Moss et al. 1987; Kruger et al. 1992; Shelke et al. 1990; Nagao 1996; Guan 1998; Kovacs et al. 2003; Hatcher and Preston 2004; Park and Baik 2004a,b; Zhao and Seib 2005), few have used pilot-scale noodle lines to prepare Asian noodles (Hou et al. 1997; Azuidin 1998; Guo et al. 2004; Hou 2007). Compared to the small-scale processing of noodles, which are often prepared by mixing noodle dough in a vertical Hobart-type mixer or pin mixer and forming a noodle sheet with one pair of sheeting rolls (such as the Ohtake noodle machine, Tokyo, Japan), the pilot-scale noodle processing method typically employs a horizontal mixer and a series of compounding and reduction rolls of different diameters. The pilot-scale noodle production process is similar to the commercial noodle line in many aspects and it uses as little as 500 g or as much as 4000 g of flour in a sample, so it is especially useful for a scaling-up experiment prior to commercial-scale testing or production.

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Although the small-scale noodle processing method often requires more water (3–5%) in noodle dough than the pilot-scale method for easy dough preparation and sheeting, the noodles prepared by the two methods appear to correlate well in the cooked noodle texture and had similar quality rankings (Guo et al. 2004). Due to the complexity of Asian noodles as a result of diverse varieties and equipment used in different regions, there has not been any approved international standard method developed yet for noodle processing and evaluation. This chapter provides pilot-scale production and evaluation protocols of eleven common noodle types, most of which were developed in the author’s lab in cooperation with research institutions, flour mills, and noodle processors in Asia. The protocols presented here could serve as a knowledge base for researchers and noodle manufacturers and allow for further discussion and standardization of laboratory-scale noodle testing methods. 8.2. GUIDELINES FOR THE LABORATORY MANUFACTURE OF ASIAN NOODLES Unlike many other standard tests or products, Asian noodles do not have international standard methods yet. In order to assist new and seasoned researchers in the Asian noodle field, Ross and Hatcher (2005) compiled a list of guidelines that could assist in the development of valid, laboratory-scale noodle processing protocols. Their guidelines are summarized as follows. 1. Noodle Dough Makeup (a) Flour moisture content The water addition in noodle formula is based on a flour moisture content of 14%. The amount of water added is adjusted for the actual flour moisture content, ensuring that the dough is made up on an equivalent dry solid basis. (b) Flour particle size and water absorption When comparing different flour samples, it is important to recognize that the flour’s millstream composition will influence the outcome of the noodle products. Every effort should be made to ensure that flour samples are from the same mill and are milled at a constant extraction yield. Variations in flour yield, particle size, and starch damage could lead to heterogeneous hydration of the noodle dough, and this is not desirable for making uniform noodle products for comparison. (c) Determination of optimum water addition for dough makeup Both subjective and instrumental methods could be used. Subjective methods are based on evaluation of the characteristics of the crumbly dough after a period of mixing. A basic guide for a well-mixed dough with optimum moisture is that the crumbly dough appears to be relatively homogeneously hydrated. It should be uniformly colored, with no obvious darker wet patches or lighter, drier regions, and should be moist to the touch. The dough crumble should be slightly cohesive when squeezed gently by hand but amenable to being subsequently recrumbled through the fingers, depending on the type of noodle being produced.

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There are two types of instrumental methods: sieving and recording dough mixer. The sieving protocol determines the percentage of the dough crumble that passes through a 3-mm sieve after being gently shaken for 3 minutes (Hatcher et al. 2002). A percentage value can be specified depending on the type of noodles produced and result desired. The second instrumental method is to use a mixograph. In a method described by Oh et al. (1986), water is added in a stepwise fashion to flour being mixed in a mixograph. The water addition corresponding to the first point at which the dough becomes cohesive is considered optimum and is indicated by the first large jump in both the mixograph trace height and bandwidth. The method was later validated by using a 10 gram pin mixer (Ross 2006). (d) Dissolving salts and other ingredients It is common to use predissolved salts and other ingredients, such as gums, because of the low moisture content of noodle dough. If these ingredients are not predissolved, it is very likely that they will not be fully solvated or hydrated in the dough. The lack of homogeneity across regions of dough can cause problems during processing and in the finished products. Caution is warranted when predissolving ingredients to ensure complete solvation, such as sodium carbonate, phosphate salts, and gums, because they tend to form lumps in water. If gums are prehydrated, they can be blended directly with flour for use. 2. Dough Mixing A variety of mixers, both vertical and horizontal, small (200–300 g) and large (500–3000 g), have been used in the laboratory-scale noodle process. Despite differences in mixing geometry, a number of mixing principles can be applied to all mixers. (a) Adding salt solution Do not add salt solution to the flour in a single dose, because the result is usually a dough with a very wet region and a region of largely unhydrated flour. This imbalance in the moisture distribution will not be fully corrected by continued mixing within the normal time frames needed for adequate laboratory throughput. A proper way is to add salt solution in a steady stream to the flour in the already operating mixer over a period of 30–60 seconds. This will assist in uniform water distribution in the dough. Additionally, stop the mixer after 1 minute of mixing to scrape down the blades, break up lumps of wet dough, and help redistribute the water evenly throughout the crumbly dough mass. (b) Mixing time In laboratory noodle manufacturing, a balance needs to be struck between optimum homogeneity of hydration, water loss through evaporation, and sample throughput. Many laboratory mixing protocols specify a mixing time of 2–10 minutes when conventional laboratory-scale vertical mixers are used. Shorter mixing times with adequate homogeneity of dough hydration are generally favored because of reduced moisture loss and increased sample throughput. After mixing, it is recommended to rest the dough crumble in a closed plastic bag for 15–30 minutes to allow more homogeneous hydration,

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promote gluten development, and improve starch gelatinization (Hatcher 2000; Hou 2001). 3. Dough Sheeting Sheeting is the process that includes dough sheet formation, thickness reduction, and slitting into noodle strands. In laboratory-scale noodle production, a variety of noodle sheeting equipment have been used, including table-top machines, free-standing motorized single-roll stands with adjustable roll gaps and integral slitters, and pilot-scale, multiple-roll stand machines. (a) Compound sheeting Compound sheeting takes the dough crumbs and makes them into a cohesive sheet. For laboratory-scale machines, dough crumbs falling through the roller gap can mean a substantial loss of dough in proportion to the original quantity. Proper ways need to be developed in each laboratory to minimize dough loss during operation, especially when one works with a small amount of flour sample. After the dough sheet is formed, it may be possible to reassess whether the water addition was correct. Dough sheets that are sticky and have long dark yellow-colored streaks indicate too much moisture. Those with long, pale, clearly dry streaks are likely too dry and may cause flaking during subsequent reduction sheeting. In the laboratory-scale sheeting process, the dough sheet is recommended to be folded in half and passed through the unchanging roll gap three or four times to form a uniform noodle sheet. A final compounding pass can be made without folding to improve surface characteristics. It is essential to maintain a consistent folding pattern because research has shown that by varying the folding pattern (i.e., 90◦ to the first fold) the gluten filament development is altered, resulting in differences in cooked noodle texture. Resting the compounded sheet is a common practice to relax the dough and improve its performance through subsequent reduction sheeting passes. Dough sheets are commonly stored in closed plastic bags to avoid dryness on the surface. (b) Reduction sheeting Reduction sheeting involves stepwise reduction of dough sheets until the dough reaches a specified final thickness. Noodle sheet thickness should not be reduced in steps greater than 15–30% during any roll pass to minimize potential damage to the gluten structure. To improve the consistency among operators making noodle sheets from the same sample series, it is important to standardize the amount of time (i.e., 45 seconds) between each noodle pass. This practice is reported to significantly reduce the coefficient of variation in subsequent texture analysis of the same sample prepared by different operators. Before being slit into noodle strands, the noodle sheet is calibrated to obtain a specified thickness by adjusting the final roll setting so the noodle thickness is consistent regardless of dough strength. This allows further assessments to be made without the confounding presence of

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variability in noodle thickness from sample to sample. Calibration of the final roll gap is achieved by taking a small piece of noodle sheet, sheeting it through the presumptive final gap, and measuring the thickness using a dial gauge. This process is repeated until the sheet is within the specifications (±0.03–0.05 mm). After this is done, the remainder of the noodle sheet is passed once through the calibrated roll gap and directly onto the slitter without further sheeting. (c) Slitting Slitters are chosen based on the desired noodle types (specified noodle width) and some practical considerations. If noodles are destined for mechanical texture testing, consider making the noodle cross section clearly rectangular. An obviously rectangular cross section makes it simpler to ensure that the noodles are always presented with the same orientation to the texture measuring instrument. Another factor to consider is whether to discard the outer few strands from near the edges of the slitter, because they may have a variable width if the dough sheet does not proceed in a precisely parallel fashion through the slitter. Unless they are further processed, fresh raw noodles are stored for up to 24 hours before final assessment of quality. Noodles must be stored at a known, controlled temperature because temperature affects rates of chemical changes such as discoloration and microbial spoilage. 4. Noodle Preservation Common methods to preserve noodles in laboratory settings are refrigeration, freezing, air-drying, parboiling, and steaming and frying (instant noodles). Air-drying typically involves a multistage process (Nagao 1996; Hou and Kruk 1998; Hatcher 2000; Hou 2001) to avoid noodle checking (cracking), splitting, and breaking. Any previously dried noodles should be allowed to equilibrate in the testing laboratory for at least 48 hours prior to testing to ensure reproducible results. Dried material stored in a freezer or cold room should be allowed to equilibrate for an additional 24 hours to optimize dried noodle moisture equilibration. Parboiling noodles is a very common practice in South Asia to manufacture hokkien-style wet noodles. Fresh raw noodles are cooked in boiling water for 45–60 seconds, rinsed in tap water, drained, and recorded for weight gain. Parboiled noodles are mixed with 2% vegetable oil to prevent them from sticking together and stored in a closed plastic bag for evaluation after 24 h and 48 h When the parboiled noodles are assessed, they are cooked again for 2 minutes. For manufacturing steamed and fried instant noodles in the laboratory, the noodle strands must be sufficiently and uniformly waved so the noodles can be steamed uniformly inside and outside of the noodle block. For best results, noodles should be steamed until they are fully gelatinized. Full gelatinization can simply be judged when the doughy core of the steamed noodles becomes clear by squeezing the noodles between two transparent glass or acrylic plates.

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Laboratory frying is generally conducted in batch fryers, rather than the continuous fryers used in commercial operations, at temperatures ranging from 130 to 160 ◦ C for 1–3 min. Proper frying time and temperature are necessary to achieve a desirable golden-brown color. Pail oil or palm olein is commonly used for frying instant noodles. Frequent oil changes to assure freshness is crucial for anyone investigating the effects of changes in raw materials, formulation, ingredient application, or process controls on oil uptake in instant noodles. The guidelines described above will help researchers avoid potential pitfalls and facilitate their progress toward meaningful results from experiments in Asian noodle products. To achieve consistent and repeatable results in the laboratory with specific types of noodles, one must pay attention to many variables encountered during the preparation and processing of the noodles, as well as their subsequent treatment, before they are assessed. Additional information on noodle processing and evaluation can be found in a recent review by Fu (2008) and in Chapters 5, 9, and 10 of this book.

8.3. PILOT-SCALE LABORATORY NOODLE TESTING EQUIPMENT 8.3.1. Mixer The mixer adopted for this test is a horizontal pin type (Model MT-1-3, Tokyo Menki Co., Tokyo, Japan), which revolves at variable speeds (Figures 8.1 and 8.2) and has 1000-g and 3000-g mixer drums. A minimum of 600 g of flour is required for the test.

FIGURE 8.1

Pilot-scale noodle dough mixer.

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FIGURE 8.2

189

Inside the mixing bowl.

8.3.2. Noodle-Making Machine The noodle-making machine (Model WR8-100, Tokyo Menki Co., Tokyo, Japan) is a pilot-scale noodle line (Figures 8.3 and 8.4) and includes two pairs of sheeting rolls (240-mm diameter), one pair of compounding rolls (300-mm diameter), and five pairs of reduction rolls (300-mm, 240-mm, 180-mm, 150-mm, and 120-mm diameters).

FIGURE 8.3

Pilot-scale noodle line from compounding rolls to reduction rolls.

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FIGURE 8.4

Noodle slitting machine.

The roller width is 100-mm. Slitters of various sizes are available (1.25–3.0-mm width) for different noodle types. 8.3.3. Tunnel Steamer The tunnel steamer has a space of 305 cm (L) × 38 cm (W) × 33 cm (H) and can operate at variable speeds to achieve the specified steaming time. Water is poured into the steamer to achieve about a 2-inch depth of water to maintain steam humidity. An electric steam generator (Model LB-20, The Electro-Steam Generator Corp., Alexandria, VA) is used to supply steam to the steamer. 8.3.4. Noodle Cooker The noodle cooker is a gas cooker (Model GCSC, Frymaster, Shreveport, LA) and has a capacity of 12.7 gallons (48.1 liters). Continuous tap water is supplied to the cooker to maintain gentle boiling and to keep boiling water clean. 8.3.5. Noodle Fryer The noodle fryer is a gas fryer (Model SG14, Pitco Frialator, Inc., Concord, NH) and has a shortening capacity of 4.8 gal (18.2 L). Fresh refined, bleached, and deodorized (RBD) palm oil is used for frying. If the fryer is turned on for a whole day, fresh oil is

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added in the morning and again in the afternoon; however, the used oil is completely replaced with fresh new oil when the fryer is used the next time. 8.3.6. Noodle Dryer The noodle dryer is a stainless steel cabinet with an inner capacity of 163 mm (height) × 109 cm (depth) × 99 cm (width). It has temperature and relative humidity control units and an adjustable fan. Fresh noodle sticks are hung on rods and placed inside the drying cabinet for drying. 8.3.7. Color Measurement Instrumental measurement of noodle color is fully reviewed in the Chapter 9 of this book. There is no international standard method available to perform noodle color measurement. In the author’s lab, the color measurement protocol is similar to that used in many other labs. Instrument: Chroma Meter CR-410 (Konica Minolta Sensing, Inc., Japan) equipped with a 50-mm diameter measuring head. Procedure: Stack three noodle sheets and take two readings on each side of two sheets (L*, a*, and b* values) at 0 h and 24 h. Take an average of eight readings. 8.3.8. Texture Measurement Instrumental measurement of Asian noodle texture has been a research subject in cereal chemistry and was well reviewed by Ross (2006). Additional updates can be found in Chapters 9 and 13 of this book. The textural measurement protocol presented in this chapter has been used in the author’s lab for many years. Instrument: TA.XTplus Texture Analyzer (Texture Technologies Corp., Scarsdale, NY) Texture Profile Analysis (TPA) Settings Pretest speed: 4.0 mm/s Test speed: 1.0 mm/s Post-test speed: 1.0 mm/s Target mode: Strain Strain: 70% Time: 1.0 second Trigger type: Auto (force) Trigger force: 10.0 gram Tare mode: Auto Advanced options: On

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Units Distance: millimeters (mm) Force: gram Time: seconds (s)

8.4. PILOT-SCALE LABORATORY NOODLE TESTING PROTOCOLS 8.4.1. Chinese Raw White Noodle (White Salted)

8.4.1.1. Formulation Flour (14% mb) Water (deionized or distilled)* Salt (NaCl)

100% 28% 1.2%

8.4.1.2. Procedure Preparation 1. Weigh and dissolve salt in distilled water. 2. Weigh flour and place in the mixing bowl. Dough Mixing 1. 2. 3. 4. 5. 6. 7.

Set the mixer speed to 90 rpm. Pour the salt solution slowly into the flour and mix for 2 min at 90 rpm. Stop to clean the beaters and inside walls of the mixer. Set the mixer speed to 120 rpm. Continue to mix at 120 rpm for 8 min. Stop to clean the beaters. Mix for another 2 min. Remove dough and place in a plastic bag.

First Dough Resting 1. Rest the dough for 30 min at room temperature. Compounding 1. Compress the dough between two pairs of rolls at 3-mm gap. 2. Combine the two dough sheets between a pair of rolls at 5-mm gap to form one dough sheet.

*More water may be needed for small mixers and dough rollers to meet the processing requirement.

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Second Dough Resting 1. Roll the dough sheet around a rolling pin and place in a plastic bag. 2. Rest the dough sheet for 30-min at room temperature. Dough Sheet Reduction and Color Measurement 1. Continue to pass the dough sheet through the sheeting rolls four (4) times with progressively reducing roll gaps of 4, 3, 2, and 1.5-mm. 2. Cut three (3) small pieces of dough sheet (8 cm × 8 cm) from the large dough sheet for color measurement at 0 h and 24 h. Thickness Calibration and Slitting 1. Cut a small piece of dough sheet (8-cm length) and pass it through the final calibration rolls. Measure the dough sheet thickness. 2. Adjust the roll gap so that the final sheeted dough thickness is 1.2 ± 0.03 mm. 3. Cut the remaining dough sheet into strips (L × W × T: 300 mm × 2.5 mm × 1.2 mm) with a #12 square type slitter. 4. Store the noodles in a plastic bag for 24 hours at room temperature. Texture Profile Analysis (TPA) of Cooked Noodle Texture 1. Boil 100 g of raw noodles for 5 min or until white core disappears. 2. Remove the cooked noodles and rinse them in 26–27 ◦ C tap water for 10 s with stirring. 3. Place the rinsed noodles in a strainer, drain excess water by tapping the strainer forcefully 10 times (∼10 s) on the edge of a sink, and place the noodles in a covered bowl. 4. Select three (3) sound and uniform noodle strands, cut into 6-cm long pieces, and place them on a plastic film. 5. Select five (5) 6-cm long noodle strands and place them side by side on the Lexan plate of the TA.XTplus Texture Analyzer. 6. Perform the TPA using a 5-mm flat Lexan pasta blade. 7. Record the values for hardness, springiness, cohesiveness, adhesiveness, chewiness, and resilience. 8. Repeat Steps 4 to 7 until the coefficient of variance (C.V., %) is less than 5% for the hardness value. Noodle Sensory Evaluation 1. Evaluate the raw noodle color at 2 h and 24 h after noodles are made in comparison to the noodles made from a control noodle flour. 2. At 24 h prepare four noodle samples (three test noodle samples and one control noodle sample), each time for sensory textural evaluation. Weigh and cook four

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TABLE 8.1

Chinese Raw Noodle Scoring Sheet

Date

Name

Sample Lab No.

Points

Quality Factor

Evaluation Item

20

Processing

Mixing (10) Sheeting (6) Slitting (4)

5

Dough sheet appearance

30

Raw noodle color (brightness and yellowness)

2 h (10) 24 h (20)

20

Texture after cooking for 5 min

Bite (10) Springiness (6) Mouthfeel (4)

25

Texture after cooking for 5 min and holding for 5 min in hot water

Bite (12) Springiness (5) Mouthfeel (3) Tolerance (5)

100

Total score

Score (1–10)a

Subscoreb

a On

a scale of 1–10; the control sample is scored 7 for each item. is the product of (score × maximum point)/10. Example: If a sample’s sheeting is scored 8 (scale: 1–10), and its maximum point is 6, the subscore is (8 × 6)/10 = 4.8. Source: Adopted from Hou (2001). b Subscore

noodle samples (100 g each) in boiling water simultaneously for 5-min or until optimally cooked. 3. Transfer the cooked noodles into four 1200-mL bowls and add 600 mL of boiling water. 4. Immediately perform the first textural evaluation as specified by the scoring sheet (see Table 8.1). 5. Keep the remaining noodles in hot water for another 5-min and perform the second textural evaluation as specified by the scoring sheet.

8.4.2. Japanese Udon Noodle (White Salted)

8.4.2.1. Formulation Flour (13.5% mb) Water (deionized or distilled)* Salt (NaCl)

100% 34% 2%

*More water may be needed for small mixers and dough rollers to meet the processing requirement.

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8.4.2.2. Procedure Preparation 1. Weigh and dissolve salt in distilled water. 2. Weigh flour and place in the mixing bowl. Mixing 1. 2. 3. 4. 5. 6.

Set the mixer speed to 120 rpm. Pour the solution slowly into the flour and mix for 2 min at 120 rpm. Stop to clean the beaters and inside walls of the mixer. Continue to mix at 120 rpm for 6 min. Stop to clean the beaters. Mix for another 2 min. Remove dough and transfer into the compounding rolls.

Compounding 1. Compress the dough between two pairs of rolls at 3-mm gap. 2. Combine the two dough sheets between a pair of rolls at 5-mm gap to form one dough sheet. Resting 1. Roll the dough sheet around a rolling pin and place in a plastic bag. 2. Rest the dough sheet for 30 min at room temperature. Dough Sheet Reduction and Color Measurement 1. Continue to pass the dough sheet through the rollers four times with progressively reducing roll gaps of 4, 3.5, 3, and 2.5 mm. 2. Cut three (3) small pieces of dough sheet (8 cm × 8 cm) from the large dough sheet for color measurement at 0 h and 24 h Thickness Calibration and Slitting 1. Cut a small piece of dough sheet (8-cm length) and pass it through the final calibration rolls. Measure the dough sheet thickness. 2. Adjust the roll gap so that the final sheeted dough thickness is 2.5 ± 0.03 mm. 3. Cut the remaining dough sheet into strips (L × W × T: 300 mm × 3.0 mm × 2.5 mm) with a #10 square type slitter. 4. Store the noodles in a plastic bag for 24 h at room temperature. Noodle Boiling 1. Boil 100 g of raw noodles for 13–14 min (60–70% of the determined full cooking time).

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2. Remove the cooked noodles and rinse them in tap water for 15 s with stirring. 3. Place the rinsed noodles in a strainer, drain excess water by tapping the strainer forcefully 10 times (∼10 s) on the edge of a sink, and place the noodles in a plastic bag. 4. Store the boiled noodles in a refrigerator for evaluation the next day. Texture Profile Analysis (TPA) of Cooked Noodle Texture 1. Boil 100 g of raw noodles for 20–24 min until white core disappears. 2. Remove the cooked noodles and rinse them in 26–27 ◦ C tap water for 15 s with stirring. 3. Place the rinsed noodles in a strainer, drain excess water by tapping the strainer forcefully 10 times (∼10 s) on the edge of a sink, and place the noodles in a covered bowl. 4. Select three (3) sound and uniform noodle strands, cut into 6-cm long pieces, and place on a plastic film. 5. Select five (5) 6-cm long noodle strands and place them side by side on the Lexan plate of the TA.XTplus Texture Analyzer. 6. Perform the TPA using a 5-mm flat Lexan pasta blade. 7. Record the values for hardness, springiness, cohesiveness, adhesiveness, chewiness, and resilience. 8. Repeat Steps 4 to 7 until the coefficient of variance (C.V., %) is less than 5% for the hardness value. Noodle Sensory Evaluation 1. Evaluate the raw noodle color 2 h and 24 h after noodles are made in comparison to the noodles made from a control noodle flour. 2. Evaluate the boiled noodle color 24 h after noodles are made in comparison to the noodles made from a control noodle flour. 3. On the same day of noodle production, prepare four raw noodle samples (three test noodle samples and one control noodle sample) each time for sensory textural evaluation. Weigh and cook four noodle samples (100 g each) in boiling water simultaneously for 20–24 min until the white noodle core disappears. 4. Place the rinsed noodles in a strainer, drain excess water by tapping the strainer forcefully 10 times (∼10 s) on the edge of a sink, place the noodles on a covered plate, and rest for 30 min. 5. Rinse the noodles in tap water and drain excess again. 6. Dip the noodles in room-temperature soy sauce soup in a separate container and evaluate for texture and taste according to the specified scoring sheet (Table 8.2). 7. Cook the refrigerated boiled noodles in boiling water for 2 min and then place into a bowl along with hot soup to evaluate for texture and taste.

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TABLE 8.2

Boiled Japanese Noodle Scoring Sheet

Date

Name

Points

Quality Factor

25

Color

20

Surface appearance

45

Texture

10

Taste

100

Total score

Sample Lab No. Evaluation Item

Score Range and Controla

Scoreb

10–25 (17.5) 8–20 (14) Softness/hardness (10) Elasticity (25) Smoothness (10)

4–10 (7) 10–25 (17.5) 4–10 (7) 4–10 (7) 40–100 (70)

a The

lowest possible score for each item assessed is 40% of the maximum score. Score for the control sample is shown in parentheses and is given 70% of the maximum score allocated to each evaluation item. b Scoring is done in increments of 10% of the maximum score. Source: Adapted from Nagao (1996, Table II, p. 190).

8.4.3. Chinese Wet Noodle (Parboiled Yellow Alkaline)

8.4.3.1. Formulation Flour (14% mb) Water (deionized or distilled)* Salt (NaCl) K2 CO3 Na2 CO3

100% 32% 2% 0.45% 0.45%

8.4.3.2. Procedure Preparation 1. Weigh and dissolve salt and alkali in distilled water. 2. Weigh flour and place in the mixing bowl. Dough Mixing 1. 2. 3. 4. 5. 6. 7.

Set the mixer speed to 90 rpm. Pour the salt solution slowly into the flour and mix for 2 min at 90 rpm. Stop to clean the beaters and inside walls of the mixer. Set the mixer speed to 120 rpm. Continue to mix at 120 rpm for 8 min. Stop to clean the beaters. Mix for another 2 min. Remove dough and place in a plastic bag.

*More water may be needed for small mixers and dough rollers to meet the processing requirement.

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First Resting 1. Rest the dough for 30 min at room temperature. Compounding 1. Compress the dough between two pairs of rolls at 3-mm gap. 2. Combine the two dough sheets between a pair of rolls at 5-mm gap to form one dough sheet. Second Dough Resting 1. Roll the dough sheet around a rolling pin and place in a plastic bag. 2. Rest the dough sheet for 30 min at room temperature. Dough Sheet Reduction and Color Measurement 1. Continue to pass the dough sheet through the rollers four times with progressively reducing roll gaps of 4, 3, 2, and 1.5 mm. 2. Cut six (6) small pieces of dough sheet (8 cm × 8 cm) from the large dough sheet for color measurement at 0 h and 24 h. 3. Boil three raw dough sheets in 1 L of boiling water for 1 min, rinse in tap water for 10 s with stirring, and then take out and dry the surfaces with a paper towel. 4. Measure the parboiled noodle sheet color. Thickness Calibration and Slitting 1. Cut a small piece of dough sheet (8-cm length) and pass it through the final calibration rolls. Measure the dough sheet thickness. 2. Adjust the roll gap so that the final sheeted dough thickness is 1.6 ± 0.03 mm. 3. Cut the remaining dough sheet into strips (L × W × T: 300 mm × 1.67 mm × 1.6 mm) with a #18 square type slitter. 4. Store the noodles in a plastic bag for 24 h at room temperature. Noodle Parboiling 1. Weigh and cook 100 g of raw noodles in boiling water for 1 min. 2. Remove the cooked noodles and rinse them in 26–27 ◦ C tap water for 10 s with stirring. 3. Place the rinsed noodles in a strainer, drain excess water by tapping the strainer forcefully 10 times (∼10 s) on the edge of a sink, and place the noodles in a bowl. 4. Record the weight gain of parboiled noodles. 5. Add 2% of vegetable oil based on the parboiled noodle weight and mix well. 6. Store the noodles in a plastic bag at room temperature.

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Texture Profile Analysis (TPA) of Cooked Noodle Texture 1. Boil 100 g of parboiled noodles in the pot to cook for 2 min or until white core disappears. 2. Remove the cooked noodles and rinse them in 26–27 ◦ C tap water for 10 s with stirring. 3. Place the rinsed noodles in a strainer, drain excess water by tapping the strainer forcefully 10 times (∼10 s) on the edge of a sink, and place the noodles in a covered bowl. 4. Select three (3) sound and uniform noodle strands, cut into 6-cm long pieces, and place on a plastic film. 5. Select five (5) 6-cm long noodle strands and place them side by side on the Lexan plate of the TA.XTplus Texture Analyzer. 6. Perform the TPA using a 5-mm flat Lexan pasta blade. 7. Record the values for hardness, springiness, cohesiveness, adhesiveness, chewiness, and resilience. 8. Repeat Steps 4 to 7 until the coefficient of variance (C.V., %) is less than 5% for the hardness value. Noodle Sensory Evaluation 1. Evaluate the raw noodle and parboiled noodle color at 2 h and 24 h after noodles are made in comparison to the noodles made from a control noodle flour. 2. At 24 h prepare four noodle samples (three test noodle samples and one control noodle sample) each time for sensory textural evaluation. Weigh and cook four parboiled noodle samples (100 g each) in boiling water simultaneously for 2 min or until optimally cooked. 3. Transfer the cooked noodles into four 1200-mL bowls and add 600 mL of boiling water. 4. Immediately perform the first textural evaluation as specified by the scoring sheet (Table 8.3). 5. Keep the remaining noodles in hot water for another 5 min and perform the second textural evaluation as specified by the scoring sheet. 8.4.4. Chuka-men Noodle (Raw Yellow Alkaline)

8.4.4.1. Formulation Flour (13.5% mb) Water (deionized or distilled)* Salt (NaCl) K2 CO3 Na2 CO3

100% 32% 1% 0.60% 0.40%

*More water may be needed for small mixers and dough rollers to meet the processing requirement.

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TABLE 8.3

Chinese Wet Noodle Scoring Sheet

Date

Name

Sample Lab No.

Points

Quality Factor

Evaluation Item

15

Processing

Mixing (7) Sheeting (6) Slitting (2)

20

Parboiled noodle color (brightness and yellowness)

2 h (10) 24 h (10)

15

Cooking yield (%) (1.5 min cooking)

20

Texture after cooking parboiled noodles for 2 min

Bite (10) Springiness (6) Mouthfeel (4)

30

Texture after cooking parboiled noodles for 2 min and holding for 5 min in hot water

Bite (15) Springiness (5) Mouthfeel (5) Tolerance (5)

100

Total score

Score (1–10)a

Subscoreb

a On

a scale of 1–10; the control sample is scored 7 for each item. is the product of (score × maximum point)/10. Example: If a sample’s sheeting is scored 8 (scale: 1–10), and its maximum point is 6, the subscore is (8 × 6)/10 = 4.8. b Subscore

Source: Adapted from Hou (2007).

8.4.4.2. Procedure Preparation 1. Weigh and dissolve salt and alkali in distilled water. 2. Weigh flour and place in the mixing bowl. Dough Mixing 1. Set the mixer speed to 120 rpm. 2. Pour the salt and alkaline solution slowly into the flour within 30 s and mix for a total of 2 min. 3. Stop to clean the beaters and inside walls of the mixer. 4. Continue to mix at 120 rpm for 6 min. Stop to clean the beaters. 5. Mix for another 2 min. 6. Remove dough and transfer into the compounding rolls. Compounding 1. Compress the dough between two pairs of rolls at 3-mm gap.

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2. Combine the two dough sheets between a pair of rolls at 5-mm gap to form one dough sheet. Resting 1. Roll the dough sheet around a rolling pin and place in a plastic bag. 2. Rest the dough sheet for 30 min at room temperature. Dough Sheet Reduction and Color Measurement 1. Continue to pass the dough sheet through the rollers four times with progressively reducing roll gaps of 4, 3, 2, and 1.5-mm. 2. Cut three (3) small pieces of dough sheet (8 cm × 8 cm) from the large dough sheet for color measurement at 0 h and 24 h. Thickness Calibration and Slitting 1. Cut a small piece of dough sheet (8-cm length) and pass it through the final calibration rolls. Measure the dough sheet thickness. 2. Adjust the roll gap so that the final sheeted dough thickness is 1.4 ± 0.03 mm. 3. Cut the remaining dough sheet into strips (L × W × T: 300 mm × 1.5 mm × 1.4 mm) with a #20 square type slitter. 4. Store the noodles in a plastic bag for 24 h at room temperature. Texture Profile Analysis (TPA) of Cooked Noodle Texture 1. Boil 100 g of raw noodles for 3 min or until white core disappears. 2. Remove the cooked noodles and rinse them in 26–27 ◦ C tap water for 10 s with stirring. 3. Place the rinsed noodles in a strainer, drain excess water by tapping the strainer forcefully 10 times (∼10 s) on the edge of a sink, and place the noodles in a covered bowl. 4. Select three (3) sound and uniform noodle strands, cut into 6-cm long pieces, and place on a plastic film. 5. Select five (5) 6-cm long noodle strands and place them side by side on the Lexan plate of the TA.XTplus Texture Analyzer. 6. Perform the TPA using a 5-mm flat Lexan pasta blade. 7. Record the values for hardness, springiness, cohesiveness, adhesiveness, chewiness, and resilience. 8. Repeat Steps 4 to 7 until the coefficient of variance (C.V., %) is less than 5% for the hardness value. Noodle Sensory Evaluation 1. Evaluate the raw noodle color at 2 h and 24 h after noodles are made in comparison to the noodles made from a control noodle flour.

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TABLE 8.4

Chuka-men Noodle Scoring Sheet

Date

Name

Sample Lab No. Evaluation Item

Score Range and Controla

Raw noodle color

0 h (10) 24 h (20)

4–10 (7) 8–20 (14)

20

Raw noodle specks

24 h (20)

8–20 (14)

40

Boiled noodle texture

0 h (20) 7 min (20)

8–20 (14) 8–20 (14)

10

Boiled noodle taste

0 h (10)

4–10 (7)

100

Total score

Points

Quality Factor

30

Subscoreb

40–100 (70)

a The

lowest possible score for each item assessed is 40% of the maximum score. Score for the control sample is shown in parentheses and is given 70% of the maximum score allocated to each evaluation item. b Scoring is done in increments of 10% of the maximum score. Source: Adapted from Nagao (1996, Table III, p. 193).

2. Evaluate the raw noodle speckiness (spotting) at 24 h after noodles are made in comparison to the noodles made from a control noodle flour. 3. At 24 h prepare four noodle samples (three test noodle samples and one control noodle sample) each time for sensory textural evaluation. Weigh and cook four noodle samples (100 g each) in boiling water simultaneously for 3 min 10 s (determined by the control flour noodle). 4. Drain noodles in a basket and gently tap the basket 2–3 times. 5. Transfer the cooked noodles into a bowl of hot Chinese soup (soy sauce may be used). 6. Immediately perform the first textural evaluation as specified by the scoring sheet (Table 8.4). 7. Keep the remaining noodles in hot soup for another 7 min and then perform the second textural evaluation as specified by the scoring sheet. 8.4.5. Hokkien Noodle (Parboiled Yellow Alkaline)

8.4.5.1. Formulation Flour (14% mb) Water (deionized or distilled)* Salt (NaCl) NaOH

100% 32% 1.5% 0.5%

*More water may be needed for small mixers and dough rollers to meet the processing requirement.

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8.4.5.2. Procedure Preparation 1. Weigh and dissolve salt and alkali in distilled water. 2. Weigh flour and place in the mixing bowl. Dough Mixing 1. 2. 3. 4. 5. 6. 7.

Set the mixer speed to 90 rpm. Pour the salt solution slowly into the flour and mix for 2 min at 90 rpm. Stop to clean the beaters and inside walls of the mixer. Set the mixer speed to 120 rpm. Continue to mix at 120 rpm for 8 min. Stop to clean the beaters. Mix for another 2 min. Remove dough and transfer into the compounding rolls.

Compounding 1. Compress the dough between two pairs of rolls at 3-mm gap. 2. Combine the two dough sheets between a pair of rolls at 5-mm gap to form one dough sheet. Resting 1. Roll the dough sheet around a rolling pin and place in a plastic bag. 2. Rest the dough sheet for 30 min at room temperature. Dough Sheet Reduction and Color Measurement 1. Continue to pass the dough sheet through the rollers four times with progressively reducing roll gaps of 4, 3, 2, and 1.5 mm. 2. Cut six (6) small pieces of dough sheet (8 cm × 8 cm) from the large dough sheet for color measurement at 0 h and 24 h 3. Boil another three raw dough sheets in 1 L of boiling water for 45 s, rinse in tap water for 10 s with stirring, and then take out and dry the surfaces with a paper towel. 4. Measure the color of parboiled noodle sheets. Thickness Calibration and Slitting 1. Cut a small piece of dough sheet (8-cm length) and pass it through the final calibration rolls. Measure the dough sheet thickness. 2. Adjust the roll gap so that the final sheeted dough thickness is 1.6 ± 0.03 mm.

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3. Cut the remaining dough sheet into strips (L × W × T: 300 mm × 1.67 mm × 1.6 mm) with a #18 square type slitter. 4. Store the noodles in a plastic bag for up to 48 h at room temperature. Noodle Parboiling 1. Weigh and cook 100 g of raw noodles in 1 L distilled boiling water for 45 s. 2. Remove the cooked noodles and rinse them in 26–27 ◦ C tap water for 10 s with stirring. 3. Place the rinsed noodles in a strainer, drain excess water by tapping the strainer forcefully 10 times (∼10 s) on the edge of a sink, and place the noodles in a bowl. 4. Record the weight gain of parboiled noodles. 5. Add 2% of vegetable oil based on the parboiled noodle weight and mix well. 6. Store the noodles in plastic bags at room temperature. Texture Profile Analysis (TPA) of Cooked Noodle Texture 1. Boil 100 g of 45-s parboiled noodles for 2 min or until white core disappears. 2. Remove the cooked noodles and rinse them in 26–27 ◦ C tap water for 10 s with stirring. 3. Place the rinsed noodles in a strainer, drain excess water by tapping the strainer forcefully 10 times (∼10 s) on the edge of a sink, and place the noodles in a covered bowl. 4. Select three (3) sound and uniform noodle strands, cut into 6-cm long pieces, and place on a plastic film. 5. Select five (5) 6-cm long noodle strands and place them side by side on the Lexan plate of the TA.XTplus Texture Analyzer. 6. Perform the TPA using a 5-mm flat Lexan pasta blade. 7. Record the values for hardness, springiness, cohesiveness, adhesiveness, chewiness, and resilience. 8. Repeat Steps 4 to 7 until the coefficient of variance (C.V., %) is less than 5% for the hardness value. Noodle Sensory Evaluation 1. Evaluate the raw noodle and parboiled noodle color at 2, 24, and 48 h after noodles are made in comparison to the noodles made from a control noodle flour. 2. At 24 h prepare four noodle samples (three test noodle samples and one control noodle sample) each time for sensory textural evaluation. Weigh and cook four parboiled noodle samples (100 g each) in boiling water simultaneously for 2 min or until optimally cooked.

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TABLE 8.5

205

Hokkien Noodle Scoring Sheet

Date

Name

Sample Lab No.

Points

Quality Factor

Evaluation Item

10

Processing

Mixing (2.5) Sheeting (5) Slitting (2.5)

10

Cooking yield (45 s boiling)

12

Parboiled noodle texture (45 s)

Hand feel (6) Stretching strength (6)

18

Fully cooked noodle texture (boil parboiled noodle for 90 s)

Bite (6) Springiness (6) Mouthfeel (6)

10

Raw noodle color

Brightness (5) 0 h (2.5) 24 h (1.25) 48 h (1.25) Yellowness (5) 0 h (2.5) 24 h (1.25) 48 h (1.25)

40

Parboiled noodle color

Brightness (20) 0 h (10) 24 h (5) 48 h (5) Yellowness (20) 0 h (10) 24 h (5) 48 h (5)

100

Total score

Score (1–10)a

Subscoreb

a On

a scale of 1–10; the control sample is scored 7 for each item. is the product of (score × maximum point)/10. Example: If a sample’s sheeting is scored 8 (scale: 1–10), and its maximum point is 10, the subscore is (8 × 10)/10 = 8.0. b Subscore

Source: Hou (2007).

3. Transfer the cooked noodles into four 1200-mL bowls and add 600 mL of boiling water. 4. Immediately perform the textural evaluation as specified by the scoring sheet (Table 8.5). 5. If desired, keep the remaining noodles in hot water for another 5 min and perform the second textural evaluation to check for texture stability in hot soup.

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8.4.6. Indonesia Yellow Alkaline Noodle

8.4.6.1. Formulation Flour (14% mb) Water (deionized)* Salt (NaCl) K2 CO3 Na2 CO3

100% 33% 1.0% 0.4% 0.6%

8.4.6.2. Procedure Preparation 1. Weigh and dissolve salt and alkaline salts in distilled water. 2. Weigh flour and place in the mixing bowl. Dough Mixing 1. 2. 3. 4. 5. 6. 7.

Set the mixer speed to 90 rpm. Pour the ingredient solution slowly into the flour and mix for 2 min at 90 rpm. Stop to clean the beaters and inside walls of the mixer. Set the mixer speed to 120 rpm. Continue to mix at 120 rpm for 8 min. Stop to clean the beaters. Mix for another 2 min. Take out the noodle dough and place in a plastic bag.

Resting 1. Rest the dough for 15 min at room temperature. Compounding 1. Compress the dough between two pairs of rolls at 4-mm gap. 2. Combine the two dough sheets between a pair of rolls at 5-mm gap to form one dough sheet. Dough Sheet Reduction and Color Measurement 1. Continue to pass the dough sheet through the rollers four times with progressively reducing roll gaps of 4, 3, 2, and 1.5 mm. 2. Cut three (3) small pieces of dough sheet (8 cm × 8 cm) from the large dough sheet for color measurement at 0 h and 24 h.

*More water may be needed for small mixers and dough rollers to meet the processing requirement.

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Thickness Calibration and Slitting 1. Cut a small piece of dough sheet (8-cm length) and pass it through the final calibration rolls. Measure the dough sheet thickness. 2. Adjust the roll gap so that the final sheeted dough thickness is 1.2 ± 0.03 mm. 3. Slit the remaining dough sheet into strips (L × W × T: 300 mm × 1.5 mm × 1.2 mm) with a #20 square type slitter. 4. Store the noodles in a plastic bag for up to 48 h at room temperature. Texture Profile Analysis (TPA) of Cooked Noodle Texture 1. Boil 100 g of raw noodles for 3 min. 2. Remove the cooked noodles and rinse them in 26–27 ◦ C tap water for 10 s with stirring. 3. Place the rinsed noodles in a strainer and drain excess water by tapping the strainer forcefully 10 times (∼10 s) on the edge of a sink and place them in a covered bowl. 4. Select three (3) sound and uniform noodle strands, cut into 6-cm long pieces, and place on a plastic film. 5. Select five (5) 6-cm long noodle strands and place them side by side on the Lexan plate of the TA.XTplus Texture Analyzer. 6. Perform the TPA using a 5-mm flat Lexan pasta blade. 7. Record the values for hardness, springiness, cohesiveness, adhesiveness, chewiness, and resilience. 8. Repeat Steps 4 to 7 until the coefficient of variance (C.V., %) is less than 5% for the hardness value. Noodle Sensory Evaluation 1. Evaluate the raw noodle color (brightness, yellowness, and speckiness) at 0, 24, and 48 h after noodles are made in comparison to the noodles made from a control noodle flour. 2. On the same day of noodle production, evaluate the raw noodles for hand-feel (dryness) and elasticity by stretching. 3. On the same day of noodle production, prepare four noodle samples (three test noodle samples and one control noodle sample) each time for sensory textural evaluation. Weigh and cook four raw noodle samples (100 g each) in boiling water simultaneously for 3 min or until optimally cooked. 4. Rinse and cool the cooked noodles in running tap water for 1 min. 5. Drain excess water in strainers for 1 min and place noodles in four bowls. 6. Perform color (brightness, yellowness, and speckiness) and textural evaluation as specified by the scoring sheet (Table 8.6). 7. On the next day, repeat Steps 2 to 4 and evaluate the boiled noodles for color (rightness, yellowness, and speckiness).

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TABLE 8.6

Indonesia Yellow Alkaline Noodle Scoring Sheet

Date

Name

Sample Lab No.

Points

Quality Factor

Evaluation Item

10

Processing

Mixing (2.5) Sheeting (5) Slitting (2.5)

10

Raw noodle texture

Hand-feel (5) Stretching strength (5)

30

Cooked noodle texture (3 min cooking on the same day of production)

Bite (7.5) Springiness (7.5) Chewiness (5) Elasticity (10)

30

Raw noodle color

Brightness (10) 0 h (5) 24 h (2.5) 48 h (2.5) Yellowness (10) 0 h (5) 24 h (2.5) 48 h (2.5) Specks (10) 0 h (5) 24 h (2.5) 48 h (2.5)

15

Cooked noodle color (boil at 0 h and 24 h)

Brightness (5) 0 h (2.5) 24 h (2.5) Yellowness (5) 0 h (2.5) 24 h (2.5) Specks (5) 0 h (2.5) 24 h (2.5)

5

Raw noodle appearance after 48 h

100

Total score

a On

Score (1–10)a

Subscoreb

a scale of 1–10; the control sample is scored 7 for each item. is the product of (score × maximum point)/10. Example: If a sample’s sheeting is scored 8 (scale: 1–10), and its maximum point is 10, the subscore is (8 × 10)/10 = 8.0. Source: Hou (2007). b Subscore

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8.4.7. Thailand Egg Noodle (Bamee)

8.4.7.1. Formulation Flour (14% mb) Water (deionized or distilled)* Fresh whole egg Na2 CO3 Salt (NaCl)

100% 28% 10% 2% 1%

8.4.7.2. Procedure Preparation 1. Weigh and dissolve salt and alkali in distilled water. 2. Weigh and hand-whip fresh eggs and mix with the salt/alkali salt solution. 3. Weigh flour and place in the mixing bowl. Dough Mixing 1. Set the mixer speed to 90 rpm. 2. Pour the egg/alkaline salt solution slowly into the flour within 30 s and mix for a total of 2 min at 90 rpm. 3. Stop to clean the beaters and inside walls of the mixer. 4. Set the mixer speed to 120 rpm. 5. Continue to mix at 120 rpm for 8 min. Stop to clean the beaters. 6. Mix for another 2 min. 7. Remove dough and transfer into the compounding rolls. Compounding 1. Compress the dough between two pairs of rolls at 3-mm gap. 2. Combine the two dough sheets between a pair of rolls at 5-mm gap to form one dough sheet. Resting 1. Roll the dough sheet around a rolling pin and place in a plastic bag. 2. Rest the dough sheet for 30 min at room temperature. Dough Sheet Reduction and Color Measurement 1. Continue to pass the dough sheet through the rollers four times with progressively reducing roll gaps of 4, 3, 2, and 1.5 mm. *More water may be needed for small mixers and dough rollers to meet the processing requirement.

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2. Cut six (6) small pieces of dough sheet (8 cm × 8 cm) from the large dough sheet for color measurement. 3. Keep the other three dough sheets in a plastic bag and store for 24 h for parboiling. 4. At 24 h boil the three raw dough sheets in 1 L of boiling water for 45 s, rinse in tap water for 10 s with stirring, and then take out and dry the surfaces with a paper towel. 5. Measure the color of parboiled noodle sheets. Thickness Calibration and Slitting 1. Cut a small piece of dough sheet (8-cm length) and pass it through the final calibration rolls. Measure the dough sheet thickness. 2. Adjust the roll gap so that the final sheeted dough thickness is 1.5 ± 0.03 mm. 3. Cut the remaining dough sheet into strips (L × W × T: 300 mm × 1.5 mm × 1.5 mm) with a #20 square type slitter. 4. Store the noodles in a plastic bag for 24 h at room temperature. Texture Profile Analysis (TPA) of Cooked Noodle Texture 1. Boil 100 g of raw noodles for 3 min (determined by the control noodles). 2. Remove the cooked noodles and rinse them in 26–27 ◦ C tap water for 10 s with stirring. 3. Place the rinsed noodles in a strainer, drain excess water by tapping the strainer forcefully 10 times (∼10 s) on the edge of a sink, and place the noodles in a covered bowl. 4. Select three (3) sound and uniform noodle strands, cut into 6-cm long pieces, and place on a plastic film. 5. Select five (5) 6-cm long noodle strands and place them side by side on the Lexan plate of the TA.XTplus Texture Analyzer. 6. Perform the TPA using a 5-mm flat Lexan pasta blade. 7. Record the values for hardness, springiness, cohesiveness, adhesiveness, chewiness, and resilience. 8. Repeat Steps 4 to 7 until the coefficient of variance (C.V., %) is less than 5% for the hardness value. Noodle Sensory Evaluation 1. Evaluate the raw noodle color at 2 h and 24 h after noodles are made in comparison to the noodles made from a control noodle flour. 2. At 24 h cook 100 g of raw noodles in 1 L of boiling water for 3 min and evaluate the cooked noodle color in comparison to the noodles made from a control flour.

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3. At 24 h prepare four noodle samples (three test noodle samples and one control noodle sample) each time for sensory textural evaluation. Weigh and cook four raw noodle samples (100 g each) in boiling water simultaneously for ∼3 min as determined by the control noodles. 4. Remove the cooked noodles and rinse them in 15–17 ◦ C tap water for 1 min with stirring. 5. Place the rinsed noodles in a strainer and drain excess water by tapping the strainer forcefully 10 times (∼10 s) on the edge of a sink and place them in a bowl. 6. Record the weight gain of parboiled noodles. 7. Add 2% of vegetable oil based on the parboiled noodle weight and mix well. 8. Evaluate for noodle cooking property and eating quality (Table 8.7).

TABLE 8.7

Thailand Egg Noodle (Bamee) Scoring Sheet

Date

Name

Sample Lab No.

Points

Quality Factor

Evaluation Item

10

Processing

Mixing (5) Sheeting and slitting (5)

21

Raw noodle color

Brightness 0 h (4) 24 h (8) Yellowness 0 h (3) 24 h (6)

9

Uncooked noodle dryness

7

Cooked noodle color (cooked at 24 h)

3

Cooked noodle surface appearance

10

Cooking property at 3 min

Degree of cooking

40

Eating quality

Bite (15) Springiness (20) Smoothness (5)

100

Total score

a On

Score (1–10)a

Subscoreb

0 h (3) 24 h (6) Brightness (4) Yellowness (3)

a scale of 1–10; the control sample is scored 7 for each item. is the product of (score × maximum point)/10. Example: If a sample’s sheeting is scored 8 (scale: 1–10), and its maximum point is 10, the subscore is (8 × 10)/10 = 8.0. Source: Adapted from Hou (2007). b Subscore

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8.4.8. Chinese Instant Fried Noodle

8.4.8.1. Formulation Flour (14% mb) Water (deionized or distilled)* Salt (NaCl) K2 CO3 Na2 CO3

100% 33% 1.5% 0.1% 0.1%

8.4.8.2. Procedure Preparation 1. Weigh and dissolve salt and alkali in distilled water. 2. Weigh flour and place in the mixing bowl. Dough Mixing 1. 2. 3. 4. 5. 6. 7.

Set the mixer speed to 90 rpm. Pour the salt solution slowly into the flour and mix for 2 min at 90 rpm. Stop to clean the beaters and inside walls of the mixer. Set the mixer speed to 120 rpm. Continue to mix at 120 rpm for 8 min. Stop to clean the beaters. Mix for another 2 min. Remove dough and place in a plastic bag.

Resting 1. Rest the dough for 5 min at room temperature. Compounding 1. Compress the dough between two pairs of rolls at 3-mm gap. 2. Combine the two dough sheets between a pair of rolls at 5-mm gap to form one dough sheet. Dough Sheet Reduction and Color Measurement 1. Continue to pass the dough sheet through the sheeting rolls four (4) times with progressively reducing roll gaps of 4, 3, 2, and 1.5 mm. 2. Cut three (3) small pieces of dough sheet (8 cm × 8 cm) from the large dough sheet for color measurement at 0 h and 24 h.

*More water may be needed for small mixers and dough rollers to meet the processing requirement.

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Thickness Calibration, Slitting, and Waving 1. Cut a small piece of dough sheet (8-cm length) and pass it through the final calibration rolls. Measure the dough sheet thickness. 2. Adjust the roll gap so that the final sheeted dough thickness is 1.2 ± 0.03 mm. 3. Cut the remaining dough sheet and form noodle waves (W × T: 1.4-mm × 1.2 mm) using a #22 square type cutter (1.4-mm width) and a waver attached to it. Steaming 1. Steam the waved noodles at 98–100 ◦ C for 4 min or until fully gelatinized (the white noodle core disappears when squeezed between two clear glasses). 2. Hand-cut steamed noodles and fold them in half to form a block shape of 125 g. Deep-frying 1. Weigh ∼125 g of noodle block and load into a frying basket (L × W × H: 12 cm × 12 cm × 3.5 cm). 2. Fry noodles at 150 ◦ C in palm oil for 75 s. 3. Drain oil for 10 s and take the noodle cake out of the basket. Cooling and Bagging 1. Cool the noodle cake for 20 min on a clean cloth or paper towel. 2. Record the noodle weight. 3. Store the noodle cake in a plastic bag. Texture Profile Analysis (TPA) of Cooked Noodle Texture 1. Boil one noodle cake for 4 min or until optimally cooked. 2. Remove the cooked noodles and rinse them in 26–27 ◦ C tap water for 10 s with stirring. 3. Place the rinsed noodles in a strainer, drain excess water by tapping the strainer forcefully 10 times (∼10 s) on the edge of a sink, and place the noodles in a covered bowl. 4. Select three (3) sound and uniform noodle strands, cut into 6-cm long pieces, and place on a plastic film. 5. Select five (5) 6-cm long noodle strands and place them side by side on the Lexan plate of the TA.XTplus Texture Analyzer. 6. Perform the TPA using a 5-mm flat Lexan pasta blade. 7. Record the values for hardness, springiness, cohesiveness, adhesiveness, chewiness, and resilience. 8. Repeat Steps 4 to 7 until the coefficient of variance (C.V., %) is less than 5% for the hardness value.

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TABLE 8.8

Chinese Instant Fried Noodle Scoring Sheet

Date

Name

Sample Lab No.

Points

Quality Factor

Evaluation Item

35

Processing

Mixing (10) Sheeting, slitting, and waving (10) Steaming (10) Frying (5)

10

Fried noodle color

Bright yellowness

25

Texture after cooking for 4 min

Bite (10) Springiness (10) Mouthfeel (5)

30

Texture after cooking for 4 min and holding for 6 min in hot water

Bite (15) Springiness (10) Mouthfeel (5)

100

Total score

Score (1–10)a

Subscoreb

a On

a scale of 1–10; the control sample is scored 7 for each item. is the product of (score × maximum point)/10. Example: If a sample’s mixing is scored 8 (scale: 1–10), and its maximum point is 10, the subscore is (8 × 10)/10 = 8. Source: Hou (2007). b Subscore

Noodle Sensory Evaluation 1. Evaluate the fried noodle cake color in comparison to the noodles made from a control noodle flour. 2. Cook four noodle cakes (including one control noodle sample) in boiling water simultaneously for 4 min or as determined by the control noodle. 3. Pour the cooked noodles into four 1200-mL bowls and add 600 mL of hot water. 4. Immediately perform the first textural evaluation as specified by the scoring sheet (Table 8.8). 5. Keep the remaining noodles in hot water for another 6 min and perform the second textural evaluation as specified by the scoring sheet. 8.4.9. Korean Instant Fried Noodle

8.4.9.1. Formulation Flour (14% mb) Water (deionized or distilled)* Modified potato starch Salt (NaCl) Alkaline salt (K2 CO3 : Na2 CO3 = 80:20)

100% 39% 13% 1.5% 0.11%

*More water may be needed for small mixers and dough rollers to meet the processing requirement.

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8.4.9.2. Procedure Preparation 1. Weigh and dissolve salt and alkali in distilled water. 2. Weigh flour and starch and blend them in a plastic bag by hand for 1 min. 3. Place the flour and starch blend in the mixing bowl. Dough Mixing 1. 2. 3. 4. 5. 6. 7.

Set the mixer speed to 110 rpm. Pour the salt/alkaline solution slowly into the flour and mix for 5 min at 110 rpm. Stop to clean the beaters and inside walls of the mixer. Set the mixer speed to 60 rpm. Continue to mix for 12 min. Stop to clean the beaters. Mix for another 2 min. Remove dough and place in a plastic bag.

Resting 1. Rest the dough for 5 min at room temperature. Compounding 1. Compress the dough between two pairs of rolls at 5-mm gap. 2. Combine the two dough sheets between a pair of rolls at 5.5-mm gap to form one dough sheet. Dough Sheet Reduction and Color Measurement 1. Continue to pass the dough sheet through the sheeting rolls four (4) times with progressively reducing roll gaps of 4, 3, 1.8, and 1.3-mm. 2. Cut three (3) small pieces of dough sheet (8 cm × 8 cm) from the large dough sheet for color measurement at 0 h and 24 h. Thickness Calibration, Slitting, and Waving 1. Cut a small piece of dough sheet (8-cm length) and pass it through the final calibration rolls. Measure the dough sheet thickness. 2. Adjust the roll gap so that the final sheeted dough thickness is 1.2 ± 0.03 mm. 3. Slit the remaining dough sheet into strands and form noodle waves (W × T: 1.7 mm × 1.2 mm) using a #18 square type cutter (1.7-mm width) and a waver attached to it.

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Steaming 1. Steam the waved noodles at 98–100 ◦ C for 5–6 min or until fully gelatinized (the white noodle core disappears when squeezed between two clear glasses). 2. Hand-cut steamed noodles and fold them in half to form a block shape of 125 g. Deep-frying 1. Weigh 125 g of noodle block and load into a frying basket (L × W × H: 12 cm × 12 cm × 3.5 cm). 2. Fry noodles at 140 ◦ C in palm oil for 60 s. 3. Drain oil for 10 s and take the noodle cake out of the basket. Cooling and Bagging 1. Cool the noodle cake for 20 min on a clean cloth or paper towel. 2. Record the noodle weight. 3. Store the noodle cake in a plastic bag. Texture Profile Analysis (TPA) of Cooked Noodle Texture 1. Boil one noodle cake for 4 min or until optimally cooked as determined by the control noodle. 2. Remove the cooked noodles and rinse them in 26–27 ◦ C tap water for 10 s with stirring. 3. Place the rinsed noodles in a strainer, drain excess water by tapping the strainer forcefully 10 times (∼10 s) on the edge of a sink, and place the noodles in a covered bowl. 4. Select three (3) sound and uniform noodle strands, cut into 6-cm long pieces, and place on a plastic film. 5. Select five (5) 6-cm long noodle strands and place them side by side on the Lexan plate of the TA.XTplus Texture Analyzer. 6. Perform the TPA using a 5-mm flat Lexan pasta blade. 7. Record the values for hardness, springiness, cohesiveness, adhesiveness, chewiness, and resilience. 8. Repeat Steps 4 to 7 until the coefficient of variance (C.V., %) is less than 5% for the hardness value. Noodle Sensory Evaluation 1. Evaluate the fried noodle cake color in comparison to the noodles made from a control noodle flour. 2. Cook four noodle cakes (including one control noodle sample) in boiling water simultaneously for 4 min or as determined by the control noodle.

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TABLE 8.9

217

Korean Instant Fried Noodle Scoring Sheet

Date

Name

Sample Lab No. Score (1–10)a

Points

Quality Factor

Evaluation Item

20

Processing

Mixing (5) Sheeting, slitting, and waving (5) Steaming (4) Frying (4) Cooking property (2)

80

Sensory evaluation of cooked noodles

Surface color and glossiness (8) Mouth feel (24) Bite texture (24) Texture stability (24) (Holding for 5 min after cooking)

100

Total score

Subscoreb

a On

a scale of 1–10; the control sample is scored 7 for each item. is the product of (score × maximum point)/10. Example: If a sample’s mixing is scored 8 (scale: 1–10), and its maximum point is 10, the subscore is (8 × 10)/10 = 8. Source: Adapted from Hou (2007). b Subscore

3. Pour the cooked noodles into four 1200-mL bowls and add 600 mL of hot water. 4. Immediately perform the first textural evaluation as specified by the scoring sheet (Table 8.9). 5. Keep the remaining noodles in hot water for another 5 min and perform the second textural evaluation as specified by the scoring sheet.

8.4.10. Thailand Instant Fried Noodle

8.4.10.1. Formulation Flour (14% mb) Water (deionized)* Salt (NaCl) K2 CO3 Na2 CO3 Carboxy methyl cellulose (CMC) Polyphosphates Sugar

100% 33% 1.0% 0.1% 0.4% 0.2% 0.2% 0.5%

*More water may be needed for small mixers and dough rollers to meet the processing requirement.

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8.4.10.2. Procedure Preparation 1. Weigh salt, alkaline salts, CMC, compound phosphates, and sugar and dry blend them in a plastic bag. 2. Dissolve the dry ingredients in deionized water by agitating. 3. Weigh flour and place in the mixing bowl. Dough Mixing 1. 2. 3. 4. 5. 6.

Set the mixer speed to 120 rpm. Pour the ingredient solution slowly into the flour and mix for 3 min at 120 rpm. Stop to clean the beaters and inside walls of the mixer. Continue to mix for 7 min. Stop to clean the beaters. Mix for another 5 min. Remove dough and place in a plastic bag.

Resting 1. Rest the dough for 5 min at room temperature. Compounding 1. Compress the dough between two pairs of rolls at 3-mm gap. 2. Combine the two dough sheets between a pair of rolls at 4-mm gap to form one dough sheet. Dough Sheet Reduction and Color Measurement 1. Continue to pass the dough sheet through the sheeting rolls four (4) times with progressively reducing roll gaps of 3, 2, 1.5, and 1.0 mm. 2. Cut three (3) small pieces of dough sheet (8 cm × 8 cm) from the large dough sheet for color measurement at 0 h and 24 h. Thickness Calibration, Slitting, and Waving 1. Cut a small piece of dough sheet (8-cm length) and pass it through the final calibration rolls. Measure the dough sheet thickness. 2. Adjust the roll gap so that the final sheeted dough thickness is 0.87 ± 0.03 mm. 3. Cut the remaining dough sheet and form noodle waves (W × T: 1.4 mm × 0.87 mm) using a #22 square type cutter (1.4-mm width) and a waver attached to it.

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Steaming 1. Steam the waved noodles at 98–100 ◦ C for 4 min or until fully gelatinized (the white noodle core disappears when squeezed between two clear glasses). 2. Hand-cut steamed noodles and fold them in half to form a block shape of 125 g. Deep-frying 1. Weigh 125 g of noodle block and load into a frying basket (L × W × H: 12 cm × 12 cm × 3.5 cm). 2. Fry noodles at 155 ◦ C in palm oil for 110 s. 3. Drain oil for 10 s and take the noodle cake out of the basket. Making Snack Noodles 1. Prepare soy sauce soup (water 87%, salt 10%, sugar 5%, and soy sauce 2%). 2. Weigh 125 g of noodle cake. 3. Dip both sides of the noodle block in 12 mL of soy sauce soup and load into a frying basket. 4. Fry the noodle at 155 ◦ C in palm oil for 110 s. 5. Drain oil for 10 s and take the noodle cake out of the basket. Cooling and Bagging 1. Cool the noodle cake for 20 min on a clean cloth or paper towel. 2. Record the noodle weight. 3. Store the noodle cake in a plastic bag. Texture Profile Analysis (TPA) of Cooked Noodle Texture 1. Boil one noodle cake for 3 min or until optimally cooked as determined by the control noodle. 2. Remove the cooked noodles and rinse them in 26–27 ◦ C tap water for 10 s with stirring. 3. Place the rinsed noodles in a strainer, drain excess water by tapping the strainer forcefully 10 times (∼10 s) on the edge of a sink, and place the noodles in a covered bowl. 4. Select three (3) sound and uniform noodle strands, cut into 6-cm long pieces, and place on a plastic film. 5. Select five (5) 6-cm long noodle strands and place them side by side on the Lexan plate of the TA.XTplus Texture Analyzer. 6. Perform the TPA using a 5-mm flat Lexan pasta blade. 7. Record the values for hardness, springiness, cohesiveness, adhesiveness, chewiness, and resilience. 8. Repeat Steps 4 to 7 until the coefficient of variance (C.V., %) is less than 5% for the hardness value.

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TABLE 8.10

Thailand Instant Fried Noodle Scoring Sheet

Date

Name

Sample Lab No.

Points

Quality Factor

Evaluation Item

10

Dough property

Mixing (5) (small sandy dough particles) Sheeting, slitting, and waving (5) (smooth and nonsticky; extensible; uniform noodle waves)

30

Steaming and frying property

Steaming (10) (no white core; glossy, nonsticky) Frying (20) (uniform golden-brown color; not oily)

5

Cooked noodle color

Light yellow

5

Cooked noodle odor

No foreign odor/rancidity

25

Texture (soaking for 5 min)

Mouthfeel (10) (no starchy or floury taste) Bite and springiness (15)

15

Texture (soaking for 8 min)

Bite and springiness

10

Swelling (soaking for 10 min) Total score

Less swelling

100

Score (1–10)a

Subscoreb

a On

a scale of 1–10; the control sample is scored 7 for each item. is the product of (score × maximum point)/10. Example: If a sample’s mixing is scored 8 (scale: 1–10), and its maximum point is 10, the subscore is (8 × 10)/10 = 8. Source: Adapted from Hou (2007). b Subscore

Noodle Sensory Evaluation 1. Evaluate the fried noodle cake color in comparison to the noodles made from a control noodle flour. 2. Place four noodle cakes (including one control noodle sample) in four sets of containers and add 500 mL of boiling water. Cover and soak noodles for 5 min. 3. Immediately perform the first textural evaluation as specified by the scoring sheet (Table 8.10). 4. Keep the remaining noodles in the containers with hot water for another 8 min and perform the second textural evaluation as specified by the scoring sheet. 5. Observe the swelling properties after soaking 10 min in hot water.

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8.4.11. Korean Dried Noodle

8.4.11.1. Formulation Flour (14% mb) Water (deionized)* Salt (NaCl)

100% 35% 3%

8.4.11.2. Procedure Preparation 1. Weigh and dissolve salt in deionized water. 2. Weigh flour and place in the mixing bowl. Dough Mixing 1. 2. 3. 4. 5. 6.

Set the mixer speed to 90 rpm. Pour the salt solution slowly into the flour and mix for 5 min at 90 rpm. Stop to clean the beaters and inside walls of the mixer. Continue to mix for 8 min. Stop to clean the beaters. Mix for another 2 min. Remove dough and place in a plastic bag.

Resting 1. Rest the dough for 5 min at room temperature. Compounding 1. Compress the dough between two pairs of rolls at 5-mm gap. 2. Combine the two dough sheets between a pair of rolls at 5.5-mm gap to form one dough sheet. Dough Sheet Reduction and Color Measurement 1. Continue to pass the dough sheet through the sheeting rolls four (4) times with progressively reducing roll gaps of 4, 3.5, 2.5, and 1.7-mm. 2. Cut three (3) small pieces of dough sheet (8 cm × 8 cm) from the large dough sheet for color measurement at 0 h and 24 h. Thickness Calibration and Slitting 1. Cut a small piece of dough sheet (8-cm length) and pass it through the final calibration rolls. Measure the dough sheet thickness. *More water may be needed for small mixers and dough rollers to meet the processing requirement.

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2. Adjust the roll gap so that the final sheeted dough thickness is 1.1 ± 0.03 mm. 3. Cut the remaining dough sheet into round strands (1.1-mm diameter) using a #27 round type slitter. Cutting into Long Strips 1. Hand-cut noodle strands into 2-m long strips. 2. Hang noodle strands on stainless steel rods from the middle point of strands (1 m long on each side). Drying 1. Set the dryer cabinet to 35 ◦ C and 60% relative humidity with proper air circulation. 2. Move the noodles hung on the rods to inside the dryer and dry for 7 h or until the noodle moisture is less than 12%. 3. Turn off the dryer and cool the noodles for 30 min. Cutting into Short Sticks 1. Carefully cut dried noodles into 22-cm long sticks with a knife. 2. Weigh out 200 g dried noodles and place in a plastic bag for storage. Texture Profile Analysis (TPA) of Cooked Noodle Texture 1. Boil 50 g of dried noodles for 4 min 20 s or until noodle white core disappears. 2. Remove the cooked noodles and rinse them in 26–27 ◦ C tap water for 10 s with stirring. 3. Place the rinsed noodles in a strainer, drain excess water by tapping the strainer forcefully 10 times (∼10 s) on the edge of a sink, and place the noodles in a covered bowl. 4. Select three (3) sound and uniform noodle strands, cut into 6-cm long pieces, and place on a plastic film. 5. Select five (5) 6-cm long noodle strands and place them side by side on the Lexan plate of the TA.XTplus Texture Analyzer. 6. Perform the TPA using a 5-mm flat Lexan pasta blade. 7. Record the values for hardness, springiness, cohesiveness, adhesiveness, chewiness, and resilience. 8. Repeat Steps 4 to 7 until the coefficient of variance (C.V., %) is less than 5% for the hardness value. Noodle Sensory Evaluation 1. Evaluate the dried noodle color in comparison to the noodles made from a control noodle flour.

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SUMMARY

TABLE 8.11

223

Korean Dried Noodle Scoring Sheet

Date

Name

Sample Lab No.

Points

Quality Factor

Evaluation Item

20

Processing

Mixing (5) Sheeting, slitting, and waving (5) Drying property (7) Cooking property (3)

80

Sensory evaluation of cooked noodles

Surface color and glossiness (8) Mouth feel (24) Bite texture (24) Texture stability (24) (holding for 6 min after cooking)

100

Total score

Score (1–10)a

Subscoreb

a On

a scale of 1–10; the control sample is scored 7 for each item. is the product of (score × maximum point)/10. Example: If a sample’s mixing is scored 8 (scale: 1–10), and its maximum point is 10, the subscore is (8 × 10)/10 = 8. Source: Adapted from Hou (2007). b Subscore

2. Prepare four noodle samples (three test noodle samples and one control noodle sample) each time for sensory textural evaluation. Weigh and cook four noodle samples (100 g each) in boiling water simultaneously for 4 min 20 s or until optimally cooked as determined by the control noodles. 3. Cool the boiled noodles in 13 ◦ C water bath for 3 min. 4. Rinse the cooled noodles in running tap water for 20 s. 5. Drain excess water by tapping the strainer forcefully 10 times. 6. Immediately perform the first textural evaluation as specified by the scoring sheet (Table 8.11). 7. Perform the second textural evaluation after holding noodles for 6 min.

8.5. SUMMARY This chapter reviews the guidelines for the laboratory production of Asian noodles and presents the pilot-scale processing and evaluation protocols of eleven major noodle types consumed around the world. These protocols were developed through collaborative efforts with the noodle industry in Asia and should be relevant to commercial production. The formulation, processing procedures, and evaluation methods presented here can serve as a reference guide when one works on noodle products in small-scale laboratory settings. Results will have valid meanings only when the product formulations and production procedures mimic commercial manufacturing processes. It is my hope that sharing these protocols could lead to initiating the standardization of noodle testing methods among laboratories.

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ACKNOWLEDGMENTS I wish to express my sincere appreciation to numerous cooperators from flour mills, noodle manufacturers, and research institutions in Asia for their generous support of the Wheat Marketing Center and my work and for helping us develop these noodle protocols collaboratively over the years. U.S. Wheat Associates is also greatly appreciated for sponsoring these Asian cooperators to come to the Wheat Marketing Center.

REFERENCES Anon. 1985. Quality assessment for wheat-sensory tests for noodles. Ministry of Agriculture, Forestry and Fisheries, National Foods Research Institute, Japan. Azudin, M. N. 1998. Screening of Australian wheat for the production of instant noodles. In: A. B. Blakeney and L. O’Brien (eds.), Pacific People and Their Foods. American Association of Cereal Chemists, St. Paul, MN, USA, pp. 101–121. Fu, B. X. 2008. Asian noodles: history, classification, raw materials, and processing. Food Res. Int. 41:888–902. Guan, F. 1998. Refinement of laboratory noodle-making methods to evaluate wheat flours for oriental noodles. Ph.D. dissertation. Kansas State University, Manhattan, KS, USA. Guo, G., Shelton, D. R., Jackson, D. S., and Purkhurst, A. M. 2004. Comparison study of laboratory and pilot plant methods for Asian salted noodle processing. J. Food Sci. 69:159–163. Hatcher, D. W. 2000. Asian noodle processing. In: G. Owens (ed.), Cereal Processing Technology. CRC Press, Boca Raton, FL, USA, pp. 131–157. Hatcher, D. W., Anderson, M. J., Desjardins, R. G., Edwards, N. M., and Dexter, J. E. 2002. Effects of flour particle size and starch damage on processing and quality of white salted noodles. Cereal Chem. 79:64–71. Hatcher, D. W. and Preston, K. R. 2004. Investigation of a small-scale asymmetric centrifugal mixer for the evaluation of Asian noodles. Cereal Chem. 81:303–307. Hou, G. 2001. Oriental noodles. Adv. Food Nutr. Res. 43:141–193. Hou, G. 2007. Asian Products Collaborative Project Report. Wheat Marketing Center, Portland, OR, USA. Hou, G. and Kruk, M. 1998. Asian noodle technology. AIB Technical Bulletin, XX (12). AIB International, Manhattan, KS, USA. Hou, G., Kruk, M., Petrusich, J., and Colletto, K. 1997. Relationships between flour properties and Chinese instant fried noodle quality for selected U.S. wheat flours and Chinese commercial noodle flours (abstract in English; text in Chinese). J. Chinese Cereals & Oils Assoc. 12:7–13. Kovacs, M .I. P., Fu, B. X., Woods, S. M., Dahlke, G., Wang, C., Sarkar, A. K., and Khan, K. 2003. A small-scale laboratory noodle sheeting machine. J. Texture Stud. 33:559– 569. Kruger, J. E., Matsuo, R. R., and Preston, K. 1992. A comparison of methods for the prediction of Cantonese noodle color. Can. J. Plant Sci. 72:1021–1029.

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Miskelly, D. M. 1984. Flour components affecting paste and noodle color. J. Sci. Food Agric. 35:463–471. Miskelly, D. M. and Moss, H. J. 1985. Flour quality requirements for Chinese noodle manufacture. J. Cereal Sci. 3:379–387. Moss, R., Gore, P. J., and Murray, I. C. 1987. The influence of ingredients and processing variables on the quality and microstructure of Hokkien, Cantonese, and instant noodles. Food Microstructure 6:63–74. Nagao, S. 1996. Processing technology of noodle products in Japan. In: J. E. Kruger, R. B. Matsuo, and J. W. Dick (eds.), Pasta and Noodle Technology. American Association of Cereal Chemists, St. Paul, MN, USA, pp. 169–194. Oh, N. H., Seib, P. A., Finney, K. F., and Pomeranz, Y. 1986. Noodles: V. Determination of optimum water absorption of flour to prepare oriental noodles. Cereal Chem. 63:93–96. Park, C. S. and Baik, B.-K. 2004a. Relationship between protein characteristics and instant noodle making quality of wheat flour. Cereal Chem. 81(2):159–164. Park, C. S. and Baik, B.-K. 2004b. Cooking time of white salted noodles and its relationship with protein and amylose contents of wheat. Cereal Chem. 81(2):165–171. Ross, A. S. 2006. Instrumental measurement of physical properties of cooked Asian wheat flour noodles. Cereal Chem. 83:42–51. Ross, A. S. and Hatcher, D. W. 2005. Guidelines for the laboratory manufacture of Asian wheat flour noodles. Cereal Foods World 50(6):296–304. Shelke, K., Dick, J. W., Holm, Y. F., and Loo, K. S. 1990. Chinese wet noodle formulation: a response surface methodology study. Cereal Chem. 67:338–342. Zhao, L. F. and Seib, P. A. 2005. Alkaline-carbonate noodles from hard red winter wheat flours varying in protein, swelling power, and polyphenol oxidase. Cereal Chem. 82:504–516.

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CHAPTER 9

Objective Evaluation of Noodles DAVID W. HATCHER

9.1. INTRODUCTION Defining noodle quality is a difficult task as it varies significantly, depending on whom you ask. A consumer would define a quality noodle product as having a clear, bright, discoloration-free surface with a good mouthfeel when cooked. A processor, recognizing his target market, would tend to agree with such a definition; however, he would add the caveat, “for a defined price.” Each consumer has different preferences for what he/she believes is quality, but it could be argued that few would accept a high-quality product if the cost of the product were prohibitive, and throughout Southeast Asia product cost is a critical component. A more realistic approach would be receiving recognized value, which intrinsically includes the price of the product. Value always lies within the particular bias of the customer and it is well recognized that, across Southeast Asia, there are wide differences in consumer preferences. The use of objective testing becomes a viable tool to provide an unbiased assessment of product quality characteristics independent of price considerations. 9.2. MILLING Wheat milling is key to any evaluation of quality, for without flour consistency, any sort of assessment or comparison of the final noodle product becomes meaningless. Millers employ a diversity of techniques to meet the specifications imposed by noodle manufacturers such as formulating mixed grists, combining millstreams to achieve a constant yield or flour ash content, or, in more recent times, blending premilled flours. Since the objective of milling is to remove both the bran and germ from the starchy endosperm to yield wheat flour, the success of this process is a function of milling efficiency and flour refinement, as highly refined flour consists almost entirely of endosperm material. The contaminants of the flour (i.e., bran and germ) influence the flour’s production potential while their presence is reflected in the flour’s price. Asian Noodles: Science, Technology, and Processing, Edited by Gary G. Hou C 2010 John Wiley & Sons, Inc. Copyright


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In general, millers tend to prefer white seed-coated wheat to that of red in that the presence of bran is not as visible to the eye. The impact of flour starch damage and particle size, a function of the milling process, has been investigated for both white salted (Hatcher et al. 2002) and yellow alkaline noodles (Hatcher et al. 2008). The topic of wheat milling for noodle production is discussed in detail in Chapters 3 and 4 and is not discussed further in this chapter.

9.3. NOODLE COLOR Independent of the type of noodle being purchased or prepared, the consumer/ manufacturer’s first opinion of the product is a visual assessment of appearance. White salted noodles and yellow alkaline noodles require a bright surface free of discolorations or specks and, dependent on noodle type, either a creamy-white color or a strong yellow color. While color may seem like a simple topic, it is actually a very complex issue with the perception of color being influenced by a number of factors. Light sources— sunlight, fluorescent light, halogen or tungsten lighting—all have different spectral power distributions, which cause noodles to appear a different color under these different light sources. This is due to the interaction of the light source’s spectral power distribution over the entire visible wavelength range and its interaction with the spectral reflectance properties of the sample, in this case noodles. There are two broad means by which instrumental color is measured. The first, the tristimulus method, consists of three sensors, essentially exhibiting red, green, and blue sensitivities in the visible light spectrum. The second, the spectrophotometric method, employs multiple sensors, each sensitive to a particular wavelength. In the spectrophotometric method, all of the individual sensor readings are integrated by a computer to generate the X, Y, and Z values, which in turn are used to calculate the color components of the noodle. The most common color components reported for noodles are the L*, a*, and b* CIELAB color space functions. L* refers to the lightness or brightness, a* highlights the position on the red–green axis, while b* provides information regarding the yellow–blue position coordinates. There are slight differences in the actual L*, a*, and b* readings of samples generated by the two different methods, but the trends and ranking of samples remain generally consistent. The quality assurance laboratories at most noodle manufacturing firms measure color at different time intervals, usually immediately after production as well as 1, 2, 7, and 24 hours later to determine the sample’s color attributes as well as to assess the retention or color stability of the noodle color over time. This is easily accomplished through the use of hand-held colorimeters (Figure 9.1) near the production line or a movable spectrocolorimeter (Figure 9.2) in the quality assurance laboratory. There is considerable debate on just how noodles should be presented to the instrument for color measurement. One method is to place a single noodle sheet on a white background and measure the color while an alternative method suggests the use of a black background. Proponents of the concept of infinite optical density suggest that no background be used, but rather

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FIGURE 9.1 A common hand-held colorimeter used for the determination of flour or noodle color characteristics.

FIGURE 9.2 Measurement of noodle color using a spectrophotometric-based system whereby the associated computer integrates the entire visible spectrum reflectance to determine the noodle sheet’s color characteristics.

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that the noodles or dough sheets be multilayered until a uniform, consistent color is achieved. An alternative method (Kruger et al. 1992) is somewhat of a compromise and suggests that three layers of folded noodle sheet be used but that the color measurement takes place within a sealed black container to eliminate any external light-source interference. At the present time, there is no definitive right answer to this question. There is general agreement, however, that whichever method is chosen, it should be maintained in order to allow the researcher to make direct comparisons as other variables in production or formulation of the noodle are changed. An example of the usefulness of these color parameters for noodles was seen in the comparison of noodle brightness (L*) and yellowness (b*) using different formulations: 1% NaCl, 1% Na2 CO3 , 1% K2 CO3 , 0.3% NaOH, and 1% NaOH on two different flour extractions, 50% and 74%, of Australian Standard White wheat at 2 hours and 24 hours after production (Miskelly 1996). This work demonstrated how both noodle color parameters were significantly affected, both at 2 h and 24 h after production, by making variations in the nature of the alkali reagent used and the flours employed. Alkaline noodles owe their characteristic yellow color to the chromophoric shift that occurs when endogenous flavonoids found in the flour react in the presence of caustic solutions of kansui (sodium and potassium carbonates) or sodium hydroxide. The intensity of the yellowness is a function of the alkali used (Miskelly 1996) and the amount of flavonoids present. Initial work (Mares et al. 1997) indicated that hydroxylamine (0.1 M), pH 7.2, was an effective solvent for their extraction. Subsequent work (Asentorfer et al. 2006) demonstrated that two flavonoid apigenin-C-digylcosides were found to be the primary compounds accounting for the color shift in alkaline noodles and were located only in the embryo and scutellum tissues. It was concluded that their presence in flour is the result of redistribution during milling. Preliminary investigations (Hatcher et al. 2006) using a 10% hydroxyl amine solution demonstrated this redistribution throughout the various millstreams (Figure 9.3). It was shown that the amount of flavonoids extracted from different wheat varieties was also under the control of both genotype and the growing location (Figure 9.4) and, as such, the source of the wheat used in noodle flour production was extremely variable. The use of hydroxyl amine solutions to extract flavonoids as a way of assessing flour quality for noodles is simple since it requires minimal equipment that is normally found in any quality control laboratory and easily facilitates batch processing. It is relatively rapid, making it an ideal objective tool. Enzymes, particularly polyphenol oxidase and peroxidase, are key to noodle color stability. Polyphenol oxidase (EC 1.10.2.2) exists as a number of different isozymes (Interesse et al. 1981), which can oxidize monophenols or diphenols to labile quinones in the presence of oxygen. These quinones can react either with themselves or with NH or SH groups on proteins to form undesirable discoloration (Pierpoint 1969; Francis and Clydesdale 1975). Since this enzyme is found primarily in the bran, millers have the ability to selectively control its levels in noodle flours by limiting their milling yield to below 75%. Above this level, the amount of the enzyme increases significantly with only minor increases in milling yield (Hatcher and Kruger 1993).

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FIGURE 9.3 Variations in flavonoid levels throughout different millstreams of hard red spring wheat varieties.

The deterioration in noodle brightness (L*) over the initial 4- and 24-hour periods has been highly correlated (r = 0.84 and 0.87, respectively) with PPO content (Kruger et al. 1995). Additionally, a significant drop in noodle b* values over the same two time periods displayed high correlations with PPO levels (r = 0.87 and 0.88, respectively). Since noodle color stability is highly influenced by PPO levels, it is normal for researchers and noodle manufacturers to assay for the enzyme in either their millstreams or their composited flours. The most discriminating, yet time-consuming, assay for this enzyme is through the use of an oxygen electrode system (Marsh and Galliard 1986). It has been shown that unlike many other enzymes, the amount of PPO that is extracted using a variety of solvent constituents, including detergents, does not offer any uniform level of enzyme extraction. Based upon this rationale, the

0.4 0.3 0.2

Regina

FIGURE 9.4 flours.

Swift Current

Vista

Superb

Snowbird

Neepawa

Elsa

Barrie

Vista

Superb

Snowbird

Neepawa

Elsa

Vista

Barrie

Superb

Snowbird

Elsa

0

Neepawa

0.1

Barrie

Flavonoid Levels (narigenin equiv)

0.5

Winnipeg

Influence of growing location and variety on flavonoid levels in noodle wheat

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FIGURE 9.5 The standard oxygen electrode-based system for the calculation of polyphenol oxidase in ground wheat or flour.

oxygen electrode method, in which the ground grain or flour is measured directly, removes the inherent problem of extraction. The method, described in detail (Marsh and Galliard 1986) and modified slightly (Hatcher and Kruger 1993), uses 4-methyl catechol or catechol as the substrate. Air-saturated buffer, pH 6.8, is allowed to equilibrate within a closed cell prior to ground meal or flour being incubated in the absence of substrate. Background oxygen consumption (i.e., by free fatty acids) is measured for a minimum of 3 minutes to account for endogenous, nonenzymatic consumption prior to the injection of the substrate (Figure 9.5). The increased oxygen consumption due to PPO action is recorded and the activity is expressed in nmoles O2 consumed /g/min. The assay is very sensitive, and by varying the amount of buffer or sample size, PPO activity can be readily, if not quickly, calculated. A new method (Fuerst et al. 2006), offering both rapidity and batch processing, has been reported in which l-dopamine is the substrate. The authors utilize ground grain or flour (200 mg) incubated in 2-mL microcentrifuge tubes with and without dopamine present in pH 6.5, 50 mM MOPS (3-[N-morpholino] propane sulfonic acid) buffer containing 0.02% Tween-20 for 1 hour. They subsequently centrifuged the tubes, 3 min at 10,000g, and subtracted the substrate-free sample absorbance at 475 nm from the substrate-containing sample in order to determine PPO activity. Activity was reported in
O.D./g/min. Recent work on this assay has indicated that the sensitivity and linearity of the assay can be improved greatly by ensuring that the buffer is air saturated prior to incubation and is highly correlated (r2 = 0.989) with the traditional oxygen electrode method as well as being very reproducible (Table 9.1). The use of the air-saturated buffer allows higher levels of the enzyme to be detected as the presence of oxygen is no longer the rate limiting factor (Figure 9.6).

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TABLE 9.1 Reproducibility of the Modified Dopamine-Based Assay Using Air Saturated (60 min) MOPS Buffer Mill Stream

Sample

Mean Net Optical Density

Standard Deviation

Coefficient of Variation (%)

6th Middling

1 2 3 Average

0.169 0.153 0.158 0.160

0.003 0.006 0.012 0.007

1.2 2.3 4.5 2.7

1st Sizing

1 2 3 Average

0.080 0.069 0.069 0.073

0.003 0.002 0.001 0.002

1.5 1.5 0.5 1.2

4th Break

1 2 3 Average

0.116 0.115 0.118 0.116

0.005 0.001 0.003 0.003

2.6 0.6 1.8 1.7

Bran flour

1 2 3 Average

0.344 0.324 0.331 0.333

0.001 0.003 0.002 0.002

0.3 0.7 0.5 0.5

Source: Hatcher (unpublished).

0.13

Mean Absorbance (n=3)

0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0

10

20

30

40

50

60

70

Time (min)

FIGURE 9.6 The impact of buffer aeration period (minutes) on the development of increasing differences in detectable polyphenol oxidase activity as assessed by optical density (Hatcher, unpublished).

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Peroxidase (EC 1.11.1.7) oxidizes a wide variety of substrates in the presence of hydrogen peroxide. It is present throughout the development of the wheat kernel (Kruger and Laberge 1974a,b) and causes arabinoxylans to undergo oxidative coupling through their ferulic acid residues. The enzyme also causes the resulting dough to be more viscous (Schooneveld-Bergmans et al. 1999); it bleaches carotenoids (Hawthorn and Todd 1955; Hsieh and McDonald 1984) and causes undesirable discoloration in noodles (Kruger et al. 1992; Baik et al. 1995). A simple, sensitive, rapid microassay for wheat peroxidase involves the use of 2,2 -azinobis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) as the substrate (Hatcher and Barker 2005). Peroxidase is extracted from either wheat flour or meal with cold (4 ◦ C) sodium acetate buffer (0.1 M, pH 4.2) for 30 min at 4 ◦ C. After centrifugation, the supernatant is filtered and stored on ice until assayed. The substrate ABTS (150 µL) is added to the peroxidase extract (25 µL) and has previously been dispensed into the microplate well and allowed to sit for 1.00 min. The reaction is stopped by the addition of 100 µL of 2 M sulfuric acid and the absorbance at 405 nm being quantified by the microplate reader (Figure 9.7). The use of a microplate system allows peroxidase standards to be included on the microplate to provide batch-to-batch repeatability. The assay has been shown to be very effective in quantifying differences in wheat varieties (Figure 9.7) and also in providing the noodle manufacturer, working in collaboration with the milling company, the ability to determine the enzyme’s levels in various millstreams and cumulative content (Figure 9.8). With such knowledge, the miller can generate a specialty flour for his noodle manufacturing client. One large noodle manufacturer in the Philippines has its own mill onsite, which handles 240 metric tons of wheat per day, generating flour to proprietary specifications.

FIGURE 9.7 The use of a microplate assay-based system for the determination of peroxidase activity in ground wheat or flour.

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1400 550

1200 1000

500

800 600

450

400 200

Cumulative Peroxidase Activity

600

1600 Stream Peroxidase Activity

235

400

Millstream

SD Br a F. n Br Br an an FI .

1 M 5 M 6 BF

B4

Q

B3

4 B1

M

3 B2

M

2 S1

M

M

1

0

FIGURE 9.8 Distribution of peroxidase activity in individual millstream as well as cumulative enzyme activity within hard wheat flour used for noodle production.

9.4. PROCESSING Production of noodles, either white salted or yellow alkaline, requires significant work input since a normal noodle production facility will employ five to seven rollers. Manufacturers and researchers have the ability to discern how differences in formulation can significantly impact the amount of work input required to produce a desirable product. A simple analog-to-digital interface attached to an Ohtake laboratory scale noodle machine’s force transducers demonstrated the influence that small changes in water absorption (28–34%) could make in the work input of both white salted and yellow alkaline noodles made from different classes of wheat flour (Hatcher et al. 1999). Utilizing a dough sheet that had undergone its first dough compression and subsequent lamination step, a 25-cm length of dough was cut out and weighed. The dough sheet was subsequently passed through seven more reduction rolls, with the corresponding force measurements recorded. Preliminary calibration of the roller against known force measurements had allowed for the Ohtake machine responses to be calibrated. In-house developed software allowed for simple conversion and integration of the work input, which, in conjunction with the known mass, allowed the work to be expressed in joules. White salted noodles from three different wheat classes displayed an approximate 50% decline in work input over the 6% change in water absorption, while yellow alkaline noodles approached an almost 75% decline in work input over the same range. Subsequent research (Hatcher et al. 2002) demonstrated the influence of particle size and starch damage, as well as how alkaline formulation influenced work input (Hatcher and Anderson 2007), confirming that this was a very effective tool to discriminate the impact of minor changes in formulation. Utilizing a 1% w/w solution of sodium and potassium carbonates, either in a 1 : 9 or 9 : 1 ratio, in the production of yellow alkaline noodles, resulted in significant differences in work input both in patent and straight-grade flour noodles made from two different wheat

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classes. It also demonstrated how the addition of salt, NaCl, toughened the dough and required significantly greater amounts of work input.

9.5. ASSESSING NOODLE APPEARANCE BY IMAGE ANALYSIS There is a preference for manufacturers to use high-quality, low-yield patent flours as they result in brighter noodles (independent of type) and display fewer areas of discoloration or speckiness. Noodle appearance generally deteriorates over time, with the greatest change being detected shortly after production and slowly declining thereafter. While the entire noodle sheet darkens, there is accelerated discoloration in small areas due to loci of contaminating bran particles, which are a source of enzymes and their substrates (Hatcher and Kruger 1993, 1996). As previously discussed, noodle color is normally assessed via a colorimeter or spectrophotometer, which calculates the CIE 1976 brightness (L*), redness (a*), and yellowness (b*). Most colorimeters, however, have a limited viewing area of 10–50 mm in diameter and provide only the average value over the entire area measured. This does not allow the manufacturer or researcher the ability to address the degree of noodle speckiness, quantify the color differences among specks, or assign relative contributions of specks to the overall color components. These different aspects of appearance play a critical role in how a consumer arrives at an assessment of noodle quality and are often misinterpreted by sensory panelists due to the known “contrast effect” (Hutchings 1994). Image analyses (IAs) of noodles address these concerns, allowing the impact of various factors or formulations on noodle appearance to be investigated objectively and independent of subjective error. This is essential for noodle researchers to compare results over prolonged periods. Image analysis has demonstrated that it can quantify and discriminate differences in noodles on the basis of wheat cultivars, flour refinement, noodle type, and growing environment (Hatcher et al. 1999; Hatcher and Symons 2000a,b; Hatcher et al. 2006). Initial work used a color camera attached to a macroscope, a commercial frame grabber, and in-house software to capture noodle dough sheet images. Adjusting the camera gain using a Kodak #3 grey scale and a standardized white tile ensured illumination consistency and optimized surface characteristic discrimination. Noodle sheet speckiness is based on an operator-defined minimum difference in darkness (0–255) between discolored specks and the surface of the noodle referred to as the delta grey (
grey). IA offers the operator the ability to examine noodles at either single or multiple
grey values with small
grey values yielding a higher number of specks. A second operator-defined parameter that discriminates specks is the minimum threshold speck size, that is, 3 × 10−3 mm2 (Figure 9.9), which must be exceeded for detection to occur. Initial research images were captured at six different positions on the noodle sheet. Each image represented a 1.5-cm × 1.1-cm section of the noodle sheet, equivalent to 9.9 cm2 , or approximately twice the size of a standard colorimeter. Noodle dough sheet size using current scanner-based systems (Hatcher et al. 2004) is only limited by available computer memory to store the captured image.

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FIGURE 9.9 Image analysis parameters under operator control for the detection and quantification of specks on noodle sheets.

IA has demonstrated the ability to significantly discriminate white wheat cultivars on the basis of differences in the number of specks detected (62 vs. 45) on a noodle sheet over a 24-hour period (Hatcher et al. 1999). Although the effect of the minimum threshold size significantly influenced the number of specks quantified, no change in the mean speck size was observed between either variety over time. It was suggested that bran speck size (a function of milling) was critical as there were no additional condensation reactions causing an increase in speck size past the perimeter of the bran speck itself. This had been anticipated because at the low noodle water-absorption level (32–36% normally used in production), there is insufficient free water available for the enzymes, substrates, or subsequent condensation products to migrate. Subsequent research (Hatcher and Symons 2000a) used IA to quantify differences in white wheat varieties flour refinement for both yellow alkaline and white salted noodles. While no significant difference could be detected between the speck counts of alkaline noodles made from patent flours of different varieties at 2 hours postproduction (12.4 vs. 15.5 specks/image), noodles prepared from straight-grade flour displayed significantly higher numbers of specks than their patent counterparts (31.9 and 28.3 specks/image). It required aging (24 h) for the patent flour alkaline noodles to reveal significant varietal distinction. The key difference between white salted and alkaline noodles quantified by IA was the lower number of discolored specks detected in either flour or variety relative to their alkaline counterparts. At 2 hours postproduction, the white salted patent

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noodles displayed less than half the number of specks of their corresponding alkaline noodles. Upon aging 24 hours, the white salted noodles displayed less than 60% of the number of specks observed in either variety or flour-type alkaline noodle. This confirmed that speck development was directly related to the type of noodle being produced. It is important to recognize that consumer (sensory) assessment is subjective, and it has been previously demonstrated that the size and darkness of a speck are exaggerated depending on the degree of contrast to the background (Francis and Clydesdale 1975; Hutchings 1994). Surprisingly, IA objectively demonstrated in white wheat varieties that alkaline noodle specks were actually lighter than those of the corresponding white salted noodles prepared from both white wheat patent and straight-grade flours (Hatcher and Symons 2000a). Flour refinement was also shown to influence speck darkness in both white salted or yellow alkaline noodles; straight-grade flour noodles yielded darker specks than the corresponding patent flours. Asian noodle manufacturers prefer white seed-coated wheat flour over red seedcoated material. The explanation for this preference may originate in the fact that noodles that are not sold within the first day after production are incorporated judiciously in the following day’s material. Examination of patent and straight-grade flour alkaline noodles derived from red seed-coated wheat by IA indicated the same general trend as white wheats with the number of detectable specks increasing over time, reaching a maximum at 7 hours postproduction (Hatcher and Symons 2000c). However, speck numbers declined slightly thereafter. The reason for this decline between the 7- and 24-hour period, which had not been previously observed in the white seed-coated material, was that the general noodle background matrix of the red wheat flour had darkened as well, thereby reducing IA’s ability to discern specks. As observed in white wheat, noodles prepared from patent flour displayed significantly fewer specks than noodles prepared from the straight-grade material. Noodle type, salted versus alkaline, from red seed-coated wheat flour, exhibited similar trends as those observed in the white wheat with significantly fewer specks compared to alkaline (Hatcher and Symons 2000c). Changing the sensitivity by altering the
grey or size threshold limit did influence the number of specks detected; however, the trend remained consistent. Unlike colorimeters or spectrophometers, IA systems have the distinctive ability to characterize the degree of darkness contributed by individual specks or by overall mean speck darkness (Hatcher et al. 1999; Hatcher and Symons 2000a,b,c). Researchers (Hatcher et al. 1999) demonstrated that the largest change in speck darkening occurred initially (0 h to 2 h), followed by a decreasingly slower change over the 8-hour postproduction period. Furthermore, significant differences in the mean darkness intensity of the specks between the two white seed-coated varieties were noted by 3 hours after production, regardless of the
grey or minimum threshold setting, offering a unique ability to discriminate varietal effects. Another unique attribute associated with IA not seen in traditional color measurements is that the researcher now has the capability to quantify and analyze the relative distribution profile of speck discoloration over time (Hatcher et al. 1999; Hatcher and Symons 2000a,b,c). As early as 2 hours postproduction, a difference in

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the distribution profile of speck darkness between the two white seed-coated cultivars was significant and, with aging (24 h), the differences between varieties were enhanced. IA provided the objective quantification that one cultivar had 36.8% of its specks brighter than the 140 grey level while the other variety had no specks brighter than this value. This confirmed the subjective visual results, by which panelists had indicated it as being less desirable. The discriminatory capability of IA speck darkness/brightness distribution profiles has been shown on alkaline versus white salted noodles (Hatcher and Symons 2000a). This study of white wheat lines showed that 94.6% of alkaline noodles were above the 130 grey value, yet only 87.3% of the salted noodle specks were at this value. Further analyses of the alkaline noodle specks profiles highlighted that 21.4% were extremely light (150–159 range) with 43.8% in the 140–149 range. However, the corresponding white salted noodle had less than 20% of its specks in these two lighter ranges. IA has the ability to overcome the consumers’ distorted perception, which causes them to rate the specks darker and larger in the white salted noodle due to the contrast perception effect. Aging the various noodles until 24 hours exaggerated differences due to variety, flour refinement, and noodle type. Utilizing the IA capability to investigate the noodle manufacturers’ preference for white seed-coated wheat, storage of raw noodles made from hard red wheat flour for 24 hours was shown to have very distinctive, quantifiable darkening of the specks, considerably darker than the previously studied white wheat materials, in both the patent and straight-grade flour alkaline noodles (Hatcher and Symons 2000c). Examination of hard red wheat flour white salted noodle speck darkness distribution profiles as early as 2 hours showed that hard red wheat patent flour specks had 44% of their spots above the 130 grey level while the alkaline noodles achieved only ∼29%. Compared to the white seed-coated varieties (Hatcher and Symons 2000a,b), a major distributional shift was highlighted, as white seed-coated lines displayed 94.6% of their alkaline specks above the 130 grey level and 87.3% of their salted noodles above this level. This difference in distribution profiles would clearly cause the consumer to perceive a difference. As observed for white wheat flours, aging the noodles for 24 hours exaggerated the differences in the speck distribution profiles, highlighting both the degree of flour refinement and type of noodle. Initial research (Hatcher et al. 1999) had been able to discriminate between two different registered varieties of hard white wheat derived from commercial shipments of grain. These individual shipments, while unique in terms of variety, represented a blend of growing locations within one year. Recently, research (Ambalamaatil et al. 2002; Hatcher et al. 2006) has unveiled the ability of IA of noodles to provide insight into the genotype, environment, and genotype × environment interactions as they pertain to noodle appearance. Within a 3-year study, whereby flour-mill yield remained constant, differences due to growing location, variety, as well as year were found to significantly influence (p < 0.0001) the number of specks detected within two classes of Canadian wheat. The impact of wheat quality grading factors and quantifying their subsequent effect on noodle appearance offers a significant role for IA to discriminate samples not discerned by other techniques. Initial research on the impact of spout damage

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(Kruger et al. 1995) indicated that changes in color, using a spectrophotometric technique, of both raw and dried white salted noodles were minimal when derived from wheat with Falling Numbers of 485–85 seconds. Differences in alkaline noodles were only apparent between the two extremes. Subsequent investigation (Hatcher and Symons 2000b) of severely sprouted wheat, compared to moderate and sound wheat, showed that alkaline noodles had the greatest number of specks at 1 hour and subsequently doubled in number by 7 hours. This represented an approximate fivefold increase over corresponding sound, nonsprouted, identical control wheat. While such an increase did not impact overall color, the customer’s perception of appearance would be strongly influenced. Additionally, IA demonstrated a significant increase in the size of discolored specks over time due to the sprout damage, that the mean darkness of the specks was significantly darker than their nonsprouted controls, and that the speck distribution profiles altered with increasing sprout damage (Hatcher and Symons 2000b). Fusarium head blight (FHB) has health implications due to potential production of mycotoxins and quality implications through the action of proteases. Alkaline noodles prepared from either patent or straight-grade flours derived from wheat samples with fusarium damage levels ranging from 0.5% to 9.6% indicated a significant increase in the number of specks/image with increasing fusarium damage (Hatcher et al. 2003). Patent flour noodles displayed fewer specks than straight-grade flour noodles, yet the regression lines for the two flour levels were almost parallel when plotted against the fusarium levels (r2 = 0.61 at 2 h and 0.63 at 24 h) . Frost can have a deleterious effect on the quality of the wheat crop, resulting in a much harder kernel than normal, which, during milling, results in a poor mill yield, increased starch damage, and poor flour color. Yellow alkaline and white salted noodles made from increasingly frost-damaged wheat were shown to display increasing numbers of undesirable specks (Hatcher et al. 2005b).

9.6. TEXTURE MEASUREMENTS FOR QUALITY ASSESSMENT While consumers rely on their initial visual assessment to purchase noodles, it is their assessment of the noodle’s texture that results in the critical repeat purchases to establish “brand loyalty.” Most major noodle manufacturers currently rely on sensory panelists to assess their product in relationship to their target market. Unfortunately, while this methodology discerns clear preferences within a market niche, it is extremely difficult to quantify what is contributing to this preference. The use and benefits of using trained panelists are discussed in Chapter 10 and readers are advised to seek further discussion in additional resources (Szczesniak 2002). The benefit of instrumental methods is that they allow the researcher to objectively quantify the physical properties of the noodles and attempt to relate them to a variety of sensory preferences. This is critical to a researcher as it is impossible for any one sensory panel to address the preferences of a large and geographically dispersed population. Prior to initiating texture evaluation, it is essential that researchers standardize their preparatory procedure in order to ascertain optimum conditions for differentiation

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as well as to improve reproducibility (Ross and Hatcher 2005). Ross (2006) discusses this in detail, highlighting the need to vary parameters in order to optimize differentiation. He points out that even the diameter of the roller head and its rotational speed on a noodle machine can significantly impact the final results. He states that mathematical modeling of traditional sheeting assumes that the resulting dough thickness is small relative to the roller but in many noodle quality laboratories, where hand-held units are used, this is not the case. He indicated that the initial dough thickness can be up to 15–20% of the roller’s diameter, which therefore negates the assumed limited influence. Furthermore, research (Engmann et al. 2005) indicated that final noodle thickness must be governed by adjusting the final gap for each sample as the inherent viscoelastic recoil, due to protein strength and content, will result in different noodle thicknesses. Hatcher and Anderson (2007) have also adopted the use of multipletimed passes (45 seconds) to improve on the reproducibility of the product and to ensure that the amount of work input remains constant. Oh et al. (1983) demonstrated that noodle thickness was positively correlated with cutting force and defined the use of maximum cutting stress to additionally address the differences in contact area (noodle width). It is of interest to note that both the thickness and the width of noodles are inherently influenced by the amount of water the noodle takes up during cooking, which is correlated with the length of cooking time. Currently, there are two different approaches to addressing this problem and each has its strengths and weaknesses. Many researchers cook their noodles for a specific period of time to standardize the process and to duplicate the manufacturer’s recommendations on its product. The alternative method is to cook the different noodles to their optimum, as defined by the disappearance of the inner core area. The latter, however, has greater difficulty achieving consistency and requires preliminary evaluation of the various noodles, which in many cases, where flour amounts are limited, cannot be achieved. This latter method also requires that a constant method is used to assess when optimum is achieved. The standard definition of “optimum” is based on the loss of a discernible inner core when the cooked noodle is pressed between two clear sheets, and it is often difficult to get agreement among individuals. This problem can be addressed by removing five cooked noodles every minute and defining optimum cooking as having been achieved when four of five cooked noodles do not display an inner core. Many noodle manufacturers’ quality assurance laboratories state that a quality noodle must take up sufficient water during cooking to increase in mass by at least 100%. Such factors as flour protein content and cooking time all influence water uptake. Determining water uptake is easily accomplished as the investigator needs only to know the initial mass of raw noodles being cooked (e.g., 25 g) and weighing the material after the predetermined cooking period. It is common practice to place the cooked noodles in a small strainer and shake them for 30 seconds to remove any excess water adhering to their surface prior to reweighing the sample. Investigation of the influence of particle size and starch damage on water uptake during cooking revealed that while there was a general decline in water uptake with starch damage, no influence of flour particle size was observed (Hatcher et al. 2002). An additional important piece of information, cooking solid loss, can also be gleaned easily from the cooking process. Using a pretared beaker prior to cooking the

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noodles, followed by a drying of the cooking liquid, can provide valuable information. The impact of particle size and starch damage on white salted noodle cooking loss was demonstrated (Hatcher et al. 2002) whereby low-starch-damaged flours exhibited less cooking loss than high-starch-damaged flours. Within each starch damage level (i.e., low, medium, and high) there was also a clear, discernible pattern of increased cooking loss as the particle size increased. It has clearly been demonstrated in both pasta (Voisey et al. 1978) and noodles (Oh et al. 1983) that standing time after cooking results in significant changes in the objective texture measurements. It is therefore essential that researchers standardize their testing regime at exactly the same time period after cooking for each replicate in order to minimize variance and maximize the technique’s discriminatory capability. Currently, there is no agreement among researchers on how many noodle strands or how many repeated measurements should be taken to optimize differentiation between samples. Investigations using pasta (Binnington et al. 1939) suggested five repeated measures, while a relatively recent noodle paper (Seib et al. 2000) recommended seven, with both the highest and lowest values being discarded. The earliest Western attempt to objectively measure noodle quality was reported by Shimizu et al. (1958), who utilized their in-house extensimeter to quantify a number of rheological parameters: spontaneous and retarded elasticity, elastic modulus, and stress relaxation on white salted noodles. They demonstrated the ability to differentiate the impact of different protein content and temperature on noodles prepared from two different wheats. Determination of a noodle’s firmness or hardness can be quantified using the AACC International (AACCI) Approved Method 66-50, whereby a beveled plexiglass or Lexan blade with a 1-mm surface is used to cut through a specified number of noodle strands of known width (Figure 9.10). Firmness is defined as the maximum force derived when cutting through the set of noodles. Firmness, divided by the cross-sectional area of contact, based on the work of Oh et al. (1983), is referred to as maximum cutting stress, MCS (g/mm2 ). Hardness is often quantified as the peak force alone, uncorrected for the cross-sectional area, and is analogous to firmness. The cross-head speed of the blade, as well as the number of noodle strands tested, varies among different researchers, and readers will find a comprehensive list of variations cited within Ross (2006), who indicated that while these are all variations on a theme, they regrettably do not allow for direct comparison of the resulting data. Key to this methodology was research (Oh et al. 1983) that demonstrated significant positive correlations between sensory hardness and MCS. The MCS technique has demonstrated the influences of variety, growing location, and growing year, as well as all of the corresponding interaction terms (Hatcher et al. 2006); differences in flour refinement (45%, 60%, 74%, and 80% yield) for both red and white wheat (Ambalamaatil et al. 2002); and differences within a wheat class (Ambalamaatil et al. 2002) and in noodle processing (Markowski et al. 2003). The MCS technique has also significantly discriminated the impact of small amounts of fungal proteases on the wheat kernel prior to milling on the noodle texture of the resulting flours (Hatcher et al. 2003). MCS also offers sufficient discriminatory capabilities to discern significant differences between barley variety flours when added at only 20% level

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FIGURE 9.10 The test apparatus, used to simulate a front tooth, in order to calculate noodle hardness and maximum cutting stress (MCS).

to common noodle flour when attempting to improve the functional food aspects of yellow alkaline noodles (Hatcher et al. 2005a) or white salted noodles (Izydorczyk et al. 2005; Lagasse et al. 2006). An additional texture component that can be derived from the MCS test is surface firmness as defined by the slope of the curve between the first point of blade contact and when the firmness measures 60g/mm2 (Oh et al. 1983). While this parameter is easy to measure, its meaningfulness is directly dependent on the cooking process/time involved as it is a function of the degree of water hydration and gelatinization of the noodle’s surface. During the mastication process, the noodle is compressed between the back molars. Oh and co-workers (1983) used a 3.5-mm flat probe to duplicate this process by using a single uniaxial compression test (Figure 9.11). They were able to demonstrate correlations between the resistance to compression (RTC), expressed as a percentage, and sensory panelists. This technique has been used to discern significant differences in variety and growing year among wheat varieties (Hatcher et al. 2006) as well as the influence of alkali reagent concentration and formulation (Hatcher and Anderson 2007). An additional texture parameter garnered from the compression test, recovery (REC), defined as the ratio of the distance recovered to the distance compressed, expressed as a percentage, has been correlated with sensory noodle firmness (r = 0.69, p < 0.05) and chewiness (r = 0.88, p < 0.01) when using three hard wheat flours, two soft wheat flours, and three commercial noodles (Oh et al. 1983). This parameter has been used to discriminate between noodles prepared from different wheat varieties within a class, where the wheat was grown, as well as the year in which it was grown

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FIGURE 9.11 The test apparatus, used to simulate a human back molar, to determine both the resistance to compression (RTC) and recovery (REC).

(Hatcher et al. 2006a). REC has also been shown to be a useful discriminator in noodle processing (Markowski et al. 2003), in the influence of alkali concentration (Hatcher and Anderson 2007), in sprout damage (Kruger et al. 1995), in fungal proteases (Hatcher et al. 2003), in particle size, and in the degree of starch damage (Hatcher et al. 2002). A very common method for assessing noodle texture parameters is based on the initial work of Bourne (1968) and has been applied to a wide variety of food products over the years. Texture profile analysis (TPA) is a two-step compression test using a flat probe to mimic the chewing action on the back molars. A number of different parameters—hardness, adhesiveness, cohesiveness, springiness, resilience, and chewiness—can all be calculated based on specified distances and areas under the curve. Cohesiveness, chewiness, and resilience were found to be effective discriminators in studying the processing of noodles (Markowski et al. 2003). Springiness is perhaps one of the most interesting characteristics, as the term is often employed by Asian quality assurance managers to highlight differences in various noodles. However, there is some debate if the term applied by quality assurance managers, primarily derived from sensory evaluation panels, is the same characteristic defined by the mathematical formula length 2/length 1. A significant correlation between TPA springiness and noodle firmness as determined by sensory panelists has been reported (Tang et al. 1999). Additionally, TPA has been used to track changes in noodle quality as a function of wash solution and storage time on noodles (Kim and Cha 1998), the influence of variety and growing year on texture (Hatcher et al. 2006),

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and barley supplementation in both white salted (Izydorczyk et al. 2005; Lagasse et al. 2006) and yellow alkaline noodles (Hatcher et al. 2005a). Stickiness is an undesirable characteristic to the noodle consumer and is often assessed by measuring the force required to pull a probe, of various shapes, off the noodle’s surface (Dunnewind et al. 2004). TPA attempts to quantify this sensory component through adhesiveness, which is the amount of work required to remove the probe from a negative to positive force between the two compression cycles (Bourne 1968). Tensile tests have also been used to differentiate noodle attributes due to a number of different variables. Perhaps the most difficult aspect of performing tensile tests is ensuring that the method of attaching the noodle to the various devices does not damage the noodle such that it breaks at the point of attachment rather than due to its inherent characteristics. Various methods have been described such as winding the noodle around specialized rubber clamps or using precut rings from the noodle sheet. Shimizu et al. (1958) demonstrated that as long as noodles were not stretched to their breaking point, the method has the ability to determine both spontaneous and retarded elasticity. The impact of guar gum additions on noodle dough was shown to increase their cooked instant noodle breaking strength (Yu and Ngadi 2004) while Ross and co-workers (1998), using noodle rings cut out of noodle sheets, demonstrated a negative correlation between tensile force and sensory noodle softness. The use of rheometry to explain noodle texture is increasing in its applications. Dynamic rheometry was used to investigate the effects of flour particle size and starch damage on raw white salted noodles (Hatcher et al. 2002). Using 25-mm diameter serrated plates, they demonstrated that doughs with lower starch damage and of varying thicknesses displayed lower storage modulus (G ), higher tan delta (G [loss modulus]/G ), and greater maximum strain during creep than raw noodles with higher starch damage regardless of particle size. They indicated that noodles prepared from flour having higher starch damage resulted in stiffer noodles than flour of lower starch damage, which was confirmed in creep test measurements. One of the difficulties of carrying out dynamic rheometry on cooked noodles is ensuring that the plates are consistently meeting the surface of the noodles due to their swelling upon cooking. The impact of amylose content has been shown on cooked noodles (Sasaki et al. 2004) where both the storage modulus (G ) and loss modulus (G ) declined as the flour’s amylose content was reduced. Recently, stress relaxation data of wheat dough was investigated using a prevalent commercial uniaxial texture analyzer (Singh et al. 2006). They were capable of using a uniaxial compression test to assess the percentage of stress relaxation, the initial rate of relaxation, the extent of relaxation, and the relaxation time that could be used to discriminate products. While they were using a 50% water content compared to the common 34–36% content of noodles, they did investigate 3-mm dough sheets similar to the first stage of noodle production. They were able to demonstrate repeatable results using a simple macro provided by the company, thus offering researchers and quality assurance staff a rapid, inexpensive means to study variations in formulations.

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9.7. SUMMARY Manufacturers and noodle researchers worldwide recognize the benefits of trained sensory panelists to assist in the evaluation of noodle quality. However, clearly defined, quantifiable objective measurement of noodle quality through noodle appearance, color, or a variety of different texture parameters is essential to provide the researcher with the ability to discriminate the influence of potentially subtle but significant changes in quality. The effort in maintaining a well-trained sensory panel, providing consistent results over time as members are replaced, is extremely onerous. The use of objective measurements of noodle quality provide the researcher or quality assurance manager with the added assurance of direct comparability of processes or changes in the raw material (i.e., flour) over time. Perhaps the biggest hurdle yet to be overcome is the development of and subsequent acceptance of standardized objective testing protocols. Although, at the present time, numerous researchers are providing key insights into noodle quality, the lack of standardized methodologies is hindering the direct application of their findings into the final product.

REFERENCES Ambalamaatil, S., Lukow, O. M., Hatcher, D. W., Dexter, J. E., Malcolmson, L. J., and Watts, B. M. 2002. Milling and quality evaluation of Canadian Hard White Spring wheats. Cereal Foods World 47:319–328. Asenstorfer, R. E., Wang, Y., and Mares, D. J. 2006. Chemical structure of flavonoid compounds in wheat (Triticum aestivum L.) flour that contribute to the yellow colour of Asian alkaline noodles. J. Cereal Sci. 43:108–119. Baik, B. K., Czuchajowska, Z., and Pomeranz, Y. 1995. Discoloration of dough for oriental noodle sheets. Cereal Chem. 72:198–205. Binnington, D. S., Johannson, H., and Geddes, W. F. 1939. Quantitative methods for evaluating the quality of macaroni products. Cereal Chem. 16:149–167. Bourne, M. C. 1968. Texture profile of ripening pears. J. Food Sci. 33:223–226. Dunnewind, B., Janssen, A. M., van Vliet, T., and Weenen, H. 2004. Relative importance of cohesion and adhesion for sensory stickiness of semisolid foods. J. Text. Studies 35: 603–620. Engmann, J., Peck, M. C., and Wilson, D. I. 2005. An experimental and theoretical investigation of bread dough sheeting. Food Bioproducts Proc. 83:175–184. Francis, F. J. and Clydesdale, F. M. 1975. Food Colorimetry: Theory and Applications. Avi, Westport, CO. Fuerst, P. E., Anderson, J. V., and Morris, C. F. 2006. Delineating the role of polyphenol oxidase in the darkening of alkaline wheat noodles. J. Agric. Food Chem. 54:2378– 2384. Hatcher, D. W. and Anderson, M. J. 2007. Influence of alkaline formulation on Oriental noodle color and texture. Cereal Chem. 84:253–259. Hatcher, D. W. and Barker, W. 2005. A rapid microassay for determination of peroxidase in wheat and flour. Cereal Chem. 82:233–237.

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Hatcher, D. W. and Kruger, J. E. 1993. Distribution of polyphenol oxidase in flour millstreams of Canadian common wheat classes milled to three extraction rates. Cereal Chem. 70: 51–55. Hatcher, D. W. and Kruger, J. E. 1996. Simple phenolic acids in flours prepared from Canadian wheat: relationship to ash content, color and polyphenol oxidase activity. Cereal Chem. 74:337–343. Hatcher, D. W. and Symons, S. J. 2000a. Assessment of Oriental noodle appearance as a function of flour refinement and noodle type by image analysis. Cereal Chem. 77: 181–186. Hatcher, D. W. and Symons, S. J. 2000b. Influence of sprout damage on Oriental noodle appearance as assessed by image analysis. Cereal Chem. 77:380–387. Hatcher, D. W. and Symons, S. J. 2000c. Image analysis of Asian noodle appearance: impact of hexaploid wheat with a red seed coat. Cereal Chem. 77:388–391. Hatcher, D. W., Anderson, M. J., Desjardins, R. G., Edwards, N. M., and Dexter, J. E. 2002. Effects of flour particle size and starch damage on processing and quality of white salted noodles. Cereal Chem. 79:64–71. Hatcher, D. W., Anderson, M. J., Clear, R. M., Gaba, D. G., and Dexter, J. E. 2003. Fusarium head blight: effect on white salted and yellow alkaline noodle properties. Can. J. Plant Sci. 83:11–21. Hatcher, D. W., Symons, S. J., and Manivannan, U. 2004. Developments in the use of image analysis for the assessment of Oriental noodle appearance and colour. J. Food Eng. 61:109–117. Hatcher, D. W., Lagasse, S., Dexter, J. E., Rossnagel, B., and Izydorczyk, M. 2005a. Quality characteristics of yellow alkaline noodles enriched with hull-less barley flour. Cereal Chem. 82:60–69. Hatcher, D. W., Symons, S. J., and Kruger, J. E. 1999. Measurement of the time-dependent appearance of discolored spots in alkaline noodles by image analysis. Cereal Chem. 76:189–194. Hatcher, D. W., Lukow, O. M., Dexter, J. E., Shahin, M., and Edwards, N. M. 2005b. Recent advances in Canadian research on Asian noodles. In: Proceedings of the 55th Cereal Chemistry Conference. Cereal Chemistry Division, Royal Australian Chemical Institute, Sydney, Australia. Hatcher, D. W., Lukow, O. M., and Dexter, J. E. 2006. Influence of environment on Canadian Hard White Spring wheat noodle quality. Cereal Food World 51:184–190. Hatcher, D. W., Dexter, J. E., and Edwards, N. M. 2008. Impacts of the particle size and starch damage of flour and alkaline reagent on yellow alkaline noodle characteristics. Cereal Chem. 85:425–432. Hawthorn, J. and Todd, J. P. 1955. Catalase in relation to the unsaturated fat oxidase activity of wheat flour. Chem. Ind. (Berlin) 446–447. Hsieh, C. C. and McDonald, C. E. 1984. Isolation of lipoxygenase iso-enzymes from flour of durum wheat endosperm. Cereal Chem. 61:392–398. Hutchings, J. B. 1994. Food Colour and Appearance. Blackie Academic and Professional, Glasgow, Scotland. Interesse, F. S., Ruggiero, P., Lamparelli, F., and D’Avella, G. 1981. Isoenzymes of wheat o-diphenolase revealed by column isoelectric focusing. Z. Lebensm. Unters. Forsch. 172:100–103.

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Izydorczyk, M. S., Lagasse, S. L., Hatcher, D. W., Dexter, J. E., and Rossnagel, B. G. 2005. The enrichment of Asian noodles with fiber-rich fractions derived from roller milling of hull-less barley. J. Sci. Food Agric. 85:2094–2104. Kim, K. H. and Char, W. J. 1998. Effects of some organic acids on shelf-life and textural properties of cooked noodles. Agric. Chem. Biotech. 41:175–180. Kruger, J. E. and LaBerge, D. E. 1974a. Changes in peroxidase activity and peroxidase isozyme patterns of wheat during kernel growth and maturation. Cereal Chem. 51:345–354. Kruger, J. E. and LaBerge, D. E. 1974b. Changes in peroxidase activity and peroxidase isozymes during germination. Cereal Chem. 51:578–585. Kruger, J. E., Matsuo, R. R., and Preston, K. R. 1992. A comparison of methods for the prediction of Cantonese noodle color. Can. J. Plant Sci. 72:1021–1029. Kruger, J. E., Hatcher, D. W., and Dexter, J. E. 1995. Influence of sprout damage on oriental noodle quality. In: K. Noda and D. J. Mares (eds.), PreHarvest Sprouting in Cereals, Center for Academic Societies, Osaka, Japan, pp. 9–18. Lagasse, S. L., Hatcher, D. W., Dexter, J. E., Rossnagel, B. G., and Izydorczyk, M. S. 2006. Quality characteristics of fresh and dried white salted noodles enriched with flour from hull-less barley genotypes of diverse amylose content. Cereal Chem. 83:202–210. Mares, D. J., Wang, Y., and Cassidy, C. A. 1997. Separation, identification and tissue location of compounds responsible for the yellow colour of alkaline noodles. In: A. W. Tarr, A. S. Ross, and C. W. Wrigley (eds.), Proceedings of the 47th Cereal Chemistry Conference. Cereal Chemistry Division, Royal Australian Chemical Institute, Melbourne, Australia, pp. 114–117. Markowski, M., Cenkowski, S., Hatcher, D. W., Dexter, J. E., and Edwards, N. M. 2003. The effects of superheated-steam dehydration kinetics on textural properties of Asian noodles. Trans. Am. Soc. Appl. Eng. 46:389–395. Marsh, D. R. and Galliard, T. 1986. Measurements of polyphenol oxidase activity in wheatmilling fractions. J. Cereal Sci. 4:241–248. Miskelly, D. M. 1996. The use of alkali for noodle processing. In: J. E. Kruger, R. B. Matsuo, and J. W. Dick (eds.), Pasta and Noodle Technology. American Association of Cereal Chemists, St. Paul, MN, USA, pp. 227–273. Oh, N. H., Seib, P. A., Deyoe, C. W., and Ward, A. B. 1983. Noodles. I. Measuring the textural characteristics of cooked noodles. Cereal Chem. 60:433–438. Pierpoint, W. S. 1969. o-Quinones formed in plant extracts: their reactions with amino acids and peptides. Biochem. J. 112:609–616. Ross, A. S. 2006. Instrumental measurement of physical properties of cooked Asian wheat flour noodles. Cereal Chem. 83:42–51. Ross, A. S. and Hatcher, D. W. 2005. Guidelines for the laboratory manufacture of Asian wheat flour noodles. Cereal Foods World 50:296–304. Ross, A. S., To, S., Chiu, P. C., and Quail, K. J. 1998. Instrumental evaluation of white salted noodle texture. In: L. O’Brien, A. B. Blakeney, A. S. Ross, and C. W. Wrigley (eds.), Cereals ’98. Proceedings of the 48th Australian Cereal Chemistry Conference. RACI, North Melbourne, Australia, pp. 199–203. Sasaki, T., Yasui, T., Matsuki, J., and Satake, T. 2004. Rheological properties of white salted noodles with different amylose content at small and large deformation. Cereal Chem. 79:861–866.

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Schooneveld-Bergmans, M. E. F., Dignum, M. J. W., Grabber, J. H., Beldman, G., and Voragen, A. G. J. 1999. Studies on the oxidative cross-linking of feruloylated arabinoxylans from wheat flour and wheat bran. Carbohydr. Polym. 38:309–317. Seib, P. A., Liang, X., Guan, F., Liang, Y. T., and Yang, H. C. 2000. Comparison of Asian noodles from some hard white and hard red wheat flours. Cereal Chem. 77:816–822. Shimizu, T., Fukawa, H., and Ichiba, A. 1958. Physical properties of noodles. Cereal Chem. 35:34–46. Singh, H., Rockall, A., Martin, C. R., Chung, O. K., and Lookhart, G. L. 2006. The analysis of stress relaxation data of some viscoelastic foods using a texture analyzer. J. Text. Studies 37:383–392. Szczesniak, A. S. 2002. Texture is a sensory property. Food Quality Preferences 13:215–225. Tang C., Hsieh, F., Heymann, H., and Huff, H. E. 1999. Analyzing and correlating instrumental and sensory data: a multivariate study of physical properties of cooked wheat noodles. J. Food Quality 22:193–211. Voisey, P. W., Larmond, E., and Wasik, R. 1978. Measuring the texture of cooked spaghetti. 1. Sensory and instrumental evaluation of firmness. J. Inst. Can. Technol. Alimentary 11:142–148. Yu, L. J. and Ngadi, M. O. 2004. Textural and other quality properties of instant fried noodles as affected by some ingredients. Cereal Chem. 81:772–776.

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CHAPTER 10

Sensory Evaluation of Noodles BIN XIAO FU and LINDA MALCOLMSON

10.1. INTRODUCTION Sensory evaluation is considered the most reliable method for measuring the quality attributes of noodles. Besides the parameters of appearance, texture, and flavor, the processing characteristics of noodles can be evaluated using sensory rating scales. Two distinct types of sensory tests exist, including product- and consumer-oriented tests. In product-oriented tests, trained panelists evaluate the quality attributes of a product, whereas in consumer-oriented tests, untrained panelists evaluate the overall acceptability or degree of liking for a product. Product-oriented tests are considered objective since they meet the criteria of objectivity: freedom from personal bias and repeatability. In contrast, consumer-oriented tests by their very nature are subjective since it is the subjective information, personal likes and dislikes, that is of interest. As indicated in Table 10.1, within each type of sensory test, there are a number of sensory methods that can be used. Descriptive tests are the main tests used to evaluate noodle quality. These tests involve rating the intensity of several attributes that define noodle quality. The resulting information provides a full description or profile of the noodles.

10.2. CLASSIFICATION OF NOODLES The invention of many noodle formulations and processing techniques by the Chinese, coupled with the advanced technology developed by the Japanese, have made Asian noodles an international food product. Despite their ancient origins, noodles have undergone considerable evolution and migration, as the products become increasingly globalized. The modification of formulations and processing techniques can be linked to regional eating habits, taste preferences, and advances in technology. The regional differences in formulations and processing have resulted in country-specific systems Asian Noodles: Science, Technology, and Processing, Edited by Gary G. Hou C 2010 John Wiley & Sons, Inc. Copyright


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TABLE 10.1

Summary of Product-Oriented and Consumer-Oriented Sensory Tests

Sensory Test Type

Sensory Methods

Product-oriented

Threshold—measures the minimum or maximum level at which a sensory characteristic can be detected. Difference—determines if a difference between two products can be detected. Scaling—measures the intensity of a product attribute. Duration—measures the duration an attribute can be detected. Descriptive analysis—measures the intensity of several attributes of a product using rating scales. Scoring—measures the intensity of several attributes of a product using a numerical scoring system.

Consumer-oriented

Acceptance—measures the overall acceptability of a product. Preference—determines which of two products is preferred. Hedonic—measures the degree of liking or disliking for a product using a rating scale.

for noodle classification. Thus, there exist wide differences in the nomenclature for noodles among countries. For example, “ramen” refers primarily to fresh yellow alkaline noodles in Japan but is mainly used to refer to instant noodles in Korea. There is a need to standardize noodle nomenclature based on the raw material used, salt composition, processing method, and even the size of noodle strands. Noodles made from nonwheat grains are easily distinguished by including the raw material as part of their name, such as is the case with rice noodles, bean threads, and buckwheat noodles. Classification of wheat flour noodles is much more complex because of the wide variation in formulations and manufacturing methods that are used. Thus, wheat flour noodles require at least the identification of the salt composition and the basic processing method used as a means for classifying the noodle type. Wheat flour noodles exist in two distinct categories based on the presence or absence of alkaline salt or salts (mainly Na2 CO3 and/or K2 CO3 ). The alkaline salt has a great impact on the color, flavor, and texture of noodles (Miskelly 1996). Noodles based on flour, water, and regular salt (NaCl) were developed in northern China, and the addition of alkaline salt appears to have originated in the very south of China in the provinces of Canton and Hokkien. Alkaline noodles represent less than 10% of total noodle production in China, the rest being mainly regular salted noodles. Although alkaline noodles were introduced to Japan from China much later than regular salted noodles, alkaline noodles today have a slightly higher market share than regular salted noodles in Japan (Nagao 1991). Confusion occurs when regular salted noodles are referred to as “Japanese type” and the alkaline salt noodles are referred to as “Chinese type.” Regular salted noodles are made from a simple flour-and-water dough with 2–8% salt based on flour weight. The actual amount of salt depends on the noodle type

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and its processing. Regular salted noodles are widely consumed in China, Japan, and Korea but represent only a very small proportion of the total noodles produced in Southeast Asia. There are three major forms of regular salted noodles—fresh, dried, and boiled. Newer types, including frozen, boiled, and long-life noodles, are becoming increasingly popular. The thin and very thin noodles are usually marketed in a dry form produced by controlled drying of fresh noodle strands. Standard udon noodles are mostly produced in the boiled form. Although most noodles are made by machine, hand-made regular salted noodles are still very popular in Asia. The application of alkaline salt in noodle making originated in southern China. In ancient times, kansui (lye water) was extracted by boiling lye stone or plant ash in water. The most common alkaline salts used today are sodium carbonate or potassium carbonate, or a mixture of the two. Other alkaline salts, such as polyphosphates, are often used in the manufacture of instant noodles. It is not uncommon to find the application of sodium hydroxide in the partially boiled noodles made in Southeast Asia. The incorporation of alkaline salts changes the pH of the noodles to a range somewhere between 9 and 11, depending on the salts used, and their ionic strengths (Miskelly 1996). Alkaline noodles have a characteristic aroma and flavor, a yellow color, and a firm, elastic texture. There are many different types of alkaline noodles in Asia. The most popular types are fresh (ramen, wonton, or bamee noodles), partially boiled (hokkien noodles), and fresh or steamed with egg as an ingredient (chow mien). Wheat-flour-based Asian noodles are produced by a relatively simple process (Wu et al. 1998). Flour, water (about half the amount for bread making), salt, or alkaline salts are mixed together to evenly distribute the ingredients and hydrate the flour particles. Other ingredients can include starch, gums, liquid egg, food colorings, and preservatives. The crumbly dough is sheeted between rollers a few millimeters apart to form a dough sheet. After the first pass, the dough sheet is not uniform and the surface is rough. Therefore, two dough sheets are usually combined before the second pass. The combined dough sheet is often rested to relax the gluten structure before continuing with a further sequence of three to five passes through the sheeting rollers. These sheeting stages serve to develop the gluten-starch network and reduce the dough sheet to the desired thickness. Sheets are cut into strands using slotted cutting rolls to produce noodles of the required width, which are then cut to the desired length. The basic process of dough mixing, sheet forming, compounding, sheeting/reduction, and cutting are essentially constant for all machine-made noodles. Noodle strands coming out of cutting rolls can be further processed to produce different types of noodles: air-dried, boiled, steamed, frozen, instant-fried, and freeze-dried noodles. Detailed processing technology and quality characteristics of these noodle types are described in Chapter 5.

10.3. QUALITY CHARACTERISTICS OF MAJOR NOODLE TYPES Due to their importance in consumer acceptance, appearance and texture play essential roles in noodle quality. The major criteria for noodle quality evaluation include

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brightness, color, color stability, and speckiness in terms of appearance, and firmness, elasticity, surface smoothness, and stickiness in terms of texture. Generally, the preferred appearance for noodle products is bright, with slow discoloration and no or very few specks. Depending on noodle types and regional preferences, noodle color will range from white, to creamy-white, to light yellow, to intense lemon-yellow. In Southeast Asia, partially boiled alkaline noodles (e.g., hokkien noodles) are much brighter and more yellow than fresh alkaline noodles (e.g., wonton noodles). The acceptable brightness of wonton noodles in Southeast Asia can be significantly lower than that of ramen noodles in Japan. Most instant noodles produced in Japan and Korea are lighter and brighter than those produced in other Asian countries. The al dente texture of spaghetti, preferred by most pasta consumers, is considered to be too firm and too brittle for Asian noodles. Consumers in Asia require noodles to have a smooth, elastic, and chewy texture. Brittleness is usually associated with low elasticity and lack of chewiness. The desired degree of firmness depends on noodle types and personal preference. Fresh noodles are raw, wet noodles. No further processing is applied in the factory after the sheeted dough is cut into noodle strands of desired length and width. The main disadvantage of fresh noodles is their relatively short shelf life, ranging from one day to several days, depending on the packaging and storage conditions. Fresh noodles should have an adequate shelf life without visible microbiological deterioration during storage. Fresh alkaline noodles should be firm, elastic, and smooth in texture, and they should maintain a good texture in hot broth. Consumers prefer noodles that are bright and clean in appearance, but the degree of yellowness preferred varies according to the region. The appearance of regular salted noodles should be bright, with clean color ranging from white to creamy white, and with a smooth, glossy surface after boiling (Nagao 1991). The preferred textural properties of boiled regular salted noodles are soft and elastic with a smooth surface (Crosbie and Ross 2004). Some consumers, however, prefer noodles with firm, elastic, and chewy texture (Huang 1996). Dried noodles are raw noodles produced by controlled drying of uncooked wet noodle strands. The final moisture content of dried noodles is usually less than 14%. Because of their low moisture content, dried noodles have a long shelf life of 1–2 years. High-quality dried noodles have a bright, clean, and smooth surface. Noodle strands should be straight and strong but not brittle, without cracking, warping, and splitting. When cooked, noodles should have a texture that is elastic, smooth, and moderately firm. Steamed noodles are partially cooked by treating fresh noodles with either saturated or unsaturated steam before they are marketed. The moisture content of the final product usually varies from 28% to 60%. The surface of steamed noodles should be smooth with limited swelling. Noodle strands should be bright, clean, and low in stickiness. A greater extent of starch gelatinization is preferred for a faster cooking and elastic texture. Boiled noodles are precooked in boiling water. These noodles are generally divided into two groups: partially boiled noodles and fully boiled noodles. Boiled noodles should not become mushy or soggy and should retain their integrity of size and shape.

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They should have a bright, clean appearance and desirable textural properties. The texture of fully boiled noodles deteriorates very quickly after cooking. The texture retention property is an important criterion when evaluating boiled-noodle quality. Steamed and deep-fried noodles are partially cooked by steaming and further cooked and dehydrated by a deep-frying process. The noodle packs should be strong enough to avoid breakage during transportation and have a reasonable shelf life without oxidative rancidity. An elastic, chewy, and smooth texture with bright appearance is preferred by most consumers (Kim 1996). The degree of firmness and yellow intensity varies greatly by region. Good texture retention properties are also important. Health concerns regarding fried noodles have led to the production of steamed and air-dried noodles. They are produced in a fully automatic production line similar to the type used for steamed and deep-fried noodles, except that a continuous drying chamber replaces the deep fryer, using hot air as the drying medium. Elasticity, chewiness, and long texture retention are key properties for hot-air dried instant noodles, which are usually much smaller in strand size than those of deep-fried instant noodles.

10.4. SENSORY EVALUATION OF NOODLE QUALITY The attributes of appearance and texture are the main criteria for evaluating noodle quality due to their importance in consumer acceptability. Both attributes will vary significantly, depending on the region where the noodles are consumed and the method used to produce the noodles. 10.4.1. Preparation of Noodles for Quality Assessment The cooking and preparation of noodles for sensory testing are dependent on the noodle type. For example, udon noodles should be rinsed in cold water before presenting to panelists, whereas yellow alkaline noodles should be served in hot broth. Evaluation of the textural properties should begin immediately after the noodles have been cooked. It is important to allow panelists time to monitor changes in texture after cooking since, for some noodles, texture and stability in hot broth are important quality attributes. The use of a standard noodle is recommended in quality assessments since it allows panelists to rate samples in relation to the standard noodle, thereby ensuring panelists are consistent in their sensory judgments. Noodle samples should be served in such a way that no information about the noodles is provided that may influence the panelists’ rating of the noodles. For this reason it is recommended that samples be coded with random three-digit numbers. 10.4.2. Panelists Panelists require training on the attributes and procedures they must follow for assessing the various quality attributes. This requires several sessions in which panelists

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receive instructions and samples varying in the intensities of the attributes being evaluated. It may be necessary to provide reference samples to assist them with their evaluations. During training, panelists learn to disregard their personal preferences and learn to focus on the attributes of interest. Training continues until panelists are in agreement with each other on their ratings, and they are able to reproduce their judgments from one session to another. 10.4.3. Sensory Facilities Sensory testing should be carried out in a setting that is comfortable and free of distractions so that panelists can focus on the task. Proper sensory facilities, designed with individual booths, are recommended. For color evaluations, proper lighting must be provided to ensure panelists are able to provide reliable and consistent ratings. 10.4.4. Sensory Test Methods Used for Assessing Noodles Several scoring methods have been developed to assess the quality attributes of noodles. The Japanese Standard Methods (Anon. 1985), designed for rating the quality of udon noodles, assigns scores for color, appearance, texture, and taste to a maximum score of 100. A high score indicates high quality. Noodles are served cold with a sauce or broth. Scores are assigned to the various attributes as follows: color (25), surface appearance (20), firmness (10), elasticity (25), smoothness (10), and taste/flavor (10). Comparison against a standard noodle is recommended. The method also allows for other assessments, including raw noodle color (before and after storage for 24 hours at room temperature), ease of processing, including condition of the mixed dough, stickiness of the dough sheet during rolling, condition of the surface of the dough sheet (smoothness), and condition of the cut noodle (cleanness of the cut). These attributes are rated as good, average, fairly good, and bad. Crosbie et al. (1992) used the Japanese Standard Methods to assess udon noodles made from Australian flours. Noodles made from the control flour were given scores for each of the attributes that were 70% of the maximum score possible on the official Japanese scale as follows: color (17.5), surface appearance (14), softness/firmness (7), elasticity (17.5), smoothness (7), and taste (7). The minimum possible score that could be assigned was 40% of the maximum, which was assigned only to very poor-quality noodles such as those prepared from weather-damaged wheats. Konik et al. (1993) devised a scoring system based on the Japanese Standard Method whereby udon noodles were served cold with broth and panelists were asked to score the noodles for smoothness (maximum 10, allowing for increments of 0.5), softness (maximum of 10, increments of 0.5), and elasticity (maximum of 30, increments of 1.5). Higher scores were assigned to noodles with a springy, more elastic texture, smoother surface texture, and soft, delicate texture when chewed. Color (maximum 30 points, increments of 0.5) was assessed on both raw and cooked noodles, with higher scores assigned to noodles with a clean, bright, and creamy appearance. Two noodle scores were calculated to provide overall noodle quality ratings. An eating-quality score was obtained by adding the scores for smoothness,

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softness, and elasticity, and a noodle score was obtained by adding the scores of eating quality and color. Konik et al. (1994) also established a scoring system to rate the quality of yellow alkaline noodles. In this scoring system, noodles were presented to the panelists in hot tap water (60 ◦ C) and the panelists assigned numbers for color and eating quality as follows: cooked noodle color (10), raw noodle color immediately after processing (10), and after 24 hours (10), smoothness (10), firmness (10), and elasticity (10). Total eating quality and color scores were then determined by adding the appropriate attributes. A final noodle score was then calculated by adding the eating-quality and color scores and converting to a percentage. Crosbie et al. (1999) developed a scoring system for assessing yellow alkaline noodles, using noodles that were held for 24 hours at 5 ◦ C prior to cooking. Once the noodles were cooked, panelists rated the noodles twice, immediately after cooking (within 2–3 min) and after immersion in hot water or soup for 7 minutes. Texture was assessed as a single score representing a balance of springiness, firmness, smoothness, and “cutting feel.” Noodles with a firm, springy, smooth, and clean, nonsticky “cutting feel” were considered to have high quality. A maximum score of 20 was allowed for the overall texture score, with 14 points (70% of the maximum score) assigned to noodles made from the control flour. Hou (2001) reported scoring systems for various noodle types based on three main sensory characteristics: process performance, noodle color, and texture. For each scoring system, there was a maximum total score of 100, but the weight assigned to each sensory characteristic that made up the final score was dependent on the noodle type (Table 10.2). The scoring sheets used to evaluate the various noodle types were provided, including Chinese raw noodles, Chinese wet noodles (Taiwan), Chinese wet noodles (Malaysia), chuka-men noodles, udon noodles, Chinese fried instant noodles, Korean fried instant noodles, and Thailand bamee noodles. In addition, the evaluation criteria for noodle color and texture and for noodle processing, including mixing, sheeting, slitting, waving and steaming, frying, air drying, parboiling, and cooking, were provided. Other researchers have used descriptive analysis techniques to evaluate the quality of noodles. Unlike scoring systems, descriptive analysis methods do not allow for the adding together of attributes to obtain an overall quality score. Each attribute is evaluated on an intensity rating scale and is reported separately so that an overall profile of the product is obtained. Yun et al. (1997) evaluated the eating quality of cooked udon noodles and the color of cooked and raw noodles using rating scales that were based on the Japanese Standard Method (Anon. 1985). Softness, elasticity, surface smoothness, brightness, yellowness (creaminess), and discoloration were rated using 15-cm unstructured line scales. The left limits on the scales were “very firm,” “very nonelastic,” “not smooth,” “very dull,” “very yellow,” and “very discolored.” Ross et al. (1997) used the same texture rating scales to measure the firmness, elasticity, and surface smoothness of yellow alkaline noodles. Tang et al. (1999) also used 15-cm unstructured line scales to rate the appearance and textural properties of wheat noodles, including yellow color (the intensity of

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TABLE 10.2

Scoring Criteria for Noodles Noodle Characteristic and Score Allocation Noodle Process

Noodle Color

Noodle Texture

25 Not included in score 15

30 25

45 45

20

40

25

40

20

Chuka-men (Japan)

Not included in score

30

40

Chinese fried instant Korean fried instant

35 25

10 9

55 30

Thailand bamee (egg noodles)

10

45

20

Noodle Type Chinese raw Japanese udon Chinese wet (Taiwan) Chinese wet (Malaysian)

Other 0 Surface appearance (20), taste (10) Cooking weight gain (25) Cooking weight gain (10), shelf life after 48 hours (5) Speckiness of raw noodles (20), taste (10) 0 Noodle cooking properties (30), taste (6) Dryness (10), cooking quality (10), cooked noodle surface smoothness (5)

Source: Hou (2001).

the yellow color of noodle surfaces), translucency (the extent to which the light glows through the noodle), shininess (the extent to which the light reflects on the noodle surface), surface smoothness (the size of the pinholes on noodle surface), firmness (the force required to cut through the noodle using the front teeth), and chewiness (the length of time required to masticate the noodle to a state ready for swallowing). Surface stickiness and elasticity were also measured using nonoral techniques. Surface stickiness was evaluated by rating the extent to which two strands of noodles stuck together when separated by using the hands, and elasticity was rated by rating the extent to which one noodle strand returned to its original size after stretching with the hands. The appearance attributes of glossiness and translucency of regular salted white noodles were measured by Solah et al. (2007) using 15-cm unstructured line scales. Each rating scale was anchored at each end with opposing extremes of “matte” and “high gloss” for the glossiness scale and “opaque” and “translucent” for the translucency scale. Kim and Wiesenborn (1996), Kim et al. (1993) evaluated the quality of edible bean and potato starch noodles by measuring the translucency, slipperiness, firmness, chewiness, and tooth packing using 15-cm line scales anchored with the terms “low intensity” and “high intensity.” They also used 10-cm unstructured line scales to rate glossiness, transparency, firmness, stickiness, and elasticity of starch noodles. Each

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scale was anchored with the terms “low intensity” and “high intensity,” and panelists rated the samples in relation to a standard noodle sample that was premarked with an assigned rating on each of the scales. Fu (personal communication, 2008) uses a combination of rating scales and a scoring system to evaluate the appearance (color and surface smoothness), texture (smoothness, firmness, elasticity), and taste/flavor of noodles. Panelists mark their ratings using 10-cm semistructured line scales anchored with the following endpoint descriptors: “dull, pale color” and “bright, creamy color” for the color scale; “rough” and “smooth” for the surface smoothness scale; “low degree” to “high degree” for the textural smoothness scale: “firm” to “soft” for the firmness scale; “low degree” to “high degree” for the elasticity scale; and “intense” to “slight” for the taste/flavor scale. Individual ratings are then weighed according to the weightings assigned to each attribute as follows: color (20), surface smoothness (15), textual smoothness (15), firmness (10), elasticity (25), and taste/flavor (15). In this way, the attribute that contributes more to the overall quality is assigned a greater value when the results are tallied and interpreted. The most extensive characterization of noodle texture was reported by Janto et al. (1998). Seventeen textural descriptors that covered four stages of evaluation— (1) surface, (2) first chew, (3) chew-down, and (4) expectoration—were compiled. The descriptors included wetness, slipperiness, microroughness, macroroughness, firmness, cohesiveness, springiness, starch between teeth, toothpull, cohesiveness of mass, starchy matrix, integrity of noodles in matrix, condition of mass, chalkiness, sticky film, and greasy mouthfeel. Panelists rated each attribute using 16-point intensity scales, where 0 = none and 15 = extreme, and reference samples were provided for each scale representing low, medium, and high ends of the scale. Janto et al. (1998) successfully used the rating scales to profile the textural properties of Taiwanese, Thai, and Malaysian noodles. Two descriptive terms, macroroughness and condition of mass, were found to be nondiscriminatory terms and were dropped. The practicality of rating so many attributes in routine quality assessments remains questionable and explains why most quality assessment programs focus on the main textural quality attributes of firmness, elasticity, surface smoothness, and stickiness.

10.5. SUMMARY The use of sensory evaluation to assess the quality attributes of noodles is critical in any quality evaluation program. Careful control must be taken to prepare and serve the noodles under conditions that are consistent with how the noodles are consumed in the marketplace. Selection of the attributes to be evaluated will be dependent on the types of noodles being evaluated as well as the interpretation of the resulting data. It is important that there is a clear understanding of the quality attributes that are critical for the noodles being evaluated; otherwise, the resulting sensory data may be misinterpreted. Panelists must be trained to perform the quality assessments on the noodles to ensure reliable data is gathered. The use of scoring systems or descriptive analysis techniques is recommended to achieve a comprehensive profile of the quality characteristics of the noodles being evaluated.

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REFERENCES Anon. 1985. Quality assessment of wheat-sensory tests for noodles. Published by National Foods Research Institute, Ministry of Agriculture, Forestry and Fisheries, Japan. Crosbie, G. B. and Ross, A. S. 2004. Asian wheat flour noodles. In: C. Wrigley (ed.), Encyclopedia of Grain Science. Elsevier Ltd., Oxford, UK, pp. 304–312. Crosbie, G. B., Lambe, W. J., Tsutsui, H., and Gilmour, R. F. 1992. Further evaluation of the flour swelling volume test for identifying wheats potentially suitable for Japanese noodles. J. Cereal Sci. 15:271–280. Crosbie, G. B., Ross, A. S., Moro, T., and Chiu, P. C. 1999. Starch and protein quality requirements of Japanese alkaline noodles (ramen). Cereal Chem. 76(3):328–334. Hou, G. 2001. Oriental noodles. Adv. Food Nutr. Res. 43:141–193. Huang, S. 1996. China—the world’s largest consumer of paste products. In: J. E. Kruger, R. B. Matsuo, and J. W. Dick (eds.), Pasta and Noodle Technology. American Association of Cereal Chemists, St. Paul, MN, USA, pp. 301–325. Janto, M., Pipatsattayanuwong, S., Kruk, M. W., Hou, G., and McDaniel, M. R. 1998. Developing noodles from US wheat varieties for the Far East market: sensory perspective. Food Quality Preference 9:403–412. Kim, S. K. 1996. Instant noodles. In: J. E. Kruger, R. B. Matsuo, and J. W. Dick (eds.), Pasta and Noodle Technology. American Association of Cereal Chemists, St. Paul, MN, USA, pp. 195–225. Kim, Y. S. and Wiesenborn, D. P. 1996. Starch noodle quality as related to potato genotypes. J. Food Sci. 61(1):248–252. Kim, Y. S., Wiesenborn, D. P., Lorenzen, J. H., and Berglund, P. 1996. Suitability of edible bean and potato starches for starch noodles. Cereal Chem. 73(3):302–308. Konik, C. M., Miskelly, D., and Gras, P. 1993. Starch swelling power, grain hardness and protein: relationship to sensory properties of Japanese noodles. Starke 45(4):139–144. Konik, C. M., Mikkelsen, L. M., Moss, R., and Gore, P. J. 1994. Relationships between physical starch properties and yellow alkaline noodle quality. Starke 46(8):292–299. Miskelly, D. M. 1996. The use of alkali for noodle processing. In: J. E. Kruger, R. B. Matsuo, and J. W. Dick (eds.), Pasta and Noodle Technology. American Association of Cereal Chemists, St. Paul, MN, USA, pp. 227–273. Nagao, S. 1991. Noodles and pasta in Japan. In: D. J. Martin and C. W. Wrigley (eds.), Cereals International. Royal Australian Chemistry Institute, Brisbane, Australia, pp. 22–25. Ross, A. S., Quail, K. J., and Crosbie, G. B. 1997. Physiochemical properties of Australian flours influencing the texture of yellow alkaline noodles. Cereal Chem. 74(6):814–820. Solah, V. A., Crosbie, G. B., Huang, S., Quail, K., Sy, N., and Limley, H. A. 2007. Measurement of color, gloss, and translucency of white salted noodles: effects of water addition and vacuum mixing. Cereal Chem. 84(2):145–151. Tang, C., Hsieh, F., Heymann, H., and Huff, H. E. 1999. Analysis and correlating instrumental and sensory data: a multivariate study of physical properties of cooked wheat noodles. J. Food Quality 22:193–211. Wu, T. P., Kuo, W. Y., and Cheng, M. C. 1998. Modern noodle based foods—product range and production methods. In: A. B. Blakeney and L. O’Brien (eds.), Pacific People and Their Food. American Association of Cereal Chemists, St. Paul, MN, USA, pp. 37–90. Yun, S.-H., Rema, G., and Quail, K. 1997. Instrumental assessments of Japanese white salted noodle quality. J. Sci. Food Agric. 74:81–88.

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CHAPTER 11

Effects of Flour Protein and Starch on Noodle Quality BYUNG-KEE BAIK

11.1. INTRODUCTION 11.1.1. Asian Noodles Wheat flour noodles are widely consumed in many Asian countries and traditionally prepared from relatively common ingredients with varied degrees of processing to yield a diversity of products. Wheat flour, salt and/or alkali, and water are mixed into crumbly dough, passed through rolls multiple times to form a dough sheet, and cut into noodle strands. Freshly prepared noodles may be further dried, cooked, or steamed and fried for the production of dehydrated, precooked, or instant fried noodles, respectively. Soft-bite white salted noodles are particularly common in Japan and Korea, while hard-bite noodles are consumed in Japan, South Asia, and China. Instant fried noodles are currently the most common noodles produced and consumed in Asian countries. The consumption of instant fried noodles is continuously growing throughout Asia, as well as in Western countries, because of their convenience and versatility. Approximately 40% of the total wheat flour utilized for food in Asian countries is consumed in the form of noodle products (Miskelly 1996). Until the late 1970s, our interest in and knowledge of quality of noodles and quality of wheat suitable for making noodles was quite minimal, especially compared to those qualities for making bread. Bread has been a major wheat-based product in many Western countries, where processors’ and consumers’ demand for high milling and baking quality wheat has led to extensive research efforts for improvement of wheat quality. Great advances in our understanding of the physical and chemical characteristics of wheat and their significance on milling and baking bread have been utilized to improve processing and end-product quality. On the other hand, noodles are produced and consumed mostly in Asian countries, where securing a large quantity of foods and the price of wheat rather than its quality have been primary concerns. Asian Noodles: Science, Technology, and Processing, Edited by Gary G. Hou C 2010 John Wiley & Sons, Inc. Copyright


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Efforts toward improving wheat bound for noodle production have focused mainly on increasing yield, with minimal consideration of its end-use quality. With economic improvements in many Asian countries, however, consumers increasingly demand noodles of improved quality, and flour millers and food manufacturers are becoming more aware of the importance of wheat grain quality in addition to price. These changes, consequently, have led to increased research efforts in wheat quality issues related to noodles in many countries that are exporting wheat to Asia. Competition among the major wheat exporting countries, including the United States, Canada, and Australia, for the wheat-market share in Asian countries has also triggered their increased attention to end-use quality improvement of wheat. Since the 1980s, numerous research articles investigating major quality parameters (such as texture and color) of noodles and their objective evaluations, significance, and role of flour components (including starch, protein, lipids, and polyphenol oxidase) on processing and product quality of noodles have been published in research journals. There has been significant progress in our understanding of important processing and product quality parameters of noodles, raw material requirements for various types of Asian noodles, and the role of each flour component in noodle making. 11.1.2. Quality Requirements for Asian Noodles The suitability of wheat flour for making noodles is assessed in terms of both processing properties and product quality. Dough mixing and sheeting properties, including water absorption, cohesiveness, smoothness, and strength of dough sheet, are crucial processing parameters for making noodles (Oh et al. 1985a). Appearance, cooking properties (time, loss, and absorption), and texture of cooked noodles ultimately determine the quality of noodles. Formation of a continuous and smooth-surfaced dough sheet that is free of gray discoloration is a universal processing quality required for the preparation of highquality Asian noodles. Small cooking loss, high cooking yield, and short cooking time are also preferred for all types of noodles. Various types of Asian noodles, however, differ widely in the preferred textural properties. Soft-bite white salted noodles, when cooked, should have a soft, cohesive texture with a smooth surface and clean bite (Lee et al. 1987). A firm, elastic texture is preferred for cooked hard-bite white salted noodles as well as for alkaline noodles. Alkaline noodles are popular in Southeast Asian countries and they are prepared from wheat flour mixed with water and alkaline instead of salt to induce yellow color and firm texture. Low fat absorption during frying and a relatively strong bite with a firm and nonsticky surface are required quality factors for instant fried noodles. Noodle color is influenced by inherent pigments of the wheat kernel, flour extraction rate and particle size, and protein and ash content. The association of polyphenol oxidase (PPO) with noodle discoloration has been verified by Hatcher and Kruger (1993), Baik et al. (1995), and Crosbie et al. (1992). Many quantitative assays of wheat have been developed to identify breeding lines of low PPO content (Bernier and Howes 1994; Kruger et al. 1994; McCaig et al. 1999; Anderson and Morris

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2001), and are commonly utilized in breeding programs to select wheat lines with desirable noodle color characteristics. Starch and protein, two major components of wheat flour, largely determine the processing and product quality of many wheat-based foods, not only because of their proportions in wheat flour, but also due to their wide variations in functional properties. Especially in Asian noodles, which are prepared from simple basic ingredients (flour, water, salt, and/or alkali) with simple and straightforward processing (dough mixing, sheeting, and slitting), physicochemical characteristics of starch and protein may play a much bigger role in processing and product quality than in any other baked products including bread, cookies, cakes, and pastries. Water absorption for making noodles, dough mixing and sheeting, frying and cooking, as well as texture of cooked noodles, are all largely governed by the quantitative and qualitative characteristics of starch and protein. Challenges in the investigation of starch and protein functional properties suitable for making noodles arise from the wide diversity of Asian noodles and their differences in end-use quality requirements. White salted noodles, popularly consumed in Japan and Korea, require soft and cohesive texture upon cooking; while Chinese white salted noodles require firm and chewy cooked noodle texture. Cooked instant fried noodles should be chewy, with minimum stickiness and sogginess upon cooking and even a few minutes after cooking. Accordingly, to meet the processing and textural property requirements for each type of noodle, it is necessary to clearly identify the role of flour components, primarily starch and protein, as well as their optimum quantity and quality in wheat flour. A better understanding of starch and protein characteristics suitable for making each type of Asian noodle is crucial for breeding noodle wheat variety as well as improvement of noodle processing and product quality. This chapter will discuss the role and significance of wheat starch and protein on processing and product quality of Asian noodles. Starch and protein of wheat flour suitable for making various types of Asian noodles in terms of quantity and quality will also be discussed even though drawing a universal conclusion is a difficult or impossible task due to the wide variation in types of noodles and their differences in ingredients, processing, and quality requirements.

11.2. PROTEIN CHARACTERISTICS FOR ASIAN NOODLES 11.2.1. Role and Significance of Protein Both quantity and quality of wheat flour protein exert a large influence on processing and product quality of noodles (Miskelly and Moss 1985; Oh et al. 1985b; Huang and Morrison 1988). Wheat flour protein affects the noodle-making process, especially in the formation of a continuous dough sheet and subsequent noodle strands. During noodle dough mixing, protein absorbs water and forms a limited gluten network, which glues other wheat flour components together, resulting in crumbly dough.

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During the continuous and repeated sheeting process (passing through a series of rolls with reduced roller gaps), gluten is further developed and aligned to the sheeting direction with further encapsulation of starch granules. The development and alignment of the gluten in the dough sheet allows noodle strands to be slit from the dough sheet without breakage or loss of shape during drying, frying, and cooking for the preparation of dried, fried, and precooked noodles, respectively. Since the preparation of a continuous, smooth-surfaced dough sheet of appropriate strength is only possible with the appropriate amount of gluten protein, degree of gluten development and its properties, optimum quantity, and quality of protein are primary requirements for making Asian noodles. During noodle dough mixing and sheeting, only partial development of gluten occurs, probably due to the limited amount of water used. Even though the degree of gluten development during noodle dough mixing and sheeting is much smaller than in bread dough, variations in physical properties of the dough sheet are easily observed among wheat flours of different protein content and quality. Excessively elastic gluten tends to produce a tough dough sheet, which shrinks back during the sheeting process, making it difficult to reduce the thickness and extend the length of the dough sheet, and making noodle strands nonpliable. On the other hand, surface peeling and tearing of the sheet could occur during sheeting through multiple rolls when the rate of gluten development is too slow or the developed gluten network is too small or weak to provide complete encapsulation of flour components. In hang-up drying of noodles, gluten provides strands with enough strength to avoid unwanted extension, which results in noodle strands of nonuniform thickness. Accordingly, a fine balance between elasticity and extensibility of the noodle dough sheet is needed in preparation of noodles to achieve smooth sheeting operation and to produce acceptable quality of fresh noodles. Park et al. (2003) reported that dough sheet thickness of white salted noodles prepared from hard white wheat flour ranged from 1.74 mm to 1.96 mm, with protein content ranging from 9.4% to 15.3%. Positive correlations between dough sheet thickness and flour protein content have been observed in alkaline noodles (Kruger et al. 1994) and in white salted noodles (Park et al. 2003). Flour protein also has a large influence on cooking quality of noodles. Gluten developed during dough mixing and sheeting bonds flour components together and encapsulates starch granules, producing a cohesive mass of dough and maintaining the integrity of noodles during cooking. During cooking, the denatured gluten network prevents gelatinized starch from easily disintegrating into cooking water, giving a clean and smooth noodle surface, and provides structural support and contributes to textural properties of cooked noodles. Accordingly, the amount and strength of developed gluten should be optimized to prepare noodles of appropriate cooking and textural properties. A number of studies have reported the influence of protein on cooking quality of noodles, including cooking loss, water gain, cooking time, and tolerance to overcooking (Oh et al. 1985b; Park and Baik 2004a,b) as well as texture of cooked noodles (Nagao et al. 1977; Oh et al. 1985b; Huang and Morrison 1988). Flour protein also affects the color of noodles and oil uptake of noodles during frying. Noodles prepared from high-protein flour are generally less bright than those prepared from low-protein flour (Miskelly 1984; Baik et al. 1995; Yun et al. 1996;

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Park and Baik 2002). Fat content of instant fried noodles tends to increase as flour protein content decreases (Park and Baik 2004b). 11.2.2. Quantity and Quality of Protein Wheat flour protein content, as in other wheat-based products, has a major influence on mixing and sheeting properties as well as on noodle appearance, surface smoothness, cooking time, fat uptake (in instant fried noodles), and textural properties (Oh et al. 1985b; Huang and Morrison 1988; Park et al. 2003). Qualitative effects of protein on noodle processing and product quality have received less attention by cereal chemists and are less well known than the role of protein content. Considering the fact that protein content of wheat largely depends on environmental conditions while protein quality is mostly determined by genotypic background, and that wheat flour with a narrow range of protein content is used by manufacturers for the production of specific types of noodles, protein quality is what wheat breeders pay attention to for the development of noodle wheat varieties and what gives rise to variations in processing and product quality of noodles. However, comparatively little is known about the protein quality of wheat desirable for making noodles, nor has a guideline for selecting and developing noodle wheat varieties been established. In addition to protein content, the protein quality of a flour, as expressed by sodium dodecyl sulfate (SDS) sedimentation volume (assuming constant protein weight), mixograph mixing time, proportion of salt-soluble protein, and high molecular weight glutenin subunits (HMW-GS) score, has a large influence on processing and textural properties of Asian noodles (Huang and Morrison 1988; Baik et al. 1994; Yun et al. 1996; Park et al. 2003). The implication of protein composition and quality on the quality of noodles is also referred to by Oh et al. (1985c) and Huang and Morrison (1988). 11.2.3. Water Absorption In contrast to bread-making, a much lower amount of water is added for the preparation of noodle dough. Water absorption of noodle dough is typically 30–35% as compared to 60–65% for making bread dough. The limited amount of water allows only partial gluten and dough development during mixing and sheeting. An increased amount of water (40–45%) is often used to increase gluten development to produce noodles having similar texture to the handmade type (Nagao 1996). This type of noodle dough, however, requires a resting period after mixing to relax the dough for smooth sheeting. During the noodle dough mixing process, water is distributed evenly through the flour. Since a limited amount of water is added to wheat flour to prepare noodle dough, flour components compete for water and the optimum amount of water needed to make properly mixed and sheeted dough depends on the quantitative and qualitative characteristics of starch, protein, and pentosans as well as flour particle size. Flour protein content is negatively related to water absorption for making noodles, as determined by the handling and sheeting characteristics of noodle dough (Oh et al.

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TABLE 11.1 Correlation Coefficients Between Protein Characteristics and White Salted Noodle Processing Parameters, Including Optimum Water Absorption of Dough and Thickness of Sheets Prepared from Sixteen Wheat Flours of Club, Soft White, and Hard White Wheat Varietiesa Parameters

Optimum Water Absorptionc

Thickness of Dough Sheetsc

−0.930*** −0.565* −0.787*** 0.898*** −0.835***

0.900*** 0.519* 0.896*** −0.926*** 0.886***

Protein content SDSPb Mixograph mixing time Salt-soluble protein HMW-GS score a Data

from Park et al. (2003). = SDS–sedimentation test was conducted on a constant protein weight (300 mg). c * Indicates significance at the 0.05 level, ** at the 0.01 level, and *** at the 0.001 level. b SDSP

1985b; Park and Baik 2002, 2004b; Park et al. 2003). The optimum water absorption needed for preparation of the noodle dough sheet, which has a continuous gluten phase, decreases as flour protein content increases. The gluten of a continuous phase must be formed quickly when flour is rich in protein. In low-protein flour, on the other hand, more water may be needed to disaggregate the flour particles and then use protein inside the flour particles for gluten development. It may also be possible that the increased amount of water added to wheat flour of low protein content promotes further development of gluten and dough. A higher degree of gluten development in low-protein flour than in high-protein flour may compensate for the low quantity of gluten in the preparation of a continuous noodle dough sheet. Oh et al. (1985b) found that water absorption for making noodles was 32% in flour of 8.6% protein and as low as 29% in flour of 14.3% protein. In addition to protein content, protein quality, flour particle size, damaged starch granules, and pentosan content, which are all known to influence mixograph water absorption of bread dough as well as water retention capacity of flour, also influence the optimum amount of water needed for making noodles. Park and Baik (2002) examined physiochemical properties of soft, hard, and commercial wheat flours and related those properties to optimum water absorption of white salted noodle dough. Both protein content and protein quality, as determined by SDS–sedimentation volume tests (based on constant protein levels), mixograph mixing time, proportion of salt soluble protein, and HMW-GS score, were significantly related to dough’s water absorption (Table 11.1). They also reported that a multiple linear equation incorporating protein content, water retention capacity, and SDS–sedimentation volume of flour provides a reliable estimation of the optimum water absorption of noodle dough, although protein content played a more significant role in optimum water absorption for making noodles than any other flour characteristic. 11.2.4. Sheeting Properties In noodle-making, crumbly noodle dough after mixing is passed through a series of sheeting rolls with successively narrower gaps to form a continuous dough sheet

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before being slit into strands of specific dimensions. During this process, further development of the gluten network, alignment of gluten molecules toward the sheeting direction, reduction in thickness of the dough sheet, and improved surface smoothness occur. Accordingly, extensible and elastic properties of gluten in the noodle dough sheet directly determine the easiness of sheeting process, thickness, and length of the dough sheet as well as its surface smoothness. Since the quantity of developed gluten would be greater in wheat flour of higher protein content than that of low protein content during the sheeting process, the formation of a continuous dough sheet from the crumbly noodle dough after mixing would occur faster in the former than in the latter. Noodle dough of low protein content would proportionally have less gluten than that of high-protein flour and may require further development of gluten to encircle starch granules and form a continuous dough sheet. Accordingly, to produce a noodle dough sheet of a smooth surfaced continuous phase, an increased amount of water and further sheeting would be required for wheat flour of relatively low protein content. A high proportion of gluten in noodle dough and its excessive elastic property, however, decrease the extensibility of noodle dough and make it difficult to reduce the thickness of the dough sheet (Park and Baik 2004a). Positive correlations between noodle dough thickness and protein content of wheat flour have been reported in white salted noodles (Park and Baik 2002; Park et al. 2003) and in Cantonese noodles (Kruger et al. 1994). Thickness of noodle dough is affected by protein quality, as evidenced by its positive relationships with SDS–sedimentation volume (based on content protein), mixograph mixing time and HMW-GS score, and negative relationship with proportion of salt-soluble protein of flour (Table 11.1), signifying the role of protein quality on sheeting properties of noodle dough. 11.2.5. Color of Noodles Investigations looking at the relationship between wheat flour characteristics and noodle quality commonly present the significant association of wheat flour protein with color of Asian noodles. Protein content is inversely related to brightness of noodles of various types (Miskelly 1984; Miskelly and Moss 1985; Oh et al. 1985b; Baik et al. 1995; Yun et al. 1996; Park and Baik 2002, 2004b). Wheat flour of high protein content produces darker noodles compared to wheat flour of low protein. In the absence of a probable mechanism to explain the role of protein on noodle color, it is speculated that wheat flour of high protein content may accompany a high level of components (probably PPO, phenolic compounds, and/or pigments) that negatively affect the color of noodles. Wheat flour of relatively higher protein content tends to produce a wetter-looking surface of the noodle sheet than flour of lower protein content. A wetter-looking surface of noodle dough gives less scattering and reflection of light, making dough prepared from flour of high protein content appear less bright-white than dough prepared from flour of low protein content. As protein content increases, water activity of noodle dough increases, which may promote increased activity of enzymes involved in discoloration reaction (Baik et al. 1995).

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11.2.6. Cooking Properties An increase in wheat flour protein content generally extends required cooking time of noodles (Moss et al. 1987; Oh et al. 1985b; Park and Baik 2004a,b). Noodles prepared from wheat flours of low protein content (<10.8%) generally required shorter cooking time than noodles from flours of high protein content (>12.2%) (Park and Baik 2004a). Because of the weak protein network, considerable surface disruption of noodles prepared from wheat flours of low protein content occurs during cooking (Moss et al. 1987), which could result in more rapid water absorption of starch, thus shortening the cooking time of noodles. Compared to high-protein (14.3%) noodles, low-protein (11.5%) noodles exhibited 40% more penetration of water during cooking when observed using a scanning electron microscope and required 3 minutes shorter optimum cooking time (Oh et al. 1985b). Positive correlations between flour protein content and cooking time of noodles have been reported in white salted noodles (Oh et al. 1985b; Park and Baik 2004a), yellow alkaline noodles (Moss et al. 1987), and instant fried noodles (Park and Baik 2004b). However, the effect of protein content on cooking time of noodles appears to be heavily compounded by starch amylose content. Despite high protein content, noodles prepared from waxy wheat flours of high protein content (>17.1%) require much shorter cooking time than noodles prepared from wheat flours of much lower protein content and regular starch endosperm (Park and Baik 2004a). The high water imbibition and weight gain of noodles during cooking are other important quality factors that are negatively affected by flour protein content. Weight gain of noodles leads to an increase in volume and yield, which is preferred in softbite white salted noodles. The water uptake of noodles during cooking decreases as flour protein content increases (Chung and Kim 1991). A well-formed gluten network in noodles could minimize loss during cooking by completely encapsulating starch granules and preventing their release into the cooking water. 11.2.7. Texture Texture of cooked noodles is one of the major quality parameters that determine eating quality of Asian noodles. There have been extensive investigations regarding the establishment of objective reproducible and reliable methods for the determination of noodle texture and the role of flour components on textural properties of cooked noodles. The major challenges have been to correctly estimate the complex eating quality of cooked noodles in an objective and reproducible manner. Sensory tests provide a direct and meaningful estimation of cooked noodle texture, while they require a well-trained panel and pretest training to obtain objective and reproducible results. In addition to sensory tests, or to replace the lengthy and costly sensory test, texture profile analysis (TPA) of cooked noodles has been proposed by many researchers and is most widely accepted as an appropriate instrumental method for the estimation of sensory texture of cooked noodles. Hardness, adhesiveness, cohesiveness, and springiness are primary TPA parameters that are commonly used to describe overall textural properties of cooked noodles. Other derived TPA parameters include gumminess and chewiness, which are calculated by the multiplication of cohesiveness and springiness by hardness, respectively. Instrumental estimation of maximum cutting

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stress and compression force is well correlated with sensory evaluation of firmness and chewiness of cooked noodles (Oh et al. 1983). The TPA of cooked noodles has been widely used in many studies investigating the role of flour components and the effect of processing on textural properties of noodles. A high degree of gluten network formation, which completely encircles starch granules and forms a compact internal structure of noodle strands, would largely contribute to increased breaking stress of dry noodles as well as hardness, springiness, and chewiness of cooked noodles prepared from wheat flour of high protein content. Oh et al. (1985b) reported positive correlations between flour protein content and breaking stress of dry noodles, and cutting stress of cooked noodles (r = 0.94, p < 0.01). TPA hardness and chewiness of cooked noodles are positively related with flour protein content in white salted, alkaline, and instant fried noodles (Baik et al. 1994). Park and Baik (2004b) reported that, compared to soft wheat flours, hard wheat flours produced harder and more elastic texture of cooked instant noodles. Relationships between flour protein content and other TPA parameters, including cohesiveness and springiness, are, however, inconsistent among different studies. Park et al. (2003) reported no relationship between protein content and springiness and cohesiveness of cooked white salted noodles. On the other hand, positive correlations of flour protein content with hardness, cohesiveness, and springiness of cooked instant noodles was observed by Park and Baik (2004b). For the production of Chinese white salted, alkaline, and instant fried noodles, which require a firm and chewy texture, wheat flour of relatively high protein content (greater than 11%) would be desirable, while low-protein flour (less than 10%) can be suitable for making soft-bite white salted noodles such as Japanese udon and somen-type noodles. The influence of wheat flour protein content on the hardness of cooked white salted noodles is well described by Park et al. (2003) using wheat grains of five different protein contents in three hard white wheat cultivars. Protein content of three hard white wheat cultivars exhibited a linear relationship with the hardness of cooked white salted noodles (Figure 11.1). The slope of the regression

Hardness of Noodles (N)

7.0 ID377S ML455

6.0

Nuwest

5.0 4.0 3.0 8

10

12

14

16

Protein Content (%) FIGURE 11.1 Relationships between the hardness of cooked white salted noodles and protein content of wheat flour in three hard white wheat varieties. Source: Park et al. (2003).

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TABLE 11.2 Correlation Coefficients Between Protein Quality Parameters and Textural Parameters of Cooked White Salted Noodles Prepared from Sixteen Wheat Flours of Club, Soft White, and Hard White Wheat Varietiesa Hardness (N)

Springinessd (Ratio)

Cohesivenessd (Ratio)

0.645** −0.845***

0.293 −0.724**

0.552* −0.857***

d

Protein Quality Parameters b

SDS–sedimentation volume Salt-soluble proteinc a Data

from Park et al. (2003). sedimentation volume based on 300 mg protein. c Proportion of salt-soluble protein. d * Indicates significance at the 0.05 level, ** at the 0.01 level, and *** at the 0.001 level. b SDS

line between the two attributes is dependent on the wheat cultivar, indicating that both protein content and quality influence the hardness of cooked noodles. Strong flours, which have high resistance and extensibility in the extensograph, produce firmer and more elastic noodles than did weaker flours (Miskelly and Moss 1985). Based on the observation that noodles prepared from hard wheat flour were stronger compared to those from soft wheat flour even if their protein content is similar, Oh et al. (1985b) postulate the involvement of protein quality and other flour quality factors on the texture of noodles. Protein quality of wheat flour, determined by SDS–sedimentation volume and proportion of salt-soluble protein, is associated with textural properties of cooked white salted noodles (Table 11.2). In an effort to identify optimum protein quality for making soft-bite white salted noodles, Park et al. (2003) compared protein quality of 10 soft and hard wheat cultivars of varying genetic background to that of commercial noodle flours based on SDS–sedimentation volume, mixograph mixing time, proportion of salt-soluble protein, and HMW-GS score. As shown in Table 11.3, commercial noodle flours commonly used in the manufacture of soft-bite white salted noodles in Japan and Korea possess protein quality attributes more similar to U.S. hard rather than soft wheat cultivars. Also, mixogram patterns of commercial noodle flours resemble those of hard wheat flours rather than soft wheat flours, even though protein content of commercial flours are 10.1–10.8% (dry weight basis) and much lower than that TABLE 11.3 Protein Quality Parameters of Soft White and Hard White Wheat Varieties, and Commercial Noodle Flours Suitable for Making Soft-Bite White Salted Noodlesa

Wheat Flourb Soft white (6) Hard wheat (4) Noodle floursc (3) a Data

SDS– Sedimentation Volume (ML)

Mixograph Mixing Time (s)

Salt-Soluble Protein (%)

HMW-GS Score

22.0–44.5 31.5–46.0 38.5–40.0

48–95 145–330 200–225

15–19 11–16 13–14

4–8 9–10 8–9

from Park et al. (2003). number in parentheses indicates the number of wheat varieties used. c Commercial wheat flours commonly used for making white salted noodles. b The

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Class

Protein (%)

Soft

10.3-12.2

Hard

13.6-17.5

271

Commercial 10.1-10.8 Flour

FIGURE 11.2 Mixograms of hard and soft wheat varieties and commercial soft-bite white salted noodle flours. Protein content of wheat flour listed is based on dry weight basis. Source: Park et al. (2003).

of hard wheat flour (Figure 11.2). These results further signify the importance of aligning the protein quality profiles of wheat intended for noodle applications to more closely match those of existing commercial noodle flours. 11.2.8. Fat Absorption Instant fried noodles are produced through steaming and deep-fat frying of fresh (wet) noodles, which are prepared by dough mixing, sheeting, and slitting/cutting. The degree of oil uptake during frying is a primary concern of instant fried noodle manufacturers. Low oil uptake is preferred since it reduces the cost for oil, the lipid oxidation, which adversely affects the shelf life of noodles during storage, and consumers’ concern about eating high-fat noodles. Well-developed gluten during dough mixing and sheeting lowers oil uptake of noodles during frying, probably by encapsulating starch granules, and producing noodle strands with a smooth surface and compact internal structure. Therefore, wheat flour of relatively high protein content would be suitable for the production of instant fried noodles with low fat absorption, as well as firm and elastic texture of cooked noodles, as described previously. Protein content is negatively correlated with free lipid content of instant noodles (Moss et al. 1987; Baik et al. 1994; Park and Baik 2004b). Protein quality, as determined by SDS–sedimentation volume and proportion of salt-soluble protein of flour, is also negatively associated with fat absorption of instant noodles (Park and Baik 2004b). 11.3. STARCH CHARACTERISTICS FOR ASIAN NOODLES Starch, in addition to protein, has received focused attention with regard to noodle texture. It is generally agreed that starch properties are most closely related to eating quality of noodles. Starch in wheat flour is present in granular form and encircled by

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a protein matrix during dough mixing and the sheeting process of noodle-making. During the cooking of noodles, starch granules uptake a large quantity of water and become gelatinized to yield moist and soft-textured cooked noodles. Since starch is composed of two distinctively different molecules, amylose and amylopectin, which differ in chemical structure, hydration capacity, and thermal behavior, the proportion of these two molecules directly affects the functional properties of starch granules including water absorption, gelatinization, and retrogradation characteristics. These functional properties of starch, in turn, affect the cooking quality and textural properties of noodles. 11.3.1. Functional Properties of Starch Functional properties of wheat starch as related to eating quality of noodles are commonly expressed in terms of its pasting parameters, which are determined using a Brabender visco/amylograph, micro-visco/amylograph, or rapid visco analyzer (RVA). Nagao (1996) argued that the superior noodle-making quality of Australian standard white (ASW) wheat over U.S. white wheat and Japanese wheat is due mainly to its starch characteristics. It is believed that the lower amylograph gelatinization temperature of ASW wheat compared to other wheat leads to the production of soft and pliable noodles (Nagao et al. 1977). Peak viscosity along with the breakdown of starch obtained from the amylograph pasting curve (as indexes of starch gelatinization characteristics) are commonly used to illustrate the functional properties of starch suitable for making soft-bite white salted noodles. High starch-paste viscosity is associated with a high amylopectin proportion in starch and is known to give desirable eating quality of soft-bite white salted noodles (Moss 1980). Oda et al. (1980) reported that starch of ASW wheat had 2.0% less amylose content and higher peak viscosity than those of U.S. white wheat cultivars. A significant relationship between starch amylose content and peak paste viscosity was also observed by Moss (1980) and Moss and Miskelly (1984). Associations of low amylose content with relatively high peak viscosity, low peak temperature, and large breakdown value of starch paste are also reported by Oda et al. (1980), Endo et al. (1989), and Zeng et al. (1997). As the proportion of waxy starch increases, peak viscosity of blends of waxy and normal starches increases and their peak temperature decreases (Baik and Lee 2003). Amylose content of wheat starch may vary from as low as 0% in waxy wheat to 40% in high amylose wheat. It is well evidenced that amylose content is mainly controlled by genetic factors, and there is large variation in starch amylose content among wheat cultivars (Oda et al. 1980; Moss 1980; Kuroda et al. 1989). The amylose proportion of wheat starch is correlated with the relative quantity of granular bound starch synthase (GBSS), which is responsible for amylose synthesis (Yamamori et al. 1992). Being allohexaploid, common wheat has three GBSS loci (Wx-A1, Wx-B1, and Wx-D1), at which one, two, or all three genes of null alleles may exist. Absence of one or two GBSS genes is denoted as single or double-null partial waxy wheat. Wild-type wheat in GBSS, which has all three functional GBSS genes, possesses normal starch of ∼25% amylose. Waxy wheat has null alleles in all three GBSS loci, and its starch is essentially absent in amylose (100% amylopectin).

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Baik et al. (2003) reported that amylose content of isolated wheat starch ranges from 22.7% to 24.9% in genotypes with single null in the Wx-B1 locus, from 24.9% to 25.8% in wild-type genotypes with normal starch, and from 15.4% to 18.9% in genotypes of double null in GBSS genes (null in both Wx-A1 and Wx-B1 or Wx-B1 and Wx-D1). The peak viscosity and breakdown viscosity of corresponding starches were 255–266 BU and 57–74 BU in Wx-B1 null genotypes, 420–445 BU and 145–193 BU in double-null genotypes, and 110–175 BU and 43–54 BU in wild types, respectively. The peak viscosities of waxy wheat starches are much greater than those of normal and partial waxy starches and can range from 1780 to 1820 BU (Baik and Lee 2003). As a relatively rapid and simple means of starch characterization, swelling power and volume tests of isolated starch and wheat flour have been introduced (Crosbie 1991) and widely adopted as swift screening tools in wheat breeding programs for the development of wheat varieties possessing high starch-pasting properties. Greater hydrophilic nature of amylopectin compared to amylose leads to increased water retention and volume of starch gel or flour gel resulting from heating starch suspensions at 92.5 ◦ C and centrifugation. Accordingly, partial waxy wheat starches or flours of relatively lower amylose content result in greater swelling power and volume of gel compared to those of normal starch. Waxy starch, however, does not form a gel and cannot be evaluated by swelling power or volume tests. Significant correlations of starch swelling power and starch swelling volume with starch paste peak viscosity were reported by Crosbie (1991). 11.3.2. Textural Properties of Noodles High peak paste viscosity is a desirable starch characteristic for making soft-bite white salted noodles, as well as instant fried noodles (Moss 1980; Crosbie 1991; Konik et al. 1992). Wheat flours with reduced starch amylose content, such as waxy and partial waxy genotypes, exhibit higher swelling power and pasting viscosity than wheat flours of normal starch amylose content (Graybosch 1998; Abdel-Aal et al. 2002; Yasui et al. 1999). Both starch swelling power and swelling volume are correlated with the texture score of boiled Japanese noodles (Crosbie 1991). The high paste viscosity of starch, however, contributes to a soft texture of cooked noodles (Seib 2000; Baik and Lee 2003; Baik et al. 2003), which is undesirable for firm-bite, white salted, and alkaline noodles. Softer and more cohesive cooked noodles are produced as the starch amylose content decreases, as evidenced by the decrease in hardness and increase in cohesiveness of cooked noodles prepared from reconstituted flours of various waxy and normal starch ratio, and blends of waxy and regular wheat flours (Baik and Lee 2003). Double-null partial waxy wheat flours containing 15.4–18.9% amylose exhibit higher peak viscosity and produce softer and more cohesive noodles than single-null partial waxy and regular wheat flours (Table 11.4). Also, soft white wheat genotypes of normal starch produce harder cooked noodles than hard wheat genotypes with single null in Wx-B1. Extremely soft and sticky but cohesive noodles are produced from waxy wheat flours (Epstein et al. 2002; Baik and Lee 2003). Using wheat flours of waxy, single-null, and double-null partial waxy and normal starches, Park and Baik

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TABLE 11.4 Textural Properties of White Salted Noodles Prepared from Regular, Partial Waxy, and Commercial Wheat Floursa TPA Parameters Wheat Flour

Amylose (%)

Hardness (N)

Cohesiveness (Ratio)

Double null BD 1 BD 2 BD 3 BD 4 BD 5 BD 6

17.6 gh 18.0 fgh 18.4 ef 17.4 h 15.4 i 18.9 e

4.24 c 4.10 cd 3.89 d 3.89 d 3.92 d 3.52 e

0.633 cde 0.639 bc 0.652 ab 0.604 gh 0.646 abc 0.623 def

AB 1

18.2 fg

4.74 b

0.632 cde

Single null B1 B2 B3

24.6 c 24.9 bc 22.7 d

4.67 b 4.36 c 3.87 d

0.608 fg 0.621 ef 0.609 fg

Commercial Com 1 Com 2

22.8 d 24.5 c

3.83 d 4.27 c

0.660 a 0.639 bcd

Soft white Alpowa Madsen

25.8 a 25.3 ab

5.22 a 5.32 a

0.601 gh 0.590 h

a Mean values in the same column with different letters are significantly different (p < 0.05). Data from Baik et al. (2003).

(2004c) observed positive correlations of starch amylose content with cooking time and hardness of cooked instant noodles. Instant fried noodles prepared from doublenull partial waxy wheat flour required shorter cooking time and produced noodles of softer texture and higher fat absorption compared with noodles prepared from wheat flour of normal starch (Park and Baik 2004c). 11.3.3. Cooking Time of Noodles As a primary processing tool of many prepared food products, cooking makes food palatable, digestible, and safe from microorganisms. Cooking time, therefore, significantly influences taste, mouthfeel, texture, handling properties, and overall quality of cooked noodles. Short cooking time is a preferred quality characteristic for all kinds of noodles, and especially for instant fried noodles. It is common that manufacturers incorporate modified potato starch at about 15% of the total flour weight for making bag-type noodles, and up to 30% for cup-type instant noodles. The modified potato starch not only improves the textural quality of cooked noodles but also shortens the cooking time requirement of noodles. The optimum cooking time of noodles is, however, a subjective trait, determined appropriately only by sensory tests based on appearance and texture of cooked noodles. Development of translucent appearance

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and disappearance of an opaque white core during cooking are generally indicative of properly cooked noodles. By squeezing noodle strands between a pair of glass plates and observing the disappearance of the white core, cooking time of noodles can be easily and swiftly estimated (Oh et al. 1983). This method, however, often fails to provide a reliable estimation of cooking time, since the white core disappearance of noodle strands is often not evident, especially in fresh noodles, and mainly relies on the water imbibition of noodle strands during cooking. The method takes little consideration of starch gelatinization and protein denaturation in noodle strands for the estimation of cooking time. Park and Baik (2004a) determined optimum cooking time of white salted noodles by sensory panel test and reported much shorter cooking time of noodles prepared from double-null partial waxy and waxy wheat flours compared to noodles prepared from wheat flour of normal starch. A high proportion of amylopectin, because of its more hydrophilic nature compared to amylose, may facilitate water penetration into noodle strands during cooking and speed up the disappearance of the white core and gelatinization of starch. Instant fried noodles prepared from waxy and double-null partial waxy wheat flours exhibit shorter cooking time than noodles prepared from wheat flour of normal starch (Park and Baik 2004c). Cooking time of instant fried noodles prepared from reconstituted flours of various amylose content (3.0–26.5%) consistently increases with the increase in amylose content (Table 11.5). Table 11.5 also shows that as starch amylose content increases, fat absorption of noodles during frying decreases while noodle cooking time and cooked noodle hardness increase. Accordingly, to produce instant fried noodles with low fat content, short cooking time, and soft-elastic texture, precise control of starch amylose content may be necessary. TABLE 11.5 Processing and Product Quality Parameters of Instant Fried Noodles Prepared from Reconstituted Wheat Flours with Differing Starch Amylose Content and Constant Protein Content (14.4%)a,b Starch Amylose Content (%) of Reconstituted Flourc 3.0 7.7 12.4 16.6 17.1 21.8 22.7 26.5 a Flour

Optimum Water Absorption (%)

Free Lipids (%)

Cooking Time (min)

Hardness (N)

49 a 46 b 43 c 41 d 41 d 39 e 39 e 39 e

35.8 a 32.5 b 29.0 c 25.4 d 25.4 d 23.3 e 23.6 e 23.3 e

6.0 h 7.0 g 7.5 f 9.5 d 9.0 e 10.0 c 10.5 b 12.0 a

1.39 f 1.69 e 2.23 d 2.88 c 2.79 c 3.39 b 3.51 a 3.57 a

characteristics were expressed on a dry weight basis. Data from Park and Baik (2004c). followed by the same letters are not significantly different at p < 0.05 within flours and reconstituted flours. c Prepared by blending gluten, tailings starch, and soluble fractions of IDO377S, and prime starch isolated from Alpowa, IDO377S, BD double-null and waxy wheat or prime starch blends of Alpowa and waxy wheat. b Values

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EFFECTS OF FLOUR PROTEIN AND STARCH ON NOODLE QUALITY

11.4. INTERACTION OF STARCH AND PROTEIN Noodles represent a complex system in which multiple components interact to achieve processing and final product attributes. Although there is a great deal of information in the scientific literature defining the distinct roles of starch and protein characteristics with respect to noodle-making quality, the majority of such reports treat starch and protein effects in a singular fashion. The interactive or combined effects of these two major wheat flour components in the processing and product quality of Asian noodles, as well as the nature of the interaction, are little known. Flour protein and starch amylose content both exhibit positive relationships with cooked noodle hardness (Baik et al. 1994; Baik and Lee 2003). Epstein et al. (2002) found that starch property fluctuations accounted for, at best, only 66% of the variability associated with white salted noodle texture. An increase in flour protein content and/or protein strength leads to increased hardness of cooked noodles, while wheat flour with reduced starch amylose content and high pasting viscosity produces soft-textured noodles. A decrease in starch amylose content results in soft-textured cooked noodles, despite a corresponding increase in flour protein content (Baik and Lee 2003). Zhao and Seib (2005) reported that the tensile force of cooked alkaline noodles increased as the starch swelling power increased from 16–17 g/g to 19–21 g/g, but then declined from its maximum value as starch swelling power further increased to 21–24 g/g. This effect was more pronounced when flour protein content was less than 11%, indicating the interactive influence of protein and starch on the textural properties of noodles. Wheat flour with reduced starch amylose content and high pasting viscosity produces noodles requiring a short cooking time while an increase in flour protein content increases the required cooking time of noodles in a linear fashion (Park and Baik 2004b). An increase in flour protein content leads to decreased fat absorption of instant fried noodles, while fat absorption of instant noodles tends to increase as starch amylose content decreases. Accordingly, it is important to identify optimum combinations of starch and protein characteristics for the production of high-quality noodles as well as the development of wheat varieties with good noodle-making potential. Interaction of starch molecules, especially amylose, with gluten protein through hydrogen bond-stabilized junction zones in cooked noodles was suggested by Ross et al. (1997). Amylose molecules exuded from starch granules during cooking could contribute to cooked noodle rigidity through retrogradation and/or interaction with protein polymers. A model depicting the interaction of leached amylose molecules with the gluten protein matrix in cooked alkaline noodles was proposed by Zhao and Seib (2005). The described starch–gluten interaction was proposed to add tensile strength to a noodle strand. In contrast to reports of starch–gluten interactions in noodle products, Grinberg and Tolstoguzov (1997) suggested that direct interaction between protein and starch is not favored in food systems due to thermodynamic incompatibility. In light of this limitation, Zhang and Hamaker (2003a,b) proposed a water-soluble three-component interaction, in which free fatty acids (FFAs) bridge starch and protein constituents to facilitate formation of an otherwise unlikely complex. In that interaction, amylose was the major functional starch molecule

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required for complexation while the FFA–protein complexation was proposed to occur through electrostatic bonding (Zhang and Hamaker 2005). They also observed the three-component interaction with a variety of different proteins accompanied by the subsequent increase in paste viscosity, and suggested that such multicomponent interactions are highly likely in a broad range of food systems. Presence of protein–carbohydrate complexes in gluten (McMaster and Bushuk 1983), binding of lipids to gluten proteins during dough mixing (Bekes et al. 1983; Chung 1986), and implication of both carbohydrate and lipid complexation with glutenin proteins (Zawistowska et al. 1985) all directly or indirectly support the possible roles of starch granular proteins and lipids in starch (as granule or amylose molecule) – gluten interactions. Within a dough system, starch exists primarily in granular form, while protein is developed into a continuous three-dimensional network. Accordingly, interaction between starch granules and gluten proteins within dough may be mediated by starch granule surface lipids and protein. The presence of starch granule surface protein or friabilin, which is a mixture of puroindoline-a and puroindoline-b proteins (Giroux and Morris 1997), has been associated with endosperm softness of the wheat kernel (Greenwell and Schofield 1986; Baldwin 2001; Hogg et al. 2004). Greenblatt et al. (1995) demonstrated that the interaction of puroindolines with starch is mediated by residual polar lipids present at the surface of starch granules. Dubreil et al. (1998) reported that addition of 0.1% puroindolines to puroindoline-free hard wheat cultivars drastically modified the rheological properties of the dough and the structure of the bread crumb. The interactions of puroindolines with lipids and their influence on the rheological properties of bread dough, as well as the three-component (starch, protein, and lipids) interaction reported by Zhang and Hamaker (2003a,b), further support the potential involvement of starch granular surface lipids and proteins in starch–gluten protein interactions. With regard to the possible interaction of starch and gluten in heated systems, such as cooked noodles, Eliasson and Tjerneld (1990) reported that interactions between starch and protein were enhanced both when developed HMW protein was used (rather than LMW protein) and when the system was heated to bring about gelatinization of starch. The occurrence of starch and protein complexation during the cooling stage of RVA profiles (after starch gelatinization) was reported by Zhang and Hamaker (2003a,b). Accordingly, it is highly possible that starch granule surface proteins and lipids may play important roles in bridging starch and gluten protein molecule interactions in noodle dough (before starch gelatinization) and in cooked noodles (after starch gelatinization). Interactive influence of starch and protein on textural properties of cooked noodles was reported by Baik and Lee (2003). Soft white wheat varieties possessing normal starch (25.3–25.8% amylose) produced harder cooked noodles than hard wheat genotypes with waxy or double-null partial waxy (15.4–18.9% amylose) starch characteristics, in spite of the fact that protein content was less than 10.9% in soft white wheat, 17.8% in waxy wheat, and 12.3–16.7% in double-null partial waxy wheat (Tables 11.4 and 11.6). Furthermore, when soft-bite white salted noodles were prepared from flour blends of normal and waxy starch wheat varieties, hardness of noodles decreased as the proportion of waxy wheat flour increased even though

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TABLE 11.6 Textural Characteristics of Cooked White Salted Noodles Prepared from Wheat Flours of Regular and Waxy Wheat, and Their Blends of Various Starch Amylose Contenta Wheat Flours Madsen Waxy wheat Madsen + waxy wheat (12%) Madsen + waxy wheat (16%) Madsen + waxy wheat (20%)

Amyloseb (%)

Proteinb (%)

Hardness (N)

23.0 0.0 20.2 19.8 18.4

10.5 17.8 11.4 11.7 12.0

5.33 a 3.14 e 4.51 b 4.39 c 3.93 d

within the same column followed by the same letter are not statistically different (p < 0.05). Data from Baik and Lee (2003). b Amylose and protein content of flour blends were calculated from the amylose and protein content of regular and waxy flour and expressed on a dry weight basis. a Means

protein content of the flour blends increased (Table 11.6). These results may suggest that the influence of the protein component on the hardness of cooked noodles is overshadowed by the variation in starch amylose content. When noodles were prepared from wheat flours of normal starch amylose content, however, both protein content and quality significantly affected the texture of cooked noodles (Park and Baik 2004b). Accordingly, it is evident that not only the starch and protein characteristics of wheat flour but also their interactive effects on noodle processing and product quality should be considered to establish an optimum quality profile for noodle wheat cultivars.

11.5. SUMMARY Asian noodles are generally prepared from wheat flour, water, and salt/alkaline through dough mixing and sheeting, followed by slitting/cutting the dough sheet into noodle strands, which is much simpler in ingredients and processing than making bread. The fresh noodles are often further cooked, dried, or fried to prepare different types of final products. Accordingly, wheat flour characteristics related to processing and end-product quality are more important issues in making noodles than for bread-making. Since the compact internal structure of noodle strands is maintained during cooking and the textural properties of cooked noodles is one of the major quality parameters of noodles, the nature of starch and protein and their interactions in the formation of noodle strands during dough mixing and sheeting are critical issues for production of high-quality noodles. Protein and starch characteristics largely determine the optimum amount of water needed for making noodles. Noodle dough mixing and sheeting properties, strength of noodle strands, surface smoothness, and appearance of noodles depend on the protein content and quality of flour. Protein and starch characteristics also determine the cooking time requirement and cooking loss of noodles, textural properties of

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cooked noodles, and fat absorption of instant fried noodles. Because of the wide diversity of Asian noodles and their differences in quality requirements, however, it is not appropriate to establish a universal quality profile of wheat flour for making noodles. A better understanding of the quality profile of protein and starch specifically suitable for each type of noodle is necessary for improvement of raw material quality as well as eating quality of noodles. Protein content of wheat flour, as in other wheat-based food products, is the single most influential factor in processing and product quality of noodles. Wheat flours of different protein content behave quite differently during noodle manufacturing and produce noodles of diverse cooking and textural quality. To maintain consistency in processing and product quality of noodles, therefore, noodle manufacturers carefully control the protein content of flour and commonly use wheat flours with specific protein content for the manufacture of specific types of noodles. For example, wheat flour of approximately 10.5%, 12.5%, or 14.0% protein (dry weight basis) is used for making soft-bite white salted noodles, instant fried noodles, and hard-bite white salted noodles, respectively (Nagao et al. 1977; Hou 2001). With constant protein content of wheat flour, protein functionality is the only protein factor influencing variations in processing and product quality of noodles. Accordingly, the identification of an optimum protein quality profile suitable for making each type of noodle and development of wheat varieties possessing those protein quality characteristics is necessary for the further improvement of raw material and noodle quality. It is clear that stronger protein than that of typical U.S. soft white wheat is necessary even for making soft-bite white salted noodles. Further detailed information regarding the protein quality and composition suitable for making each type of noodle still needs to be investigated. Gelatinization properties of wheat starch, expressed by amylograph peak temperature and pasting property, largely depend on amylose content and are correlated with cooking and textural properties of noodles. Starch of reduced amylose content, as in single- or double-null partial waxy starch, produces relatively lower peak temperature and higher peak viscosity than normal starch and is responsible for the production of noodles with relatively shorter cooking time and softer and more cohesive texture of cooked noodles. Accordingly, wheat flour of reduced starch amylose content is suitable for production of soft-bite white salted noodles, which also require a relatively short cooking time. Starch of extremely low amylose content, as in waxy starch, tends to produce overly soft and sticky cooked noodles. While short cooking time of noodles is also a desirable trait for both instant fried noodles and hard-bite noodles, softening of cooked noodles due to decreased starch amylose content needs to be carefully controlled, possibly by increasing protein content and strength of wheat flour used. Evidently, starch and protein interactively affect processing, cooking, and textural quality of noodles. It is therefore necessary to consider the interactive effects of starch and protein in addition to their singular role for production of improved quality noodles as well as for the establishment of the optimum quality profile of noodle wheat.

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REFERENCES Abdel-Aal, E. S. M., Hucl, P., Chibbar, R. N., Han, H. L., and Demeke, T. 2002. Physicochemical and structural characteristics of flours and starches from waxy and nonwaxy wheats. Cereal Chem. 79:458–464. Anderson, J. V. and Morris, C. F. 2001. An improved whole-seed assay for screening wheat germplasm for polyphenol oxidase activity. Crop Sci. 41:1697–1705. Baik, B.-K. and Lee, M.-R. 2003. Effects of starch amylose content of wheat on textural properties of white salted noodles. Cereal Chem. 80:304–309. Baik, B.-K., Czuchajowska, Z., and Pomeranz, Y. 1994. Role and contribution of starch and protein contents and quality to texture profile analysis of oriental noodles. Cereal Chem. 71:315–320. Baik, B.-K., Czuchajowska, Z., and Pomeranz, Y. 1995. Discoloration of dough for oriental noodles. Cereal Chem. 72:198–205. Baik, B.-K., Park, C. S., Paszczynska, B., and Konzak, C. F. 2003. Characteristics of noodles and bread prepared from double null partial waxy wheat. Cereal Chem. 80:627– 633. Baldwin, P. M. 2001. Starch granule-associated proteins and polypeptides: a review. Starch 53:475–503. Bekes, F., Zawistowska, U., and Bushuk, W. 1983. Protein–lipid complexes in the gliadin fraction wheat flour, bread-making properties. Cereal Chem. 60:371–378. Bernier, A. M. and Howes, N. K. 1994. Quantification of variation in tyrosinase activity among durum and common wheat cultivars. J. Cereal Sci. 19:157–159. Chung, G. S. and Kim, S. K. 1991. Effects of wheat flour protein contents on ramyon (deep fried instant noodle) quality. Korean J. Food Sci. Technol. 23:649–655. Chung, O. K. 1986. Lipid–protein interactions in wheat flour, dough, gluten, and protein fractions. Cereal Foods World 31:242–244, 246–247, 249–252, 254–256. Crosbie, G. B. 1991. The relationship between starch swelling properties, paste viscosity and boiled noodle quality in wheat flours. J. Cereal Sci. 13:145–150. Crosbie, G. B., Lambe, W. J., Tsutsui, H., and Gilmour, R. F. 1992. Further evaluation of the flour swelling volume test for identifying wheats potentially suitable for Japanese noodles. J. Cereal Sci. 15:271–280. Dubreil, L., M´eliande, S., Chiron, H., Compoint, J.-P., Quillien, L., Branlard, G., and Marion, D. 1998. Effect of puroindolines on the breadmaking properties of wheat flour. Cereal Chem. 75:222–229. Eliasson, A.-C. and Tjerneld, E. 1990. Adsorption of wheat proteins on wheat starch granules. Cereal Chem. 67:366–372. Endo, S., Okada, K., and Nagao, S. 1989. Starch properties of Australian standard white (Western Australia) wheat related to its suitability for Japanese noodles. In: T. Westcott, Y. Williams, and R. Ryker (eds.), Proceedings of the 39th Australian Cereal Chemistry Conference. Cereal Chemistry Division, Royal Australian Chemical Institute, Parkville, Victoria, Australia, pp. 122–127. Epstein, J., Morris, C. F., and Huber, K. C. 2002. Instrumental texture of white salted noodles prepared from recombinant inbred lines of wheat differing in the three granule bound starch synthase (waxy) genes. J. Cereal Sci. 35:51–63.

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Giroux, M. J. and Morris, C. F. 1997. A glycine to serine change in puroindoline b is associated with wheat grain hardness and low levels of starch-surface friabilin. Theor. Appl. Genet. 95:857–864. Graybosch, R. A. 1998. Waxy wheats: origin, properties, and prospects. Trends Food Tech. 9:135–142. Greenblatt, G. A., Bettge, A. D., and Morris, C. F. 1995. The relationship among endosperm texture, friabilin occurrence, and bound polar lipids on wheat starch. Cereal Chem. 72:172–176. Greenwell, P. and Schofield, J. D. 1986. A starch granule protein associated with endosperm softness in wheat. Cereal Chem. 63:379–380. Grinberg, V. Y. and Tolstoguzov, V. B. 1997. Thermodynamic incompatibility of proteins and polysaccharides in solutions. Food Hydrocolloids 11:145–158. Hatcher, D. W. and Kruger, J. E. 1993. Distribution of polyphenol oxidase in flour millstreams of Canadian common wheat classes milled to three extraction rates. Cereal Chem. 70:51–55. Hogg, A. C., Sripo, T., Beecher, B., Martin, J. M., and Giroux, M. J. 2004. Wheat puroindolines interact to form friabilin and control wheat grain hardness. Theor. Appl. Genet. 108:1089–1097. Hou, G. 2001. Oriental noodles. Adv. Food Nutr. Res. 43:141–193. Huang, S. and Morrison, W. R. 1988. Aspects of proteins in Chinese and British common (hexaploid) wheats related to quality of white and yellow Chinese noodles. J. Cereal Sci. 8:177–187. Konik, C. M., Miskelly, D. M., and Gras, P. W. 1992. Contribution of starch and non-starch parameters to the eating quality of Japanese white salted noodles. J. Sci. Food Agric. 58:403–406. Kruger, J. E., Anderson, M. H., and Dexter, J. E. 1994. Effect of flour refinement on raw Cantonese noodle color and texture. Cereal Chem. 71:177–182. Kuroda, A., Oda, S., Miyagawa, S., and Seko, H. 1989. A method of measuring amylose content and its variation in Japanese wheat cultivars and Kanto breeding lines. Jpn. J. Breed. 39(Suppl. 2):142–143. Lee, C. H., Gore, P. J., Lee, H. D., Yoo, B. S., and Hong, S. H. 1987. Utilisation of Australian wheat for Korean style dried noodle making. J. Cereal Sci. 6:283–297. McCaig, T. N., Fenn, D. Y. K., and Knox, R. E. 1999. Measuring polyphenol oxidase activity in a wheat breeding program. Can. J. Plant Sci. 79:507–514. McMaster, G. J. and Bushuk, W. 1983. Protein – carbohydrate complexes in gluten: fractionation and proximate composition (functionality of gluten in bread doughs). J. Cereal Sci. 1:171–184. Miskelly, D. M. 1984. Flour components affecting paste and noodle colour. J. Sci. Food Agric. 35:463–471. Miskelly, D. M. 1996. The use of alkali for noodle processing. In: J. E. Kruger, R. B. Matsuo and J. W. Dick (eds.), Pasta and Noodle Technology. American Association of Cereal Chemists, St. Paul, MN, USA, pp. 227–274. Miskelly, D. M. and Moss, H. J. 1985. Flour quality requirement for Chinese noodle manufacture. J. Cereal Sci. 3:379–387. Moss, H. J. 1980. The pasting properties of some wheat starches free from sprout damage. Cereal Res. Commun. 8:297–302.

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Moss, H. J. and Miskelly, D. M. 1984. Variation in starch quality in Australian flour. Food Tech. Australia 36:90–91. Moss, R., Gore, P. J., and Murray, I. C. 1987. The influence of ingredients and processing variables on the quality and microstructure of Hokkien, Cantonese and instant noodles. Food Microstructure 6:63–74. Nagao, S. 1996. Processing technology of noodle products in Japan. In: J. E. Kruger, R. B. Matsuo and J. W. Dick (eds.), Pasta and Noodle Technology. American Association of Cereal Chemists, St. Paul, MN, USA, pp. 169–194. Nagao, S., Ishibashi, S., Imai, S., Sato, T., Kanabe, Y., Kaneko, Y., and Otsubo, H. 1977. Quality characteristics of soft wheats and their utilization in Japan. III. Effects of crop year and protein content on product quality. Cereal Chem. 54:300–306. Oda, M., Yasuda, Y., Okazaki, S., Yamauchi, Y., and Yokoyama, Y. 1980. A method of flour quality assessment for Japanese noodles. Cereal Chem. 57:253–254. Oh, N. H., Seib, P. A., Deyoe, C. W., and Ward, A. B. 1983. Noodles. I. Measuring the textural characteristics of cooked noodles. Cereal Chem. 60:433–438. Oh, N. H., Seib, P. A., and Chung, D. S. 1985a. Noodles. III. Effects of processing variables on quality characteristics of dry noodles. Cereal Chem. 62:437–440. Oh, N. H., Seib, P. A., Ward, A. B., and Deyoe, C. W. 1985b. Noodles. IV. Influence of flour protein, extraction rate, particle size, and starch damage on the quality characteristics of dry noodles. Cereal Chem. 62:441–446. Oh, N. H., Seib, P. A., Ward, A. B., and Deyoe, C. W. 1985c. Noodles. VI. Functional properties of wheat flour components in oriental dry noodles. Cereal Foods World 30:176–178. Park, C. S. and Baik, B.-K. 2002. Flour characteristics related to optimum water absorption of noodle dough for making white salted noodles. Cereal Chem. 79:867–873. Park, C. S. and Baik, B.-K. 2004a. Cooking time of white salted noodles and its relationship with protein and amylose contents of wheat. Cereal Chem. 81:165–171. Park, C. S. and Baik, B.-K. 2004b. Relationship between protein characteristics and instant noodle making quality of wheat flours. Cereal Chem. 81:159–164. Park, C. S. and Baik, B.-K. 2004c. Significance of amylose content of wheat starch on processing and textural properties of instant noodles. Cereal Chem. 81:521–526. Park, C. S., Hong, B. H., and Baik, B.-K. 2003. Protein quality of wheat required for making white salted noodles and its influences on processing and texture of noodles. Cereal Chem. 80:297–303. Ross, A. S., Quail, K. J., and Crosbie, G. B. 1997. Physicochemical properties of Australian flours influencing the texture of yellow alkaline noodles. Cereal Chem. 74:814–820. Seib, P. A. 2000. Reduced-amylose wheats and Asian noodles. Cereal Foods World 45:504–512. Yamamori, M., Nakamura, T., and Kuroda, A. 1992. Variations in the content of starch-granule bound protein among several Japanese cultivars of common wheat (Triticum aestivum L.). Euphytica 64:215–219. Yasui, T., Matsuki, J., Sasaki, T., and Matsuki, J. 1999. Milling and flour pasting properties of waxy endosperm mutant lines of bread wheat (Triticum aestivum L.). J. Sci. Food Agric. 79:687–692. Yun, S. H., Quail, K., and Moss, R. 1996. Physicochemical properties of Australian wheat flours for white salted noodles. J. Cereal Sci. 23:181–189.

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Zawistowska, U., Bekes, F., and Bushuk, W. 1985. Gluten proteins with high affinity to flour lipids. Cereal Chem. 62:284–289. Zeng, M., Morris, C. F., Batey, I. L., and Wrigley, C. W. 1997. Sources of variation for starch gelatinization, pasting and gelation properties in wheat. Cereal Chem. 74:63–71. Zhang, G. and Hamaker, B. R. 2003a. A three component interaction among starch, protein, and free fatty acids revealed by pasting profiles. J. Agric. Food Chem. 51:2797–2800. Zhang, G. and Hamaker, B. R. 2003b. Detection of a novel three component complex consisting of starch, protein and free fatty acids. J. Agric. Food Chem. 51:2801–2805. Zhang, G. and Hamaker, B. R. 2005. Sorghum (Sorghum bicolor L. Moench) flour pasting properties influenced by free fatty acids and protein. Cereal Chem. 82:534–540. Zhao, L. F. and Seib, P. A. 2005. Alkaline-carbonate noodles from hard winter wheat flours varying in protein, swelling power, and polyphenol oxidase activity. Cereal Chem. 82:504–516.

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CHAPTER 12

Effects of Polyphenol Oxidase on Noodle Color: Mechanisms, Measurement, and Improvement E. PATRICK FUERST, JAMES V. ANDERSON, and CRAIG F. MORRIS

12.1. INTRODUCTION Noodles made from wheat (Triticum aestivum L.) are major food products around the world but are especially important to the peoples and cultures of eastern Asia. As noted in other chapters, an almost limitless variety of noodle styles are manufactured in which the most important ingredient is wheat flour. Normally, white flour obtained through modern roller milling processes is used. Milling and wheat processing is a subject unto itself (Posner and Hibbs 1997). For this chapter, it is important to recognize that the basic ingredient for noodles—white flour—comes from the wheat grain, a living, biological organism, one stage in the reproductive life cycle of the plant. Like all biological organisms, wheat has genes and enzymes that allow it to grow, reproduce, and resist attack by pathogens. In wheat, polyphenol oxidase (PPO) is composed of a group of closely related enzymes that are extremely important to Asian noodle quality. Color, appearance, texture, mouthfeel, and taste are all important noodle quality attributes, and all of these attributes are the result of the interplay of ingredients and processing. Color is a primary quality attribute of all noodles as noodles are “seen” before they are eaten. Noodles may have desirable color traits, such as brightness and yellow pigments, as well as undesirable colors and/or appearance. In this regard, Asian noodle discoloration (Figure 12.1), including general darkening

Disclaimer: Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. Asian Noodles: Science, Technology, and Processing, Edited by Gary G. Hou C 2010 John Wiley & Sons, Inc. Copyright


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FIGURE 12.1 Yellow alkaline noodle color in two hard white wheat cultivars after 24 hours at room temperature (noodle sheets and cut noodles are uncooked). “ID377s” (right) produces high-quality noodles with low discoloration and yellow tones, while “Klasic” (left) has high PPO levels that contribute to darkening and the grey tones seen here.

as well as dark spots, is unacceptable to consumers (Mares and Panozzo 1999; Morris et al. 2000, 2002). Darkening can occur in many refined white flour products including yellow alkaline (Cantonese) and white salted (udon) noodles that have high moisture content and are stored for longer periods of time (refrigerated doughs and batters are also subject to darkening). Conversely, darkening of wheat products is not a universal problem and may be considered a “non-issue” when it comes to most U.S. baked products, including the leading use of refined wheat flour—pan bread; therefore, selection for reduced darkening potential is not a priority when developing wheat cultivars for such products. Over the past three decades, the close relationship between kernel PPO activity and darkening of alkaline and white salted Asian noodles has become apparent. Developing wheat varieties with minimal discoloration is a crucial issue in all of the countries exporting wheat to Asia, including the United States, Australia, and Canada. The importance of this chapter and much of the research that it reviews is a direct result of the noodle darkening problem and the desire of major wheat exporting countries to better serve the needs of the Asian consumer. Time-dependent darkening is not limited to wheat foods such as noodles. Similar darkening reactions are routinely encountered in fruits and vegetables. Food product

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darkening is usually attributed to enzymatic oxidation of phenolics, leading to multiple reactions that form complex, dark-colored products (melanins) (Whitaker and Lee 1995; Yoruk and Marshall 2003). The role of PPO is perhaps the most thoroughly studied aspect of this process. PPO has repeatedly been shown to be a leading cause of undesirable darkening in raw Asian noodles (Kruger et al. 1994a; Mares and Panozzo 1999; Morris et al. 2000, 2002; Fuerst et al. 2006b). Such darkening can readily be inhibited by the addition of antioxidants like ascorbate, but food processors generally want to minimize such additives and would prefer flour that does not darken in the first place. Therefore, reducing or eliminating PPO-based darkening via genetic improvement of wheat is the approach discussed in this chapter and indeed appears quite plausible for the purpose of improving Asian noodle color. Rapid whole-kernel PPO assays have substantially facilitated and accelerated the development of wheat cultivars with low PPO activity. However, further improvement is possible if specific alleles for low PPO can be identified and combined during the cultivar development process. In this chapter, we discuss the biology, genetics, and enzymology of PPO, the mechanisms of noodle darkening, and strategies for measuring PPO activity in wheat and improving the color quality of noodles through the development of superior wheat cultivars.

12.2. PPO BIOCHEMISTRY AND BIOLOGY IN PLANTS Plant PPO biochemistry and biology have been discussed in several reviews (Mayer and Harel 1979; Steffens et al. 1994; Van Gelder et al. 1997; Yoruk and Marshall 2003; Mayer 2006). PPOs are copper-containing metalloproteins that catalyze the hydroxylation of p-hydroxy monophenols (“monophenols”) to o-dihydroxyphenols (EC 1.14.18.1) and/or dehydrogenation of o-dihydroxyphenols (“diphenols”) to o-quinones (EC 1.10.3.1) (Figure 12.2). The o-quinones undergo autooxidation, initiate polymerization with phenolics, and covalently bind to amino acids, peptides, and other nucleophilic constituents to produce colored products (Pierpoint 1969; Taylor and Clydesdale 1987). The dark-colored complex polymers (melanins) are associated with browning in many food products (Whitaker and Lee 1995). The melanins Tyrosine CH2 CH

OH

COOH NH2

phenolic substrates

O

PPO O

polymerization R

OH OH

CH2 CH

COOH NH2

o -quinone + oxygen

Melanins

L-DOPA

FIGURE 12.2 The PPO reaction. Monophenol (tyrosine) and diphenol (l-DOPA) substrates are oxidized to o-quinones, which undergo polymerization to produce dark melanin products.

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formed in these reactions may reduce nutritional value of plant constituents and/or seal wounded tissue, while the quinones, hydroxyphenols, and melanins formed may have antimicrobial activity (Yoruk and Marshall 2003). PPOs are most often associated with defense against pathogens and herbivores although they can have other roles as well (Constabel et al. 1995; Li and Steffens 2002; Mayer 2006). In most plant tissues, PPO is localized in plastids while most potential phenolic substrates are localized in the vacuole. Consequently, browning reactions are initiated when tissue is disrupted, as in mechanical damage to plant tissue or processing of fresh foods (Whitaker and Lee 1995). In plants, PPO is synthesized as a preprotein (68–73 kDa), translocated into the chloroplast, and processed further to the “mature” protein (58–68 kDa) (Van Gelder et al. 1997). Further modification of PPOs by protease cleavage can result in a final 37–47-kDa active form (Van Gelder et al. 1997; Schmitz et al. 2008). PPO is usually present as the “mature” 58–68-kDa protein when extracted from plant tissues and is latent or only partially active (Steffens et al. 1994; Van Gelder et al. 1997; Schmitz et al. 2008). Extracted plant PPOs are often activated in vitro by relatively harsh treatments including detergents, solvents, chaotropes, and proteolysis (Steffens et al. 1994; Okot-Kotber et al. 2002; Jukanti et al. 2003). Activation by such chemical treatments may be due to conformational changes in the “mature,” relatively inactive form of PPO (Steffens et al. 1994).

12.3. PPO BIOCHEMISTRY AND BIOLOGY IN WHEAT PPO (tyrosinase) was first reported in the bran layer of wheat in 1907 (Bertrand and Muttermilch 1907). However, it was not until 2003 that wheat kernel PPO was first purified to homogeneity (Anderson and Morris 2003) and was subsequently purified by other investigators (Kihara et al. 2005; Jukanti et al. 2006). Wheat PPO activity includes both soluble and bound forms of PPO, with the bound form predominating (Marsh and Galliard 1986; Fuerst et al. 2006a). Homogenizing the bran (an aggressive tissue disruption/extraction procedure) and adding detergents to the extraction buffer did not substantively change the fact that most PPO remained “bound” and associated with the “pellet” after centrifugation. Both PPO and its phenolic substrates are localized primarily in the bran layer of the wheat kernel (Figure 12.3) and therefore flour PPO activity and phenolic content increase with flour extraction rate (Baik et al. 1994; Hatcher and Kruger 1993, 1997; Demeke et al. 2001a,b; Okot-Kotber et al. 2001; Rani et al. 2001; Every et al. 2006). Very low levels of PPO are associated with the germ and white flour (Marsh and Galliard 1986). The specific phenolic substrates that cause PPO-mediated darkening in wheat products are currently unknown. However, in a later section we review the phenolics of wheat grain and discuss possible PPO substrates. A number of compounds are known to be effective inhibitors of PPO activity. Among these, tropolone and salicylhydroxamic acids are relatively potent inhibitors (Asenstorfer et al. 2007); each inhibitor at 1 µM reduced wheat kernel PPO activity

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FIGURE 12.3 PPO staining of the bran layer of wheat. Wheat kernel cross section of high PPO cultivar “Penawawa” incubated in 10 mM tyrosine. In lower right is a piece of bran that has been detached from the kernel and rotated 90◦ .

by approximately 50% (Fuerst et al. 2006b). These chemicals have proved to be effective tools in unraveling the role of PPO in noodle darkening (Mares et al. 2001; Fuerst et al. 2006b; Asenstorfer et al. 2007). It is possible that there are endogenous inhibitors of wheat PPO (Yoruk and Marshall 2003). This possibility is suggested by the increases in total PPO activity observed during PPO purification steps, which may remove inhibitors (Anderson and Morris 2003), and by increases in specific activity following removal of phenolics by adsorbents (Soysal and S¨oylemez 2004). However, results can also be explained as changes in enzyme latency due to the treatments involved. Proanthocyanadin-free barley lines had much higher PPO activity, suggesting that proanthocyanadins or their precursors could be PPO inhibitors (Quinde-Axtell 2004; Quinde-Axtell and Baik 2006). Le Bourvellec et al. (2004) showed that procyanidins and PPO products from apples inhibited apple PPO. The possibility of endogenous PPO inhibitors deserves further investigation. Antioxidant activity of phenolics could inhibit activity by terminating chain reactions. We have observed inhibition of browning when wheat bran extracts were applied to flour (data not shown). Similarly, rice bran extracts inhibited browning of fruits and vegetables (Theerakulkait and Boonsiripiphat 2007). Wheat PPO is surprisingly stable, both in mature kernels and in vitro, and tolerates relatively harsh physical and chemical treatments. PPO in dry wheat kernels appears to be stable at room temperature indefinitely and we are not aware of any reports documenting decreased PPO activity over time. PPO in wheat flour tolerates heat treatment in a dry state and, to a lesser extent, under moist conditions (Wrigley and McIntosh 1975; Vadlamani and Seib 1996). Microwave heating of wheat grain at

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18% moisture led to 93% inhibition of PPO activity and likewise reduced darkening in refrigerated whole wheat dough (Yadav et al. 2008). Extracted PPO in solution shows significant heat tolerance as well (Soysal and S¨oylemez 2004; Kihara et al. 2005; Anderson et al. 2006). Genetics is a major determinant of PPO activity, as discussed below, and is clearly the strongest tool available to reduce PPO-related darkening. However, the environment (i.e., fluctuations due to location and year) also influences PPO activity (Baik et al. 1994; Park et al. 1997; Zhang et al. 2005). Increased nitrogen fertility led to increased darkening of Asian noodles in two studies (Wang et al. 2004; Ma et al. 2009). Low soil moisture (irrigation) led to increased PPO and increased protein content and darkening, but nitrogen fertility had little effect on PPO and darkening (Guttieri et al. 2005). Although little is known about the role that PPOs may play in wheat defense mechanisms, Fusarium head blight increased kernel PPO and peroxidase activity in wheat heads (Mohammadi and Kazemi 2002). The potential detrimental effect of reducing or eliminating PPO from wheat grain is largely unknown, but we are not aware of any reports linking low PPO activity with susceptibility to disease. The effect of reducing or eliminating PPO expression in the kernel on wheat’s susceptibility to Fusarium head blight and other diseases needs to be thoroughly evaluated.

12.4. PPO GENETICS AND MARKERS IN WHEAT The first nearly complete wheat PPO gene sequence was obtained by Demeke and Morris (2002). This and subsequent wheat PPO gene sequences were initially classified in two clusters, with each cluster having three closely related genes based on EST and genomic sequence homologies (Jukanti et al. 2004). The “kernel” cluster represented genes known to be expressed in wheat kernels, whereas the “nonkernel” cluster represented genes not expressed in kernels (Jukanti et al. 2004; Anderson et al. 2006). Massa et al. (2007) characterized the diversity of kernel-type genes by sequencing a polymorphic coding region in wheat and related species. A total of 21 distinct PPO sequences were obtained, indicating that there is a diversity of kernel-type PPO genes both within and among different wheat relatives. We refer to these as “kernel-type” PPO genes because, although they are related to genes expressed in the kernels, expression in kernels has not been documented in most cases. The genomic sequence for kernel-type PPO gene sequence AY596268 was mapped to chromosome 2AL and contained two introns (Sun et al. 2005). The first intron was 191 bp longer in cultivars with low kernel PPO activity than in cultivars with high kernel PPO activity. Sun et al. (2005) hypothesized that the chromosome 2AL-based PPO activity levels were related to this difference in intron length. The chromosome 2AL alleles were designated as PPO-A1a (high PPO activity) and PPO-A1b (low PPO activity) by He et al. (2007) and as TaPPO-A1b and TaPPO-A1a, respectively, by Chang et al. (2007). The importance of the 2AL gene has been confirmed at the

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protein level. Peptide sequences of wheat kernel PPO purified from cultivars with high PPO activity (Anderson and Morris 2003; Jukanti et al. 2006) were highly homologous to AY596268 (Jukanti et al. 2004), substantiating the significance of this gene. Additional genetic evidence corroborates the contribution of chromosome 2AL to high PPO activity (Zeven 1972; Wrigley and McIntosh 1975; Simeone et al. 2002; Raman et al. 2005, 2007; Sun et al. 2005; Zhang et al. 2005; Watanabe et al. 2006; Chang et al. 2007). A locus on chromosome 2DL also contributes substantially to kernel PPO activity but not as much as the 2AL locus (Zhang et al. 2005; Chang et al. 2007; He et al. 2007). The 2DL allele for low PPO activity still contributes a significant amount of PPO activity, since several wheat accessions with an apparent null 2DL allele had lower PPO activity than those with the 2DL low PPO activity allele (Chang et al. 2007). Finally, a locus on chromosome 2BL appears to contribute to kernel PPO activity (Watanabe et al. 2004), but this may be a minor factor in kernel PPO activity, as seen in T. dicoccum (Fuerst et al. 2008). Numerous SSR, RFLP, and STS markers were reported for the 2AL and 2DL loci in the above studies and these can now be used in breeding low PPO cultivars. The high PPO trait was usually present on only one of these chromosomes in most cultivars and, in these cases, was inherited as a dominant single gene trait. However, the high PPO trait was present on both the 2A and 2D chromosomes of “Timstein” and “Zhongyou 9507” (Wrigley and McIntosh 1975; Zhang et al. 2005). Taken collectively, the current evidence indicates that a single genetic locus on the long arm of homoeologous chromosomes 2A and 2D are the primary basis for high kernel PPO activity (Zeven 1972; Wrigley and McIntosh 1975; Jim´enez and Dubcovsky 1999; Demeke et al. 2001a; Mares and Campbell 2001; Simeone et al. 2002; Raman et al. 2005, 2007; Sun et al. 2005; Zhang et al. 2005; Anderson et al. 2006; Watanabe et al. 2006; Chang et al. 2007; He et al. 2007).

12.5. PHENOLIC SUBSTRATES FOR PPO Little is known about the exact identity of endogenous phenolic substrates involved in the darkening of wheat foods, including Asian noodles. However, extensive groundwork has been laid, since considerable research has been conducted identifying the phenolic constituents of wheat grain and identifying darkening-related substrates in other species. This information is summarized below. Ferulic acid is the predominant phenolic acid in most cereals including wheat. Other phenolic acids commonly reported in wheat include sinapic, syringic, coumaric, caffeic, and vanillic acids. In addition, minor quantities of tyrosine, phydroxybenzoic, gentisic, chlorogenic and protocatechuic acids, as well as flavonoids, anthocyanins, and proanthocyanidins (condensed tannins) have also been extracted from wheat samples (Kuninori and Nishiyama 1986; McCallum and Walker 1990; Pietrzak and Collins 1996; Okot-Kotber et al. 2001; Abdel-Aal and Hucl 2003; Bunzel et al. 2004). Most phenolics (>80%) in wheat grain are present in bound, insoluble forms, whereas a smaller fraction (≤17%) is present as soluble ester conjugates, and a very small fraction (≤6%) is present as free phenolic acids (Sosulski et al. 1982;

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Hatcher and Kruger 1997). Wheat PPO is capable of oxidizing a range of substrates including monophenols such as tyrosine and phenol, diphenols such as catechol, caffeic acid, l-DOPA, dopamine, and methyl-catechol, and the trihydroxyphenols, gallic acid and pyrogallol (Lamkin et al. 1981; Anderson and Morris 2001; Kihara et al. 2005). Of the phenolics reported in wheat, tyrosine, sinapic acid, caffeic acid, and chlorogenic acid can contribute off-colors and thus are potential darkening agents, but not ferulic acid and vanillic acid (Figure 12.4). With the exception of tyrosine, monohydroxyphenols generally do not cause color changes whereas dihydroxyphenols tend to be better PPO substrates and have been shown to cause color change more readily; other reports confirm that ferulic acid, though abundant, does not contribute to darkening or color change (Pierpoint 1969; Taylor and Clydesdale 1987; Cochrane 1994; Kruger and Hatcher 1997).

Check

Tyrosine

L-DOPA

Ferulic

Vanillic

Sinapic

Caffeic

Chlorogenic

Catechin

Protochatechuic Aldehyde

FIGURE 12.4 Phenolic staining of wheat flour. Phenolic compounds (1 mM) were applied in an alkaline kansui wetting solution using “Klasic” refined white flour. “Klasic” is a high PPO cultivar. Flour layers were dried in a polyacrylamide gel electrophoresis gel drier after reaction. The check sample was wetted with kansui containing no added phenolic.

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The specific phenolics responsible for food darkening have been determined in fruits, cassava, and barley. Several substrates have been implicated in the browning of fruits, including caffeic acid, caffeic acid esters such as chlorogenic acid (apples) and proanthocyanadins, including catechin; PPO is thought to play a primary role in the browning of fruits (Macheix et al. 1990; Tomas-Barberan and Espin 2001; Yoruk and Marshall 2003). In cassava, oxidation of hydroxycoumarins including scopoletin via peroxidase appears to be a key mechanism of darkening (Reilly et al. 2004). In barley, proanthocyanidins were the strongest darkening substrates, and proanthocyanidin-free barley mutants had by far the least darkening among several cultivars (Quinde-Axtell 2004; Quinde et al. 2004). Darkening in barley products was primarily enzymatic, attributed to PPO, but lower levels of nonenzymatic darkening also occurred. Proanthocyanidins were fractionated, and the monomeric fraction, primarily catechin, caused the greatest darkening in barley products (Quinde-Axtell 2004; Quinde-Axtell and Baik 2006). Catechin has been shown to be a wheat PPO substrate (Lamkin et al. 1981) and a discoloration substrate in our flour assay (Figure 12.4). Furthermore, phlobaphene pigments in red wheat are also products of the flavonoid biosynthesis pathway (Warner et al. 2000; Matus-Cadiz et al. 2008), which also have potential to darken wheat products (Salunkhe et al. 1982). Proanthocyanidins were reported at low levels in red wheat bran in an earlier report (McCallum and Walker 1990), while both catechin and proanthocyanadins were more recently reported at high levels in red wheat bran and low levels in white wheat bran (MatusCadiz et al. 2008). Catechin and proanthocyanadins must therefore be considered potential darkening substrates.

12.6. MEASURING PPO ACTIVITY IN WHEAT KERNELS PPO activity assays are widely used to identify superior wheat germplasm with reduced PPO levels. Lines with low PPO activity have a markedly higher potential for producing Asian noodles and other products with better color (i.e., less darkening). The PPO assay that has been used the longest is direct kernel staining (Figure 12.5) since major differences in PPO activity can be qualitatively distinguished by this method. Many phenolic substrates have been used in such assays, including catechol, phenol, tyrosine, and l-DOPA (Fraser and Gfeller 1936; Milner and Gould 1951; Walls 1965; Joshi et al. 1969; Csala 1972; Maguire et al. 1975; Wrigley and McIntosh 1975; Kruger 1976; Mahoney and Ramsay 1992; Anderson and Morris 2001). The first method for quantifying wheat PPO activity involved measuring oxygen consumption while incubating ground wheat in an oxygen electrode, discussed in the next section. More recently, PPO activity has been quantified by incubating whole kernels in a buffered aqueous phenolic substrate solution and measuring the change in absorbance after a set period of time using a spectrophotometer. These whole-kernel assays are often good predictors of noodle darkening because nearly all of the PPO activity in flour comes from bran contamination, as previously discussed. One of the earliest spectrophotometric assays for whole-kernel PPO was developed by Kruger et al. (1994a). A revised nondestructive, high-throughput whole-kernel

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A

B

C

D

FIGURE 12.5 Stained kernels of low PPO cultivars, “ID377s” (A) and “Eltan” (B), and high PPO cultivars, “Madsen” (C) and “Penawawa” (D), incubated in 1 mM phenol for 2 hours at room temperature.

assay was subsequently developed for evaluation of PPO activity in large numbers of seed lots, and was adopted as Approved Method 22-85 (AACC International 2000; Anderson and Morris 2001) (Figures 12.6 and 12.7). This method was validated in a collaborative study in several laboratories (Bettge 2004). This assay is described below and can easily be modified to measure PPO activity in bran and flour (Figure 12.8), as well as enzyme extracts and kernel leachates. Incorporation of known PPO inhibitors, such as tropolone, can be included to ascertain whether substrate oxidation is caused by PPO or by other mechanisms (Anderson et al. 2006; Fuerst et al. 2006b). In Approved Method 22-85 (AACC International 2000), five kernels are placed in a 2-mL microcentrifuge tube. The assay is initiated by adding 1.5 mL of 10 mM l-DOPA (diphenol) substrate in 50 mM MOPS (3-[N-morpholino] propane sulfonic acid) buffer, pH 6.5. Tween 20 (0.02% v/v) is added to overcome surface wetting issues on the kernel and/or in the microcentrifuge tubes, and to facilitate aeration during incubation by allowing the air bubble to circulate. Samples are incubated with rotation (aeration) for 1 hour (Figure 12.6), after which the absorbance of

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FIGURE 12.6 The l-DOPA whole-kernel assay using the AACC International Approved Method 22-85. Five kernels per tube were incubated in 1.5 mL of 10 mM l-DOPA for 1 hour on an end-over-end mixer before measuring color change (absorbance) at 475 nm.

an aliquot of the substrate buffer solution is measured at 475 nm (Figure 12.7). An automatic sampling attachment for the spectrophotometer, such as a “sipper,” greatly expedites the process. The process can be further automated using microtiter plates, as discussed below. Significant variability is often present within a grain lot and thus replicate samples are advised. We also include duplicate “standard” or “check” samples of two cultivars, one having very low PPO activity and the other

FIGURE 12.7 Change in solution color from three cultivars following the procedure described in Figure 12.6: near-zero PPO cultivar “ID580” (left), low PPO cultivar “ID377s” (middle), and high PPO cultivar “Klasic” (right).

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Kernels

Bran

Flour

Penawawa

ID377s

FIGURE 12.8 The l-DOPA assay using the AACC International Approved Method 22-85. Comparisons using five whole kernels, 100 mg bran, and 100 mg refined white flour from high PPO cultivar “Penawawa” and low PPO cultivar “ID377s.” Samples were incubated in 1.5 mL of 10 mM l-DOPA for 1 hour and then centrifuged.

having very high PPO activity, to ascertain that the procedure is running properly each day. Tyrosine is also commonly used in whole-kernel PPO assays. Tyrosine disodium salt (10 mM) dissolves readily in Tris buffer pH 9, but the acid form of tyrosine has very low solubility (Fuerst et al. 2006a). The ranking of cultivars for PPO activity was similar regardless of the substrate (tyrosine or l-DOPA) used. Activity with tyrosine at pH 9 was approximately half that with l-DOPA at pH 6.5. Both tyrosine and l-DOPA substrates have negligible absorbance at ≥400 nm, while the PPO-mediated oxidation products have a broad range of absorbance and can be measured between 400 and 550 nm. Approved Method 22-85 specifies 475 nm. Kruger et al. (1994a) may have been the first to report assays using microtiter plates. The Approved Method 22-85 (AACC International 2000) whole-kernel assay can be modified for higher throughput using microtiter plates, eliminating the need to conduct individual measurements on a spectrophotometer. The assay solutions and conditions (Figure 12.9) are essentially identical to those described for the standard method. Samples are incubated in 2-mL deep-well microtiter plates. Aliquots from the incubated samples are quickly transferred to a standard microtiter plate with a multichannel pipetter and absorbance is measured with a microtiter plate reader. Data are automatically stored in spreadsheet format. When assaying kernel leachates or protein extracts on standard microtiter plates, reactions are initiated by adding the substrate, which becomes diluted to the desired final assay concentration.

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2

3

4

5

6

7

8

9

10

11

297

12

FIGURE 12.9 Three variations on PPO assays using methods similar to the AACC International Approved Method 22-85 in which five kernels of the indicated wheat cultivar were incubated in 1.5 mL of 10 mM l-DOPA for 1 hour. (A) Kernels were incubated in 2-mL deep-well microtiter plates on a rotary shaker. (B) Kernels were incubated in 2-mL deep-well microtiter plates on an end-over-end shaker. (C) Kernels were incubated in 2-mL microcentrifuge tubes on an end-over-end shaker. Aliquots (0.2 mL) were transferred to a standard 96-well microtiter plate and absorbance at 490 nm was recorded using a microtiter plate reader. Three replicate samples from the standard microtiter plate are shown above each bar. Error bars represent standard deviations. Langdon durum bars are barely visible above the zero axis.

Quantitative PPO assays are also possible using kernel leachates and immuno assays, although these have only received preliminary validation as indicators of kernel PPO activities. Initial findings indicated that PPO activity in kernel leachates was a good indicator of PPO activity in kernels (Fuerst et al. 2006a; J. V. Anderson, unpublished data). Also, Western blot staining intensity was highly correlated with extracted PPO activity across a wide range of wheat-related taxa (Fuerst et al. 2008), suggesting that it may be possible to develop a rapid immunoassay using kernel leachates or flour extracts. PPO activity measured in whole-kernel assays includes both soluble and bound forms (Fuerst et al. 2006a). Up to 20% of the PPO activity from hexaploid wheat samples was soluble (i.e., leached from the kernels) when measured over a 1-hour assay period, while the remainder of the activity was “bound” to the kernel (ostensibly at or near the surface within the limits of passive substrate diffusion). It is noteworthy that the kernel leachate itself had a low absorbance at 475 nm, such that a correction for this background leachate absorbance, using a “no-substrate control” was needed for accurate measurements when comparing samples with very low PPO activity.

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Also, it was interesting that soluble wheat PPO, whether leached from kernels or extracted from bran, had no activity with the monophenol substrate tyrosine even though tyrosine is an excellent PPO substrate in whole-kernel assays (Fuerst et al. 2006a). There are a number of possible explanations for this apparent discrepancy: (1) substrate specificity of PPO isoforms—only the ‘bound’ PPO had activity with tyrosine substrate, (2) endogenous diphenols activated monophenol oxidation activity in the microenvironment of the kernel surface, or (3) tyrosine was indirectly oxidized as part of a chain reaction in the kernel assay, in which the primary substrate was an endogenous phenolic compound.

12.7. MEASURING PPO ACTIVITY IN FLOUR Flour PPO activity can be a better predictor of noodle darkening than whole-kernel activity (Kruger et al. 1994a; Ge et al. 2003; Fuerst et al. 2006b), presumably because the milling efficiency and flour extraction rate may differentially influence the amount of bran, and hence PPO and phenolics, in the end product. PPO in flour and ground wheat samples was first measured as oxygen uptake using an oxygen electrode (Kruger 1976; Lamkin et al. 1981; Marsh and Galliard 1986; Hatcher and Kruger 1993, 1997; Baik et al. 1994, 1995; Kruger et al. 1994a; Every et al. 2006). The advantage of this method is that PPO activity and kinetics can be measured directly in the suspension, whereas the spectrophotometer requires a clarification (filtration or centrifugation) step. However, use of the oxygen electrode assay is limited, since each assay takes ≥10 minutes and is not well adapted to high-throughput. Spectrophotometric assays of flour and ground wheat (Figure 12.8) require weighing a small sample (∼100 mg), incubation with buffered substrate for 30–60 minutes, and centrifugation before measuring absorbance (Fuerst et al. 2006b). A no-substrate control is required to correct for the absorbance of the leachate itself. The added steps make this procedure significantly more time consuming than the whole-kernel assays discussed previously. Alternatively, PPO activity can be measured by extracting the enzyme from flour or ground wheat followed by a kinetic assay (Park et al. 1997; Jukanti et al. 2003); this eliminates the need to correct for leachate absorbance noted above. A high-throughput approach to this assay was developed using detergent-based extraction and a microtiter plate kinetic assay (Jukanti et al. 2003). This method appears to be a good indicator of flour PPO activity, but the substantial insoluble component of PPO activity is excluded from the measurement.

12.8. MEASUREMENT OF NOODLE COLOR AND DARKENING The focus on PPO in this chapter is relevant because of the importance of noodle color and the important role that PPO plays in noodle darkening. To improve noodle color and achieve progress in producing noodles with superior and consistent color attributes, the objective measurement of noodle color is essential. Although both desirable colors (e.g., “creaminess”) and undesirable color attributes must be measured

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to allow a complete evaluation of noodle color and appearance, brightness is the single most important aspect. Noodles that darken or that have dark spots are less desirable or even unacceptable to consumers. The following section reviews methods of noodle color measurement. The routine analysis of noodle sheet color is conducted using color meters that quantify the CIE triaxial L*a*b* color space (Wyszecki and Stiles 2000). Change in L* over time (
L*), which describes the amount of darkening in the L* color axis (black to white, 0 to 100, respectively), is obtained by measuring the color of a freshly produced noodle sheet and comparing it with the color at later times. This measurement is the most commonly reported parameter in the literature on darkening of Asian noodles. Noodle darkening is usually measured over periods such as 24 to 48 hours, but most darkening of alkaline noodles occurs during the first 4 hours, suggesting that the procedures for evaluating color change could be expedited as long as timing is precise; precise timing is not as critical for the longer time periods because the rate of color change is slow after 24 hours (Morris et al. 2000; Fuerst et al. 2006b). The CIE triaxial color space also includes scales of a*, ranging from red to green, positive to negative scale, respectively, and b*, ranging from yellow to blue, positive to negative scale, respectively. The b* value is very important in raw Asian noodles since a creamy color is desirable in white salted noodles and a deeper, bright yellow color is desirable in alkaline noodles. The L*, a*, and b* parameters are not completely independent of one another. For example, decreasing L* (darkening) directly decreases b* (Mares et al. 2001). Yellow color comes from at least two sources: xanthophylls and flavonoids. The xanthophylls, lutein and its fatty acid esters, contribute to yellow color at both neutral and alkaline pH and are the basis for the yellow color of pasta made from durum wheat (Mares et al. 1997, 2001). Xanthophylls are subject to undesirable bleaching by lipoxygenase (Borrelli et al. 1999; Mares et al. 2004). Flavonoid apigenin-C-glycosides, localized in the embryo and incorporated in flour during milling, are colorless at neutral pH but experience a chromophore shift to yellow at alkaline pH and are thought to be the principal basis for the increased yellow color in alkaline noodles (Asenstorfer et al. 2004). Although color meters provide an objective measurement of overall color, they do not allow determination of spots, or discrimination of spots from background color. These spots are caused by flecks of wheat bran, which can be high in PPO and phenolics. The digital analysis of noodle color has been pioneered by Hatcher and colleagues from the Grain Research Laboratory of the Canadian Grain Commission (Hatcher et al. 1999, 2004; Shahin et al. 2006). Digital image analysis allows quantification of the number, size, intensity, and color of these spots as well as discrimination of background color from spots. Software using neural networks appears to be the best way at present to analyze data, allowing results to be reported according to the CIE color parameters (Shahin et al. 2006). In addition to these benefits, digital color measurements of noodle sheets can be taken using a scanner, which is much less expensive than a color meter. Software specifically designed for this purpose is not yet commercially available and thus limits widespread adoption of this technology. The following section describes efforts at reducing sample size and increasing throughput. Evaluation of wheat germplasm for color characteristics is often limited

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to late-generation material due to the relatively large amount of flour required to make noodles, typically 100–200 g (Kruger et al. 1992, 1994b; Morris et al. 2000; Ross and Hatcher 2005). High-throughput methods of analyzing color characteristics using smaller quantities of flour would greatly reduce labor and accelerate wheat breeding and other research. Methods for predicting noodle color stability via NIR analyses of refined flour and grain have been reported (Black and Panozzo 2003). Several researchers have scaled noodle size down using ≤20 g flour, although mixing time was not substantively changed (Kruger et al. 1992; Mares and Panozzo 1999; Bartkowski et al. 2001; Mares and Campbell 2001; Mares et al. 2001; Asenstorfer et al. 2006; Fuerst et al. 2006b). In contrast, a high-throughput centrifugal mixer allows for very short mixing times (30 seconds) and small sample size (5–50 g) (Hatcher and Preston 2004). Smaller-scale noodle-sheeting machines or methods are needed to optimize the final step of this process. Small, commercially available pasta machines have been used (Bartkowski et al. 2001; Asenstorfer et al. 2006; Fuerst et al. 2006b) but these machines typically lack the precision of machines made for larger-scale noodles. A motorized machine has been designed that handles as little as 5–10 g of noodle dough (Kovacs et al. 2003). We have developed an in situ method of analyzing color change in very small (∼2.5 g) flour samples. Briefly, a 1-mm thick layer of flour was spread with minimal packing on a filter paper using a spatula and template with a 6.5-cm diameter opening (this specific opening was based on our color meter). The filter paper with flour layer was placed in a Petri dish containing an aqueous salt solution to simulate either yellow alkaline or white salted noodle formula. The flour layer was wetted from below through capillary action. Excess moisture was removed and the flour layer was covered with plastic wrap. This method was used for evaluations of white flour (Figure 12.10A), 10% whole-meal flour (Figure 12.10B), or the effect of specific phenolics (Figure 12.4) on color change. The small sample size is useful for research purposes, but this method is not well adapted for high-throughput because the rate of wetting varied widely due to (1) the cultivar and (2) nonuniform flour layers resulting from variability in degree of packing of the flour layer. Both factors contributed to difficulty in making zero-time measurements. The wetting problem was overcome by placing the dry flour layers in a humidified chamber for 4–16 hours before wetting. Longer incubations (>24 hours) under high humidity led to very rapid darkening. We compared color change using the in situ methods, above, with standard raw noodle sheets and whole-kernel PPO activity among seven cultivars (Figure 12.11). In situ
L* (0–24 h) using white flour (Figure 12.10A) was well correlated (r2 = 0.96) with standard noodles in these seven cultivars. The magnitude of
L* (0–24 h) was much lower using the in situ methods, because darkening was mainly confined to spots (Figure 12.10), due to lack of mixing. Takata et al. (2003) similarly reported relatively small
L* (0–24 h) using an in situ assay of color change in flour paste. The strong and immediate darkening of 100% whole-meal flour did not allow detection of varietal differences and also suffered the wetting problems discussed above. However, white flour from our low PPO noodle standard variety “ID377s” wetted quickly and consistently, and worked very well as a basis for comparing

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B

FIGURE 12.10 Thin-layer flour assay. A 1-mm thick layer of flour was spread on filter paper, moistened from below, and incubated 24 hours at room temperature. (A) White flour from low PPO cultivar “Eltan” (left) and high PPO cultivar “Madsen” (right) shows that darkening is mainly confined to spots in this assay, which involves no mixing after wetting. (B) A 10% whole-meal flour was blended with 90% (w/w) white flour from “ID377s” before wetting. Darkening spots had lower intensity with 10% whole-meal flour from the low PPO cultivar “ID377s” (left) and greater intensity with 10% whole-meal flour from the high PPO cultivar “Klasic” (middle). Ascorbate (1000 ppm) effectively inhibited much but not all of the darkening from “Klasic” (right). 12.0

2.0

1.5 8.0 6.0

1.0

4.0 0.5

PPO Activity (∆A475 /h)

Darkening (∆L* 0-24 h)

10.0

2.0 0.0

Eltan

Noodle Darkening

ID377s ID580 In Situ White Flour Darkening

Langdon Klasic Penawawa Madsen In Situ 10% Whole-meal Flour Darkening

0.0

Whole-kernel PPO Activity

FIGURE 12.11 Comparisons among cultivars for (i) darkening (
L*, 0–24 h) in raw alkaline noodle sheets (first bar in each cultivar series), (ii) in situ darkening assay with refined white flour (second bar in each series), (iii) in situ assay with 10% whole-meal flour added to “ID377s” white flour (third bar in each series), and (iv) whole-kernel PPO activity (solid bars, fourth bar in each series).

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darkening among cultivars using 10% whole-meal flours (∼0.25 g) from different varieties, each mixed with the white flour standard. In situ
L* (0–24 h) using 10% whole-meal flour (Figure 12.10B) was also reasonably well correlated (r2 = 0.86) with color change of standard noodles in these seven cultivars (Figure 12.11). Whole-kernel PPO activity was not as well correlated (r2 = 0.54) with standard noodle darkening among these cultivars because two of the cultivars, ID580 (aka IDO580, PI 620638) and Langdon durum, had near-zero whole-kernel PPO activity yet both cultivars darkened substantially due to a non-PPO mechanism (Fuerst et al. 2006b). Ascorbate substantially reduced darkening in samples containing 10% whole-meal flour (Figure 12.10B) and is also known to inhibit darkening of noodles made from refined white flour (Baik et al. 1995). The concept of blending small quantities of whole-meal flour of various cultivars with a single standard or base refined flour could be applied to a small-scale noodle method such as that discussed previously (Hatcher and Preston 2004), to achieve both high throughput and small grain sample size for early-generation evaluations.

12.9. MECHANISMS OF NOODLE DARKENING Although it is now well established that PPO plays a major role in the darkening of Asian noodles, 30 years ago this was not clearly established (Kruger 1976). One body of evidence that continues to build is the correlation between kernel PPO activity and darkening of both alkaline and white salted (udon and Chinese) noodles. Correlations between kernel PPO activity and
L* in alkaline and/or white salted noodles ranged from r = 0.41 to 0.87 (Kruger et al. 1994a; Baik et al. 1995; Davies and Berzonsky 2003; Ge et al. 2003; Jukanti et al. 2003; Fuerst et al. 2006b). As previously discussed, correlations with noodle darkening are often higher with flour PPO than with kernel PPO. However, the association between flour PPO activity and alkaline noodle darkening was relatively weak in the study by Martin et al. (2005). In this study, PPO activity was three to five times greater in flour from high versus low PPO population groups, yet the increase in darkening was relatively small, approximately 0.7 units on average (
L*, 0–24 h), in alkaline noodles from the high versus low PPO groups. Collectively, these studies suggest that kernel and flour PPO assays have not been completely effective in predicting noodle darkening. The concentration of PPO and phenolics increases as extraction rate is increased due to increased contamination with bran particles, as previously discussed. Likewise, Asian noodle color darkens as flour extraction increases (Kruger et al. 1994b; Ye et al. 2008), and this can largely be attributed to increased content of phenolics and PPO (Hatcher and Kruger 1993, 1997). Likewise, darkening is far greater in whole wheat products (100% extraction), which contain all of the phenolics and PPO associated with bran fractions. The impact of only 10% whole wheat on darkening in this assay is indicated in Figure 12.10B. Another association between PPO activity and darkening can be noted in the case of Fusarium head blight. Fusarium head blight increases PPO and peroxidase activity in maturing wheat kernels (Mohammadi and

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Kazemi 2002) and also causes severe darkening in Asian noodles (Hatcher et al. 2003). The relative contribution of PPO, peroxidase, phenolic compounds, and other mechanisms to this darkening is unknown, however. Noodle darkening is also often correlated with flour ash and flour protein (Miskelly and Moss 1985; Kruger et al. 1994b; Baik et al. 1995; Zhang et al. 2005; Zhou and Seib 2005; Fuerst et al. 2006b; Ma et al. 2009). The relationship with flour ash is not surprising, since flour ash is largely derived from the bran layer and thus ash content is an indicator of bran contamination. Flour protein, as affected by moisture and soil nitrogen, is not always correlated with increased darkening (Guttieri et al. 2005), which may best be explained if a specific group of proteins is linked to the darkening reactions (Asenstorfer et al. 2009). It is possible that proteins directly participate in darkening reactions. Increased flour protein levels may lead to increased production of colored protein products (Asenstorfer et al. 2009) since quinone products of phenolic oxidation, including the PPO reactions (Figure 12.2), bind to amino acids and peptides to produce colored products (Pierpoint 1969), as previously discussed. Evidence for the role of PPO in noodle darkening also comes from studies using the PPO inhibitors, tropolone and SHAM (salicyl hydroxamic acid). Tropolone and SHAM are potent inhibitors of PPO in kernel assays and also inhibit noodle darkening to some extent (Asenstorfer et al. 2007; 2009; Asenstorfer and Mares 2008; Fuerst et al. 2006b; Mares et al. 2001). Inhibition of darkening by tropolone and SHAM was greater in a high PPO cultivar than in a low PPO cultivar (Fuerst et al. 2006b) and there was no inhibition in a zero-PPO cultivar (Asenstorfer et al. 2009). Although these results strongly implicate PPO as a primary factor in darkening, this incomplete prevention of darkening by inhibitors suggests that there are non-PPO darkening mechanisms. Additional lines of evidence point to the involvement of non-PPO darkening mechanisms. Flour and kernel PPO activities have been only partially effective at predicting noodle darkening, as noted above. In addition, when data from these studies are analyzed by linear regression, extrapolating the regression line to zero PPO activity does not lead to a predicted zero
L*. The predicted
L* at zero PPO activity was 4.4 (Fuerst et al. 2006b) and 10.3 (Mares and Panozzo 1999), implying that substantial darkening would occur at zero PPO activity. Indeed, noodles made from cultivars having near-zero kernel PPO activity still had substantial darkening (Figure 12.11) (Fuerst et al. 2006b; Asenstorfer et al. 2009). Alternative (non-PPO) darkening mechanisms could include increased levels of the darkening substrates, nonenzymatic reactions, and oxidation of phenolics by other enzymes such as peroxidase. It is not surprising that levels of phenolic substrates can influence the degree of darkening, as previously discussed for proanthocyanidins in barley products (Quinde-Axtell 2004; Quinde et al. 2004). Until the darkening substrates (possibly including phenolics and proteins) of wheat have been identified, it will not be possible to directly assess the extent to which these substrates contribute to genetic variability in darkening of wheat products. Alternatively, several nonenzymatic darkening reactions can also be proposed. Nonenzymatic reactions

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might involve the autooxidation of some phenolic compounds at alkaline pH (Anderson and Morris 2001), reactions that could be enhanced in alkaline noodles. Asenstorfer et al. (2009) recently suggested that nonenzymatic darkening reactions may involve reactions with the aromatic amino acids of proteins. In addition, metallic cations may catalyze nonenzymatic darkening. For example, iron may play a nonenzymatic role in darkening of porridges (Theur et al. 2002). Other oxidative enzymes might also contribute to darkening. Peroxidase is known to play a role in darkening of cassava and strawberry products (L´opez-Serrano and Ros Barcel´o 2001; Reilly et al. 2004). Peroxidase has been evaluated as a potential darkening agent in pasta made from durum wheat, but results were equivocal (Feillet et al. 2000). Hexaploid wheat contains peroxidase (Hatcher and Barker 2005) but its role in darkening of wheat products remains obscure. Peroxidase levels are higher in wheat bran than in endosperm, but significant levels may also be present in the endosperm (Fraignier et al. 2000; Rani et al. 2001). Other oxidative enzymes are also candidates for causing darkening. Indeed, in-gel assays suggest that l-DOPA acts as a substrate for a wheat kernel enzyme other than PPO based on the fact that l-DOPA oxidation in immature kernel extracts was not inhibited by tropolone (Anderson et al. 2006). A very important recent study demonstrated that the effects of temperature, pH, PPO inhibitors, and newly identified inhibitors of nonenzymatic darkening collectively indicate that non-PPO darkening in alkaline noodles is primarily nonenzymatic and support a growing body of evidence that it is the major mechanism of darkening in most wheat cultivars (Asenstorfer et al. 2009). The five inhibitors of nonenzymatic darkening all interact with proteins, which strongly implicates proteins in the darkening process (Asenstorfer et al. 2009). Further study will be needed to determine whether the initial darkening reactions involve the aromatic amino acids of proteins or oxidation of phenolic compounds with subsequent polymerization reactions and covalent binding to amino acids, peptides, and other nucleophilic constituents to produce melanins, as previously discussed (Figure 12.2). Either way, the involvement of proteins in the darkening process would explain the positive correlation between protein content and darkening. To summarize, although many observations substantiate the contribution of PPO to Asian noodle darkening, many observations clearly indicate the involvement of a non-PPO mechanism. Before significant advances in control of noodle darkening can be made, additional information is needed on the identity of the darkening substrates, including phenolic compounds and proteins, and on the mechanism of nonenzymatic darkening.

12.10. SUMMARY Many wheat breeding programs now routinely screen germplasm and breeding lines for noodle color quality potential since this is a key trait in consumer acceptability of Asian noodles. Substantial progress has been made in understanding darkening mechanisms, especially the role of PPO, and improving the color of foods made from

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wheat. Research overwhelmingly indicates that high PPO levels can substantially contribute to the darkening of raw Asian noodles. Reducing or eliminating PPO-based darkening via genetic improvement is a plausible goal and a proven approach for reducing darkening. The development of wholekernel assays for PPO activity (Section 12.6) has enabled many wheat breeding programs to identify and eliminate problematic wheat lines early in the breeding process. Recent advances in our understanding of PPO genetics and the development of genetic markers (Section 12.4) will facilitate the development of elite breeding germplasm with near-zero PPO activity and the capability to monitor PPO genes and alleles at any stage in the breeding process. The elimination of PPO activity alone will not eliminate darkening because of the presence of nonenzymatic darkening (Asenstorfer et al. 2009) and possibly other darkening mechanisms. Therefore, once PPO-based darkening has been minimized the question becomes “What is the next step in improving noodle color?” In part, the answer lies in determining all of the factors that contribute to the darkening process, including (1) the potential role of endogenous inhibitors of PPO and/or inhibitors of other darkening reactions (Section 12.3), (2) the extent to which proteins (Section 12.9) and specific phenolic substrates (Section 12.5) contribute to darkening, and (3) the specific reactions involved in nonenzymatic and other darkening mechanisms (Section 12.9). Additional information is especially needed on the role of genetics in the non-PPO darkening mechanisms. Finally, all of this research would benefit from the development of small-scale high-throughput assays for color change and darkening (Section 12.8); such assays would also enable early-generation screening of germplasm for these key traits.

ACKNOWLEDGMENTS The authors thank Arthur Bettge, Shawna Vogl, and Stacey Sykes for assistance with the figures and manuscript preparation.

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Lamkin, W. M., Miller, B. S., Nelson, S. W., Traylor, D. D., and Lee, M. S. 1981. Polylphenol oxidase activities of hard red winter, soft red winter, hard red spring, white common, club, and durum wheat cultivars. Cereal Chem. 58:27–31. Le Bourvellec, C., Le Qu´er´e, J.-M., Sanoner, P., Drilleau, J.-F., and Guyot, S. 2004. Inhibition of apple polyphenol oxidase activity by procyanidins and polyphenol oxidation products. J. Agric. Food Chem. 52:122–130. Li, L. and Steffens, J. C. 2002. Overexpression of polyphenol oxidase in transgenic tomato plants results in enhanced bacterial disease resistance. Planta 215:239– 247. L´opez-Serrano, M. and Ros Barcel´o, A. 2001. Histochemical localization and developmental expression of peroxidase and polyphenol oxidase in strawberries. J. Am. Soc. Horticul. Sci. 126:27–32. Ma, D., Guo, T., Wang, Z., Wang, C., Zhu, Y., and Wang, Y. 2009. Influence of nitrogen fertilizer application rate on winter wheat (Triticum aestivum L.) flour quality and Chinese noodle quality. J. Sci. Food Agric. 89:1213–1220. Macheix, J.-J., Fleuriet, A., and Billot, J. 1990. Fruit Phenolics. CRC Press, Boca Raton, FL, USA. Maguire, J. D., Steen, K. M., and Grzelak, K. 1975. Classification of Pacific Northwest winter and spring wheat cultivars by phenol reactions. Proc. Official Assoc. Seed Analysts 65:143–146. Mahoney, R. R. and Ramsay, M. 1992. A rapid tyrosinase test for detecting contamination of durum wheat. J. Cereal Sci. 33:267–270. Mares, D. J. and Campbell, A. W. 2001. Mapping components of flour and noodle colour in Australian wheat. Australian J. Agric. Res. 52:1297–1309. Mares, D. J. and Panozzo, J. F. 1999. Impact of selection for low grain polyphenol oxidase activity on darkening in Asian noodles. In: P. Williamson, P. Banks, I. Haak, J. Thompson, and A. Campbell (eds.), Proceedings of the 9th Assembly Wheat Breeding Society of Australia. Toowoomba, Queensland, Australia, pp. 32–33. Mares, D. J., Wang, Y., and Cassidy, C. A. 1997. Separation, identification, and tissue location of compounds responsible for the yellow colour of alkaline noodles. In: A. W. Tarr, A. S. Ross, and C. W. Wrigley (eds.), Proceedings of the 47th Cereal Chemists Conference. Perth, Australia, pp. 114–117. Mares, D. J., Wang, Y., and Baydoun, M. 2001. Colour of Asian noodles: stability of xanthophylls and flavonoids and interaction with darkening. In: M. Wootton, I. L. Batey, and C. W. Wrigley (eds.), Cereals 2000, Proceedings of the 50th Australian Cereal Chemistry Conference. Royal Australian Chemical Institute, North Melbourne, Victoria, Australia, pp. 320–322. Mares, D. J., Mrva, K., and Fincher, G. B. 2004. Enzyme activities. In: C. Wrigley, H. Corke, and C. E. Walker (eds.), Encyclopedia of Grain Sciences, Vol. 1. Elsevier Ltd., Oxford, UK, pp. 357–365. Marsh, D. R. and Galliard, T. 1986. Measurement of polyphenol oxidase activity in wheat milling fractions. J. Cereal Sci. 4:241–248. Martin, J. M., Berg, J. E., Fischer, A. M., Jukanti, A. K., Kephart, K. D., Kushnak, G. D., Nash, D., and Bruckner, P. L. 2005. Divergent selection for polyphenol oxidase and its influence on agronomic, milling, bread, and Chinese raw noodle quality traits. Crop Sci. 45:85–91.

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Massa, A. N., Beecher, B., and Morris, C. F. 2007. Polyphenol oxidase (PPO) in wheat and wild relatives: molecular evidence for a multi gene family. Theor. Appl. Genet. 114:1239–1247. Matus-Cadiz, M. A., Daskalchuk, T. E., Verma, B., Puttick, D., Chibbar, R. N., Gray, G. R., Perron, C. E., Tyler, R. T., and Hucl, P. 2008. Phenolic compounds contribute to dark bran pigmentation in hard white wheat. J. Agric. Food Chem. 56:1644–1653. Mayer, A. M. 2006. Polyphenol oxidases in plants and fungi: Going places? A review. Phytochemistry 67:2318–2331. Mayer, A. M. and Harel, E. 1979. Review: polyphenol oxidases in plants. Phytochemistry 18:193–215. McCallum, J. A. and Walker, J. R. L. 1990. Proanthocyanidins in wheat bran. Cereal Chem. 67:282–285. Milner M. and Gould, M. R. 1951. The quantitative determination of phenol oxidase activity in wheat varieties. Cereal Chem. 28:473–478. Miskelly, D. M. and Moss, H. J. 1985. Flour quality requirements for Chinese noodle manufacture. J. Cereal Sci. 3:379–387. Mohammadi, M. and Kazemi, H. 2002. Changes in peroxidase and polyphenol oxidase activities in susceptible and resistant wheat heads inoculated with Fusarium graminearum and induced resistance. Plant Sci. 162:491–498. Morris, C. F., Jeffers, H. C., and Engle, D. E. 2000. Effect of processing, formula and measurement variables on alkaline noodle color—toward an optimized laboratory system. Cereal Chem. 77:77–85. Morris, C. F., Massa, A., Anderson, J. V., and Demeke, T. 2002. Progress in identification and selection of desirable genetic traits for wheat breeding and improvement. In: C. K. Black, J. F. Panozzo, C. W. Wrigley, I. L. Bately, and N. Larsen (eds.), Cereals 2002, Proceedings of the 52nd Australian Cereal Chemistry Conference. The Royal Australian Chemical Institute, North Melbourne, Australia, pp. 227–230. Okot-Kotber, M., Liavoga, A., Yong, K.-J., and Bagorogoza, K. 2001. Activity and inhibition of polyphenol oxidase in extracts of bran and other milling fractions from a variety of wheat cultivars. Cereal Chem. 78:514–520. Okot-Kotber, M., Liavoga, A., Yong, K.-J., and Bagorogoza, K. 2002. Activation of polyphenol oxidase in extracts of bran from several wheat (Triticum aestivum) cultivars using organic solvents, detergents, and chaotropes. J. Agric. Food Chem. 50:2410–2417. Park, W. J., Shelton, D. R., Peterson, C. J., Martin, T. J., Kachman, S. D., and Wehling, R. L. 1997. Variation in polyphenol oxidase activity and quality characteristics among hard white wheat and hard red winter wheat samples. Cereal Chem. 74:7–11. Pierpoint, W. S. 1969. o-Quinones formed in plant extracts. Their reactions with amino acids and peptides. Biochem. J. 112:609–616. Pietrzak, L. N. and Collins, F. W. 1996. Comparison of fluorometric reagents for microspectrofluorometric determination of flavonoid glycosides in wheat germ. J. Cereal Sci. 23:85–91. Posner, E. S. and Hibbs, A. N. 1997. Wheat Flour Milling. American Association of Cereal Chemists, St. Paul, MN, USA. Quinde-Axtell, Z. 2004. Dark discoloration of barley-based food products. Ph.D. dissertation, Washington State University, USA, 170 pp. Quinde-Axtell, Z. and Baik, B.-K. 2006. Phenolic compounds of barley grain and their implication in food product discoloration. J. Agric. Food Chem. 54:9978–9984.

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Theuer, R. 2002. Effect of iron on the color of barley and other cereal porridges. J. Food Sci. 67:1208–1211. Tomas-Barberan, F. A. and Espin, J. C. 2001. Phenolic compounds and related enzymes as determinants of quality in fruits and vegetables. J. Sci. Food Agric. 81:853–876. Vadlamani, K. R. and Seib, P. A. 1996. Reduced browning in raw Oriental noodles by heat and moisture treatment of wheat. Cereal Chem. 73:88–95. Van Gelder, C. W. G., Flurkey, W. H., and Wichers, H. J. 1997. Sequence and structural features of plant and fungal tyrosinases. Phytochemistry 45:1309–1323. Walls, W. E. 1965. A standardized phenol method for testing wheat seed for varietal purity. In: The Handbook on Seed Testing, Contribution No. 28. The Association of Official Seed Analysts, Lincoln, NE, USA, pp. 36–43. Wang, C., Kovacs, M. I. P., Fowler, D. B., and Holley, R. 2004. Effects of protein content and composition on white noodle making quality: color. Cereal Chem. 81:777–784. Warner, R. L., Kudrna, D. A., Spaeth, S. C., and Jones, S. S. 2000. Dormancy in white-grain mutants of Chinese spring wheat (Triticum aestivum L.). Seed Sci. Res. 10:51–60. Watanabe, N., Takeuchi, A., and Nakayama, A. 2004. Inheritance and chromosomal location of the homoeologous genes affecting phenol colour reaction of kernels in durum wheat. Euphytica 139:87–93. Watanabe, N., Masum Akond, A. S. M. G., and Nachit, M. M. 2006. Genetic mapping of the gene affecting polyphenol oxidase activity in tetraploid durum wheat. J. Appl. Genet. 47:201–205. Whitaker, J. R. and Lee, C. Y. 1995. Recent advances in chemistry of enzymatic browning: an overview. In: C. Y. Lee and J. R. Whitaker (eds.), Enzymatic Browning and Its Prevention. American Chemical Society, Washington, DC, USA, pp. 2–7. Wrigley, C. W. and McIntosh, R. A. 1975. Genetic control of factors regulating the phenol reaction of wheat and rye grain. Wheat Information Service 40:6–10. Wyzecki, G. and Stiles, W. S. 2000. Color Science. Concepts and Methods, Quantitative Data and Formulae, 2nd ed. John Wiley & Sons, Hoboken, NJ, USA. Yadav, D. N., Patki, P. E., Sharma, G. K., and Bawa, A. S. 2008. Effect of microwave heating of wheat grains on the browning of dough and quality of chapattis. Int. J. Food Sci. Technol. 43:1217–1225. Ye, Y., Zhang, Y., Yan, J., Zhang, Y., He, Z., Huang, S., and Quail, K. J. 2008. Effects of flour extraction rate, added water and salt on color and texture of Chinese white noodles. In: J. F. Panozzo and C. K. Black (eds.), Cereals 2008, Proceedings of the 58th Australian Cereal Chemistry Conference. AACC DownUnder, New South Wales, Australia, pp. 113–116. Yoruk, R. and Marshall, M. R. 2003. Physicochemical properties and function of plant polyphenol oxidase: a review. J. Food Biochem. 27:361–422. Zeven, A. C. 1972. Identification of chromosomes carrying a locus for a gene conditioning the production of tyrosinase in wheat grains. Wheat Information Service 35:3–8. Zhang, L.-P., Ge, X.-X., He, Z.-H., Wang, D.-S., Yan, J., Xia, X.-C., and Sutherland, M. W. 2005. Mapping QTLs for polylphenol oxidase activity in a D H population from common wheat. Acta Agronom. Sinica 31:7–10. Zhao, L. F. and Seib, P. E. 2005. Alkaline-carbonate noodles from hard winter wheat flours varying in protein, swelling power, and polyphenol oxidase activity. Cereal Chem. 82:504–516.

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CHAPTER 13

Effects of Flour Characteristics on Noodle Texture ANDREW S. ROSS and GRAHAM B. CROSBIE

13.1. INTRODUCTION All the quality attributes of wheat-flour noodles, including their texture, depend primarily on the characteristics of the wheat flour used as a raw material. The wheat chosen for milling should be clean, plump, predominantly free from defects, and sound (i.e., free from sprout damage) (Hou 2001; Crosbie and Ross 2004; Fu 2008). Relevant flour characteristics include the size distribution of the flour particles, flour protein composition, the state of the starch granules (proportion of damaged granules, granule size distribution), the molecular composition of the starch, and a recognition of the possible effects of the minor components such as pigments, lipids, fiber components (primarily arabinoxylans), and enzymes. Additionally of significance are interactions between flour components, between the flour components and water (e.g., the flour’s absorption capacity), and the behavior of noodle dough, which has its own influence on finished-product quality. As Asian noodles are made most commonly from refined flour, this chapter is focused primarily on the physical characteristics and composition of the wheat kernel endosperm and the resulting “white” flour. In some cases, no attempt has been made to differentiate between white salted (nonalkaline), alkaline, or instant noodles as the major impact on the texture of noodles is from the flour polymers. As the physicochemical attributes of the polymers are first and foremost related to their size and structure, changes in polymer composition derived from changes in grain composition are likely to have parallel effects regardless of noodle formulation, including formulations of contrasting pH. Whether these parallel effects (e.g., additional firmness with increased flour protein) are desirable is dependent on noodle type.

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13.1.1. Texture Texture is a sensory characteristic (Szczesniak 2002). The sensory signals of texture perceived by the consumer are derived from the interactions of the structural, physical, and geometrical properties of the food with the hands and mouth during handling and eating. In Asian noodle research, it has been common practice to employ either or both sensory and instrumental analyses for measuring texture and physical properties, respectively. As we will see, both types of evaluation have their strengths as well as their attendant limitations and assumptions.

13.1.2. Instrumental and Sensory Methods Instrumental methods tend to dominate noodle texture research primarily as a result of their accessibility and relative ease-of-use. However, they have the limitation that they do not measure texture per se, if one accepts the assertion that texture is solely a sensory attribute. Under this condition, instrumental methods are restricted to measuring selected physical or mechanical properties of the noodles. This is not a bad circumstance as the quantification of physical properties is a necessary function in noodle research. By extending this idea, the selected physical properties would ideally be related to key texture attributes derived from sensory analyses. Despite the contention of Szczesniak (2002) and others that texture is only a sensory property, phrases like “instrumental texture testing” persist in the commercial and scientific literature. Among the “others” noted above, Engmann et al. (2006) went so far as to say that instrumental texture measurements were a delusive [sic] concept and suggested that in their view it was more correctly put that there were “instrumental measurements of physical properties that were relevant to texture” (their emphasis). Another arguable drawback in the use of instrumental methods to predict sensory attributes or mimic sensory testing is that instrumental tests generally use precise geometries that employ relatively simple deformation pathways: often just uniaxial compression or tension, or sinusoidal oscillation. However, neither uniaxial or sinusoidal deformations come anywhere near to the complexity of the combined compressive and shear forces exerted in the mouth by the teeth and tongue during chewing (Lucas et al. 2002; Ross 2006), let alone the further dynamic effects of saliva and its component enzymes (Ross 2006). Sensory evaluations can assess foods across two important but different categories: liking and intensity. In the liking category, hedonic testing is crucial in determining quality preferences of specific markets and consumers. In the intensity category, intensity ratings of individual attributes provide a critical link between consumer preference assessments and instrumental tests, as well as providing data on the human perception of the intensity of specific attributes (e.g., in the hard–soft dimension). Sensory analysis is a demanding discipline if it is to provide credible data. Vigilance is required in a number of areas: panelist training, agreed-upon definitions for descriptors, the design and application of rating scales, and in the application of the necessary statistical analyses. The sensory tests most commonly referred to in this chapter are of the category “intensity rating.” In intensity rating tests, noodle texture

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has commonly been subdivided into three primary categories: elasticity, smoothness, and the hard–soft dimension. Subsidiary descriptors like stickiness, chewiness, cohesiveness, and viscoelasticity are also used, and other research groups have employed an even wider lexicon (Janto et al. 1998). These attributes and their descriptors can sometimes be difficult to define accurately, even just within the English language (Ross and Crosbie 1997; Ross 2006). Additionally, the descriptors as defined in the native languages of the primary consumers may not always map well to the English descriptors, leaving considerable room for interpretation and the potential for misunderstandings. Difficulties with definitions occur even just within the English language. This is probably most evident for the sensory attribute “elasticity.” Ross and Crosbie (1997) argued that an obstruction to widespread adoption of any single instrumental method for cooked noodle elasticity is the difficulty of correlating the elasticity of physics with sensory ratings of noodle elasticity. This situation has arisen, in part, because of the lack of a consistent and widely accepted sensory definition of noodle elasticity. Additionally, the often exchangeable use of the terms “elasticity” and “springiness” in the case of noodle assessment perhaps do not help in attempts to develop a simple mechanical method. Nonetheless, progress is being made and the stress relaxation technique recently applied to cooked noodles by Hatcher and co-workers (Hatcher et al. 2008; Bellido and Hatcher 2009; Hatcher et al. 2009) is a constructive advance. The possibility for misinterpretation can be seen in these three definitions of elasticity: r Rheological Definition: the ability of an object to fully recover its original dimensions after the removal of a deforming force. r Sensory Definitions Example 1: the amount of rebound force felt when the noodles are squeezed gently between the molars (from BRI Australia’s sensory testing definitions; K. Quail, personal communication; Ross and Crosbie 1997; Ross 2006). Example 2: elastic and cohesive when chewed (Zhang et al. 2005). Example 1 of the two sensory definitions is debatably based on the same concept of the residual force parameter in instrumental stress relaxation tests. The second sensory example is self-referent and therefore lacks utility for other researchers trying to duplicate the method. Sensory elasticity determinations become more problematic when one takes the concept of fracture strain into account. Fracture strain is the extent of relative deformation beyond which the structural integrity of the object is destroyed. Having invoked fracture strain, one now needs to consider the concepts of brittleness and ductility with respect to the responses of cooked noodles to deformation. Materials that are greatly elastic by the definitions of rheology, and which also possess short fracture strains, are considered to be brittle. This is not an uncommon phenomenon. Noodles that are perceived as losing integrity early in the bite stroke and will be scored as less elastic by the above sensory definitions. Materials that are less energetically elastic (less stiff: i.e., with a lower modulus of compression or deformability

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[Bourne 2002]) but that have large fracture strains are considered to be ductile. For noodles, this suggests that they would retain a detectable residual force between the teeth even close to the full bite stroke, and thus meet the Example 1 criterion for mouthfeel elasticity. Ductile fracture might also be described as a “longer” bite or “longness” (Walstra 2003). Other work has supported this idea. In one study, noodles from waxy flour had higher resistance to compression than noodles made from flour with normal starch, when the strain was >80%, suggesting that even though the waxy wheat noodles were softer, their fracture strain exceeded 80% (Sasaki et al. 2004). Higher fracture strains for noodles made from reduced amylose wheat flour were also observed by Ross and Crosbie (1997). The point here is not to define noodle elasticity in any concrete sense, but rather to point out that we ought to recognize the assumptions in our choices of sensory definitions and techniques, and in the design and application of the derived instrumental methods. Limitations and assumptions aside, both sensory intensity ratings and instrumentally derived physical parameters have proved to be of great value in providing quantitative descriptions of the textural and physical properties of cooked noodles. 13.1.3. Noodle Microstructure The architecture or internal microstructure of cooked noodles is another factor that influences the way in which flour composition expresses itself as noodle texture. Cooked noodles are a composite material with recognizable continuous and discrete phases. The composite nature is especially evident in the interior of the noodle strands where water penetration is limited (Wu et al.1998; Kojima et al. 2004) and well-defined remnant starch granules are visible under both transmission (Moss et al. 1987) and scanning electron microscopy (SEM) (Dexter et al. 1979; Lai and Hwang 2004). The continuous phase is likely to be made up primarily of interpenetrating and entangled gluten proteins and arabinoxylans. There is a possibility that these two components could be phase separated, but we are not aware of any evidence published in relation to this. Another component of the continuous phase of the cooked noodle is amylose. Exudation of amylose from the remnant granules has been visualized using SEM (Dexter et al. 1979). The exuded amylose “glues” the remnant granules into the continuous phase and probably contributes to noodle elasticity. The amount of amylose leached from individual granules is likely to decline as distance from the surface of the noodle strand increases because granules in the interior are less swollen and more intact (Dexter et al. 1979; Moss et al. 1987). Under the high solids concentrations of a cooked (cooking) noodle strand, there is effectively no opportunity for lateral translational motion of the linear amylose chains and the only mode available for translational motion is reptation (Rennie 1997), which is slow by molecular standards. However, Rennie (1997) calculated from the theory of PierreGilles De Gennes that the time for a linear molecule with a degree of polymerization (DP) of around 10,000 to reptate its entire length would be around 10 seconds, leaving plenty of time for amylose molecules, with commonly accepted DP values in the range of 250–1000, to move some distance from the source granule during cooking. Hug-Iten et al. (2001) suggested that the driving force for amylose leaching

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from the granules during heating, and the concurrent plasticization of the system by water, was the thermodynamic incompatibility and subsequent phase separation of the amylose and amylopectin. The discrete phase of remnant granules takes up the largest volume fraction of the cooked noodle strand and hence the deformability of the remnant granules is likely to be a key aspect of their overall mechanical and textural properties. Cooked granule deformability will be determined through interactions between a number of phenomena: the water content of individual gelatinized granules, which decreases steadily from the exterior toward the center of the noodle (Wu et al. 1998; Kojima et al. 2004), the initial amylose:amylopectin ratio of the starch, the structure of the amylopectin, and the molecular weight of the amylose. For example, higher amounts of amylopectin with chain length DP > 35 have been associated with higher starch swelling power (Sasaki and Matsuki 1998). Rice texture is also affected by amylopectin fine structure (reviewed by Bhattacharya 2009) and there is no reason to think this would not affect remnant granule deformability in a cooked wheat-flour noodle strand. Amylose molecular weight may also be related to the Wx loci (Akashi et al. 1999), to the thermodynamic drive for amylose leaching, and hence to the swelling potential of the granules.

13.2. PHYSICAL FLOUR PROPERTIES It is considered that flour milled specifically for noodle making should have a fine particle size distribution (PSD) without excessive starch damage (Fu 2008). This position appears to be largely supported by the primary literature with only minor caveats. Hatcher et al. (2002) indicated that flour with fine PSD and low starch damage, in salted noodles made from doughs with comparable consistencies, produced noodles that had higher cutting stress and resistance to compression (firmness) with higher recovery from deformation (elasticity). These authors claimed that these textural attributes were “better” texture. This may well be true for salted noodles in some markets or regions. However, it opens up the question of how the additional firmness associated with low PSD flours with minimal starch damage might be perceived in, for example, udon, where softer textures are desired. Elbers et al. (1996) also showed harder textures (as higher extrusion force; Lee et al. 1987) in both salted and (carbonate) alkaline noodles with increased levels of starch damage. However, that study did not separate the effects of starch damage and PSD as did the more sophisticated later study of Hatcher et al. (2002). In a further sophistication of understanding of the effects of PSD and starch damage on noodle texture, Hatcher et al. (2005) reported that the influence of these physical flour properties on alkaline noodles was interactive with the type of alkali. Carbonate-based kansui noodles again showed increased hardness (cutting stress) and also increased elasticity (recovery from deformation) with increased starch damage, but hydroxide-based alkaline noodles softened and became less elastic as starch damage increased. The decline in elasticity for hydroxide-based alkaline noodles as the flour PSD became coarser was described by the authors as “dramatic.” This data led the authors to the conclusion

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that the general recommendation for noodle flour to have fine PSD and low starch damage was even more critical for hydroxide-based alkaline noodles. Storlie et al. (2006) reported softer textured cooked salted noodles from doubled haploid lines containing the “soft” puroindoline b (Pinb-D1a) allele, which also had higher PSD, thereby agreeing with the findings of Hatcher et al. (2002) and Elbers et al. (1996). However, Martin et al. (2008) reported increased cooked firmness in salted noodles as kernel texture became softer in a group of hard red spring transgenic isolines that overexpressed either or both Pina-D1a and Pinb-D1a. The differences in noodle texture related to puroindolines were, according to Martin et al. (2008), mediated through the association of the Pin loci with kernel texture and hence the effects of kernel texture on milling properties, flour PSD, and starch damage. Another study (Chen et al. 2007) reported salt-free nonalkaline noodles (Zhang et al. 2005) with significantly higher sensory firmness from the combinations Pina-D1a/Pinb-D1a (soft, wild type), and Pina-D1a/Pinb-D1b, compared to Pina-D1b/Pinb-D1a. The differentiation for sensory viscoelasticity was not clear-cut and there was no significant effect on cooked noodle smoothness.

13.3. STARCH Starch is arguably the most influential of the flour components that affect cooked noodle texture. The physicochemical properties of starch that influence texture include its gelatinization temperature and swelling capacity when cooked and the underlying structural and compositional factors: amylose:amylopectin ratio, amylopectin structure, and granule size distribution. These factors can be addressed in a functional way through either paste viscosity (Bason and Blakeney 2007) or swelling capacity measurements (Crosbie 1991; Crosbie et al. 1992) performed either on flour or isolated starch. However, when assessing flour in these tests, as opposed to isolated starch, it is important to get results that are not confounded by other flour components. Chief among these is α-amylase, which exists at low levels even in flour milled from sound grain, and should be inactivated with an appropriate concentration of silver nitrate (Crosbie et al. 1999). Starch attributes can now be predicted within certain bounds from the current understanding of the genetic basis of starch composition and functionality. This is particularly so for amylose synthesis where all three Wx loci in wheat and their effects on amylose concentration are now well described. In summary, the Wx loci code for the enzyme, granule bound starch synthase 1 (GBSS1). Presence of null alleles at any locus reduces the amylose content and this reduction is dose dependent: that is, double-null “partial waxy” types generally have less amylose than singlenull partial waxy types, which generally have less amylose than wild types with three active GBSS1 genes. Triple nulls—fully waxy wheats—have effectively zero amylose (Graybosch 1998). It has also been reported that there is a subtle change in overall starch molecular structure related to the null alleles but there is disagreement about whether increased levels of isoamylase isolated chains with DP > 35 or 40 are associated with higher or lower swelling (Sasaki and Matsuki 1998; Zhao et al. 1998).

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More recently, Ral et al. (2008) showed no relationship between starch swelling or peak viscosity and chains with DP values of 15–17 or 18–25. However, these longer chain lengths were associated with higher cold-paste or setback viscosities, as is higher amylose content (Geera et al. 2006a), suggesting firmer noodles from genotypes with these longer chain lengths. There is also not complete agreement on the effect of the extent of branching. One study reported no relationship between the amount of DP 5 fragments and swelling volume (Zhao et al. 1998), and another reported a negative relationship between the amount of DP 5 fragments and RVA peak viscosity (Batey and Mueller 1991). The latter authors suggested a more open amylopectin branching structure was an advantage in increasing the swelling power of starch. However, it may be that the increase in swelling potential can be ascribed simply to the increased proportion of amylopectin in partial waxy types. It remains to be seen if the attributes of rice texture reportedly related to amylopectin fine structure are relevant to wheat-flour noodles (Bhattacharya 2009). The functional starch properties that are relevant to noodle texture are swelling power or volume, and peak and breakdown hot-paste, and final cold-paste viscosities in viscometric analyses (e.g., in rapid visco analyzer or visco-amylograph tests). In summary, higher peak viscosity, or greater breakdown in paste viscosity, or higher starch swelling properties (Zhao and Seib 2005) are associated with softer noodle texture (Figure 13.1). Whether or not softer noodle texture is desired is highly dependent on noodle type. For example, in most alkaline and other noodle types where firmer texture with a “clean break” (or more brittle type of fracture behavior) is desired, a moderate consensus is that lower peak viscosity (in the absence of α-amylase activity: i.e., not low viscosity derived from preharvest sprouting) and higher paste stability, or lower swelling volume, is the correct starch “template.” In alkaline noodles this is a result of a general requirement for moderately firm to firm textures (Hou 2001; Crosbie and Ross 2004; Fu 2008). Akashi et al. (1999) favored higher swelling starches for enhanced noodle elasticity even in alkaline noodles and this may be becoming a more widespread viewpoint. Conversely, in noodles requiring a soft bite and ductile type of fracture behavior (udon and some Korean instant

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FIGURE 13.1 Sensory firmness versus flour swelling volume (FSV) scores for 61 flour samples representing 25 genotypes from the 1993–1994 Australian Interstate Wheat Variety Trials. Null4A samples indicated by open symbols and dashed regression line; Plus4A samples indicated by closed symbols and solid regression line (Ross et al. 1997).

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noodles), it is evident that the template of high peak viscosity and low paste stability, or higher swelling volume, is largely correct (Crosbie et al. 1998; Hou 2001; Crosbie and Ross 2004; Fu 2008). Wheat varieties with fully waxy starches have not yet become a mainstream inclusion in noodle formulations. However, it is possible that they could have a place. Two studies (Baik and Lee 2003; Guo et al. 2003) reported that salted noodle hardness decreased as the proportion of admixed fully waxy wheat flour increased. One study (Guo et al. 2003), using texture profile analysis, showed that noodles made from 100% waxy wheat flour were softer, springier, more cohesive, and less adhesive. These authors suggested that a nonsticky (less adhesive) character was desirable. However, the 100% waxy wheat noodles scored very poorly in sensory analyses of hardness and chewiness. Unfortunately, the authors did not describe the sensory analysis in sufficient detail for readers to determine if this was a hedonic rating or an intensity rating. The uses of waxy and newer high-amylose wheats in noodle products were briefly reviewed by Hung et al. (2006), who suggested a role for high-amylose wheats in alkaline noodles. Granule size distribution has also been thought to exert an effect on noodle texture. A recent study (Ral et al. 2008) showed some variability in average size and B-granule volume percentage (from 23% to 42%) among a diverse range of genotypes. However, no apparent relationships were observed between pasting or swelling characteristics and average granule size or percentage of B-granules. Conversely, another study (Geera et al. 2006b) showed that isolated A-granule fractions had overall higher paste viscosities across the complete pasting profile compared to those from isolated B-granules. This was true for wild-type and waxy genotypes. These authors suggested that granule size and the ratio of A- to B-granules in wheat starch could affect starch swelling, gelatinization, and pasting properties. One could infer that anything that affects these functional starch properties would also affect cooked noodle texture. This idea was confirmed at least once, for durum pasta, where higher B-granule volume percentages were associated with firmer texture (Soh et al. 2006). 13.4. PROTEIN 13.4.1. Flour Protein Concentration Protein affects noodle texture profoundly, and a broad overview of the literature suggests that the effects of changes in protein concentration in flour are parallel in nonalkaline (salted and salt-free), alkaline, and instant noodles. In the first case, a simple increase in the concentration of protein in the flour is generally associated with increased instrumental and sensory hardness of cooked noodles. This has been reported repeatedly in the literature where the sample set chosen has had a wide enough flour protein range to express this relationship (Figure 13.2) (Kruger et al. 1994; Ross et al. 1997; Seib et al. 2000; Park et al. 2003, 2004, 2006; Uthayakumaran and Lukow 2003; Nakatsu et al. 2007). However, the opposite has been observed, for example, in the contrived situations of blending high-protein waxy wheat flour with lower-protein wheat flour with normal starch (Baik and Lee 2003) or where samples were deliberately selected to have a narrow range of flour protein concentrations (Crosbie et al. 1999). Flour protein concentration determines the gluten:starch ratio,

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FIGURE 13.2 Sensory firmness versus flour protein content (%) scores for 62 flour samples representing 25 genotypes from the 1993–1994 Australian Interstate Wheat Variety Trials. Null4A samples indicated by open symbols and dashed regression line; Plus4A samples indicated by closed symbols and solid regression line (Ross et al. 1997).

and the increased amount of starch at lower protein concentration will serve to increase the impact of starch properties on cooked texture. Flour protein concentration has also been implicated in modulating other cooked noodle texture parameters. There seems little doubt in the literature that higher-protein flour produces noodles with rougher (really “less smooth”) surface characteristics (Park et al. 2006), although there are studies that show no relationship between lower-protein flour and improved surface smoothness (Liu et al. 2003; Zhang et al. 2005). Protein concentration is, on occasion, reported to be either negatively or positively correlated with noodle elasticity (Fu 2008). Both weak (Yun et al. 1997; Liu et al. 2003) and strong (Ross et al. 1997) positive correlations between cooked salted noodle elasticity and flour protein concentration have been reported. Park and Baik (2004) reported no significant effect of flour protein concentration on the texture profile analysis parameters of springiness and cohesiveness, which are associated with mouthfeel elasticity. Furthermore, flour protein concentration affects the optimum water absorption of noodle doughs. All kernel proteins, including the high molecular weight glutenins, have been negatively correlated with optimum absorption (Deng et al. 2008; Ohm et al. 2008). As the water addition to noodles affects optimum boiling time, this aspect of the influence of flour protein concentration is likely also to have an indirect effect on noodle texture. In practice, different types of noodles have characteristic flour protein ranges related to the desired range of cooked firmness, different crosssectional dimensions, and different post-sheeting processes. For example, in instant noodles, higher protein is associated with decreased oil uptake during frying (Wu et al. 2006) and a practical compromise must be reached between acceptable oil content in the noodles, the price of the frying oil, and the higher price of higher protein flour. 13.4.2. Flour Protein Composition and Dough Strength Measurements or Predictors The major difficulty in determining the influence of flour protein composition on noodle texture has been the task of separating the signals from the abundance

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(concentration) of the protein and its composition. This is required because of (1) the strong influence flour-protein concentration has on noodle texture and (2) a view held by us that flour-protein concentration may be more influential than flour-protein “quality” (Ross et al. 1997). It may also be the case that protein composition expressed as dough strength and extensibility is more important in the sheeting process rather than in the cooked product. In general, higher flour-protein content and stronger gluten characteristics are associated with firmer and more elastic noodles (Miskelly 1981; Moss 1984), but also reduced smoothness (Konik et al. 1994; Ross et al. 1997). Hu et al. (2004) found that noodles made from cultivars with higher proportions of insoluble glutenin gave firmer noodles. As yet unpublished data from author Ross’s laboratory indicated, from size-exclusion high-performance liquid chromatography (HPLC) of kernel proteins, that a lower-protein soft wheat sample set showed more dependence on gluten molecular weight distribution than the higher-protein hard wheat sample set, where cooked noodle hardness appeared more dependent on flour-protein concentration. Other examples abound. For example, increased cooked-noodle cutting force and cooked-noodle viscoelasticity were observed in Canadian hard spring wheats containing high molecular weight glutenin subunit (HMWGS) pair 5 + 10, when HMWGS 1 replaced HMWGS 2*, and when HMWGSs 17 + 18 replaced HMWGSs 7 + 8 (Wesley et al. 1999). In contrast, Beasley et al. (2002) showed that raw noodle doughs were significantly affected by variation in HMWGS composition but that this was not reflected in changes to cooked-noodle texture. Another study using 10 near-isogenic lines differing in HMWGS composition showed that breaking force and breaking force to breaking distance ratio (an index of elasticity) of boiled noodles was positively correlated with HMWGS that had strengthening effects on doughs (Yamauchi et al. 2007). Yet another recent study (Hu et al. 2007) has shown, in partial agreement with Hu et al. (2004), that both insoluble and soluble glutenin contents were positively correlated with cooked-noodle cutting firmness. Another perspective shows that protein structure, related to the potential for crosslink formation, can affect noodle texture (Wu and Corke 2005) and can be shown under specific circumstances to be independent of changes in flour-protein concentration or composition. In this study, a transglutaminase, which catalyzes covalent ε-(γ-Glu)Lys cross-links, was added to formulations and was reported both to strengthen doughs and to increase the texture profile hardness of cooked salted noodles. This suggests by analogy that one could envisage that increased proportions of polymeric (disulfide cross-linked) glutenins might do the same. Interestingly, as noted above for the unpublished data from author Ross’s laboratory, in the Wu and Corke study (2005) the effect of additional cross-linking was most evident in the noodles made from flour of lower protein concentration.

13.5. LIPIDS The most important contribution of lipid components to cooked-noodle texture would appear to be focused on their effects on starch swelling, which, we have seen, profoundly affects noodle texture. It would also seem apparent that, as most internal

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starch lipids are associated with the amylose fraction, starches with higher amylose would have higher levels of these lipids, and so, in interpreting studies looking at lipids and noodles, one needs to keep this factor in mind. The effect of internal granule lipids has been reported to have the greatest impact on the onset or rapidity of pasting or swelling, with the abundance of the fatty acids lignoceric and cis-11-eicosenoic acid positively correlated with peak time and temperature in RVA analyses (Ral et al. 2008). Nonstarch lipids may also play a role. Kim and Seib (1993) inferred from pasting curves that increased amounts of nonstarch lipid in soft wheat flours restricted starch swelling, leading to more compact cooked structure that was interpreted as being more elastic. Another way of addressing the potential effect of lipids on noodle texture is to alter them in situ (Lustenbeger and Qi Si 2000). Addition of a 1,3-lipase, with the concomitant production of 1,2- or 2,3-diglycerides, or 2-monoglycerides, induces a structural strengthening of the outermost layer of the noodle strands. The treatment also increased firmness and was associated with smoother surface characteristics, better tolerance to overcooking, and reduction of amylose leaching into the cooking water.

13.6. ARABINOXYLANS There is extremely limited information available on the effects of flour arabinoxylans (AXs) on noodle texture. One could surmise that if added gums have an effect, then so might the endogenous nonstarchy polysaccharides, which are present in comparable quantities. The process of making noodles, at least from durum wheat, influences the partitioning of AX between the water-unextractable (WU-AX) and water-extractable forms. Ingelbrecht et al. (2001) showed that extended cooking solubilized nearly 50% of the AX in the original flour. Recently, Turner et al. (2008) reported in durum pasta a dough weakening effect of supplementation with WE-AX although it decreased cooked-product stickiness. AXs have been implicated in increased stickiness of salted noodles (Asawaprecha 2004) but almost no other specific information exists.

13.7. STARCH AND PROTEIN INTERACTIONS The main components of the flour, starch and protein, clearly have effects on noodle texture that can be ascribed to each other separately. However, they exist in flour and noodles together and one would expect with some certainty that their interactions might modify their individual properties. The issues of lipid effects, which are interactive with starch, were discussed above. Starch–protein interactions should have a testable effect on cooked-noodle texture. As the proteins make up the continuous phase of the noodle microstructure (Moss et al. 1987) it could be speculated that the proteins could provide a diffusion barrier to water, and thus differences, say, in the ability of the proteins to form uniform unbroken sheets could be key to certain facets of noodle texture. Ito et al. (2007) reported that the tendency to reduced hardness as a result of low amylose content was not as evident

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as expected in noodles made from the wheat variety Kitanokaori. They suggested that this was because the gluten properties of this line are strong. Data from another study (Ross et al. 1997) suggested that the increase in cooked-noodle firmness generated by additional flour protein was easier to detect in noodles made from partial waxy wheats as illustrated by the higher slope for the relationship between firmness and flour protein in cooked noodles made from null4A partial waxy wheats (Figure 13.2). Further indication of interaction between starch and gluten in determining noodle texture comes from multiple regression and multivariate analyses that show that including both starch and protein components can improve the prediction of noodle texture attributes. Ohm et al. (2006) improved prediction of texture profile hardness in cooked salted noodles in the original models from accounting for 85.5% of the variation in hardness to 92.8% by including RVA data with protein data. Konik et al. (1993) were able to improve the predictive value of multiple regressions by adding wheat protein and kernel texture data compared to regressions created with starch swelling power alone. From another viewpoint, the general concurrence of higher dough strength with harder/firmer noodle texture at equivalent protein concentration may not be a causal relationship: that is the stronger dough per se does not make the cooked noodles harder. Rather, it can be speculated that the tendency of larger polymers to create higher viscosities or consistencies at equivalent solids concentrations (strong and stiffer doughs) is simply parallel to the tendency of larger polymers (proteins in this case) to have lower thermostability and to denature or heat set earlier in thermal processing. In the case of noodles in the process of being cooked, ideally heat setting would occur before the onset of extensive granule swelling. Retention of a continuous protein network should help limit both granule swelling during cook-up, and further swelling as noodles reside in the serving soup. At least one study supports our contention (Kovacs et al. 2004). This study reported lower thermostability for gluten containing higher proportions of monomeric and low M r glutenins. Indirect evidence is also supportive. Sørensen et al. (2000) showed decreased cooked noodle yield in sheeted and cut salted durum noodles in the presence of added glucose oxidase, which reputedly improves the cross-linking of gluten proteins and should have limited, if any, direct effect on the starch. Two things: first, if the starch was oxidized under these conditions, higher swelling and higher cooked yield could be expected; second, we contend that the additional cross-linking decreased the gluten thermostability and ensured that it heat set before the onset of extensive granule swelling, allowing it to act as a better diffusion barrier. All in all, the area of starch–protein interactions on thermal processing of noodles is an interesting and potentially fruitful area of new research into the genesis of cooked-noodle texture.

13.8. SUMMARY The texture of wheat-flour noodles is dependent on the characteristics of the wheat flour used as a raw material. Noodle texture is influenced not only by the individual components of the flour used but also by a number of physical flour properties such

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Ohm, J.-B., Ross, A. S., Ong, Y.-L., and Peterson, C. J. 2006. Using multivariate techniques to predict wheat-flour dough and noodle characteristics from size exclusion HPLC and RVA data. Cereal Chem. 83:1–9. Ohm, J.-B., Ross, A. S., Peterson, C. J., and Ong, Y.-L. 2008. Relationships of high molecular weight glutenin subunit composition and molecular weight distribution of wheat flour protein with water absorption and color characteristics of noodle dough. Cereal Chem. 85:123–131. Park, C. S. and Baik, B. K. 2004. Relationship between protein characteristics and instant noodle-making quality of wheat flour. Cereal Chem. 81:159–164. Park, C. S., Hong, B. H., and Baik, B. K. 2003. Protein quality of wheat desirable for making fresh white salted noodles and its influences on processing and texture of noodles. Cereal Chem. 80:297–303. Park, C.-S., Baik, B.-K., Kang, M.-S., Park, J.-C., Park, J.-G., Yu, C.-Y., Choung, M.-G., and Lim J.-D. 2006. Flour characteristics and end-use quality of Korean wheats with 1Dx2.2+1Dy12 subunits in high molecular weight glutenin. J. Food Sci. Nutr. 11:243–252. Ral, J.-P., Cavanagh, C. R., Larroque, O., Regina, A., and Morell, M. K. 2008. Structural and molecular basis of starch viscosity in hexaploid wheat. J. Agric. Food Chem. 56:4188–4197. Rennie A. R. 1997. Building with snakes: the physics of long-chain molecules. Phy. Educ. 32:154–159. Ross A. S. 2006. Review: instrumental measurement of physical properties of cooked Asian wheat-flour noodles. Cereal Chem. 83:42–51. Ross, A. S. and Crosbie, G. B. 1997. Elasticity and springiness in Asian noodles. In: A. W. Tarr, A. S. Ross, and C. W. Wrigley (eds.), Cereals ’97, Proceedings of the 47th Australian Cereal Chemistry Conference. Royal Australian Chemical Institute, North Melbourne, Australia, pp. 70–74. Ross, A. S., Quail, K. J., and Crosbie, G. B. 1997. Physicochemical properties of Australian flours influencing the texture of yellow alkaline noodles. Cereal Chem. 74:814–820. Sasaki, T. and Matsuki, J. 1998. Effect of wheat starch structure on swelling power. Cereal Chem. 75:525–529. Sasaki, T., Kohyama, K., Yasui, T., and Satake, T. 2004. Rheological properties of white salted noodles with different amylose content at small and large deformation. Cereal Chem. 81:226–231. Seib, P. A., Liang, X., Guan, F., Liang, Y. T., and Yang, H. C. 2000. Comparison of Asian noodles from some hard white and hard red wheat flours. Cereal Chem. 77:816–822. Soh, H. N., Sissons, M. J., and Turner, M. A. 2006. Effect of starch granule size distribution and elevated amylose content on durum dough rheology and spaghetti cooking quality. Cereal Chem. 83:513–519. Sørensen, H. R., Ross, A. S., Budolfsen, G., and Larsen, L. M. 2000. Effects of added enzymes on the processing and quality of fresh durum pasta products. Abstract. ACCC International, St. Paul, MN, USA. Available at http://www.aaccnet.org/meetings/ 2000/posters. Storlie, E., Yang, E. N., Zou, Y. C., Chen, D. S., Sheppard, J., Martin, D., Huang, S., and Sutherland, M. W. 2006. Effect of the puroindoline locus and environment on Chinese fresh noodle texture. Australian J. Agric. Res. 57:537–542. Szczesniak, A. S. 2002. Texture is a sensory property. Food Quality Preference 13:215–225. Turner, M. A., Soh, C. H. N., Ganguli, N. K., and Sissons, M. J. 2008. A survey of waterextractable arabinopolymers in bread and durum wheat and the effect of water-extractable

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arabinoxylan on durum dough rheology and spaghetti cooking quality. J. Sci. Food Agric. 88:2551–2555. Uthayakumaran, S. and Lukow, O. M. 2003. Functional and multiple end-use characterisation of Canadian wheat using a reconstituted dough system. J. Sci. Food Agric. 83:889–898. Walstra, P. 2003. Soft solids. In: The Physical Chemistry of Foods. Marcel Dekker, New York, NY, USA, p. 687. Wesley, A. S., Lukow, O. M., Ames, N., Kovacs, M. I. P., Mckenzie, R. I. H., and Brown, D. 1999. Effect of single substitution of glutenin or gliadin proteins on flour quality of Alpha 16, a Canada Prairie Spring wheat breeders’ line. Cereal Chem. 76:743–747. Wu, J. and Corke, H. 2005. Quality of dried white salted noodles affected by microbial transglutaminase. J. Sci. Food Agric. 85:2587–2594. Wu, J., Aluko, R. E., and Corke, H. 2006. Partial least-squares regression study of the effects of wheat flour composition, protein and starch quality characteristics on oil content of steamed-and-fried instant noodles. J. Cereal Sci. 44:117–126. Wu, T. P., Kuo, W. Y., and Chen, M. C. 1998. Modern noodle based foods—product range and production methods. In: A. B. Blakeney and L. O’Brien (eds.), Pacific People and Their Foods. AACC Press, St. Paul, MN, USA, pp. 37–89. Yamauchi, H., Ito, M., Nishio, Z., Tabiki, T., Sun, J.-K., Hashimoto, N., Noda, T., Takigawa, S., Matsuura-Endo, C., Takata, K., Ohta, K., Fukushima, M., Miura, H., and Ism, Z. 2007. Effects of high-molecular-weight glutenin subunits on the texture of yellow alkaline noodles using near-isogenic lines. Food Sci. Technol. Res. 13:227–234. Yun, S.-H., Rema, G., and Quail, K. 1997. Instrumental assessments of Japanese white salted noodle quality. J. Sci. Food Agric. 74:81–88. Zhang, Y., Nagamine, T., He, Z. H., Ge, X. X., Yoshida, H., and Pena, R. J. 2005. Variation in quality traits in common wheat as related to Chinese fresh white noodle quality. Euphytica 141:113–120. Zhao, L. F. and Seib, P. A. 2005. Alkaline-carbonate noodles from hard winter wheat flours varying in protein, swelling power and polyphenol oxidase. Cereal Chem. 82:504–516. Zhao, X. C., Batey, I. L., Sharp, P. J., Crosbie, G., Barclay, I., Wilson, R., Morell, M. K., and Appels, R. 1998. A single genetic locus associated with starch granule properties and noodle quality in wheat. J. Cereal Sci. 27:7–13.

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CHAPTER 14

Noodle Plant Setup and Resource Management ´ ´ ˜ GARY G. HOU, SYUNSUKE OTSUBO, VERONICA JIMENEZ MONTANO, ´ and JULIO GONZALEZ

14.1. INTRODUCTION As detailed in other chapters of this book, a wide range of noodle products can be found in the global marketplace. To meet the growing demand for noodle types, customized noodle plants have been designed, constructed, set up, and put into production. The facilities of a noodle plant must follow the international norms and food safety programs, including operational methods and personnel practices, that assure the quality and safety of the product. This chapter will set out the specifics for noodle plant setup and resource management. The noodle plant must operate in accordance with the Code of Federal Regulations, designed to prevent production of food ingredients or products that may lead to contamination with filth, hazardous substances, or adulteration, whether operating under the Food and Drug Administration (FDA) or U.S. Department of Agriculture (USDA). It is also important to comply with the consolidated norms of Good Manufacturing Practices (GMP) (FDA 2002a), Hazard Analysis and Critical Control Points (HACCP) (FDA 2002b), ISO 22000:2005 (International Organization for Standardization 2005), ISO 9001:2008 (International Organization for Standardization 2008), and other regional and local food safety programs (Anon. 2001; AIB International 2009). One other agency concerned with plant sanitation is the U.S. Environmental Protection Agency (EPA), which is responsible for the implementation of FIFRA (Federal Insecticide, Fungicide and Rodenticide Act). In Japan, the Code of Hygiene Practice for Fresh Raw Noodles established by the Ministry of Health, Labor, and Welfare Supervision is an essential part of the GMP (Anon. 1991). Since noodle factories are food processing facilities, they must be designed and constructed based on similar standards. However, there are some unique requirements to noodle manufacturing. This chapter provides guidelines for planning and setting Asian Noodles: Science, Technology, and Processing, Edited by Gary G. Hou C 2010 John Wiley & Sons, Inc. Copyright


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up new noodle plants that will not only meet requirements and regulations prescribed for food manufacturing but also produce good-quality products.

14.2. PLANT LOCATION AND GENERAL REQUIREMENTS General guidelines for constructing a food manufacturing facility are outlined in many publications (Vieira 1996; FDA 2002a; Codex Alimentarius Commission 2003; Cramer 2006), and specific recommendations are available for noodle product manufacturing (IRMA 2001). Noodle plants must comply with all the requirements specified for food processing plants. The landscape layout of a typical noodle plant is shown in Figure 14.1. The land on which the noodle plant is to be located should be in the best condition possible to protect against any contamination. The site should be separated from residential areas and filthy places. A partition wall is required for security to reduce the risk of unauthorized entry and product tampering. The surroundings for the noodle plant should be neat, trimmed, and well landscaped. Litter and waste must be removed, and weeds or grass should be kept trimmed within the immediate vicinity of any plant buildings or structures that could constitute

Greenbelt Parking Parking Entrance

Parking

Parking

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FIGURE 14.1 Landscape layout of a typical noodle plant. (Courtesy of Nippon Engineering Co., Ltd., Japan.)

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an attractant, breeding place, or harborage for pests. All parking spaces, roadways, and walks should be paved so that dust contamination of the air will be minimized, and contamination, such as animal droppings, will be washed away with each rain rather than be soaked into the ground and become airborne during dry spells. The area surrounding the plant, including platforms, should not be used for storing crates, boxes, or machinery, as these materials may harbor rodents that could eventually find their way into the plant. Adequate waste containers shall be installed in an outside area and must be covered to avoid insects and other animals to intrude and take contaminants out to the inside part of the plant. The area around the plant should be free from potholes or depressions of any kind in which water may accumulate and become a breeding place for insects, which then could become established within the plant. The area should be provided with adequate drainage to avoid water accumulation that may contribute contamination to food by seepage, foot-borne filth, or providing a breeding place for pests. Trees, shrubs, and grass species that are not prone to insect infestation are preferred for the landscape around the building. Food materials, ensilage piles, or other organic wastes should not be present in any exposed areas near the plant because they attract and become breeding places for insects, especially flies, which are difficult to control in the plant even under the best conditions. There should be no neighboring industrial plants, such as chemical, sewage, poultry, or tanneries, that may transfer bacteria or chemicals to the noodle plant. Because a large volume of water is used in noodle production, the quantity and quality of the water is very important. If well water is used, avoid plant facilities close to pollution, domestic animal farms, and hot springs. If tap water is used, there is usually no problem but water quality still needs to be checked to ensure it is potable. Soft water is preferable for noodle production; however, if water is too hard (containing 150 ppm or more CaCO3 and MgCO3 ), then a water deionization system may be required to soften the water. Operating systems are required for waste and wastewater treatment and disposal in an adequate manner. An adequate wastewater treatment system is recommended to avoid contamination of the city sewage. In manufacturing any type of steamed noodles, it is recommended that the plant be set up in an area with an altitude near sea level or below. Since altitude determines the water boiling temperature, it also affects the degree of starch gelatinization during the steaming process, and ultimately the finished-noodle texture.

14.3. FACTORY CONSTRUCTION AND DESIGN The food factory building(s) and structures should be suitable in size, construction, and design to facilitate maintenance and permit sanitary operations for food manufacturing purposes (FDA 2002a,b; Oda 2003). Food manufacturing plants are best constructed of brick or concrete, as wood is difficult to maintain in a clean and sanitary condition. Wood is also more vulnerable to invasion by rodents, birds, and other pests.

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A typical noodle factory is composed of offices, production areas, warehouse and storage areas, sanitary facilities, laboratories, maintenance facilities, and waste handling and treatment facilities (Figure 14.2). If there are legal provisions to design and construct a food factory in a particular country, it is only natural to comply with them; otherwise, certain guidelines can be followed (Vieira 1996; IRMA 2001; FDA 2002a).

14.3.1. Factory Interior Design Where appropriate, the internal design and layout of the noodle factory should permit good food hygiene practices, including protection against cross-contamination by foodstuffs between and during operations. The following guidelines are generally considered: 1. Locate the offices, conference rooms, laboratories, dining rooms, locker rooms, and lavatories away from manufacturing areas because they are sources of contamination to the finished products. These areas must be designed and equipped for ease of cleaning. Other facilities, such as the garbage disposal area, electric cubicle, boiler room, and storage areas, should be separate and closed off on the premises for efficiency and convenience. Garbage dumpsters with lids must be used and should be washable. 2. Provide sufficient area and space for such placement of equipment and storage of materials as is necessary for the maintenance of sanitary operations and the production of safe food. 3. Provide enough space between equipment and walls to permit employees to perform their duties and to protect against contaminating food or food-contact surfaces with clothing or personal contact. 4. Set up production areas to accommodate each processing step. They should be zoned according to purpose and degree of cleanliness required, such as pollution work area, semiclean room, and clean room, so as not to cause crosscontamination. Designated zoning areas may be clearly marked by color coding to accommodate different uses and circumstances. 5. Provide an entrance room (buffer room) next to the hallway doors to reduce outside pollution from entering. An air-shower room should be located between the entrance room and the processing facilities to avoid introducing contaminants into the production areas. 6. Locate fixed machinery, as well as machinery apparatus that is not easily moved, in positions where it can be cleaned and sanitized easily. 7. Partition facilities for raw material storage, handling, preparation/processing, and packaging/packing with walls, boards, and others, respectively. 8. Position fixtures, ducts, and pipes in the workshop so that dust and condensed water drops do not contaminate food, food-contact surfaces, or food-packaging materials. They should be installed where they can easily be cleaned.

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Typical boiled noodle plant layout. (Courtesy of Nippon Engineering Co., Ltd., Japan.)

Garbage Room

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FIGURE 14.2

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MOVEMENT

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9. Provide adequate ventilation or control equipment to discharge odors and vapors (including steam and noxious fumes) in areas where they may contaminate food; and locate and operate fans and other air-blowing equipment in a manner that minimizes the potential contamination of food, food-packaging materials, and food-contact surfaces. 14.3.2. Internal Structures and Fittings Structures within the noodle factory should be soundly built of durable materials and be easy to maintain and clean and to disinfect when appropriate. In particular, the following conditions should be satisfied where necessary to protect the safety and suitability of food: 1. The surface of walls, partitions, and floors should be made of impervious materials with no toxic effect in intended use. 2. Floors, walls, and ceilings of workshops should be constructed in such a manner that they are easy to clean and keep in a sanitary condition with scheduled maintenance. 3. Floors should be made of acid-resistant unglazed tile or epoxy resin material, an epoxy tile grout laid on cement, for instance. A cement surface is undesirable, as it tends to become pitted, leaving areas where water and food scraps can accumulate and where bacteria may grow to large numbers, thus becoming a source of contamination and putrid odors. A slip-resistant material should be used wherever necessary to prevent possible accidents, especially in areas near a fryer where oil causes a slippery surface. In wet production zones, the floor should have a minimum of 2% inclination so that wash water can flow to the drains and not cause accumulation. 4. Walls should be made of concrete or solid blocks with a smooth finish to avoid the accumulation of insects and dust and make for easy cleaning. The lower part of the wall, 1–1.5 m from the floor, should be covered with glazed tile to facilitate cleaning. In food processing or utensil-washing areas, the junction of the walls and floor should be curved and have no angled corners so as to facilitate cleaning. The walls and roof junction of the plant should be weatherproof and impenetrable by insects. 5. Ceilings are required in production zones where raw material treatment and preparation, processing, and packaging are performed. Ceilings and overhead fixtures should be constructed and finished to minimize the buildup of dirt and condensation, and the shedding of particles. 6. Windows should be easy to clean, be constructed to minimize the buildup of dirt, and where necessary, they should be fitted with removable and cleanable insect-proof screens. Window ledges should be slanted to prevent their use by personnel for storage of materials. 7. Doors should have smooth, nonabsorbent surfaces, and be easy to clean and, where necessary, disinfected.

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8. Working surfaces that come into direct contact with food should be in sound condition, durable, and easy to clean, maintain, and disinfect. They should be made of smooth, nonabsorbent materials, and impermeable to the food, detergents, and disinfectants under normal operating conditions. 14.3.3. Lighting Adequate natural or artificial lighting should be provided to enable the processing areas to operate in a safe and hygienic manner. Where necessary, lighting should not be such that the resulting color is misleading. The intensity should be adequate to the nature of the operation. The following guidelines are generally followed in noodle plants: 1. Adequate lighting must be provided in hand-washing areas, dressing and locker rooms, and toilet rooms and in all areas where food is examined, processed, or stored, and where equipment or utensils are cleaned. In places where natural light is not adequate, light fixtures should be installed. Breakage- and fallingparts prevention film should be used on overhead fluorescent lamps. 2. Lights must be situated so they are not directly above production lines to prevent dust and broken apparatus from falling into food being processed. Installation of safety-type light bulbs, fixtures, skylights, or other glass fixtures suspended over exposed food in any step of preparation is recommended to protect against food contamination in case of glass breakage. 3. The brightness of working areas should always be an appropriate intensity of illumination. Suggested minimum light requirements for food processing plants are 50 foot-candle for sorting, grading, and inspection areas; 20 foot-candle for processing and active storage areas; 10 foot-candle for instrument panel and switchboard areas; 10 foot-candle for toilet rooms, locker rooms, and so on; and 5 foot-candle for dead storage areas (Vieira 1996).

14.4. MACHINES, TOOLS, AND EQUIPMENT Since the initial development of instant noodles in small plants, the noodle manufacturing plant has grown much larger, more automated, and more labor-saving. Various types of noodle products have been introduced and many types of machines and equipment have been introduced to accommodate advances in noodle processing technology as detailed in Chapter 5. The noodle manufacturing process includes primary and secondary processing units (Hou 2001; Fu 2008). The primary processing unit for machine-made noodles includes mixing raw materials, resting the crumbly dough, sheeting the dough into two dough sheets, compounding the two dough sheets into one, gradually reducing the dough sheet to a specified thickness by roll pressure stretching, and slitting into noodle strands. In the secondary noodle processing unit, noodle strands are further processed according to noodle type, which could

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involve boiling, rinsing, steaming, drying, frying, sterilizing, cooling, freezing, and packaging. In addition to noodle processing machines, many other types of equipment, tools, and devices are required to operate the noodle plant. Because many of these are commonly used in transportation, warehousing, laboratories, and other operations similar to any other food manufacturing facility, only those unique to the noodle plant are discussed in this chapter.

14.4.1. General Requirements Food processing equipment should be so designed that all food-contact surfaces are smooth, relatively inert, nonabsorbent, and made of materials that are easily cleaned and sanitized. Equipment that can be cleaned without disassembling is preferred, but where required, equipment should be designed so that it can easily be disassembled for cleaning purposes. Machines and equipment must be properly selected and installed for disassembling, cleaning, washing, and sanitizing. For instance, dead space on the processing floor can be avoided by positioning permanent equipment with some clearance from walls and floor. The use of CIP (clean-in-place) equipment is also effective. These basic requirements are desirable because they ensure that sanitation of equipment is possible and that it can be accomplished quickly, effectively, and inexpensively (Vieira 1996). The NSF International (http://www.nsf.org) offers a Food Equipment Program to certify food processing and food service equipment to meet the relevant NSF/ANSI standards. In addition to these general provisions for food machinery and equipment, the following specific requirements should be considered when planning and setting up noodle processing plants: 1. The liquid ingredient tanks, noodle-making machine, steamer, fryer, dryer, boiling tank, sterilizer, washing and cooling tanks, water chiller, packaging machine, and boiler must have sufficient capacity for manufacturing needs. 2. Temperature, time, flow, and pressure-gauge monitoring devices must be installed on boiling, steaming, sterilizing, frying, drying, washing, and cooling equipment. 3. If boiling, washing, and cooling tanks of the continuous-bucket type are used, the bucket must have enough height from the floor level for collateral contamination prevention from the splashing of water. 4. Weighing apparatus and containers must be designated for use with each material to avoid allergen cross-contamination. 5. Scales must be accurate for their intended use. Weight checkers must be equipped to remove rejected products. 6. A metal detection machine and X-ray devices to detect foreign materials should be installed. These devices must be equipped with the appropriate sensitivity and the ability to detect accurately and remove rejected products.

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7. The packaging machinery must have parts that can easily be replaced and cleaned, especially the parts that come into direct contact with the noodles. The machinery must also have a print function to allow for lot management. 8. Washing equipment for the containers, tools, and machine parts must be installed. 9. The cleaning tools and equipment for processing areas must be stored in a designated storage facility, which must be properly managed and kept sanitary. 10. Color-coded cleaning tools, that can easily be identified when broken pieces contaminate food products, must be used. 14.4.2. Primary Noodle Processing Unit The primary noodle processing unit includes the liquid mixing/preparation tank, metering (measuring) tank, dough mixer, feeder, compounding rolls, aging chamber (continuous or batch type), a series of sheeting rolls (5–8 pairs of rollers), and a slitter and/or cutter. The function of each component is described in Chapter 5. These machines are essential for manufacturing almost any noodles in large-scale noodle manufacturers that require more automation and continuous processing noodle lines. In small- and medium-scale operations, batch-type noodle processing lines may be used. In these operations, the compounding rolls, sheeting rolls, and slitter/cutter are often combined in one freestanding motorized single-roll stand with adjustable roll gap and integral slitter. This type of noodle equipment is also used in many laboratory-scale noodle testing. There are many choices in terms of noodle equipment manufacturer, the level of automation, production capacity, quality, service, and price. Each company shall make its own decision based on production needs and capital investment budget. However, all machine parts that will have direct contact with the noodles should meet the general requirements described previously (Section 14.1). 14.4.3. Secondary Noodle Processing Unit Machines used in the secondary processing unit are determined by the types of noodles to be manufactured. As discussed in Chapter 5, fresh noodles coming from the primary processing unit can be made into many forms/types using specialized equipment and unique processing technology. It is not possible to provide a full list of noodle equipment, tools, and devices to meet every noodle plant’s needs, but an attempt is made to present the main machinery and tools that are commonly employed in noodle plants worldwide.

14.4.3.1. Instant Noodles (Steamed and Fried or Steamed and Hot Air-Dried) As described in Chapter 5, there are two types of instant noodles: steamed and fried, and steamed and hot-air dried. The fried instant noodles are packed into two common forms—bags and cups—while the hot-air dried instant noodles are typically

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contained in flexible packages, such as plastic bags. As a result, the machines and equipment required for producing each type of instant noodles vary: 1. Noodle waver: forms noodle strands into condensed and uniform waves for easy and fast steaming. This is generally required for all instant noodle production. 2. Noodle steamer: traditionally, a single-layer, continuous-steaming tunnel. Today, the multilayer steaming tunnel has become a popular choice because it is much shorter in length (space-saving) and can especially accommodate a longer steaming-time requirement at high-elevation plants without comprising throughput in production. 3. Seasoning shower or tank: applies seasoning liquid onto noodles prior to frying by showering (spraying) or dipping into a liquid tank. This is optional equipment. 4. Cutting, folding and molding machine for bag-type instant noodles: cuts steamed noodle waves into desired weight/size with a rotary knife, folds noodle blocks in half, and puts them into square-shaped frying baskets. 5. Stretching conveyor for cup noodles: stretches steamed noodle waves to prepare for cutting into short strips. 6. Cutting and molding machine for cup-type instant noodles: cuts stretched noodles into desired weight with a portion cutter, and directly deposits (drops) them into cup-shaped baskets for frying. 7. Fryer: allows the conveyor carrying molds (frying baskets) to pass through the frying tank continuously. Heating device, fresh-oil supply tank, and oil filter are integral parts of the frying system. 8. Hot-air dryer for nonfried instant noodles: allows steamed noodle cakes to dry in a multilayer drying chamber equipped with temperature and humidity controls. Air heating is carried out by fin heat exchangers with steam. 9. Cooling machine: a continuous cooling conveyor inside a tunnel installed with fans to reduce the temperature of the fried or hot-air dried noodles to room temperature. 10. Packaging system for the bag-type instant noodles: includes a metal detector, an automatic noodle-block arranging machine, an automatic soup-seasoning supplying machine, an automatic packaging (wrapping) machine, a soup-detecting machine, an automatic weight sorter, an automatic boxing machine, an automatic palletizing machine, and a strapping machine. 11. Packaging system for cup-type instant noodles: includes an automatic noodleblock arranging machine, a cup-packaging machine (includes noodle-filling equipment, dehydrated-vegetable and soup filling equipment, a metal detector, a lid-supplying equipment, and a lid sealer), an automatic packaging machine, a hot-air shrink tunnel, an automatic weight sorter, an automatic boxing machine, an automatic palletizing machine, and a strapping machine. Both the automatic packaging machine and the automatic box sealer are equipped with a date printer for both bag and cup noodles.

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14.4.3.2. Dried Noodle Sticks Air-dried noodle sticks are one of most popular noodles in Asia because of convenient processing and longer noodle shelf life. Fresh raw noodles are hung on rods and dried in a controlled drying chamber for several hours (see Chapter 5 for processing details). In addition to the primary processing unit, the major machinery components to set up a commercial dried-noodle manufacturer include a noodle cutting and hanging bar device, dryer, cutter, and packaging machine. 1. Cutting and hanging bar device: cuts noodle strips to a certain length and hangs them on metal bars/rods from the middle of the noodle strands. 2. Noodle dryer: a room of different zones set with different rates of temperature, relative humidity, air velocity, and exhaust air, through which noodles pass. Heating devices, humidifier, dehumidifier, air-conditioning, and fans are employed to control these parameters in the dryer, and they influence the drying capacity. A stand-still drying cabinet may be used if making dried noodles in batch production. In some areas where sunlight is available all year round, noodles could be sun-dried; however, caution is warranted to minimize contaminations from dust, insects, and birds. 3. Noodle stick cutter: a knife to cut dried noodle sticks to a determined length for packaging. 4. Packaging machine: in many factories, dried noodle sticks are weighed and hand-packed into desired shapes and packages. However, there are packaging machines available to do the job. Dried noodle sticks have similar length (25–50 cm) and shape to long-cut pastas, and these items can be packaged using horizontal equipment (Varriano-Marston and Stoner 1996). The cartonpacking line scales the product to assure accurate weight. Volumetric filling may be done where material and labor costs are low enough to justify product giveaway. For automated weighing systems, rates of 120 weighings or more per minute are possible. After sealing, the carton is passed through a metal detector and a check weigher and is then sent to a case packer.

14.4.3.3. Parboiled Wet Noodles Parboiled wet noodles refer to hokkien-style yellow alkaline noodles (see Chapter 5 for processing details). Parboiled wet noodles are produced by boiling fresh raw alkaline noodles for 45–60 seconds, rinsing with tap water, draining, and mixing with 2% vegetable oil to prevent noodles from sticking together in the package. Unlike instant noodle production where highly automated and mass-production machines are predominant in the market, parboiled wet noodles are often produced in small- and medium-scale noodle plants where batch or semiautomatic production is common. Some of the key machines and equipment include the boiling machine, water chiller, rinsing and cooling machine, blowing fans, and packaging machine: 1. Boiling machine: a batch-type cooker or continuous boiling tank. Fresh water can be added continuously and the heating capacity of the machine should be sufficient to maintain boiling temperature throughout cooking.

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2. Rinsing and cooling machine: batch-type tanks and continuous conveyors equipped with cool water spraying nozzles are available. 3. Blowing fans: often installed on the conveyors to blow away excess water from the rinsed noodles. 4. Water chiller: used to chill water for dough mixing or noodle rinsing. This is a good option to consider in manufacturing facilities located in hot-weather climates. 5. Packaging machine: available in many models/types, depending on noodle packaging size and shelf life of noodle products. Vacuum-packaging machine is recommended for fresh noodles or high-moisture noodles stored at room temperature or under refrigeration for longer shelf life.

14.4.3.4. Long-Life (LL) Noodles LL noodles are fully boiled noodles and are pasteurized with steam heat to achieve a shelf life of 5–8 months (see Chapter 5 for processing details). They are typically produced on a highly automated noodle line. A vacuum dough mixer is often required to prepare dough for such noodles. Other key components of machines that are used commercially to process fresh raw noodles to LL noodles include the boiling machine, water chiller, washing and cooling tank, packaging machine, and steam sterilizer: 1. Boiling machine: a continuous boiling tank with moving conveyors carrying noodles through it. The tank is automatically filled with fresh water and the boiling temperature is constantly maintained. 2. Water chiller: equipment that chills water for rinsing boiled noodles. 3. Washing and cooling tank: a continuous cooling tank filled with chilled water and sometimes equipped with a chilled water spraying device above the conveyors. 4. Packaging machine: a machine that has more functions than the packaging machines employed in other noodle production. The machine portions and weighs the noodles before dropping them into bags and sealing the bags. 5. Steam sterilization chamber: a crucial component of LL noodle manufacturing. A commercial sterilization chamber has multilayer conveyors and packed noodles are heated by hot steaming of more than 90 ◦ C for 40 minutes.

14.4.3.5. Chaomein Noodles Chaomein noodles are long-steamed, air-dried noodles that are very popular in Latin America. In some ways, they are similar to air-dried instant noodles, but there are some differences in the manufacturing processes. In commercial production of chaomein noodles, both batch-type and automatic processing technologies exist. In traditional batch-type production, preformed fresh raw noodle blocks are steamed for 1–3 hours in a closed-door, stand-still steamer and dried in a stand-still drying cabinet for 6–18 hours. In continuous production, fresh raw noodles are steamed in a conveyor tunnel for 15–30 minutes, molded into the desired form, and dried in a continuous drying

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chamber for 45–60 minutes. As a result, the equipment varies with the mode of production, but the key components are steamer, drier, and packaging machine: 1. Steamer: chaomein noodles typically require much longer steaming time than instant noodles; therefore, the configuration of steamers is somewhat different. A stand-still steaming cabinet with a closed door is commonly used, but the steaming time ranges from 1 to 3 hours. The retort steamer is a better choice because the steam pressure is higher (60–80 psi) and it requires shorter steaming time (30–60 min). Nevertheless, both types are suitable only for batch production and the capacity is small. To meet high-speed, continuous production requirements, a conveyor steaming tunnel should be employed; however, a multilayer steaming tunnel may be required to accommodate longer steaming time and high-production capacity without occupying too much space. 2. Drier: similar to noodle steaming, there are batch-type and continuous noodle driers. The batch-type drier is a stand-still drying cabinet equipped with heating devices to control temperature and installed with fans to control circulation. The door is closed during the drying process. This kind of drier is less efficient and takes 6–18 hours to complete the process. Nowadays, more and more chaomein noodle plants in Latin America use continuous multilayer pasta dryers to dry noodles. As a result, the drying time is reduced to less than 60 minutes and both the production speed and product-quality consistency are much improved. 3. Packaging machine: depending on the chaomein noodle weight, size, and shape, several types of packaging machines can be used. The most common type is the pillow-type automatic packing machine that is typically used for packing bag-type instant noodles.

14.4.3.6. Frozen Noodles Many types of fresh raw noodles and boiled noodles can be frozen and preserved for a long period of time and still maintain a high degree of safety, nutritional value, sensory quality, and convenience. For example, the quality of frozen boiled noodles can be preserved for up to 1 year if noodles are properly stored in a freezer. This type of noodles is mostly consumed in noodle restaurants, where frozen noodles are quickly thawed in the boiling pot and immediately served to guests, thus saving time and labor costs. Therefore, frozen noodles have become a favorite noodle product of manufacturers, retailers, restaurants, and consumers. Obviously, key machinery components for manufacturing frozen noodles are the quick-freezer and storage freezer. These freezers are in addition to the noodle line and processing equipment required to produce the nonfrozen noodles. Quick-freezing is necessary to produce good-quality frozen noodles. The quick-freezer must have the capacity to reduce product temperature from 0 to −5 ◦ C quickly to minimize ice crystal size and to bring product core temperature to −15 ◦ C (see Chapter 5 for processing details). The quick-freezing methods include air (gas) freezing, contact freezing, brine freezing, and cryogenic freezing (Magnussen et al. 2008). Each technology has its

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own advantages and disadvantages. Air-freezing is by far the most widely used method of freezing food, as it is economical, hygienic, and relatively noncorrosive to equipment. Most of the existing air/gas freezer types are found in three most common types: tunnel freezers, continuous freezers, and fluidized-bed freezers. The first two options are more suited to noodle products. A decision can be made after considering the features of each freezer and the noodle processing needs. 14.4.4. Purchasing Noodle Machines It should be mentioned that although standardized noodle lines are available, most noodle plants require custom-made machines to meet the requirements of production capacity, space, local regulations, safety, product uniqueness, degree of automation, and costs. A common practice in industry is that the noodle manufacturer discusses all its requirements, preferences, and limitations with several noodle machinery suppliers. Each machine-maker then custom-designs the noodle line, provides the noodle line layout charts, determines the price of each component and the total noodle machine, and reports back to the noodle manufacturer with designs and quotes. The noodle manufacturer reviews the quotes and makes revisions of the machinery components as needed (this process may take more than one round between the buyer and seller). The noodle machine makers propose the final design of the noodle line, the details of each component, the noodle line layout charts in the workshop, and the itemized price quotations. Finally, the noodle manufacturer makes the decision for acceptance or makes a counteroffer to the machine maker. After the purchasing contract has been signed, it typically takes 3 months for the noodle machine manufacturer to complete the production and start delivery to the buyer. 14.5. UTILITIES AND SERVICES Similar to many other food-processing facilities, the noodle plant must be equipped with all the services and utilities needed to function. In many plants, pipes for utilities and service lines are defined by the ASME/ANSI Standard for both color and size (Standard A13.1, American Society of Mechanical Engineers 2007). However, not all plants follow this standard. For example, the Japanese Industrial Standard (JIS) is different from the ASME/ANSI Standard. Nevertheless, all utilities and services pipes must be placed in an accessible area for appropriate service and maintenance. 14.5.1. Water Supply The water supply must meet two criteria: quantity and quality. It should come from a nonpolluted source and be of sufficient quantity to meet all operation needs in the plant. All water that comes into contact with foods or food-contact surfaces must be potable quality, as specified in the latest edition of Guidelines for Drinking Water Quality (WHO 2008). The water used for noodle processing, cleaning of equipment, utensils, and food-packaging materials or for employee sanitary facilities should be of a suitable temperature and pressure to meet needs (FDA 2002a,b). A

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chlorination equipment system must be available if well water is used so that the water contains between 0.1 and 0.3 ppm of chlorine residue, depending on each country’s requirements (White 1978), but shall not exceed the maximum residual disinfectant limit of 4 ppm as chlorine under the Environmental Protection Agency (EPA) Safe Drinking Water Act. Nonpotable water should have a separate system and can be used for fire control, steam production, refrigeration, and other similar purposes in areas where it would not contaminate food. Nonpotable water systems should be identified and should not connect with, or allow reflux into, potable water systems. 14.5.2. Boiler and Steam Supply The boiler is required to generate enough steam and heat for production processes, such as noodle steaming and frying, cleaning, and sanitizing processes. The water supplied to the boiler requires special treatment for two main reasons: first, the water has to be free of magnesium and calcium salts to avoid incrustations and corrosion of the equipment; and second, the water produces steam that will be in direct contact with the noodles, so it has to be clean and free of any toxic agents. Table 14.1 lists the limits for boiler feed water quality as specified by the American Boiler Manufacturers Association (ABMA) and American Society of Mechanical Engineers (ASME). There are several modes to operate the steam generator. It can be done with natural gas, butane, diesel, biocarburant, and so on, and this depends on the environmental restrictions of the place where it operates, and also of the availability and convenience of the noodle manufacturer. 14.5.3. Plumbing The plumbing system is an important part of any food plant because fresh clean water is constantly needed for production, and almost equal amounts of sewage and liquid disposable waste must be conveyed from the plant (FDA 2002a). Therefore, the plumbing must be of adequate size and design and properly installed and maintained at all times. In the noodle production area, there must be adequate floor drainage in all areas where floors are subject to flood-type cleaning or where normal operations release or discharge water or other liquid waste onto the floor. Every effort must be made to ensure that the plumbing does not become a source of contamination to food, water supplies, equipment, or utensils, or to create any other unsanitary condition. 14.5.4. Sewage Disposal Sewage must be disposed of through a public sewerage system or through a system of equal effectiveness in carrying liquid disposable waste from the plant. The sewerage system must conform to building codes and in no way be a source of contamination to the products, personnel, equipment, or plant. Drains must be sufficient to ensure the rapid and complete transfer of all wash water, spilled liquids, and other liquid waste to the sewerage system (Vieira 1996).

346 140–700 120–600 100–500 40–200 30–150 25–125 Notee Notee Notee Notee

Total Alkalinityb,c (ppm) 15 10 8 3 2 1 1 Not applicable Not applicable Not applicable

Suspended Solids in Boiler Water (ppm)

0.1 0.1 0.05 0.05

0.2–1.0 0.2–1.0 0.2–1.0 0.1–0.5 0.1–0.5

Total Dissolved Solidsb,d (TDS) in Steam (maximum expected value) (ppm) 0.100 0.050 0.030 0.025 0.020 0.020 0.010

Iron (Fe, ppm)

0.050 0.025 0.020 0.020 0.015 0.015 0.010

Copper (Cu, ppm)

0.300 0.300 0.200 0.200 0.100 0.050 0.00

Total Hardness (CaCO3 , ppm)

b Actual

values within the range reflect the TDS in the feed water. Higher values are for high solids, lower values are for low solids in the feed water. values within the range are directly proportional to the actual value of TDS of boiler water. Higher values are for high solids, lower values are for low solids in the boiler water. c Expressed as equivalent calcium carbonate in parts per million (ppm). d These values are exclusive of silica. e Dictated by boiler water treatment. Source: http://www.banksengineering.com/blrwater.htm and http://www.altret.com/article.php.

700–3500 600–3000 500–2500 200–1000 150–750 125–625 100 50 25 15

Total Dissolved Solidsa (TDS) in Boiler Water (ppm)

Boiler Feed Water Quality

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a Actual

0–300 301–450 451–600 601–750 751–900 901–1000 1001–1800 1801–2350 2351–2600 2601–2900

Drum Pressure (psi)

TABLE 14.1

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14.5.5. Compressed Air Compressed air is necessary in noodle plants to operate pneumatic equipment, packaging machine, and tools. It is often used for dry cleaning purposes as well. There are three main types of industrial air compressors: (1) reciprocating air compressor, (2) rotary screw compressor, and (3) centrifugal compressor. The reciprocating air compressors are available at the pressure range of 70–250 psi. The rotary screw compressors generate an air pressure of 70–175 psi. Their features include smooth, pulse-free air output in a compact size with high output volume over a long life. Centrifugal air compressors produce high-pressure discharge (100–250 psi) and are designed for higher capacity needs because the flow through the compressor is continuous. Each noodle plant will select the right type based on the needs of production lines, especially flow and pressure. For instance, a typical instant noodle plant producing 150–300 units of 70-g cup per minute consumes 0.5 m3 /minute of compressed air, and a reciprocating air compressor can be employed. When deciding on an air compressor system, it is also important to consider its noise pollution level. It needs to be properly located in the plant to isolate the inherent noise. Compressed air in the noodle plant can be a potential contamination source to noodle products, because it has direct contact with the noodles, noodle-contact surfaces, and the packaging materials. Therefore, it must be filtered and dried to avoid any risk of carrying contaminants that can be introduced into the noodles. 14.5.6. Electricity All electrical installation must be made according to local regulations and equipment specifications. Avoid placing electrical units or components near production of corrosive gas, inflammable products, dusty areas, and areas subject to spraying of water or oil or exposed to direct sunlight. Cable and wires are wrapped inside ducts but remain outside of the construction to facilitate maintenance. It is important to consider one electrical auxiliary station for each machine. A central power control room is needed to house high-tension circuits and control the power supply system of the plant. The electrical diagrams of all the facilities must be posted inside the control panels in case of emergency. Voltage transformers must be installed to minimize voltage fluctuation to avoid potential damage to the equipment and computers.

14.6. SANITARY FACILITIES AND CONTROLS Sanitation in food manufacturing plants is an important issue. The building should be equipped with physical barriers and partitions that separate it from the external area. Preventive measures must be taken to control dust (contains soil bacteria), poisonous substances, insects, rodents, and birds inside and outside the building. At

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the surroundings of the buildings, concrete or asphalt paving 3 to 4 meters wide is recommended to prevent insects from invading the buildings. The pavement should be designed so that water pools do not form, as discussed previously (Section 14.2). It is also important to recognize that humans are big polluters. Prevention of human contamination of foods is an essential part of sanitation programs in any food processing plant. A sticking roller and an air-shower room should be located at the employee entrances to production areas to avoid introducing contaminants into the production areas. Each plant should be equipped with adequate facilities and accommodations to ensure sanitary operation of food production. 14.6.1. Hand-Washing Facilities Hand-washing facilities should be adequate, convenient, and equipped with running water at a suitable temperature. They are usually located at the main entrance to the processing areas and in other appropriate sites. Hand-washing and sanitizing stations should be provided for the exclusive use of production employees. The hand-washing facilities are equipped with automatic doors and wash basins and supplied with antibacterial odor-free soap, hand sanitizers, and sanitary towel service or suitable drying devices. Fixtures or devices, such as water control valves, are designed and constructed to protect against recontamination of clean, sanitized hands. Readily understandable signs should be posted in hand-washing and processing areas to direct employees who handle unprotected food, unprotected food-packaging materials, or food-contact surfaces to wash and, where appropriate, sanitize their hands before they start work, after each absence from post of duty, and when their hands may have become soiled or contaminated. 14.6.2. Dressing Rooms and Lavatories Each plant shall provide adequate dressing rooms and lavatories for all personnel. These facilities must be isolated from the production areas. The dressing rooms must have lockers where the employees can leave their own clothes and personal belongings. The tops of the lockers must be inclined to make easy cleaning and must not be used as shelves. The number of lavatories required can be estimated based on the ratio of one for every 25 men and one for every 15 women, if the number of employees is less than 100. Lavatories should be equipped with flush toilets and a hand-washing facility. Both the changing rooms and lavatories must be maintained in a good and sanitary condition at all times. Self-closing doors are generally required in lavatories. 14.6.3. Pest Control Pests pose a major threat to the safety and suitability of food. Pest infestations can occur where there are potential breeding sites and a supply of food. Good hygiene practices should be employed to avoid creating an environment conducive to pests. Good sanitation, inspection of incoming materials, and proper monitoring

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can minimize the likelihood of infestation and thereby limit the need for pesticides (Codex Alimentarius Commission 2003). Pest control is part of the overall sanitation plan; in fact, a major part of pest control is sanitation (Cramer 2006). It is intended to prevent contamination of ingredients and food products and is a requirement for conformance to the Code of Federal Regulations (21 CFR 110.35, FDA 2002a). No pests shall be allowed in any area of a food plant, either inside or outside the building. Effective measures shall be taken to exclude pests from the processing areas and to protect against the contamination of food on the premises by pests. The use of insecticides or rodenticides is permitted only under precautions and restrictions that protect against the contamination of food, food-contact surfaces, and food-packaging materials (FDA 2002a). The following specific measures are recommended to contain pests: 1. Buildings should be kept in good repair and condition to prevent pest access and to eliminate potential breeding sites. Holes, drains, and other places where pests are likely to gain access should be sealed. For example, drainage ditches are covered with iron plates with small holes, and the drainage outlets are covered with wire nets. Installation of wire mesh screens on open windows, doors, and ventilators will reduce the problem of pest entry. Large doorways are equipped with high-speed shutters or vinyl curtains. Doorways used for transporting products in and out should be the automatic shutting spring-type. Screens of 32-mesh may be installed on windows so that they may be left open if desired. The lighting of the doorways should be yellow for insect-prevention measures. Animals should be excluded, wherever possible, from the grounds of factories and food processing plants. 2. Potential food sources should be stored in pest-proof containers and/or stacked above the ground and away from walls because the availability of food and water encourages pest harborage and infestation (Codex Alimentarius Commission 2003). Areas both inside and outside food areas should be kept clean. Where appropriate, rejects (dough, noodles, etc.) should be stored in covered, pestproof containers. 3. Noodle plant buildings and surrounding areas should regularly be examined for evidence of infestation. Monitoring devices are placed along the walls outside of the building facilities. These devices are checked periodically to inspect whether rodents live outside the facilities. Bait stations are placed, anchored in place, locked, and properly leveled. Glue pads, not poisonous materials, are used inside the stations, so rodents can be held inside; otherwise they could take the poisoned materials and go to die in different areas where they won’t be found until contamination of the area has already occurred. These bait devices are also placed inside the plant at intervals of 50–100 feet or 15–30 meters. Outside building areas or areas of high rodent activity may require a higher concentration of bait devices. 4. Pest infestations should be dealt with immediately using physical, chemical, or biological agents without posing a threat to the safety or suitability of food

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(Codex Alimentarius Commission 2003). For example, insect light traps may be installed at least 10 feet or 3 meters away from food contact-surfaces, exposed products, packaging, and raw materials in processing or storage areas. The devices should be monitored every week to control flying insect activities. Birds may be controlled with nets, traps, and avicides, depending on local regulations. Other rodents, insects, and birds on the facility grounds may be removed by dogs, cats, or other animals in accordance with regulations and local ordinances. It may be the choice of plant or a company to utilize the services of a licensed pest control operator (PCO), someone with specific training in the identification, prevention, and treatment of pests. However, the PCO should work closely with the Quality Assurance Manager of the noodle plant and perform all services as per the applicable federal, state, and local laws and regulations (Cramer 2006). 14.6.4. Waste Management Facilities Suitable provisions must be made for the removal and storage of waste, such as waste materials and wastewater in noodle plants. Waste must not be allowed to accumulate in food handling, food storage, and other working areas and the adjoining environment except when it is unavoidable for the proper function of the business. Waste management facilities include wastewater treatment and waste material handling. The wastewater treatment facility must be equipped with sanitary drainage that meets regulatory standards and has sufficient drainage capacity. Generally, the wastewater treatment facility requires 1 ton of water for every 25 kg of flour in a boiling-noodle factory. The containers for holding waste/garbage must be waterproof and have a secure lid, have sufficient capacity, be easy to clean, and not leak polluted liquid or odor. 14.6.5. Toxic Material Storage Toxic cleaning compounds, sanitizing agents, and pesticide chemicals should be identified, held, and stored in a manner that protects against contamination of food, food-contact surfaces, or food-packaging materials. They should be kept in a fresh and clean area, free of flames, and separated from electrical power (FDA 2002a). It is highly recommended that separated storage spaces be provided for these toxic materials according to their intended uses: materials for cleaning and maintaining sanitary conditions in the plant; materials for laboratory testing; materials for maintenance and operations of equipment; and pesticide chemicals. These materials shall be received with a supplier’s warranty or certification and be identified properly with labels indicating their toxicity grades.

14.7. WAREHOUSE AND STORAGE FACILITIES Sufficient and adequate spaces are required for properly storing raw materials, supplies, containers, packaging materials, and finished products under conditions that

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will protect food against any kind of contamination as well as against deterioration of the food and other materials. Racks are needed in order to keep raw materials and finished products organized. All food-related materials must be stored in the best manner to prevent contamination, and receiving dates should be recorded in a visible place. The basic requirements for warehouse and storage facilities are as follows: 1. Dedicated areas with adequate space should be provided to store raw materials, supplies, food ingredients, semifinished products, packaging materials, and finished products. They should be clearly classified and partitioned to avoid causing confusion and mishandling in warehousing. Care must be taken to keep potential allergens strictly separated. 2. The floor and the inner wall structures must be made of an impermeable material that can easily be cleaned. 3. Pallets and stands must be provided to avoid direct contact of the ingredients or finished products with the floor. Pallets must be placed at least 18 in. (or 45 cm) away from walls and ceilings. The minimum distance between pallet rows is 35 cm. 4. The temperature of refrigerators, freezers, and other storage places required to keep a constant temperature should be measured at regular intervals every day and records must be kept for at least 2 years. An accurate temperaturemonitoring device must be installed where it can be seen easily. Raw ingredients and finished products are kept away from high temperatures and humidity to prevent the degradation of products. 5. Proper protective measures against rats, insects, and other pests must be taken. 6. The storage facilities must be able to store portable equipment, containers, and hand tools in a secure and sanitary manner.

14.8. QUALITY ASSURANCE PROGRAMS As will be discussed fully in Chapter 15, the Quality Assurance (QA) programs in noodle manufacturing have expanded to cover the many areas of concern and requirements of customers, consumers, government regulators, and their own industrial needs for improvement. The QA department plays an important role in the overall Quality Management System (QMS) in noodle manufacturing. It has three main functions: (1) quality control inspection, (2) laboratory testing, and (3) support and maintenance of the Quality Management System. As a result, the QA laboratory should be adequately equipped and follow Good Laboratory Practices (21 CFR 58, FDA 2004) to perform essential tests to ensure the product safety and quality. The QA laboratory is generally composed of four divisions: (1) physical and chemical analysis, (2) microbiological testing, (3) sensory evaluation, and (4) office.

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14.8.1. Physical and Chemical Analysis The main function of the physical and chemical analysis division is to conduct routine analysis of raw materials, packaging materials, supplies, ingredients, products-inprocess, finished products, culinary steam, and water and wastewater quality. Types of instruments, apparatus, and analysis methods are described in Chapter 15.

14.8.2. Microbiological Testing Many noodle products, such as raw noodles and parboiled or boiled wet noodles, have high moisture content and water activity, so they are prone to the rapid growth of undesirable microorganisms, particularly those of public health significance, during storage. Even with certain noodles that are heat-treated, such as instant fried noodles, the QA lab must still check for microbial counts on the noodles and seasonings and make sure the counts do not exceed the maximum allowance levels. To perform microbiological tests, there must be a clean and sanitary room for sample preparation. Common equipment required in the microbiological laboratory includes homogenizer, stomacher, incubator, water bath, autoclave (high-pressure sterilizer), hot dry-air sterilizer machine, colony counters, microscopes, and glass apparatus for microbiological examinations. Common microbes that are inspected by noodle manufacturers are aerobic plate count (APC), or total plate count (TPC), mold, Clostridium perfringers, Staphylococcus aureus, Escherichia coli, and Salmonella, but there are no standard allowable levels among countries.

14.8.3. Sensory Evaluation Sensory evaluation is routinely performed in noodle plants to evaluate finished products for acceptability because it is a convenient and reliable test. There are two types of sensory tests: (1) product-oriented and (2) consumer-oriented tests. In the productoriented test, trained panelists evaluate the quality attributes of a product, whereas in the consumer-oriented test untrained panelists evaluate the overall acceptability or degree of liking for a product (see Chapter 10 for more details). In the noodle plant quality control laboratory, the product-oriented test is performed the most. In a formal sensory testing facility, individual booths are provided, so the panelists can focus on the sensory evaluation task without any distractions. For color evaluation, proper lighting must be provided to ensure panelists are able to provide reliable and consistent ratings. Facilities must be available for the preparation of noodle samples for sensory testing.

14.8.4. Office A secure on-site office should be available to keep all product specifications, written procedures, operation manuals, certificates, records, and documents related to the operation of the noodle plant for review and inspection. Essential office facilities

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and supplies are provided to the QA manager and staff in which they can perform their duties.

14.9. MAINTENANCE PROGRAMS Similar to any other food production plant, an effective maintenance system must be established in the noodle plant to guarantee the sanitary operation of noodle manufacture, prevent potential contaminations of food, and maintain an on-time production schedule. Separate maintenance programs should be available for the plant facility and equipment. 14.9.1. Plant Facility Maintenance The noodle plant facility should be kept in good repair and condition to function as intended. The exterior of the facility should be thoroughly inspected and repaired on a routine basis. The floors and walls of the buildings are inspected and repaired so that there are neither holes nor damage. Drain ditches are cleaned and repaired regularly. Pest control systems are in place and these include monthly inspections, rotation in use of FDA approved pesticides, and adjustment of the control programs based on the seasons and the pests. Air filters used in the ventilation and air-conditioning systems are inspected and replaced regularly to ensure air quality in the plant because air is an important source of contamination of food. Finally, a detailed record must be kept of all repairs and inspections of the above-mentioned tasks. 14.9.2. Machinery Maintenance Routine maintenance schedules and procedures must be established for each machine and piece of equipment. The maintenance program must prescribe a schedule for inspections and maintenance in time increments of daily, weekly, monthly, biannually, and annually. Table 14.2 shows an example of a daily maintenance checklist by the machine operators at the instant noodle dough-mixing station. The outcome of the inspection could force the operators to halt production if an immediate repair is necessary. During the annual inspection, all machines should be inspected and repaired as necessary. It is important to restrict access to the production area when maintenance and repairs are being conducted to avoid contamination of food. After the maintenance service is completed, the machines and equipment must be fully cleaned and sanitized before use. It’s important to thoroughly dry the fryer after it has been cleaned because excess water promotes frying oil oxidation and degradation. Preventative maintenance is performed on a regular basis to eliminate the danger of foreign materials, such as loose screws or parts, dropping into product lines. Falling parts, rust, and peeling paint are regularly checked and repaired. Proper lubrication of machines and parts is required to prevent wear and improve machine reliability. This should be done on a regular basis, and only lubricants approved for

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TABLE 14.2 Daily Maintenance Checklist at Instant Noodle Mixing Station Machine/Equipment

Control Points

Dough mixer

Oil level in gear motor Drip of oil Belt Coupling Motor temperature Bearings Noises or vibrations

Alkaline solution pipeline

Dripping Valves functioning

Compressed air pipeline

Dripping Valves functioning Air cylinders

Gum solution tank

Agitator functioning Motor temperature

Alkaline solution tank

Dripping Motor temperature Agitator functioning Noises or vibrations

Alkaline solution pump

Motor temperature Noises or vibrations Dripping

Scales

Calibration

Control panel

Warning lights

application to equipment that comes into contact with food are used. Scales, metal detectors, and X-ray devices are inspected, serviced, and calibrated monthly by their manufacturers or other authorized agents. The thermometer must be calibrated once a year with a standard thermometer. The record of all repairs and checks of the abovementioned equipment must be maintained permanently until such equipment/device is disposed of. 14.10. INVENTORY CONTROL In addition to all the areas described above, it is also important to establish a work schedule and have a smooth inflow of raw materials with the precise quantity and at the right time to maintain the on-time production schedule. Two systems have been introduced to help new and existing noodle companies to manage and improve the inventory control: Material Requirements Planning (MRP) and Radio Frequency Identification (RFID).

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14.10.1. Materials Requirements Planning (MRP) MRP systems have been adopted by almost all manufacturers, including those considered small firms. These systems can be applied in noodle plants as well, because noodle products are produced in batches or in a continuous manner with the same machine. MRP is a computer-based inventory management system designed to assist production managers in scheduling and placing orders for dependent-demand items. Dependent-demand items are components of finished goods—such as raw materials, component parts, and subassemblies—for which the amount of inventory needed depends on the level of production of the final product. For example, in a plant that manufactures instant fried noodles, dependent-demand inventory items may include flour, salt, frying oil, seasonings, and packaging materials. The first MRP systems of inventory management evolved in the 1940s and 1950s. They used mainframe computers to export information from a bill of materials for a certain finished product into a production and purchasing plan for components. Later, it was expanded to include information feedback loops so that production personnel could change and update the inputs into the system as needed. The next generation of MRP, known as Manufacturing Resources Planning or MRP II, was developed in the 1980s (Waldner 1992). MRP II incorporated marketing, finance, accounting, engineering, and human resource aspects into the planning process. The newer versions of the software programs that have been developed since the early 1990s allow more open exchange of data, embrace a larger part of the firm’s operations (such as multiple sites, global costumers, languages, and currency rates), and operate in real time (Chase et al., 2006).

14.10.2. Radio Frequency Identification (RFID) RFID is a generic term that is used to describe a system that transmits the identity (in the form of a unique serial number) of an object or person wirelessly, using radio waves. Unlike ubiquitous UPC bar-code technology, RFID technology does not require contact or line of sight for communication. RFID data can be read through the human body, clothing, and nonmetallic materials. A basic RFID system consists of three components: (1) a transponder (tags, smart labels), (2) a reader (interrogator), and (3) a host computer installed with software. The reader communicates with the tag that holds digital information (electronic product code, EPC) in a microchip. The microchip, attached to an antenna, picks up signals and sends them to the reader. The reader converts the radio waves returned from the tag into a form that can be passed on to the computer. Once the EPC is retrieved from the tag, it can be associated with dynamic data about the item such as date of production or its origin. RFID technology has significant value in enterprise supply chain management to improve the efficiency of inventory tracking and management. The unique features of RFID technology make it ideal for implementing lean manufacturing, a management tool that has the potential to bring unprecedented efficiency to business

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(Stauffer 2005). Each step in the supply chain is governed by the needs of a succeeding step, that is, pull-instead-of-push scheduling controls the process, and the production is kept in balance with demand. When implemented correctly, RFID can realize the full benefits of supply chain management. RFID tags can be placed on the pallets or other units of goods passing through the supply chain. When the flow of materials is controlled by a computer, the entire process becomes automated. The business is operated in real time, and lean manufacturing is the payoff (Stauffer 2005). RFID is an excellent real-time business tool that helps better manage supply chains, decrease costs, and increase profits by improving visibility (and confidence) into your inventory management system, reducing storage space requirements, overall inventory levels, labor, and working capital, increasing speed and productivity, and improving product quality in noodle plants.

14.11. MANAGEMENT AND EMPLOYEE REQUIREMENTS Nearly all firms and organizations have as their mission the delivery of something of value to their customers, and in this case it is noodle products. The core process of the noodle manufacturing firm is to produce safe and quality noodle products for the consumers. Therefore, a horizontal organization structure is well suited for the noodle company (Figure 14.3). In this organizational structure, there are three

General Manager

Marketing

Selling

Sales Promotion

Training Operation

Plant Manager

Advertising

Production Control Scheduling Planning

Purchasing

Grain Procurement

Manufacturing

Tooling Production Packaging

Finance

Quality Assurance Process Control

Engineering Support Machinery Maintenance

Quality Analysis

Disbursements Credit Fund Control Source of Funds Capital Requirements

Audits

Logistics Officer

Purchasing Supervisor

Production Supervisor

Quality Assurance Supervisor

Maintenance Supervisor

Warehouse Staff

Staff

Machine Operators

Analysts

Electricians Mechanics

General Workers

FIGURE 14.3 1999.)

Organizational structure of noodle plant. (Adapted from Chart A in Ostroff

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main divisions: (1) marketing, (2) manufacturing (noodle plant), and (3) finance. All divisions/departments work together and coordinate their efforts to maximize the value of products delivered to customers (Ostroff 1999). The noodle plant is the heart of the firm and two other divisions (marketing and finance) are organized around the noodle manufacturing group. 14.11.1. Plant Management Noodle plant management can be divided into five departments based on the plant production capacity and required operations: (1) production control (logistics), (2) purchasing, (3) manufacturing, (4) quality assurance, and (5) engineering support (maintenance). As a result, a typical management team for a noodle plant includes one plant manager and five department heads. Within each department, a number of operators and support staff are assigned to perform specific jobs or tasks. The basic qualifications and requirements for the plant manager are proven leadership and management skills, because the person is responsible for the management and daily operation of the noodle plant. Preferably, the plant manager has an engineering degree or some food processing experience and is familiar with human resources administration. The mission of the plant manager is to accomplish the goals set by the firm’s top management and shareholders. 14.11.2. Production Control Production control is an important part of logistics. It is responsible for scheduling and planning production, ordering and handling raw materials, delivering products, and coordinating logistics for efficient processes and operations. The logistics officer is expected to have an industrial engineering degree. This person will be in charge of securing and providing all materials on time to the production area as well as delivering noodle products to customers. The person should be knowledgeable in inventory management, good storage practices, codex general hygiene (pest control in transport and warehouse), HACCP, ISO, computer program systems, international commerce, product specifications, and product recall and traceability. One of the main responsibilities of the logistics officer is to provide traceability of all materials in the noodle process, and this is achieved by performing codification and identification of raw materials and packaging materials received and accepted by the QC department. 14.11.3. Purchasing The purchasing department is responsible for procuring the raw materials and packaging materials needed to produce the noodles. The purchasing team should be able to access the appropriate supplier options to secure materials and supplies at low cost and high quality. The team should also provide superior internal customer service and on-time delivery of materials to meet production schedules.

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14.11.4. Manufacturing The manufacturing department manages the tooling, production, and packaging of the noodle products. In noodle manufacturing, people play the most important role in achieving high productivity and excellent quality with minimum waste in the process. The production supervisor is responsible for noodle manufacturing through coordination with other departments. This person must have the ability to develop and execute the training of the production workers, preparation of the operation manuals, and revision of the written documentation and department records. The person preferably has some management skills and is knowledgeable about food processing, so he/she is capable of learning the process quickly and accomplishing the production goals. The production supervisor should be able to make quick decisions concerning processing issues and acceptance of the product. He/she is expected to receive extensive training, such as GMP (Good Manufacturing Practices), codex general hygiene, HACCP, and ISO 9001:2008 to gain knowledge and proficiency in manufacturing procedures, processes, troubleshooting, and strategic planning. Machine operators are generally required to have some technical background and be able to successfully complete job-specific training as needed. They should have the ability to examine any problem in the machine and be able to decide whether to repair small failures in the machine or report the problem to the maintenance department. One of their main responsibilities is to maintain a clean and safe working environment by following safety instructions. Machine operators must be trained in GMP and HACCP programs for food safety and receive special training in operating machines responsibly and safely. Machine operators are also responsible for generating written records of the process control. The records must be clear and reflect the process conditions because they constitute the evidence of fulfillment to the process control limits. General production workers also play an important role in the noodle plant, because they assist the machine (noodle production and packaging) operators in noodle manufacturing. Each person is expected to complete a training program with the goal of having a basic understanding of production control, sanitation control, and quality control systems. It would be useful if they also completed intensive seminars on GMP, so they could support the supervisor to maintain the highest quality and safety standards. An evaluation process must be developed to ensure worker competence and empower the workers to provide suggestions for improvement in production procedures and processes. A positive attitude in these employees is essential because they need to have the motivation to work hard and hold high standards to make the noodle plant succeed in manufacturing safe and good-quality products.

14.11.5. Quality Assurance The function of the quality assurance (QA) program has been described previously (Section 14.8). The QA supervisor is expected to have a food science, food technology, or food engineering degree and have the ability to control the process parameters, perform analyses, and assure the quality of the product. The specific responsibility of this individual involves examining raw materials and packaging materials, following

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the processes along the production line with established protocols, analyzing the finished products, and releasing the products with accountability. The QA supervisor also manages the coordination and completion of the audits on noodle production processes and follows up with the preventive and corrective actions. The QA department handles all complaints and suggestions from the internal and external clients, analyzes them, and provides resolutions and implements the actions. Quality control inspectors must have knowledge and technical skills for conducting physical and chemical analyses, microbiological tests, and sensory evaluation. In addition, they should be knowledgeable of manufacturing processes, sanitation programs, and quality control procedures. 14.11.6. Engineering Support The engineering support department must have very skilled supervisor and staff with knowledge of mechanics, electricity, and safety issues so they have the ability to develop written procedures of preventive and corrective maintenance procedures for the plant machines and equipment. The goal is to assure that all machines work properly, avoid dead times, and avoid breakdowns in the line for any nonpreventive maintenance. Scheduled stops should be planned in advance to allow for preventive maintenance of the noodle lines. The engineering support supervisor will be fully trained with GMP and ISO and is expected to become an active member of the HACCP team. The maintenance supervisor works closely with the suppliers of spare parts and keeps up with the technological advances in noodle plant machinery.

14.12. MARKETING Marketing is an independent branch of a manufacturing firm (Figure 14.3) and constitutes an essential part of a successful business. Marketing is the performance of business activities designed to plan, price, promote, and direct the flow of a company’s goods and services to consumers or users for a profit (Cateora et al. 2008). Competition, legal restraints, government controls, weather, fickle consumers, and any number of other uncontrollable elements can, and frequently do, affect the profitable outcome of good, sound marketing plans. Generally, the marketer cannot control or influence these uncontrollable elements. Marketing has the challenge of molding the controllable elements of marketing decisions (product, price, promotion, and distribution) within the framework of the uncontrollable elements of the marketplace (competition, politics, regulations, consumer behavior, level of technology, and so forth) in such a way that marketing objectives are achieved (Cateora et al. 2008). Even though marketing principles and concepts are universally applicable, the environment within which the marketer must implement marketing plans can change dramatically from country to country or region to region. The difficulties created by different environments are the international marketer’s primary concern.

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Making food convenient is an important trend in the noodle industry. Cup-type instant noodles, frozen boiled noodles for microwave-oven cooking, and retortprocessed noodles are an increasing trend in convenience foods. Instant noodles require the most attention in marketing. It is important to understand the consumer’s potential needs. This information is collected through quantitative investigation and qualitative research (group interview) and consumer surveys; a new concept is then created. Since it is quite difficult to make a dramatic improvement in the noodle products themselves, the noodle seasoning (soup) becomes the target of change for instant noodles. Because trends in taste change very fast, many different taste types with short-term product cycles have been actively commercialized. After the concept design of the product is determined, promotion becomes crucial to successful sales. Collaborations with famous restaurants are commonly used in the double-branded products. The commodity design that considers regional differences has proved to be effective. Finally, the commercialization of noodle products from different geographical areas where the globalization of food is reflected is also effective. 14.13. SUMMARY Setting up a noodle plant is a complex process and requires a great deal of preparation, requirements, and operations that are not only related to basic operations of food plants in general, but also to noodle manufacturing in particular. This chapter has provided specific guidelines concerning each aspect of setting up a new noodle plant. These guidelines include factory land requirements, factory design and construction, machinery and equipment needs, utilities and services, sanitary facilities and controls, warehouse and storage facilities, quality assurance programs, maintenance programs, inventory control, management and employee requirements, and product marketing. Prior experience in the food processing business is certainly helpful in setting up a new noodle plant. We hope the information presented here will provide valuable guidance to anyone or any company who is interested in running a noodle manufacturing business.

ACKNOWLEDGMENTS The authors wish to thank Bon Lee for translating Japanese literature into English, and Dr. Mario Leon, Janet Hom, and Efrain Olmedo for their review of the manuscript. REFERENCES AIB International. 2009. Consolidated Standards for Inspection: Prerequisite and Food Safety Programs. AIB International, Manhattan, KS, USA. American Society of Mechanical Engineers. 2007. A13.1-2007: Scheme for the Identification of Piping Systems. American Society of Mechanical Engineers, New York, NY, USA.

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Anon. 1991. The Code of Hygiene Practice for Fresh Raw Noodles. All Japan Federation of Noodle Manufacturer Association, Hygiene Technical Center of Noodles, Japanese Food Hygiene Association, and the Ministry of Health, Labor, and Welfare Supervision, Shibuyaku, Japan. Anon. 2001. HACCP Manuals of Noodle Manufacturing (Japan). All Japan Federation of Noodle Manufacturer Association and Japanese Food Industry Association, Tokyo, Japan. Cateora, P. R., Gilly, M. C., and Graham, J. 2008. International Marketing, 14th ed. McGrawHill/Irwin, New York, NY, USA. Chase, R. B., Jacobs, F. R., and Aquilano, N. J. 2006. Operations Management for Competitive Advantage, 11th ed. McGraw-Hill/Irwin, New York, NY, USA. Codex Alimentarius Commission. 2003. Recommended International Code of Practice: General Principles of Food Hygiene, CAC/RCP 1-1969, Rev. 4-2003. Codex Alimentarius Commission, Food and Agricultural Organization of the United Nations (FAO) and the World Health Organization (WHO). Cramer, M. M. 2006. Food Plant Sanitation: Design, Maintenance, and Good Manufacturing Practices. CRC Press, Taylor & Francis Group, Boca Raton, FL, USA. FDA. 2002a. Current good manufacturing practice in manufacturing, packing, or holding human food. In: 21 CFR Chapter I: Part 110. Food and Drug Administration, U.S. Department of Human Health and Services, Washington, DC, USA, pp. 214–223. FDA. 2002b. Hazard analysis and critical control point (HACCP) systems. In: 21 CFR Chapter I: Part 120. Food and Drug Administration, U.S. Department of Human Health and Services, Washington, DC, USA, pp. 259–268. FDA. 2004. Good laboratory practice for nonclinical laboratory studies. In: 21 CFR Chapter I: Part 58. Food and Drug Administration, U.S. Department of Human Health and Services, Washington, DC, USA, pp. 330–344. Fu, B. X. 2008. Asian noodles: history, classification, raw materials, and processing. Food Res. Int. 41(9):888–902. Hou, G. 2001. Oriental noodles. Adv. Food Nutr. Res. 43:141–193. International Organization for Standardization. 2005. ISO 22000:2005. ISO, Geneva, Switzerland. International Organization for Standardization. 2008. ISO 1991:2008. ISO, Geneva, Switzerland. IRMA. 2001. GMP for the manufacture of instant ramen noodles (2000). Circulation paper in technical committee meeting, the 3rd World Ramen Summit, Bangkok, Thailand. Magnussen, O. M., Hemmingsen, A. K. T., Hardarsson, V., Nordtvedt, T. S., and Eikevik, T. M. 2008. Freezing of fish. In: Judith A. Evans (ed.), Frozen Food Science and Technology. Blackwell Publishing Ltd., London UK, pp. 151–164. Oda, M. 2003. Shin Men no Hon [in Japanese New Book of Noodles]. Shokuhin Sangyou Shinbun Sha (Food Indutry News Paper Company), Tokyo, Japan. Ostroff, F. 1999. The Horizontal Organization. Oxford University Press, New York, NY, USA. Stauffer, J. E. 2005. Radio frequency identification. Cereal Foods World 50(2):86–87. Varriano-Marston, E. and Stoner, F. 1996. Pasta packaging. In: J. E. Kruger, R. B. Matsuo, and J. W. Dick (eds.), Pasta and Noodle Technology. American Association of Cereal Chemists, St. Paul, MN, USA, pp. 75–93. Vieira, E. R. 1996. Elementary Food Science, 4th ed. Chapman & Hall, New York, NY, USA.

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Waldner, J.-B. 1992. CIM, Principles of Computer Integrated Manufacturing. John Wiley & Sons, Chichester, UK. White, G. C. 1978. Current chlorination and dechlorination practices in the treatment of potable water, waste water and cooling water. In: R. L. Jolley (ed.), Water Chlorination: Environmental Impact and Health Effects, Vol. 1. Ann Arbor Science, Ann Arbor, MI, USA, pp. 1–18. WHO. 2008. Guidelines for Drinking Water Quality: Incorporating 1st and 2nd Addenda, Vol.1, Recommendations, 3rd ed. World Health Organization, Geneva, Switzerland.

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CHAPTER 15

Quality Assurance Programs for Instant Noodle Production ´ SUMONRUT KAMOLCHOTE, TOH TIAN SENG, JULIO GONZALEZ, and GARY G. HOU

15.1. INTRODUCTION Quality Assurance (QA) programs in noodle manufacturing have expanded to cover the many concerns and requirements of customers, consumers, and government regulators as well as their own industrial needs for improvement. Quality is a function related to all activities of the entire company and it needs to be managed. QA is no longer limited to routine technical tasks; it has become a crucial part of the total company commitment to achieve excellence. Basic requirements for food manufacturers established by government regulators for consumer safety are the Good Manufacturing Practice (GMP) (FDA 2002a) and Hazard Analysis and Critical Control Points (HACCP) systems (FDA 2002b). As in many other food plants, these two systems are often required to operate instant noodle plants. This chapter will explain the scope of the Quality Management System, including QA, QC (Quality Control), GMP, and HACCP and their applications in instant noodle manufacturing. 15.2. QUALITY MANAGEMENT SYSTEM Not until late in the 20th century did the Quality Management System (QMS) become a popular concept required by all manufacturers engaged in exporting goods, particularly exports to developed countries. Manufacturers must comply with the world QMS such as ISO 9002:1994. This ISO 9002 series was revised to ISO 9001:2004 in 2004 and to ISO 9001:2008 in 2008 by the International Organization for Standardization (2008). ISO 9001:2008 Quality Management Requirements are listed in Table 15.1. Asian Noodles: Science, Technology, and Processing, Edited by Gary G. Hou C 2010 John Wiley & Sons, Inc. Copyright


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TABLE 15.1

Quality Management Requirements Specified in ISO 9001:2008

Clause

ISO 9001:2008 Requirements

4 4.1 4.2

General Requirements Quality Management System (QMS) development Documentary requirements

5 5.1 5.2

Management Requirements Commitment to quality Customer focus

5.3

Quality policy

5.4 5.5

Planning Responsibility and authority

5.6

Management reviews

6 6.1 6.2

Resource Requirements Provision of required resources Human resources

6.3

Infrastructure

6.4

Work environment

7 7.1

Product Realization Planning of product realization

Specific Actions Establish, document, implement, maintain, and improve QMS Manage and control documents, prepare manuals and instructions, and establish records Show commitment to quality Identify customer requirements and meet customer satisfaction by proper handling of complaints and recall system Serve overall purpose, meet requirements, improve effectiveness, enhance internal communication, and review for suitability Establish quality objectives and plan QMS Define responsibilities and authorities of QA manager and QA department, create management role, and support internal communication Review QMS for improvement and changes, examine review inputs from employees and customers, and generate review outputs for improvement Identify and provide the needed resources Ensure competent QC inspection team and provide training to meet competence requirements Identify, provide, and maintain the needed infrastructure, such as GMP compliance, potable water quality, and appropriate facilities Identify and manage work environment to meet production needs by controlling temperature, humidity, and cleanliness of air and food-contact surface Establish planning process, develop product processes, and realize products by developing process flow diagrams, monitoring each processing step, identifying control points, and measuring procedures

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(Continued)

7.2

Customer-related processes

7.3

Product design and development

7.4

Purchasing

7.5

Product and service provision

7.6

Control of monitoring and measuring devices

8 8.1

Remedial Requirements Monitoring and measurement processes

8.2

Monitoring and measurement

8.3

Identification and control of nonconforming products

8.4

Analysis of data

8.5

Improvement and remedial actions

Identify unique product requirements, review product specifications from customers, and communicate with customers Identify inputs, generate outputs, perform reviews, conduct validations, and manage changes: for example, keep product formulations, product and process information up-to-date Establish purchasing process, specify requirements, and verify purchased products: for example, perform audits and evaluation of vendors Conduct process and provide services under controlled conditions, validate processes, identify and track products, protect customer’s property, and preserve products and components Identify monitoring requirements, establish processes, calibrate equipment, protect equipment, keep software up-to-date, and validate measuring results Identify, plan, and implement monitoring, measurement, and analytical processes to demonstrate conformity and make improvements Monitor and measure customer satisfaction of product and service, perform regular internal audits, measure QMS processes, and monitor and measure product characteristics Establish and maintain nonconforming products procedure: for example, raw materials and product on hold Provide characteristics and trends of processes and products, analyze customer satisfaction, and analyze raw material receiving deviation Improve the effectiveness of QMS, correct nonconformities to prevent recurrence, and prevent the occurrence of nonconformities

Source: International Organization for Standardization (ISO).

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The requirements of the QMS in the first issue (1994) did not include the HACCP system. As a result, many food industries were urged by government regulators to implement the HACCP system. The HACCP system has been widely introduced and enforced by the USDA Food Safety and Inspection Services (FSIS), targeted at animal-based foods such as poultry, meats, and seafood. Later, the low-acid foods of fruits and vegetables were included. This HACCP system is one of the best food production systems. Many noodle manufacturers around the world have implemented this system in their QA programs. 15.3. ROLE OF THE QUALITY ASSURANCE DEPARTMENT The Quality Assurance (QA) Department plays an important role in the overall Quality Management System in noodle manufacture (Figure 15.1). The department can be

FIGURE 15.1

Roles of QA/QC in the Quality Management System.

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divided into three sections: Quality Control (QC) inspection, laboratory testing, and the Quality Management System. 1. QC inspection is essential for daily quality control of raw materials and packaging materials received as well as the process line control. Finished products are evaluated by QC inspectors to conform to product specifications. QC line inspectors are directly responsible for inspecting all physical properties of the noodles but not exclusive to other duties. QC inspectors also perform sensory evaluation of finished products such as tasting. QC inspectors must perform these simple tests in a timely manner to provide immediate response to any deviations from the quality specifications. 2. The Laboratory section provides routine analyses of raw materials, packaging materials, finished-product quality, and used-water and wastewater quality. Both physicochemical and microbiological tests are required. Types of equipment and test methods required for evaluating the noodle quality are listed in Table 15.2. 3. The role of the Quality Management System section is to support and maintain the quality assurance system. The tasks include issuing, distributing, and recordkeeping of all quality assurance documents. Other supporting tasks include arranging internal and external audits, monitoring the corrective and preventive action requests, and displaying awareness of quality work and service to all employees.

15.4. GOOD MANUFACTURING PRACTICE (GMP) The basic practice of the instant noodle plant is to assure food safety by implementing Good Manufacturing Practice. GMP covers a wide range of aspects, including facilities, personal hygiene, sanitation programs, and each step of process controls (FDA 2002a). 15.4.1. Plant and Grounds General guidelines and requirements for considering a site for a noodle plant are described in Chapter 14. Additional considerations are taken into account when designing an instant noodle plant: 1. In areas where the noodle fryer is located, floor materials should be resistant to oil and have protection against slipperiness for workplace safety. The lower part of the walls, 1–1.5 meters from the floor, is tiled with water-resistant materials. Areas for raw material preparation, raw material moving through the process, production line, and packaging facility, are under a covered ceiling. A canopy is constructed over the processing line to protect noodles from contamination. In steaming and frying areas, a high roof (6–8 meters) is recommended

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TABLE 15.2 List of Instrument and Test Methods in Instant Noodle Quality Control Laboratory Instrument

Quality Factors

Analysis Materials

Analytical balance/digital balance Grinder

Determination of weight

Raw materials, ingredients, and noodles Raw materials, noodles

Standard sieve Burettes and flasks or quick testing kits

Water bath Capillary tube Moisture analyzer (moisture oven, infrared moisture meter, etc.) High-temperature furnace Glutomatic Nitrogen determination equipment pH meter Soxhlet fat extractor

Polar Compound Meter (3M PCT 120 or Testo 265) Brookfield viscometer Texture analyzer

Grinding powder samples for determination of moisture, fat, and iodine blue value Prepare samples for iodine blue value and particle sizes Titration uses

To heat evaporator and dissolve solids and melt fat Measuring melting point Determination of moisture content

Determination of ash content Wet-gluten measurement Determination of protein content Determination of pH value Extraction of fat for measuring oil content and iodine blue value Measurement of polar compounds

Colorimeter

Viscosity measurement Measurement of texture (hardness, chewiness, springiness) and bag end-seal strength Color measurement

Refractometer

Checking Brix

Spectrophotometer

Measurement of chemical oxygen demand (COD), turbidity, and iodine blue value Measurement of iodine blue value

Centrifuge separator

Noodles, ingredients, seasonings % Acidity, alkali content, % NaCl, acid value (AV), peroxide value (POV), etc. Wastewater, noodles Fresh oil Wheat flour, noodles (finished product), powder ingredients Wheat flour Wheat flour Wheat flour, noodles (finished product) Alkali water, potable water, and others Noodles (finished products)

Frying oil

Gum solution Noodles (after cooking), seasoning oil packaging

Dough sheet, noodle color, chili color, seasoning solution color, etc. Sugar solution, liquid glucose, sweet soy sauce Wastewater, water, noodles

Noodles

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for better ventilation. Exhausters are installed to remove steam, oil fumes, and heat from the fryer. These exhausters should prevent condensation of oil drops/accumulation. Ventilation of fresh air is supplied to workers, especially in factories in tropical areas. Air filters are periodically cleaned. 2. Entrance to the processing plant should be designed in such a way that workers in the packing room do not enter directly into the frying and dough preparing areas. 3. The packing room has easy access to packaging materials such as cartons, seasoning sachets, and rolls of film.

15.4.2. Machines, Equipment, and Utensils General provisions and specifications for noodle processing machines and equipment are outlined in Chapter 14. Additional requirements and procedures in instant noodle plants are followed to be in compliance with the GPM requirements: 1. The preferred oil tank is made of stainless steel. During storage, oil may be in the solid stage; thus, heating elements, such as steam coils, are installed to facilitate pumping the oil to the fryer. Avoid oil in the storage tank from coming into contact with air and avoid oil bubbling when transferring. 2. Use of brass or copper should be avoided in any parts of the fryer or oil tank that have direct contact with oil to avoid the risk of rapid rancidity. Brass valves are not recommended for use in the oil pipeline. 3. If anti-sticky frying baskets (Teflon-coated) are used, care should be taken to avoid rubbing them with scratchy materials. 4. The noodle conveyor net at the section of noodle soup showering may be corroded by salt solution spraying or showering onto the noodles. The lifetime of this conveyor net needs to be monitored closely. Otherwise, any broken wires (net) can be sources of contamination. 5. The exhaust hood must be designed to extend from the fryer to the top of the roof. A device should be installed that can collect condensed oil droplets. Without this device, condensed oil may drop into the fryer and contaminate the frying oil inside. Accumulation of burnt carbon in the exhaust box may cause fire. Annual cleanup of the exhaust is recommended. 6. A cool room is needed to store raw materials that are sensitive to heat such as seasoning powders and meat extracts. The appropriate temperature in the cool room is around 5–10 ◦ C.

15.4.3. Sanitary Facilities and Sanitation Controls Sanitation in noodle manufacturing plants is an important issue. General requirements for setting up sanitary facilities and sanitation controls are described in Chapter 14.

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Additional information and specific recommendations on instant noodle plant sanitation management are provided below: 1. Cleaning apparatus, such as water buckets, mops, scrubbers, and detergents, are stored in designated areas outside the processing facility. It may be necessary for cleaning crews to do some light cleaning at the end of each shift while production is still in operation. Cleaning crews must be well trained and be knowledgeable about any contamination that might occur to the products during cleaning. 2. Waste from the noodle line includes dirty dough pieces, rejected steamed noodles, rejected fried noodles, broken noodles, and scraps from packaging materials. These waste materials are bagged properly and disposed of in a timely manner to minimize the development of odors and to protect against pests. 3. Wet cleaning from dough mixer to feeder and to dough rollers is not required. Scraping of dough particles/pieces and air vacuuming are needed daily to remove any dough accumulation in corners, especially in the mixer, dough hopper, and dough disk feeder. Conveyor chains from the steamer to just before the fryer must be wet-cleaned using foam detergent, sanitizer, or hot water to remove sticky noodles from the conveyor nets. Because salt solutions cause corrosion, cleaning conveyor nets properly with a soap solution helps to prolong their usage time. Wet-cleaning is also needed for the noodle cooling tunnel at least once a month. This is to avoid mold growth both in the cooling tunnel and on the plastic pallets (conveyor bars). A microbial testing schedule should be established for both. 4. Frying baskets are cleaned and rubbed with Scotch-Brite fiber cleaner on a weekly basis. When fried noodle cakes begin to stick to the baskets, it is time to clean the baskets; otherwise, the fried noodle cakes will be transferred back to the fryer. After the noodle line has been running 24 hours a day for 10 days, the fryer is due for a cleaning using a 2–3% NaOH solution to circulate through the heat exchanger and the fryer at about 80 ◦ C. Proper safety equipment must be used when working with this caustic solution. Burnt noodles are removed from the fryer. After these steps, hot water is applied to circulate in the system and weak acid is added to neutralize the leftover alkali solution. If the noodle line has been running 16 hours a day for one month, one cleaning of the fryer is required, and all water residue must be completely removed from the bottom of the fryer after cleaning. 5. Dry cleaning is employed on the packing line. A solution of 70% alcohol is sprayed or wiped on the conveyors and on the working space on the sides of conveyors as frequently as possible and at the end of an operation shift. All broken noodle debris should be removed from the packing line at the end of every shift. 6. All workers operating in the food-handling section must have a medical checkup before being hired. Anyone with illness or any abnormal symptoms that may be a food contamination hazard shall be excluded from operations.

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7. Employees with wounds or cuts on the skin must use special bandages that can be detected by a metal detector. However, bandages on hands should be covered with gloves. 8. All persons working in the noodle processing plant shall conform to hygienic practices such as wearing clean and proper uniforms and aprons, washing/ sanitizing hands before entering the plant and after using the toilets, maintaining gloves in good condition or changing disposable plastic gloves in a timely fashion, and wearing hair nets to fully cover hair. The mixing operators and roller operators must sanitize their hands prior to working because they must check the dough conditions using bare hands. For such purposes, 70% ethanol liquid is provided. In some cases, packing crews may use bare hands to handle noodles or seasoning sachets, so their hands also require sanitation with 70% ethanol. 9. Pests are strictly controlled in all areas of the food plant. In flour storage areas, such as silos or bag flour storage rooms, weevils are controlled. When silos are not in use for several days, they must be emptied and fumigated with phosphine gas (in the form of aluminum phosphide tablets) to prevent weevil infestation. In hot areas, flour stored for more than 2 months must be fumigated by adding one tablet of aluminum phosphide per 1 m3 of flour.

15.4.4. Process Control

15.4.4.1. Dough Mixing Besides formulation of the particular noodles being mixed, mixing time, dough temperature, and dough appearance are to be controlled. When a deviation occurs, such as dough temperature being too hot or too cold (25–35 ◦ C), it will affect the development of good gluten, and thus result in poor chewing property of noodles. Dough characteristics, such as too-dry or too-wet dough, are monitored. A practical way to adjust dough conditions is by varying the amount of water added. If dough is too wet, the amount of water will be reduced in the next batch. Wet dough causes difficulty in the sheeting process and results in noodle sheet tearing. The amount of mixing water is generally at 28–35 liters for 100 kg flour. When starch is added in the formulation, dry dough may result in insufficient starch gelatinization during steaming. Spraying water onto waved noodles before steaming may improve starch gelatinization. Adding starch little by little during the mixing process and adding more water in the formulation can improve dough characteristics. 15.4.4.2. Dough Rolling Rollers are divided into two sections: compounding rollers and reducing rollers. More reducing roller units (5–7) are beneficial to improving noodle texture. Dough thickness should be reduced gradually and in more steps. Noodle thickness should not be reduced by more than 50% in any step because too much stress on the dough sheet damages gluten structure and is not desirable for the texture of finished products. Noodle sheet thickness is periodically checked and controlled during operation because it affects not only the noodle texture but also noodle weight. Noodle thickness

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on both sides should be equal, but it is more difficult to obtain a uniform noodle thickness with wide rollers. In this case, noodle cakes on one side might have a higher or lower weight than required. Keeping all rollers (surface and moving parts) in good condition is essential to control noodle sheet thickness. A metal detector may be employed before the reduction rollers to detect any metal pieces in the dough that may cause damage to the roller surface.

15.4.4.3. Steaming Steaming is used to pregelatinize starches in noodles, to fix noodle waves, to strengthen noodle blocks, and to reduce cooking time before serving. If the steaming is insufficient, the fried noodle cakes/blocks will become fragile and after boiling or soaking in hot water, the served noodles will taste starchy. On the other hand, if the noodles are steamed for too long, the fried noodle blocks will become hard and lose their snacking property. Saturated steam is used for steaming and the temperature is about 100 ◦ C. Noodle steaming time varies from 1 to 5 minutes, depending on the noodle thickness and starch content. 15.4.4.4. Frying The objective of frying is to quickly remove moisture from steamed noodles and it also serves the purpose of pasteurization (killing germs). Both frying time and temperature are important parameters. Frying temperature ranges from 130 to 160 ◦ C and frying time is less than 2 minutes, depending on the noodle width and weight. Moisture content below 3% is often achieved in the finished products, but, in some cases, maximum moisture of 8% is also acceptable. For making snack noodles, steamed noodles are showered with the seasoning solution or dipped in the solution and then deep-fried. The finished products are crispy and tasty. Frying imparts the desired flavor and color to the noodles. A color of yellow to golden-brown is expected for instant fried noodles. Instant fried noodles that are not properly steamed and fried take longer to cook in hot water before serving to reduce starchy taste at noodle cores. It has also been noticed that the noodles tend to become rancid faster if they are not fried enough. 15.4.4.5. Frying Oil Frying oil heated with an indirect heat exchanger gives better quality to fried noodles compared to the direct heat exchanger type. This is because the indirect heat exchanger has the ability to control oil temperature more accurately with a deviation of less than 2 ◦ C. Oil is added to the fryer automatically to keep the oil level even. An oil level that is too high could cause a rapid increase of acid value in the oil. This can be seen when frying low-weight noodles in comparatively too big baskets. The resultant fried noodles tend to develop an objectionable odor from oxidative reaction and have shorter shelf life. The acid value (AV) of frying oil should be monitored closely. When AV reaches over 1 mg KOH/g oil, the usual cause is too much water or liquid soup getting into the oil. Water comes mainly from soup showering onto the steamed noodles before frying.

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Therefore, control of soup absorption by the steamed noodles is necessary. Dripping of excessive liquid can be achieved by allowing a longer holding time after liquid showering or applying fans to remove excessive liquid from the noodles. However, if the noodles are too dry, they may not slide easily into the frying baskets/cups. The peroxide value (POV) of frying oil is measured daily as well as whenever oil starts to produce an objectionable odor. POV rises as a result of thermal oxidation, especially when high heat is applied and no products are fried. Metals, such as copper and brass, should be kept away from contact with oil, because they activate and promote an oxidative reaction, resulting in high POV and other secondary products from decomposition of hydroperoxide. POV over 20 meq/kg is considered too high, and the maximum AV of frying oil is 1.2–1.5 mg KOH/g. The Japanese Standard and Codex Standard allow the AV in the finished product to be at a maximum of 2.0 mg KOH/g (JAS 1986; Codex Alimentarius Commission 2006). In Japan, POV is considered to be one of the important quality aspects for instant fried noodles, and the maximum value is 30 meq/kg. However, it should be cautioned that POV is not a very reliable quality indicator. When the POV measures low but the oil odor smells bad, the operator should trust the result from the detected odor. Frying noodles in oil having a high POV causes a shorter shelf life. Sticky materials over the frying hood can drop into the frying oil and cause high POV. Therefore, the side of the hood is designed to collect oil condensates. Periodical cleaning of the hood prevents the dropping of oil and other materials into the frying oil. Palm oil is the most popular choice for frying noodles because it contains about 45% saturated fat and is more stable than oils that contain a high content of unsaturated fats (Fennema 1985). When oil of low saturated fat, such as soybean oil, is used to fry noodles, the shelf life of fried noodles is reduced by half. Antioxidants, such as TBHQ, tocopherols (vitamin E), BHA, or BHT or their mixtures, are often added to palm oil. Among these, TBHQ is reported to have the best efficiency to prolong the shelf life of fried noodles (Ng 1996). These antioxidants help to stabilize the oil quality during transport and storage in the plant. Adding additional antioxidants to the oil during frying is not necessary if the frying conditions and oil properties are closely monitored. If the frying temperature is not too high, some antioxidants may have a “carry through” property and impart their stability to the finished products. However, most antioxidants cannot survive at frying temperatures of 160 ◦ C or higher and are therefore not active in the finished products.

15.4.4.6. Cooling The function of the cooling tunnel is to cool the fried noodle temperature down to room temperature. If noodles are packed while hot, the quality of the seasoning sachet will be affected by the heat and water condensation that will occur and cause mold to grow. 15.4.4.7. Weight The weight of the fried noodle block, together with the seasoning sachet and flavoring oil sachet (optional) that are bagged together, is monitored by automatic weight checkers, with the upper and lower control limits established. These items are wrapped

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in plastic film, codes are printed on the package for traceability, and information is given on the production date and expiration date or the “best before” date to indicate preferred consumption period. Individual bags are then packed into cartons and ready for distribution.

15.4.4.8. Dough Piece Reuse Recycled dough pieces and steamed noodles are stored in different bags and labeled with batch numbers to control the time of use because they may become fermented if kept for too long. Usually, steamed noodles are safe to reuse if stored for less than 3–4 hours at room temperature. Recycled steamed noodles, with a limit up to 3% in the noodle formula, do not affect the noodle quality when the steamed noodles are added to the fresh noodle dough mixture little by little after an initial 3 minutes of mixing.

15.5. HAZARD ANALYSIS AND CRITICAL CONTROL POINTS (HACCP) Since instant noodles are ready-to-eat products, a control system must be implemented in the production plant to identify, evaluate, and control hazards that pose safety threats to each production stage. The implementation of the HACCP system in the noodle plant is to assure product safety. The prerequisite programs for the establishment of the HACCP plan include Good Manufacturing Practices (GMPs), Standard Operation Procedures (SOPs), Sanitization System Operation Procedures (SSOPs), pest control, equipment maintenance, and allergen program. The information discussed previously provides some basic and necessary operative conditions to develop and implement a successful HACCP plan (FDA 1997; USDA 1997). 15.5.1. Preliminary Tasks for the Establishment of the HACCP Plan

15.5.1.1. HACCP Team Formation The HACCP team should have a combination of multidisciplinary knowledge and experience in developing and implementing the food safety management system. This will include personnel from production, quality control, maintenance, and especially from top management, because they all contribute to the process. 15.5.1.2. Product Description The name and a clear description of the product allow for a focus on the application area of the HACCP plan. See example in Table 15.3. 15.5.1.3. List of Ingredients and Raw Materials Develop a complete list of ingredients and raw materials. This will ensure each and every component of the finished product is taken into consideration. See example in Table 15.4.

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TABLE 15.3

375

Product Description

Number

Category

Description

1 2 3 4 5 6 7 8 9 10

Product name Type Use/application Target consumer Market previewed Main process safety parameters Main product safety parameters Potentially hazardous ingredients Distribution Preparation

11

Shelf life

12 13 14

Labeling Regulatory considerations Health claims

15

Packaging

16 17 18 19

Intended production site Process line Line status Process

20

Product specifications

Fried instant noodles Dehydrated Instant foods General public, 6 years of age and above United States Cooking Low water activity (Aw ≤ 0.6) Not applicable Existing distribution channels in market Add 450 mL boiling water and soak for 3 min or cook for 2 min 6–10 months depending on storage conditions As per legal requirements in market According to the Codex/local legislations Market is responsible for the compliance of the claim, based on local legislation Current packaging material (OPP 18 µm/PP 15 µm) ABC Factory, USA Noodle line 1 Shared, but all products contain wheat flour Produced by mixing for 20 min, steaming at 100 ◦ C for 70 s, followed by frying at 140 ◦ C for 90 s; the product is then air-cooled to room temperature before packing into packaging material Refer to manufacturing document

15.5.1.4. Develop a Flow Chart The next step is to develop a flow chart, beginning with the reception of the raw materials and ending with the finished product delivery. See example in Figure 15.2. 15.5.2. Seven Principles to Implement HACCP Plan

15.5.2.1. Principle 1: Conduct Hazard Analysis Using the flow chart, the HACCP team analyzes the physical, chemical, and biological hazards in each stage of the process. The HACCP team can use brainstorming to generate ideas and conduct a hazard analysis of those hazards that can pose a risk to consumer’s health: 1. Physical Hazards: A physical hazard is an object or physical material that normally is not part of the product and can cause damage to the consumer’s

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TABLE 15.4

Ingredients and Raw Materials List

Number

Type

Description

1

Raw Material

Flour Edible oil Freeze-dried vegetables (green peas, carrot pieces, etc.) Texturized protein Freeze-dried shrimps Hot pepper powder

2

Ingredients/additives

Salt (sodium chloride) Sodium polyphosphates Sodium carbonate Potassium carbonate Guar gum

3

Seasoning powder

Chicken flavoring Seafood flavoring

4

Liquids

5

Packaging materials

Beef flavoring Water Polystyrene cup Shrink-wrap label Aluminum lid Paper lid Shrinkable polyolefin Corrugated carton Adhesive tape Wrapper film Polyethylene laminate Polypropylene laminate Plastic fork

health. The most frequent physical hazards are wood chips, plastic, glass, or metal pieces in the flour and screws. 2. Chemical Hazards: Chemical hazards are chemicals that are added intentionally or unintentionally to the product and can cause damage to the consumer’s health. Some examples are cleaning chemicals, lubricants, machinery painting residues, and pesticide or insecticide residues. 3. Biological Hazards: Biological hazards are live organisms that can put human health at risk. Some of these organisms are pathogenic bacteria such as Staphylococcus aureus and Escherichia coli as well as molds and yeasts.

15.5.2.2. Principle 2: Identify Critical Control Points A critical control point (CCP) is a point, step, or procedure in a food manufacturing process at which control can be applied and, as a result, a food safety hazard can be prevented, eliminated, or reduced to an acceptable level.

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Additive Solution Ingredients - Salt - Sodium/potassium carbonate - Sodium polyphosphate - Gums

Cereals - Wheat flour

Sieving

Weighing

Water

Cooking Oils e.g. Vegetable Oil

Weighing

Visual Inspection

Mixing Ingredient Solution

Dough Mixing

Dough Sheet Forming & Combining Salt

Dough Sheet Reduction Soy Sauce Slitting

Showering

Waving Steaming

Culinary Steam

Slitting

Folding*

Randomization*

Molding Processed Hot Air

Drying**

Frying** CCP No. 1 Cooling

Metal Detection

CCP No. 2

CCP No. 3 Final Packing Materials

Packing

Seasoning Powder / Garnishes / Flavor oil

Labeling

Storage & Distribution

* Steamed noodle cakes are either folded or randomized before moulding. ** After moulding, noodle cakes are dehydrated either through frying or hot-air drying.

FIGURE 15.2 and bowl).

Flow diagram of instant noodle manufacturing (fried, air-dried for bag, cup,

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A very useful tool in the identification of the critical control points is the decision tree (Figure 15.3), which allows separating the CCP from other controls such as SSOPs, GMPs, or other operation procedures.

15.5.2.3. Principle 3: Establish Critical Limits for Each Critical Control Point A critical limit is the maximum or minimum value to which a physical, biological, or chemical hazard must be controlled at a critical control point to prevent, eliminate, or reduce the hazard to an acceptable level. The critical limits are expressed in numerical values or specific parameters based on visual observation, such as: r Absence of foreign objects in the sifted raw materials r Frying temperature r Frying time

15.5.2.4. Principle 4: Establish Critical Control Point Monitoring Requirements Monitoring activities are necessary to ensure that the process is under control at each critical control point. In the United States, the Food Safety and Inspection Service (FSIS), an agency of the United States Department of Agriculture (USDA), requires that each monitoring procedure and its frequency be listed in the HACCP plan. The HACCP team specifies the vigilance criteria to maintain the CCP within critical limits. Therefore, specific actions are established that include the frequency and the responsible person to perform them. The vigilance results are used to establish a procedure to fit the process. 15.5.2.5. Principle 5: Establish Corrective Actions These are actions to be taken when monitoring indicates a deviation from an established critical limit. The final rule requires a plant’s HACCP plan to identify the corrective actions to be taken if a critical limit is not met. Corrective actions are intended to ensure that no product injurious to health or otherwise adulterated as a result of the deviation enters commerce. 15.5.2.6. Principle 6: Establish Recordkeeping Procedures The HACCP regulations require that all plants maintain certain documents, including its hazard analysis and written HACCP plan, and records documenting the monitoring of critical control points, critical limits, verification activities, and the handling of processing deviations. Records are kept to show that the system controls have been working and that adequate corrective actions have been taken when deviations from the critical limits are found. This will confirm the safety of manufactured products.

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Identify potential hazards for each production step

For each potential hazard identified, identify existing preventive/control measure

Is this preventive/control measure effective to reduce the hazard to an acceptable level? Yes

No

Not a significant hazard

The hazard is significant

Can the hazard be controlled by other means than by appropriate allergen labeling of the product? Yes No Eliminate (e.g., by segregation of equipment, change of raw material supplier)

Control by specific cleaning procedure

Control measure: Labeling

CCP (= Label approval)

CCP (= Equipment to be cleaned)

Monitor CCP Validate your decision/control measure: - Provide justification and data to support your decision and document - Establish verification activities - Document - Implement and train

FIGURE 15.3

Decision tree for identifying CCP (e.g., allergen).

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15.5.2.7. Principle 7: Establish Procedures for Ensuring the HACCP System Is Working as Intended Validation ensures that the plants do what they were designed to do; that is, they are successful in ensuring the production of safe products. Plants will be required to validate their own HACCP plans. FSIS will not approve HACCP plans in advance but will review them for conformance with the final rule. Verification ensures the HACCP plan is adequate; that is, working as intended. Verification procedures may include such activities as review of HACCP plans, CCP records, and critical limits and microbial sampling and analysis. FSIS requires that the HACCP plan includes verification tasks to be performed by plant personnel. Verification tasks would also be performed by FSIS inspectors. Both FSIS and the industry will undertake microbial testing as one of several verification activities. Verification also includes “validation”—the process of finding evidence for the accuracy of the HACCP system (e.g., scientific evidence for critical limitations). The seven HACCP principles are included in the international system ISO 22000. This standard is a complete food safety management system incorporating the elements of prerequisite programs for food safety, HACCP, and quality management system, which together form an organization’s Total Quality Management. An example of an instant noodle plant HACCP, which reviews the application of all the principles explained above, is shown in Table 15.5.

15.6. QUALITY CONTROL Table 15.2 lists laboratory instruments and methods recommended for the Quality Assurance Department to perform a standard quality assessment and evaluation. Some tests are for monitoring raw material quality while others are for process control or for finished products. Important tests are described in this section. 15.6.1. Visual Test Although chemical analysis is important, visual evaluation is perhaps the most commonly used technique employed by quality inspectors in noodle manufacturing plants. Some of the common tests are listed below.

15.6.1.1. Noodle Color Noodle color is related to flour ash and the presence of alkali salt in the recipe. Usually, if one desires to produce a bright and white color noodle cake, lower ash flour is required. If flour ash is high, noodle dough color will be dull and brown spots will likely be scattered on the dough-sheet surface. The appearance of the finished products will be “specky.” Higher alkali salt in the recipe causes dough color to be yellowish. It also leaves an alkali taste in the cooked noodles.

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TABLE 15.5 CCP 1

2

3

381

HACCP Master Sheet

CCP Location

Hazards

Control Measure

Monitoring Procedures

Critical Limits

Frying station

Survival of Verify heating Monitor Temperature: pathogenic mitemperature achievement minimum croorganisms and time of heating 122 ◦ C; holding time: (Staphylococparameter minimum cus aureus and during batch 40 seconds Salmonella) due to inadequate heat treatment Metal Presence of Detect by metal Pass products Limit: 2 mm detection metallic detector through metal stainless foreign matter detector steel; target: due to wear before no sounding and tear of packing into of alarm from process packaging the metal materials or detector contaminated ingredients Packing Incomplete listing Visual Visual Complete listing station of allergenic inspection of inspection of of allergenic ingredients the label on the label ingredients the packaging present

15.6.1.2. Gelatinization of Noodles Starches in noodles are gelatinized during steaming. The degree of starch gelatinization can be checked by squeezing steamed noodle strands between two glass plates and observing the size of the white core area. If the core area is opaque, the noodles are not fully cooked/steamed. Instant noodles that require only soaking in hot water for consumption have much less white core area than those that require boiling preparation. 15.6.1.3. Frying Oil Quality Frying oil is scored subjectively on a scale of 1–5 based on its color (Table 15.6) to determine its acceptability. This is a practical way commonly used in the instant noodle industry although it’s not very precise. 15.6.1.4. Fried Noodle Cake Appearance Noodle color is one of the major quality characteristics listed in the specifications. Color can also be graded visually by a score of 1–5 (Table 15.7). In addition, an oily surface is to be noted. Excess oil is absorbed back into the noodles at the end of the frying section. When internal pressure is too low (too-low

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TABLE 15.6

Subjective Scoring of Frying Oil

Score

Description

1 2 3 4 5

Dark red oil with many specks (recommended not to use) Darker color oil with more specks floating and the oil requires filtering Red-brown color with some specks floating in the oil Slightly orange color Fresh oil color

moisture left in noodles), oil from the oil bath will penetrate into the noodle strands, which is difficult to remove by forced air immediately after frying and causes an oily appearance on the surface.

15.6.1.5. Black Specks on Noodles Usually, the continuous fryer is equipped with wire mesh strainers to remove relatively large particulate matter from the cooking oil. A separate filtering unit is used to further clean the oil. The oil is pumped through paper filters or through a combination of paper filters and cellulose powder to remove small suspended solids. The speed of oil moving through the filter varies. If the oil is filtered more quickly, suspended solids from over-fried soup or broken noodle parts will be more thoroughly removed. If the oil is not cleaned well, not only will the free fatty acid rise faster but the particulate matter may also attach to the noodles. Noodles with black specks are rejected because they are not accepted by consumers. If fried noodles are soaked or boiled in hot water for a few minutes, black specks can easily be identified. A simple judgment from acceptable to unacceptable level can then be established. 15.6.2. Sensory Test

15.6.2.1. Color Instant noodle color varies according to market preferences and quality grade level. Japanese instant noodle color is usually characterized by a light cream color to a yellow color. Fried snack crispy noodles showered with liquid soy sauce soup before frying are expected to show a golden-brown color; a light color is considered unusual or undesirable. This type of noodles with a lighter color could have a shorter shelf life because the noodle moisture may be high or some parts of the noodle blocks might not be properly cooked.

TABLE 15.7

Subjective Scoring of Fried Noodle Cake

Score

Description

1 5

Too-pale color (not fried enough) or too brown (over-fried) Noodles are properly fried and have good color

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15.6.2.2. Texture Noodle texture is perhaps the most important characteristic of the product. Japanese udon noodles have a soft and smooth surface while other types of noodles may be different. In general, Japanese noodles have a soft and elastic texture while noodles in Southeast Asia countries, such as Thailand and Indonesia, exhibit a harder and chewier texture (Hou 2001). Therefore, evaluation of texture depends on expected characteristics. Choosing the optimum grade of wheat flour is the key to producing specific types of noodles. Preparation methods also have a big impact on the noodle texture. Enough starch gelatinization will result in good texture, so noodles that require cooking on the stove always have a pleasant texture. Noodles that require only submerging in hot water for 3 minutes must undergo complete gelatinization during processing. Instant noodles are allowed to rehydrate for 2–4 minutes prior to serving. Rehydration ratio can be simply measured by dividing the drained weight of the noodles by the starting dry weight. Good rehydration ratio is around 2–2.5. Again, this depends on expected characteristics. Stability of texture should be determined at 3 minutes (time to start eating) and no longer than 10 minutes (time to finish eating). If the noodle texture is still hard or too soft at 3 minutes, it is to be graded at a lower score. After 10 minutes, mushy texture develops for noodles that have absorbed an excessive amount of water. If this characteristic occurs too early, the noodle texture score will be reduced. To minimize this, CMC (carboxy methyl celluslose, or edible gum) is a useful food additive in the formulation of instant noodles. CMC helps prolong the period of eating; without CMC, noodles expand faster and result in mushy texture. In addition to the wheat-flour quality and formulation, the type of noodle slitter used has an impact on the noodle texture too. Usually, a round slitter requires more force to push the noodles through the hole than a flat or square slitter; therefore, the texture of round noodles is firmer and chewier than flat-shaped noodles. Cookednoodle texture can be graded on a scale of 1–5 (Table 15.8) in the noodle plant. 15.6.2.3. Odor Fried noodle odor is affected by frying oil quality and flour quality although oil quality plays a more important role. When noodles are kept at a high temperature (100–120 ◦ C), thermal oxidation occurs after 15–30 hours, causing a rancid smell. A quick test to predict noodle shelf life can be performed by recording the number of hours that samples are kept in the same environment before they develop a rancid

TABLE 15.8

Subjective Scoring of Cooked Noodle Texture

Score

Description

1 2 3 4 5

Not properly cooked according to the given preparation method Mushy texture or rough surface that also affects appearance Standard texture of noodles at an acceptable level Good bite (elastic and chewy) Excellent texture and excellent bite, together with a smooth surface and springiness

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smell. If the number is high, it indicates that the noodles could be kept for a longer time than normal. If steamed noodles are fried in oil with a high peroxide value (POV) or in heat-abused oil, it is expected that a rancid smell could be detected from the fried noodles in a shorter time after they are kept in the above-mentioned storage condition. Noodles can also develop a stale odor from rancid flour. It is always a good idea to inspect flour odor when it is first received and again when the flour is used. Hot and humid weather causes flour to become stale during storage. Flour stale odor can be detected by adding 25–30 mL of hot water into a 50-g flour sample while stirring fast. Normal flour gives off a fresh smell with no objectionable odor from being damp or stale. Noodles with a stale odor from stale flour cannot be easily detected from direct smell on a noodle block, but the stale odor can be noticeably detected during tasting noodles already cooked/prepared.

15.6.2.4. Taste The taste of fried instant noodles is affected by the recipes and the process. For instance, if noodles are sprayed with seasonings before frying, they would have a different taste. As for when to evaluate salty taste, it is recommended that the accuracy of the panelists be confirmed by analyzing the percentage of NaCl by the titration method (AOAC Method 971.27, 1995). For evaluation of the finished product, it is preferred that noodles be tasted in seasoned soup. A sensory score of 1–5 is suggested for routine inspection. Different noodle recipes give different tastes even in the same seasoning soup. This is because leaching of starch into boiling water during cooking makes soup thicker or saltier and that influences the taste. For freshly received oil, tasting the oil could confirm the quality rather than measuring the acid value (AV) alone. It can easily be detected by tasting if the oil is contaminated with even a small amount of low-quality oil. 15.6.3. Analytical Tests (Physical and Chemical Tests) Quality Assurance personnel rely on the quality of the lab facilities combined with the requisite knowledge and the experience to put the internationally approved analysis methods into practice. The results of these analyses allow for monitoring the physicochemical and microbiological characteristics of products-in-process and finished products with the objective to guarantee the quality and innocuousness of the instant noodles.

15.6.3.1. Moisture Methods to measure the moisture content of some raw materials and noodle products are listed in Table 15.9. The moisture content in each product can be analyzed by both the moisturebalance method and the hot-air-oven method. The moisture-balance method is for daily quick tests while the hot-air-oven method is a standard method approved by the AACC International, AOAC International (130 ◦ C, 1 hour), and Codex (105 ◦ C, 2 hours for fried noodles, 4 hours for air-dried noodles) (Fennema 1985). The range

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TABLE 15.9 Determination of Moisture Content in Raw Materials and Instant Noodles Product Wheat flour Fried noodles

Nonfried noodles Seasoning powder

Moisture Content a

14% maximum 2–5% (after production), 10% maximumb (in market) 14% maximumb 3% maximuma

Instrument

Temperature

Moisture balance Moisture balance

120–140 ◦ C 120–140 ◦ C

Moisture balance Moisture balance

120–140 ◦ C 120–140 ◦ C

a Suggested b From

figures. Codex STAN 249 (2006).

of set temperatures recommended in Table 15.6 must be verified against the standard method to get the right temperature to provide the closest moisture content result.

15.6.3.2. Protein Content Protein content can be determined by the Combustion Nitrogen Analyzer (CNA). Compared to the traditional Kjeldahl (digestion and distillation) method, the CNA method is much quicker and more accurate. Protein content is obtained by multiplying the nitrogen value by 5.7 for wheat-flour products. Medium protein of 10–12% wheat flour is suitable for making elastic and firm-bite noodles. Soft wheat flour of 8.5–9.5% protein is suitable for udon noodles. Instant noodles (fried) contain 7–10% protein but, in most countries, protein content is not a required quality factor in the product specification of noodles. 15.6.3.3. Wet Gluten A 10-g flour sample could be used for this test by placing the sample in a Glutomatic washing machine. Since gluten is directly responsible for the elasticity and extensibility of dough, each batch of flour at receiving is tested for wet gluten content to assure the consistency of noodle texture. Although protein content has a close correlation with the wet gluten, the wet gluten is considered more related to the dough quality and product texture. 15.6.3.4. Fat Content Fat in the noodles is extracted by Soxhlet extraction. Fried instant noodles contain about 16–22% fat depending on type of flour, recipe, frying conditions, and quality of oil. Fried noodles with less than 18% fat could be achieved by removing excessive oil by forced air immediately after the noodles emerge from the oil bath. 15.6.3.5. NaCl Content in Noodles The salt content in noodles is determined by the following method (AOAC International Method 971.27, 1995): grind 5 g of noodles, add into 100 mL of distilled water,

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mix well in a blender, and titrate the sample with 0.1 N AgNO3 solution until the end point; solution turns a red-brown color.

NaCl (%) =

mL of AgNO3 × 0.1 × 5.844 × 100 Wt. (5.000 g or as weighed)

15.6.3.6. Rehydration Test This test is used to determine the rehydration rate of instant noodles. The noodles are soaked in boiling water according to the instructions on the package. After the soaking time is up, the noodles are drained onto the sieve for 2 minutes without shaking and then weighed. The rehydration rate is calculated by using the following equation:

Rehydration rate (%) =

(Wt. of drained noodles − Wt. of dry noodle) × 100 Wt. of dry noodles

A rehydration rate of 120–150% is associated with good eating quality. Good texture noodles allow high rehydration in boiling water in 2–3 minutes. If the noodles do not rehydrate well, parts of the noodle strands will not be fully cooked and the texture may be starchy.

15.6.3.7. Noodle Texture Noodle texture is often determined by sensory evaluation in the noodle plant; however, the instrument method, such as the Texture Analyzer, is very useful to distinguish between soft-bite and hard-bite noodles, between elastic and less elastic noodles, and between chewy and mushy noodles. Readers are advised to read Chapters 8, 9, and 13 for more discussion on instrumental measurement of noodle texture.

15.6.4. Microbiological Test Instant noodles are considered shelf-stable foods because they are at low risk for microbial spoilage. Table 15.10 lists the types of microbes and their allowable levels in fried instant noodles in Thailand (Thai FDA 2000; Thai Industrial Standard Institute 2005).

15.6.5. Other Tests Instant noodles are made from wheat flour. In addition to testing flour quality attributes that are important to noodle quality, parameters related to food safety such as DON (deoxynivalenol) and pesticide residue may also require regular monitoring.

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TABLE 15.10

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Allowable Levels of Microbes in Instant Noodles

Microbes

Specificationa

Reference Method

APC (aerobic plate count), or TPC (total plate count)

Noodles: < 1 × 103 cfu/g Seasonings: < 5 × 105 cfu/g

Mold

Noodles: < 10 cfu/g Seasonings: < 1–5 × 102 cfu/g

Clostridium perfringens

Negative in 0.01 g (seasonings) Negative in 0.01 g (noodles and seasonings) < 3 MPN/g (noodles and seasonings)

Compendium, 4th ed., 2001 (American Public Health Association) FDA Bacteriological Analytical Manual, 8th ed. (Rev. A) 1988; Chap. 18 or Compendium, 4th ed., 2001 (American Public Health Association) AOAC International (2000), Chap. 976.30 AOAC International (2000), Chap. 987.09 FDA Bacteriological Analytical Manual, 8th ed. (Rev. A) 1988; Chap. 18 or Compendium, 4th ed., 2001 (American Public Health Association) ISO 6579, 2002

Staphylococcus aureus Escherichia coli

Salmonella a cfu

Negative in 25 g (noodles and seasonings)

= colony forming unit; MPN = most probable number.

Sources: Thai FDA (2000) and Thai Industrial Standard Institute (2005).

15.7. PACKAGING MATERIALS Packaging of instant noodles is important not only because it serves as a food container but also because it provides an attractive image of the product to consumers. This section focuses on the importance of packaging that serves as a food container. Bag-type instant noodles are popular all over the world because of their affordable prices. The plastic film used to pack instant noodles must have a good heat-sealing property. Polypropylene is the most popular choice for making this type of packaging material. Polypropylene is usually combined with an outer layer, in most cases, oriented polypropylene (OPP), without a metalized vapor. After 2 months, moisture is absorbed by the noodles and the noodle moisture increases to 4–5% and continues to increase, depending on the surrounding humidity. At this point, instant noodles start to lose their crispness and may even pick up some bad smells, such as strong chemicals like perfume or detergent, from the surrounding environment. The problem of unpleasant odor can be solved by using laminated and metalized films. Very thin aluminum vapor sprayed on co-polypropylene laminated with OPP film (OPP/MCPP) can be used as a packaging film to keep noodle moisture below 5% for 6 months. This type of packaging material is suitable for a good-quality premium product. For air-dried instant noodles, it is acceptable to use a plastic film

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TABLE 15.11

Types of Instant Noodle Products and Their Packaging Materials

Type of Product

Type of Packaging

Packaging Materiala

Bag-packaged noodles

Noodles (inner bags)

PET/PE/CPP OPP/PE/CPP OPP/PP ONY//CPP, ONY//PE

Powder seasonings

PET/PE/Al/PE ONY/PE/Al/PE OPP/PE/Al/PE

Liquid soup (oil, paste)

ONY//Al//LLDPE ONY//VMPET//LLDPE PET//Al//PET//LLDPE

Spices, seasoned fish meal

ASPET/PE/ASCCP OPP/PE/Al/PE

Dehydrated vegetables

PET//Al//CPP

Containers

Polystyrene foam High impact polystyrene (HIPS) Polyethylene coated paper Polypropylene

Lids

Paper/PE/Al/heat-sealing agent High impact polystyrene (HIPS)

Shrinkable film

Heat skrinkage PP

Snack-type noodles

a Note:

/ stands for extrusion lamination, // stands for dry lamination. Abbreviations: PET, polyethylene telephthalate; PE, polyethylene; OPP, oriented polypropylene; CPP, unoriented polypropylene; Al, aluminum; ONY, oriented nylon; LLDPE, linear low density polyethylene; VMPET, aluminum metalized polyester; AS, antistatic; PP, polypropylene.

that has a lower water vapor barrier as long as the noodle moisture content is not more than 10–12%. Packaging materials recommended for instant noodles are shown in Table 15.11 (IRMA 2001). In contrast, containers for cup and bowl instant noodles are designed for eating noodles directly from the containers. Noodles are prepared for eating by either adding hot water in the container to soak for about 3 minutes or cooking in a microwave oven for 2 minutes. Properties of the containers are related to noodle cooking methods. If noodles are cooked by adding hot water into the cup or bowl without further heating in a microwave, the containers can be made from plastics. Two popular choices are polypropylene (PP) and polystyrene (PS). Polypropylene cups/bowls have good moisture and oxygen barrier properties. Production of these food containers is done by injecting plastic resins into the desired molds. These food containers are safe and can maintain the product with the same quality as in the laminated metalized films. Polypropylene cups can be used safely in the microwave. Polystyrene is also popular and can be found in two forms: PS foam with and without outer lamination. This has been widely used because of its low cost and excellent heat-insulating properties. The cup can hold hot soup while protecting the

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holder’s hands from burns. PS foam materials have less moisture and oxygen-barrier properties compared with PP. This can be overcome by using a shrink-wrap outside the cup or bowl to serve as an extra barrier and to provide space for more attractive printing (labeling area). However, PS foam is not permitted in some markets for the following reasons: 1. Styrene monomer is considered to be a potential carcinogenic substance and could transfer from the PS foam to the noodles. In 2002, a report was submitted to the U.S. Food and Drug Administration (FDA) by the Polystyrene Packaging Council Technical committee (Anon. 2002) and demonstrated that the estimated daily intake (EDI) from PS packaging at the maximum amount (calculated to be 9 µg per person per day) was very small and presented no health and safety concerns when compared with the acceptable daily intake (ADI = 90,000 µg per person per day). Another study conducted by Cohen and co-workers (2002) also concluded that there is no cause for concern for the general public from exposure to styrene from foods. However, in 2008 the NTP (National Toxicology Program, U.S. EPA) invited public comments on the recommendations from an expert panel on the listing status for styrene as reasonably anticipated to be a human carcinogen. However, the risk does not come from foods; instead, it is from inhalation of styrene exposure in the packaging manufacturing plants. 2. Environmental issues have been a concern. In the past, PS foam was made by using chlorofluorocarbon (CFC) gas, which is known to destroy ozone in the stratosphere, resulting in acceleration of global warming. But now the manufacturers can produce the product without using CFC gas. 3. PS does not easily decompose and remains in landfills for a long time. There is no practical way to recycle it. 4. PS foam containers cannot be heated in a microwave and the label should clearly state this. PP containers can be used in a microwave. Today, in many countries, such as China, Japan, and Korea, polyethylene (PE)coated paper cups are gradually replacing some of the PP and PS foam containers for their environmental and cost-saving aspects. Packaging in contact with food must be analyzed with the migration tests as specified in 21 CFR Part 170.39 (FDA 2003), 21 CFR Part 174.6 (FDA 2008a), and 21 CFR Part 177 (FDA 2008b). An example of PP film can be found in 21 CFR Part 177.1520 clauses (c) (FDA 2004), which details maximum level of extractable fraction of polymer in a specific solution (n-heptane and xylene) at a specific temperature.

15.8. SUMMARY Quality assurance for instant noodle manufacturing plays an important role in safeguarding the product quality for the customer. Quality assurance is an integral part of the food safety management system that is referred to as the Quality

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Management System (QMS). In QMS, quality assurance involves resource management. Important resources for the Quality Assurance (QA) Department are competent inspectors and staff as well as reliable laboratory instruments and approved test methods. In addition to QA, factories must assure their product qualities by operating under the GMP and HACCP systems. These are minimum requirements needed by most regulatory agencies for world food trade. Without implementation of these safety systems, the safety of noodle products could not be assured for human consumption. Quality of the noodles depends on the raw materials; as a result, the quality control department must assure the quality of wheat flour, frying oil, and other ingredients to be consistent and suitable for the product formulation. It is important to have a trained panel to conduct routine sensory tasting of noodles to determine acceptability. Last but not least, quality of packaging materials cannot be ignored. Packaging preserves and protects the noodles throughout the prospective shelf life without introducing additional contaminants that are hazards to human health.

REFERENCES Anon. 2002. The safety of styrene-based polymers for food-contact use. Submitted to the U.S. Food and Drug Administration (FDA) Food Additive Master File (FAMF) Update by the Polystyrene Packaging Council Technical Committee on November 18, 2002. Available at http://www.americanchemistry.com/s plastics/doc pfpg.asp?CID=2302&DID=10014. Codex Alimentarius Commission. 2006. Codex STAN 249: Codex Standard for Instant Noodles. Available at www.codexalimentarius.net/download/standards/10658/CXS 249e. pdf;jsessionid=2F703686C48B41A6F7E617A3D652047C. Cohen, J. T., Carlson, G., Charnley, G., Coggon, D., Delzell, E., Graham, J. D., Greim, H., Krewski, D., Medinsky, M., Monson, R., Paustenbach, D., Petersen, B., Rappaport, S., Rhomberg, L., Ryan, P. B., and Thompson, K. 2002. A comprehensive evaluation of the potential health risks associated with occupational and environmental exposure to styrene. J. Toxicol. Environ. Health Part B 5(1 & 2):1–263. FDA. 1997. Hazard Analysis and Critical Control Point Principles and Application Guidelines. Adopted by the National Advisory Committee on Microbiological Criteria for Foods on August 14, 1997. U.S. Food and Drug Administration, U.S. Department of Health and Human Services, Washington, DC, USA. Available at http://www.cfsan.fda.gov/ ∼comm/nacmcfp.html#defs. FDA. 2002a. Current good manufacturing practice in manufacturing, packing, or holding human food. In: 21 CFR Chapter I: Part 110. Food and Drug Administration, U.S. Department of Human Health and Services, Washington, DC, USA, pp. 214–223. FDA. 2002b. Hazard analysis and critical control point (HACCP) systems. In: 21 CFR Chapter I: Part 120. Food and Drug Administration, U.S. Department of Human Health and Services, Washington, DC, USA, pp. 259–268. FDA. 2003. Threshold of regulation for substances used in food-contact articles. In: 21 CFR Chapter I: Part 170.39. Food and Drug Administration, Department of Health and Human Services, Washington, DC, USA. Available at http://www.access.gpo.gov/ nara/cfr/waisidx 00/21cfr170 00.html (accessed October 2009).

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FDA. 2004. Indirect food additives: Polymers. In: 21 CFR Chapter I: Part 170. Food and Drug Administration, Department of Health and Human Services, Washington, DC, USA. Availabel at http://www.access.gpo.gov/nara/cfr/waisidx 04/21cfrv3 04.html (accessed October 2009). FDA. 2008a. Threshold of regulation for substances used in food-contact article. In: 21 CFR Chapter I: Part 174.6. Food and Drug Administration, Department of Health and Human Services, Washington, DC, USA, pp. 153–154. FDA. 2008b. Indirect food additives: Polymers. In: 21 CFR Chapter I: Part 177. Food and Drug Administration, Department of Health and Human Services, Washington, DC, USA. Available at http://www.access.gpo.gov/nara/cfr/waisidx 08/21cfr177 08.html (accessed October 2009). Fennema, R. O. 1985. Food Chemistry, 2nd ed. Marcel Dekker, New York, NY, USA. Hou, G. 2001. Oriental noodles. Adv. Food Nutri. Res. 43:141–193. International Organization for Standardization. 2008. ISO 9001:2008—Quality Management Systems. ISO, Geneva, Switzerland. IRMA (International Ramen Manufacturer Association). 2001. GMP for the manufacture of instant ramen noodle (2000). Circulation paper in technical committee meeting, the 3rd World Ramen Summit, Bangkok, Thailand. JAS (Japanese Agricultural Standard for Instant Noodles). 1986. Notification No. 1571, p. 5. Ng, A. 1996. A long shelf life for instant noodles. J. Asia Pacific Food Industry, 58–63. Thai Industrial Standard Institute. 2005. Instant Noodles Standard, TISI 271-2548, pp. 3–6. Ministry of Industry, Bangkok, Thailand. Thai FDA. 2000. Public Health Ministry Notification No. 210:2000 (B.E. 2543), Food Act B.E. 2522. Ministry of Public Health, Thailand. USDA. 1997. Guidebook for the Preparation of HACCP Plans. United States Department of Agriculture Food Safety and Inspection Service, Washington, DC, USA. Available at http://haccpalliance.org/alliance/haccpmodels/guidebook.pdf.

GLOSSARY OF TERMS Good Manufacturing Practices (GMP) These are standard guidelines set out by the FDA to ensure production of food is carried out in safe and quality-assuring processes so as to avoid contamination and ensure repeatability. Hazard Analysis and Critical Control Points (HACCP) This is a system in which points in a process are identified and controls are put in place to ensure that food safety hazards are eliminated. Each plant must have an HACCP plan for each class of product(s) produced. ISO 9001 This is the International Qrganization for Standardization definition of the Quality Management System that ensures the quality of a product. ISO 9001 is the model for Quality Assurance in design, development, production, installation, and servicing. ISO registration is just one of the building blocks for achieving world-class products. Quality This is a characteristic that a product or service must have. However, not all qualities are equal. Some are more important than others. The most important qualities are the ones that meet customer satisfaction.

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Quality Assurance (QA) This is defined as a set of activities whose purpose is to demonstrate that an entity meets all quality requirements. QA activities are carried out in order to inspire the confidence of both customers and managers, confidence that all quality requirements are being met. Quality Management System (QMS) QMS is defined as a set of policies, processes, and procedures required for planning and execution of products and/or services in the core business area of an organization. QMS integrates the various internal processes within the organization and intends to provide a process approach for project execution.

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CHAPTER 16

Rice and Starch-Based Noodles ZHAN-HUI LU and LILIA S. COLLADO

16.1. INTRODUCTION The term “Asian noodles” is used very broadly to describe noodle-like products from Eastern, Southeastern, or Pacific Asian countries that are made from wheat flour, rice flour, or other starch materials as the main structural ingredient (Lu and Nip 2006). Rice- and starch-based noodles differ from wheat noodles in many aspects. Wheat flour and water easily form dough through appropriate mixing and kneading techniques that facilitate sheeting and slitting into strips or strands to produce noodles. This unique ability to form cohesive, elastic, and extensible dough is attributed to gluten, the unique protein in wheat (Hoseney 1990a,b). In the absence of gluten in other starch-based raw materials, a pregelatinized starch binder must be added before the dough can be kneaded and extruded into threads or strings. An alternative process may involve the pouring of a starch batter onto a cloth or metal sheet followed by steaming, cooling, scraping, tempering, and slicing into thin strands. These products are known as nonwheat noodles or, more appropriately, as starch noodles. The characteristics of starch noodles are heavily dependent on the functional properties of the starch as it undergoes one or two heat treatments during processing (Mestres et al. 1988). The heat treatment may involve boiling or steaming that gelatinizes the starch, and the subsequent retrogradation sets the structure of the starch noodles (Tam et al. 2004). These products include noodle sheets, strips, and threads from the flour and starch of cereals, and legume and root-crop starches. Rice (Oryza sativa L.) supports more than half of the world population (FAO 2007a). The Food and Agriculture Organization (FAO) of the United Nations forecasts for global milled-rice production in 2007 stands at 426 million metric tons, which is 1% higher than 2006 (FAO 2007b). Rice is the staple food in most Asian countries and is consumed in most households on a daily basis. There is an increasing need for conveniently processed rice products to keep up with the fast pace of modern lifestyles. Rice noodles are the main processed food product made from rice. The Asian Noodles: Science, Technology, and Processing, Edited by Gary G. Hou C 2010 John Wiley & Sons, Inc. Copyright


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processing of rice into noodles provides benefits for both consumers and manufacturers. It has a large potential market because it is served not only as a snack food but also as a main dish. The processing technology of rice noodles is also simpler than the production of other starch-based noodles, such as mung bean and potato noodles that start with the extraction of starch. The whole polished rice kernel is utilized completely in the finished product and this confers certain nutritional benefits to consumers. Rice noodles generally have higher protein content than other starch noodles. It has also been demonstrated that rice noodles provide a lower glycemic blood index when eaten by diabetic patients (Panlasigui et al. 1991, 1992). This can be attributed to the fact that starch noodles are retrograded and are, therefore, a source of resistant starch (RS) (Collado et al. 2001). Rice noodles are made by soaking rice and then milling, cooking, and kneading it into dough and extruding it into threads or slicing the sheet into strips. The rice noodles may then be eaten fresh; otherwise, they are dried to extend their shelf life. Rice noodles are popularly known in China as mifen, or as mixian (thin threads) and hefen (flat strips). It is believed that noodles originated in China several thousand years ago but that the present-day form was developed within the last 2000 years. The Chinese character for fen (starch noodles) is written with mi (rice) on the left side as part of its written structure, indicating that it originated from rice. It is also believed that fen spread from China to neighboring countries. This is supported by terms with similar sounds in these countries (Lu and Nip 2006). A Chinese story explains how rice noodles were invented. In 214 BC, the first emperor of the Qin Dynasty, Qin Shi Huang, sent his army to conquer southern China, where rice was the staple food. Most of the soldiers were from northern China, where wheat noodles were the staple food. They could not adapt to daily rice meals, so a wise chef tried to make noodles from rice flour in the same way that wheat flour noodles were processed, but he failed. After several trials, he understood the problem and made modifications in the process. He invented a stone mortar with a hole drilled into the bottom. The wet rice dough was placed into the mortar and then pressed down by a wooden cork through a wooden lever. The threads were extruded from the hole and fell directly into the boiling water in a big kettle. The cooked noodles were perceived to be very similar to wheat noodles and were well accepted by the soldiers. Later, traditional Chinese spices and herbal medicines were added to the noodle soup to prevent diseases and cure illnesses. Eventually, the meat of dead war horses was also added to the soup and became the earliest Guilin mifen from Guangxi Province of China. It is still cooked and consumed today. This noodle soup became known in many other provinces and was called Guoqiao mixian (Guoqiao means “cross the river”) in Yunnan Province, Changde mifen (Changde is a place name) in Hunan Province, and hefen (or shahefen) in Shahe Town, Guangdong Province (Sun 2006). The processing method for rice noodles has not changed in the different provinces, but the different flavors of the soup in each of the provinces gave distinctive character to the otherwise bland-tasting noodles. Starch noodles are also produced from corn (Zea mays), buckwheat (Fagopyrum esculentum), mung beans (Vigna radiata), peas (Pisum sativum), sweet potatoes (Ipomea batatas), potatoes (Solanum tuberosum), canna (Canna edulis), arrowroot

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(Maranta arundinaceae), cassava (Manihot esculenta), and yam (Amorphophallus konjac). A portion of the substrate is gelatinized to serve as a binder for the dough or batter, which may then be extruded, sheeted, and further molded into the desired shape. Variations in processing are made to suit the substrate and intended product.

16.2. TYPES OF RICE AND STARCH-BASED NOODLES AND THEIR CONSUMPTION 16.2.1. Types of Rice The classification of rice varieties has changed through the years as shown in Table 16.1, but the most recent and recognized varieties are classified into four groups: Japonica, Javanica, Indica, and Scinica (Matsuzaki 1995). Only nonglutinous Indica rice is used to produce rice noodles due to its high amylose content, which ranges from 25% to 33% (Juliano 2005). Japonica rice is seldom used for rice noodle production because of its high stickiness but it may be partially blended with Indica rice to improve the noodle texture. 16.2.2. Types of Rice Noodles Rice noodles (mifen) are produced in different ways in different geographic locations. According to the preparation methods for making noodles of different dimensions, noodles can be classified into two groups, qiefen and zhafen, as shown in Figure 16.1 (Cheng 2000). Qie in Chinese means “slice into broad strips from a large and thin sheet” and measurements that range from 1 to 2 mm thick, 4 to 6 mm wide, and TABLE 16.1

Classification and Characteristics of Asian Rice

Researchers

Classification of Variety Groups

Kato and others (1928)

Japonica

Morinaga (1954)

Japonica

Javanica

Nakagawara (1978)

Japonica (Japanese Type)

Javanica Indica (Javanese Type) (Indian Type)

Short kernel Short, narrow Many Usually absent Difficult Short

Large kernel Long, wide Few Usually present Difficult Long

Indica Indica Scinica (Chinese Type)

Major Characteristics (Matsuo 1952) Shape of seed Shape of flag leaf Number of tillers Awn Shedding habit Panicle length Source: Matsuzaki (1995).

Long kernel Long, narrow Many Usually absent Easy Medium

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Hefen: shahefen Cut rice noodles (qiefen) Rice noodles (mifen)

Juanfen or changfen (with filling) Fermented rice noodles

Extruded rice noodles (zhafen)

FIGURE 16.1

Extrusion-cooked rice noodles

Types of rice noodles classified by noodle-shaping methods.

around 200 mm long. Zha means “extrude into threads” that have a round shape with a diameter ranging from 1 to 3 mm and a length ranging from 50 to 400 mm (Figure 16.2). Rice noodles are either fermented or nonfermented, but only zhafen is a typically fermented product. Fermented rice noodles are also called sour mifen because of their slight sour smell. This method for classifying rice noodles is favored by researchers because it indicates the processing technology of the products. Another convenient way to classify rice noodles in the industry is based on the moisture content and processing methods used that dictate the way products are packaged, distributed, prepared, cooked, and consumed (Figure 16.3). Traditionally, in China, rice noodles are also named after their place of origin such as Shahefen made in Shahe Town, Guangdong; Guilin mifen made in Gulin, Guangxi; Changde mifen from Changde City, Hunan; and Guoqiao mixian from Yunnan. In recent years, some manufacturers have begun to use corn starch or other starches combined with or in place of rice flour to make similar products, and still call them “rice noodles.” While they have similar properties, they do not have the same quality characteristics of original rice noodles (Lu and Nip 2006). 16.2.3. Types of Other Starch Noodles The variety of other starch noodles is presented in Table 16.2, which lists the crop from which substrate is produced, the equivalent English names, and the countries where they are produced. It must be pointed out that this table presents the typical starchnoodle products to which the authors had access. It can be noted that starch noodles are produced extensively not only in China but also in Malaysia, the Philippines,

FIGURE 16.2

Types of rice noodles.

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⎧Fresh (wet) rice noodles ⎪Dry rice noodles ⎪ ⎪⎪Frozen rice noodles Rice noodles (mifen) ⎨ ⎧Dried (Instant hefen, waved instant rice noodles etc.) ⎪ ⎪Instant rice noodles⎪⎨ ⎧Fermented rice noodles ⎪ ⎪Fresh (wet) ⎨ Nonfermented rice noodles ⎩ ⎩ ⎩⎪

FIGURE 16.3

Types of rice noodles based on moisture content and processing methods.

Vietnam, Thailand, Korea, and Japan. And there are many more from other countries such as India and Pakistan. Some of these starch noodles are shown in Figure 16.4. 16.3. RAW MATERIALS AND QUALITY REQUIREMENTS 16.3.1. Rice and Other Substrates Indica rice is commonly used because of its high amylose content, cheap price, and high yield. Indica rice is also classified as early Indica and late Indica according to their harvesting season (early Indica is harvested around August, and late Indica is harvested around October in southern China). Early Indica rice is particularly predominant as an early-season crop. Its inferior eating and cooking qualities account for its lower price in the market. TABLE 16.2

Types of Starch Noodles from Crops Other Than Rice

Crop

Equivalent English Names

Mung bean, pea

Green bean thread noodles Vermicelli Translucent noodles Silver noodles Shining noodles Glass, crystal noodles Jelly noodles

Corn Buckwheat

Corn starch noodles Buckwheat noodles

Canna Sweet potato, potato Cassava Arrowroot

Canna starch noodles Sweet potato noodles Tapioca sticks Arrowroot starch noodles

Yam

Yam noodles, devil’s tongue noodles

Source: Alden (2005).

Regional Names of Noodles (Country) Bai fun, Sai fun Fen szu, Fensi (Chinese) Soo hoon, Su boon (Cantonese) Tung boon (Indonesia) Sotanghon (Philippines) Woosen (Thailand) Ban tau (Vietnam) Harusame (Japan) Luglug (Philippines) Naeng myon (Korea) Soba (Japan) Mie´ˆ n, Mie´ˆ n dong (Vietnam) Dang myeun, Tang myun (Korea) Hu tieu bot loc (Vietnam) Bˆo.t dong, Bˆo.t ho`ang tinh, Bˆo.t m`ı tinh (Vietnam) Shirataki, sirataki, ito konnyaku (Japan)

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Sweet potato noodles

Corn sticks

Potato noodles

Green bean noodles

Instant rice ribbons

Instant corn noodles

FIGURE 16.4

Selected starch noodles.

The rice should be aged and stored for at least 9 months before being processed into noodles. Rice stored for more than 1 year is considered better. A small amount of late Indica rice or Japonica rice might be mixed with early Indica rice to adjust the texture of rice noodles, but this technique depends on the technician’s experience. The properties of rice starch, which account for around 85% of rice dry weight, strongly affect the quality of rice noodles. In the traditional cottage production, selection of rice raw material for rice noodle production is conducted by sensory evaluation of the cooked rice. The evaluation is based on acquired knowledge and experience of the processor. National quality standards of rice raw materials for industrial noodle production are not presently available.

16.3.1.1. Amylose Based on amylose content, rice is classified as waxy 0–2%, very low 2–9%, low 10–20%, intermediate 20–25%, and high >25%. Many of the long-grain varieties have higher amylose content than the short grain varieties. This difference in starch composition may largely be responsible for the well-known differences in cooking and eating quality of rice varieties. In China, Indica rice varieties with amylose

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content higher than 22%, and in Thailand, varieties with greater than 27% amylose content are used in the production of rice noodles (Tungtrakul 1998). Generally, highamylose rice varieties give high hardness, high tensile strength, and high consistency. These attributes and parameters are highly valued in noodle processing and packaging. However, this must be balanced by a low retrogradation rate and the ability to deform without breakage of finished noodle products. Generally, the best substrate for starch noodles is considered to be starch from legumes like mung beans, which normally have more than 30% amylose content. The eating and cooking qualities of mung bean starch noodles are usually the benchmark for high standards when working on experimental substrates and process parameters for starch noodles. Aside from high tensile strength and chewiness, bean noodles are also known for clarity and gloss not observed in other substrates. This characteristic is the reason they are referred to as transparent, glassy, or even invisible noodles. These types of noodles also have high tensile strength in both their raw and cooked forms. The pasting profile obtained from the amylograph that is characterized by high hot paste stability and high setback has been used by several researchers as screening criteria for evaluation of different substrates and starch modification processes for suitability in noodle production (Lii and Chang 1981; Chang and Lii 1987; Collado et al. 2001). Morphological properties, gel properties, and starch granular size were also found to correlate with the textural properties of the cooked starch noodles (Chen et al. 2002, 2003; Singh et al. 2002).

16.3.1.2. Protein Protein content is one of the indices of the nutritional value of milled rice. It can be an indirect indicator of cooking quality because its hydrophobic nature acts as barrier to inward water diffusion during cooking of the grain. The protein content of milled rice ranges from 5% to 15%. High-protein rice varieties have a harder texture than average-protein rice (Tungtrakul 1998). Low-protein rice varieties tend to be flavorful, tender, and cohesive (Ohtsubo et al. 1993). 16.3.1.3. Fat Acidity Fat acidity is one of the important rice quality indices that must be monitored during storage. Free fatty acids and volatiles increase during drying and storage due to hydrolytic and oxidative reactions. Free fatty acid content is higher in broken rice compared with milled rice (41.6–45.5 mg KOH/100 g), as determined by the improved Duncombe method (Ohtsubo et al. 1987). High-amylose milled rice contains a fat acidity value of 10.8–22.1 mg KOH/100 g. Broken rice that is known to produce good-quality rice noodles should be stored for 0.5–1 year (aged rice), and free fatty acid content should be less than 100 mg KOH/100 g. 16.3.1.4. Viscosity and Gel Consistency of Rice Flour Viscosity measurements of paste or gel made from milled rice flour or starch have long been in use for evaluating cooked rice texture (Perez and Juliano 1979). The Brabender Viscoamylography test has been the standard method for studying the pasting characteristics of starch and starch-based products. The Rapid Visco Analyzer (RVA) can provide similar information in a shorter time and with a smaller sample

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size. Flour from well-aged rice will have higher viscosity than freshly harvested milled rice. Hard gel is preferred for noodle making because hard gel rice will be more stable to overcooking and will retain its form. It has been suggested that the ideal starch base for preparing noodles is one with restricted swelling and a viscosity that remains constant or even increases during continued heating and shearing, indicative of good hot paste stability (Collado et al. 2001). Stability ratio (holding viscosity/peak viscosity) is correlated to noodle firmness, rehydration (cooked weight), and swelling volume of the starch (Collado and Corke 1997). Setback correlates negatively with noodle tensile strength and extensibility. Pasting temperature shows positive correlations with noodle hardness, tensile strength, and extensibility (Hormdok and Noomhorm 2007). 16.3.2. Water Quality Water quality has a noticeable effect on rice noodle texture. The pH value of the water should range from 6 to 6.5; water hardness must be less than 50 mg/kg; turbidity must be less than 3◦ ; and coliform count must be less than 3 cfu/100 g. In a study, we found higher contents of Mg and K elements in nonfermented rice flour (139.0 ± 0.6 mg/kg of Mg, 359.6 ± 2.1 mg/kg of K) than in fermented rice flour (50.9 ± 1.2 mg/kg, 75.5 ± 1.8 mg/kg) when preparing fermented rice noodles. It was also noticed that even 30 mM of Na+ could increase the differential scanning calorimetry (DSC) peak temperature by 1.5 ◦ C of 38% w/w slurry (unpublished data). According to the Hoffmeister series, Mg2+ has a much stronger effect than Na+ on the gelatinization inhibition, while K+ and Na+ have a similar effect (Levine and Slade 1991). Therefore, Mg2+ needs more careful consideration because it is common and abundant in many water resources used in production systems. Water hardness has been found to impact the stickiness of cooked noodles. The effects of cooking water composition on the stickiness of spaghetti have been studied and it was suggested that higher stickiness was obtained in spaghetti cooked in harder water and that mineral composition of the water played a role in influencing the cooking quality of spaghetti (Malcolmson and Matsuo 1993; Numfor et al. 1995). However, there were no studies on the effect of water quality on rice noodles found in the literature reviewed. Rice noodles made from neutral water (pH 7) have the highest retrogradation rate. At acidic conditions (pH 5.5), the retrogradation rate slows slightly. Noodles prepared from water with pH 9.5 have the lowest retrogradation rate. The texture of rice noodles prepared from alkaline water (pH 10) or acidic water (pH 5.5) is improved and the best tensile properties are achieved with acidic water (Sun 2006). 16.3.3. Additives

16.3.3.1. Modified Starches and Starches from Other Sources Acid-modified starch is used to inhibit the starch retrogradation of products during distribution and storage. Corn starch is usually used to increase hardness and decrease adhesiveness of rice noodles. It is attributed to the high amylose content of corn starch (34.4%). Edible canna (Canna edulis) is a perennial herb of the family Cannaceae, native to the Andean region of South America. This plant has large, starchy rhizomes and has been used traditionally as a staple food by the Andean people for more than

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4000 years (Thitipraphunkul et al. 2003). Edible canna starches have large granules and high amylose content, and they are used mostly for preparing transparent starch noodles. The noodles made from edible canna starch had excellent eating qualities such as high tensile strength, minimal swelling, and good transparency. Adding edible canna starch can improve the viscosity and pliability of hefen and increases chewiness as well as transparency. Its amylose content is around 29%. Potato starch can also improve the transparency and elasticity of hefen. The gelatinization temperature of potato starch is lower but its swelling power is 48 times that of corn starch. Potato starch also has slower retrogradation rate and is very effective in decreasing the percentage of broken noodles. Chufa (Cyperus esculentus L. var. sativus Boeck.) starch can be used to improve the chewiness of hefen. Composite starches are more effective than single starches for textural improvement of rice noodles. A recommended formula is 5% corn starch, 2% edible canna starch, 2% potato starch, and 1% Chufa starch. This formula can increase the tensile property of hefen and decrease the percentage of broken noodles and cooking loss significantly (Sun 2006).

16.3.3.2. Sodium Chloride Sodium chloride (NaCl) at 0.5–1% can increase the water-holding capacity of rice noodles and inhibit the growth of microorganisms that are present as contaminants (Sun 2006). 16.3.3.3. Phosphate Compounds Phosphate compounds (Na2 HPO4 ·12H2 O, NaH2 PO4 ·2H2 O, Na4 P2 O7 ·10H2 O, Na5 P3 O10 , (NaPO3 )6 , etc., 0.1–0.4%) can increase the soluble materials leaking out from starch granules, enhance the binding ability of starch molecules that tend to improve the tensile strength of noodles, and decrease the percentage of broken strands (Sun 2006). 16.3.3.4. Glycerin Monostearate Glycerin monostearate (0.3–0.5%) is an emulsifier often used to improve the texture of rice noodles and to inhibit the retrogradation of noodles, although the mechanism remains unclear (Sun 2006). 16.3.3.5. Plant Oil Plant oil (0.5–2%) is used as a coating on the surface of rice noodles. Peanut oil is used most often. In industrial production, the oil is used for lubrication of the machine and prevention of stickiness between noodle sticks. The use of oil makes the handling of rice noodles easier. Although adding oil cannot inhibit the starch retrogradation, the hardness of noodles tends to decrease when oil content is increased (Sun 2006).

16.4. EQUIPMENT, PROCESSING, AND PRODUCT QUALITY This section is divided into four subsections corresponding to (1) fresh rice noodles, (2) dry rice noodles, (3) frozen rice noodles, and (4) instant rice noodles. Fresh rice noodles are discussed first since their basic processing is common to all

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the other noodle types. Furthermore, for fresh noodles, the classification based on noodle dimension used is qiefen and zhafen because their processing represents the typical procedures and practices used in rice noodle manufacturing. Instant rice noodles are included in this section because of their emerging importance in the food industry. 16.4.1. Fresh Rice Noodles Considerable amounts of fresh rice noodles are produced for the retail market, restaurant trade, and household market, especially for breakfast. The noodles are usually produced at night and then distributed to markets before dawn. The shelf life of fresh rice noodles is less than 24 hours in summer and 48 hours in winter, so noodles are fresh and their mouthfeel is the best. Fresh rice noodles include qiefen (flat strip) and zhafen (round thread). The representative qiefen type of noodle is hefen (shahefen) and juanfen, which is a rolled-noodle type with fillings inside and will not be discussed in this chapter. Zhafen includes fermented rice noodles and extrusion-cooked rice noodles. Fermented rice noodles have a pliant, chewy texture while extrusion-cooked rice noodles have a chewy and firmer texture (Sun 2006).

16.4.1.1. Fresh Hefen Hefen (shahefen) are Cantonese oily rice-based noodles that are produced by preparing a rice slurry from Indica rice flour, followed by steaming a thin layer of the slurry on an oil-coated stainless tray or bamboo sheet. The gelatinized fen is then folded into layered slabs, followed by slicing of the slabs into strips. Oily rice-based hefen is very soft and smooth in texture (Lu and Nip 2006). The characteristics of hefen are as follows: 1. Easy to serve and smooth mouthfeel. Hefen is excellent for soup dishes in which hefen is just placed into boiling soup and it is ready to serve. It cooks fast because its thickness is less than 1 mm and it has a high moisture content of about 70%. It is also easier to digest because of its high degree of gelatinization. 2. Simple and low-cost processing method. The processing operations include washing, soaking, grinding, steaming, cooling, and slicing. Only a few pieces of equipment, a small workplace, and only one or two workers are required. 3. Various products can be derived from hefen. Small shrimps, ginger, and shallot can be added during production. The gelatinized slab can also be sliced into squares instead of strips and then used as wrappers to produce juanfen and changfen. Miscellaneous grain crops can also be used as raw materials to produce hefen. The shelf life of hefen is only 1–2 days. It can be dried to make dried hefen or instant hefen. The schematic diagram for fresh Cantonese hefen is presented in Figure 16.5. There is no special equipment for fresh hefen, and bigger pieces of equipment are used when production is larger scale.

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Rice (early Indica) ↓ Soak for 2–3 hours ↓ Grind to make pulp of 18 °Bé ↓ Apply a small amount of oil on canvas conveyor belt or stainless trays to coat the trays evenly ↓ Pour rice slurry to form a thin layer (about 1 mm thick) ↓ Steam the thin layers of rice slurry to gelatinize the starch (100–105 °C; steam pressure, 0.25–0.35 MPa; 100–120 s) ↓ Cool and slice the layered rice sheets into 1 cm wide strips

FIGURE 16.5 (2006).

Typical production scheme for fresh Cantonese oily hefen. Source: Sun

In some areas, the process procedure is modified a little. Rice is cleaned and steeped in water for 2–3 hours. Steeped rice is ground with water into a starch slurry and allowed to stand for 1–2 hours. A rotating drum touching the wet-milled rice slurry forms a film, which is then passed on to a stainless steel or cotton conveyor belt that carries the film into a steam tunnel for gelatinization. The gelatinized sheet with 1-mm thickness is air-dried on the moving conveyor belt, which is immersed in peanut oil. The grated conveyor belt is coated with peanut oil to reduce adhesion and give the noodles sheen and a peanut aroma. The noodles are then sliced into big squares and piled together. Then the noodle sheets are sliced into 1-inch wide noodle strips with a paper cutter for the big-strip type (Tungtrakul 1998).

16.4.1.2. Fermented Rice Noodles The processing of fermented rice noodles is the same as for traditional extruded rice noodles (nonfermented), except that the rice grains of nonfermented noodles are soaked for about 3 hours while fermented rice noodles are soaked for a longer time period of 2–6 days. Due to the short shelf life after production, quality standards and operation control depend heavily on the worker’s skill (Lu et al. 2003, 2005, 2007). The process is schematically presented in Figure 16.6. Among factories in southern China, fermentation is conducted in several steel tanks (volume 6–8 m3 , depth 2–2.5 m) in plants with a seasonally dependent ambient temperature of 10–30 ◦ C. Tanks are almost completely filled with milled rice grains and covered with a thin layer (8–15 cm) of water. The rice grains are statically fermented with or without a starter for 4–6 days and then wet-milled, steamed, and extruded into rice noodles (Lu et al. 2005). Nowadays, processing lines are designed to greatly improve the scale of production (Figure 16.7). An illustration of a workshop in a fermented rice noodle factory is shown in Figure 16.8. A schematic diagram of the processing line of fermented rice noodles is shown in Figure 16.9.

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Rice ← Add inocula ↓ ↑ Soak Inocula preservation ↓ ↑ Fermentation → Extract of inocula ↓ Wash and de-sand ↓ Grind ← adding left-over rice noodles ↓ Pour rice slurry on a canvas conveyor belt and steam in a steam tunnel (about 75% of degree of gelatinization) ↓ Extrude the steamed sheet into threads ↓ Cook in boiling water ↓ Steam threads (over 90% of degree of gelatinization) ↓ Wash and cool down ↓ Slice to certain length ↓ Final products

FIGURE 16.6 (2006).

Typical production scheme for fresh fermented rice noodles. Source: Sun

FIGURE 16.7

Processing line of fermented rice noodles.

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FIGURE 16.8

405

An illustration of a workshop for fermented rice noodles.

In Thailand, fermented rice noodles are called khanom jeen. Rice is cleaned and steeped in water for 2–3 days. Steeped rice is washed many times and ground with water. Water from the starch slurry is removed by draining in a cheesecloth bag or by filtration using a filter press. The starch cake is partially gelatinized by steaming. The gelatinized cake and raw starch cake are kneaded in a screw kneader. The starch ball is extruded through a die into boiling water, and noodles float when cooked. The

FIGURE 16.9

Processing line for fermented rice noodle. Source: Sun (2006).

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TABLE 16.3 Temperature and Duration of Soaking and Fermentation in Producing Fermented Rice Noodles Season ◦

Initial water temperature ( C) Soaking temperature (◦ C) Soaking time (days)

Winter

Spring/Autumn

42–45

30–35

<10 5

10–25 4

Summer 20–30 or room temperature 25–35 3

Source: Sun (2006).

cooked noodles are immediately cooled with water. The fermented rice noodles are sold fresh (Tungtrakul 1998).

Descriptions of Processing Technology fermentation Rice is soaked in tap water (1:1.4 w/w rice:water) and fermented at room temperature for 3–4 days in summer and 5–6 days in winter. Inoculum comes from the sinks, which contain supernatant fermented over 2 days. Soaking temperature affects the duration of soaking time and may be varied depending on the season of the year (Table 16.3). When warm water is used, fermentation duration can be shortened to 1–2 days in summer and 3–4 days in winter. However, it has been observed that fermentation in cold water is better because of the development of pleasant flavor and aroma. Insufficient fermentation affects the chewiness of noodles, whereas overfermentation normally causes development of off-flavor noodles. At the end of fermentation, the pH value of the viscous supernatant is around 4.1 and the rice grains are easily crushed with the fingers (Figure 16.10). The surfaces of the rice grains are then washed thoroughly with tap water to remove adhering foreign matter. adding leftover rice noodles Leftover or unsold rice noodles are used to improve the texture of fermented rice noodles. The leftover rice noodles are soaked for 1–2 days, sliced into short sticks, and mixed with the fermented rice grains before grinding. About 30% of leftover rice noodles are added in Guilin mifen, and 10–20% are added in Changde mifen. The texture of Guilin mifen is a little softer than the latter. The mechanism of improvement is not fully understood. It may serve as a binder like pregelatinized starch or texture improver. grinding The slurry should be fine enough to pass through an 80-mesh screen. In practice, a technician places a drop of slurry on his/her back of hand and touches it with the other fingers to determine if it has a sandy feeling or not. The moisture content of the slurry is maintained within the range of 50–55%. A frequently used grinder is shown in Figure 16.11. A schematic diagram of the thread-shaping extruder is shown in Figure 16.12. mixing and spreading the slurry on a canvas conveyor belt and steaming to form a sheet The slurry is mixed to prevent sedimentation and the homogeneous slurry leaks out from a narrow gap of the slurry container to a canvas

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FIGURE 16.10 Fermentation sinks and foams on surface of fermented supernatant (rice grains are sticky and easy to crush).

Grinding section

FIGURE 16.11

Grinder.

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FIGURE 16.12 Schematic diagram of thread-shaping extruder: (1) motor, (2) small strap wheel, (3) strap, (4) big strap wheel, (5) flange, (6) jacket, (7) press bearing, (8) vertical bearing, (9) feed inlet, (10) feed tank, (11) screw, (12) cooling set, (13) water outlet, (14) block, (15) sealing, (16) square plate, (17) square aperture, (18) bolt, (19) screw edge, (20) water inlet, (21) screw sealing, (22) bolt, (23) sealing, and (24) stand. Source: Sun (2006).

conveyor belt and forms a thin layer (2 mm). The conveyor belt goes into a steaming tunnel and the film is steamed to form a rice sheet. Steam pressure is 0.2–0.3 MPa, steaming time is 50–100 s, and the temperature is around 92–95 ◦ C. The degree of gelatinization of the rice sheet is about 70–80%. extruding the sheet into boiling water and cooking The apertures on the screen are the symbol for diameter, ø 1.5–1.7 mm. The extruding pressure should be controlled to prevent noodle expansion. The threads fall down into the boiling water and cook for 20 seconds at a temperature above 95 ◦ C. A photo of the extruding and cooking process is shown in Figure 16.13. steaming of noodles The threads are drawn out from the boiling water sink and steamed again in another steam tunnel for full gelatinization. Steam pressure is 0.1–0.2 MPa and the noodles are cooked at 100 ± 2 ◦ C for 2 minutes more. washing to cool The noodles must be cooled down immediately in cold tap water after steaming, and continuously washed for around 18 minutes (Figure 16.14). The moisture of the final products is 63–68%. The yield of rice noodles is more than 225%. The finished product is presented in Figure 16.15.

16.4.1.3. Extrusion-Cooked Rice Noodles This type of rice noodles needs a special extruder with a screw designed to perform two functions so that the rice dough is mixed and gelatinized inside the

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FIGURE 16.13

Extruding the threads into boiling water.

FIGURE 16.14

Steamed threads are cooled in tap water.

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FIGURE 16.15

Fermented rice noodle products.

extruder before threads are formed (Figure 16.16). Although early Indica rice is mainly used for the production of rice noodles, Japonica rice, corn starch, or potato starch is normally added to improve the texture of the noodles. The general production flow chart of extrusion-cooked rice noodles is presented in Figure 16.17.

18

19 1

17

2

16 15 3

14 13 12 11

10

9

8

7

6

5

4

FIGURE 16.16 Diagram of an extrusion-cooking extruder: (1) mixing tank, (2) driving mechanics, (3) motor, (4) feeding screw, (5) feeding canister, (6) joint, (7) pre-gelatinizing screw jacket, (8) pre-gelatinizing screw, (9) valve, (10) sampling valve, (11) noodle outlet, (12) extruder screw, (13) extruder jacket, (14) cooking section, (15) heating set, (16) valve, (17) feed inlet, (18) motor, (19) reducer. Source: Sun (2006).

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Rice (early Indica) ↓ Soak at room temperature for 2–3 h ↓ Grind to pass through an 80-mesh screen ↓ Mix into dough with 38–40% moisture content, some additives may be added into the water at this step ↓ Gelatinize the dough and make threads with an extruder ↓ Slice and cool with fans ↓ Keep the noodles in a closed room for 5–12 h to increase pliability and make separation of threads easier in the next step ↓ Wash in water and separate the bound threads ↓ Cook in boiling water (90–95 °C, 15 min) to further gelatinize the noodles ↓ Final products

FIGURE 16.17 (2006).

Generalized production scheme for extruded rice noodles. Source: Sun

16.4.2. Dry Rice Noodles The main advantages of dehydrated products are stability and ease of handling during transport. There are two main types of dry rice noodles: extrusion-cooked dry rice noodles and waved rice noodles.

16.4.2.1. Extrusion-Cooked Dry Rice Noodles (Straight Strip) This kind of rice noodles is dried and sliced into straight strips, and then wrapped in paper in a way similar to dried wheat noodles. They have a shelf life of more than 1 year, so they can be distributed over long distances. Therefore, this is the main type of rice noodles sold in the international markets. The general production flow chart is presented in Figure 16.18. In Thailand, the process procedure is modified. Rice is cleaned and steeped in water for 2–3 hours. Steeped rice is ground with water into a slurry and left resting for 1–2 hours. The starch slurry is drained in a cheesecloth bag. The starch cake is partially gelatinized by steaming and then kneaded and extruded by a hydraulic press into vermicelli. The vermicelli is hung on racks in an oven for drying until the moisture content is about 13% (Tungtrakul 1998). 16.4.2.2. Waved Rice Noodles This kind of product was previously listed as instant rice noodles but has been reclassified because of its poor rehydration and requirement of 5–10 minutes cooking time. The general process flow chart for waved rice noodles is presented in Figure 16.19. A waved rice noodle product is shown in Figure 16.20. The processing of

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Rice composite (early Indica/late Indica = 7:3) ↓ Wash and soak ↓ Grind the rice to pass through a 60-mesh screen (dry-milling) ↓ Mix into rice dough (moisture content 30–32%) ↓ Extrusion-cook and form threads ↓ Cool with fans after extruding ↓ First retrogradation (12–24 h) ↓ Steam threads to increase the degree of gelatinization (0.04MPa, 5–8 min) ↓ Second retrogradation (6–10 h) ↓ Wash and comb the threads to separate ↓ Dry to moisture content of 13–14% ↓ Slice to 18–20 cm sticks and shape the noodles into bundles or blocks ↓ Package (600–800 g per package) ↓ Final products

FIGURE 16.18 Sun (2006).

Generalized production flow chart for extruded dry rice noodles. Source:

waved rice noodles is one of the most fully automated among all rice noodle products (Figure 16.21). 16.4.3. Frozen Rice Noodles Fresh rice noodles are fast-frozen at −25 ◦ C. The water changes to fine ice crystals so quickly that the starch gel network is not damaged and the fresh noodle properties can be completely recovered after thawing. This can be attributed not only to the inhibition of starch retrogradation at −18 ◦ C but also to the inhibition of growth of microorganisms that may contaminate the product during storage. The product retains its best quality even after a shelf life of 1 year. The general process flow chart is presented in Figure 16.22. Figure 16.23 shows a diagram of the freezing tunnel for fast-frozen rice noodles. 16.4.4. Instant Rice Noodles For noodles, the term “instant” refers to convenience during consumption of product. Instant noodles are often sold with a complete seasoning packet and are ready to serve within 3–5 minutes of preparation. Good rehydration is the most important

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Rice Rice ↓ ↓ Wash and soak (0.5–2 h) Wash and soak (2–4 h) ↓ ↓ Dry-mill (60-mesh screen) Wet-mill ↓ ↓ Add water Vacuum de-water ↓ ↓ Adjust moisture content (32–34%) ↓ Mix into rice dough at controlled temperature ↓ Extrude to sheet ↓ Extrude to threads ↓ Form waves ↓ Steam (15–20 min) ↓ Slice (10 cm) ↓ Dry ↓ Pack (75 g per package) ↓ Final products

FIGURE 16.19 (2006).

Generalized production schemes for waved rice noodles. Source: Sun

consideration in instant noodles. This is attained in wheat instant noodles by the multipore structure formed during frying. In instant rice noodles, faster rehydration is achieved by the very thin diameter of noodles that ranges from 0.5 to 0.6 mm and by longer steaming time for complete gelatinization. Currently, there are three kinds of instant rice noodles: (a) instant rice vermicelli, (b) instant hefen, and (c), instant fresh rice noodles.

FIGURE 16.20

Waved rice noodles.

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FIGURE 16.21 Processing equipment for waved rice noodles: (1) elevator, (2) jet washing machine, (3) trough, (4) filter, (5) grinder, (6) steamer/mixer, (7) conveyor, (8) receiver, (9) extruder, (10) shaping equipment, (11) steamer, (12) cutter, (13) dryer, (14) sheet extruder, (15) soaking tank, (16) dryer, (17) cooler, (18) packaging machine, and (19) conveyor. Source: Sun (2006).

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Fresh rice noodles ↓ Slice (30–40 cm) ↓ Chill in cold water (0–10 °C) ↓ Weigh (150–200 g per package) ↓ Fast-frozen by liquid nitrogen (–35 to –25 °C, 10–30 min) ↓ Coat with ice for easy separation ↓ Package at < –5 °C ↓ Cold storage (–21 to –18 °C, around 95% of relative humidity)

FIGURE 16.22 (2006).

Generalized production scheme for fast-frozen rice noodles. Source: Sun

16.4.4.1. Instant Rice Vermicelli Instant rice vermicelli is classified into two categories, extrusion-cooked instant rice vermicelli and fermented instant rice vermicelli. The general process flow charts for extrusion-cooked and fermented instant rice vermicelli are shown in Figures 16.24 and 16.25, respectively. The traditional drying method for instant rice vermicelli is similar to that of instant wheat noodles. The noodles are exposed to different temperatures, humidity, and time combinations for different functions and stages. Noodles are conditioned for 30 minutes at 30 ◦ C and 70% RH, sweated for 80 minutes at 40 ◦ C and 85% RH, dried for 50 minutes at 50 ◦ C and 85% RH, and then the shape is finalized for 40 minutes at 40 ◦ C and 75% RH. Then the noodles are finished at a low temperature (temperature, 30 ◦ C; humidity, 60%; 70 minutes). This method has proved to decrease the ratio

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Freeze tunnel for fast-frozen rice noodles. Source: Sun (2006).

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Rice (early Indica) ↓ Wash (10–20 min) ↓ Soak for 6–8 hours depending on seasons, final moisture content 26–28% ↓ Grind with water to pass through a 50-mesh screen ↓ De-water to 38–40% moisture content and mix with other ingredients (potato starch, corn starch, etc.) ↓ Extrusion-cook and extrude to vermicelli with a single-screw extruder ↓ Cool and slice ↓ Retrogradation (4–12 h depending on season) ↓ Steam to fully gelatinize ↓ Dry to moisture content less than 13% ↓ Package with soup pouches ↓ Final product

FIGURE 16.24 Generalized production scheme for extrusion-cooked instant rice vermicelli. Source: Sun (2006).

of broken noodles but is time consuming (4–5 hours). An alternative method is to remove the surface water on the noodles before drying in hot air to finalize the noodle shape and to dry out the moisture inside the noodles using a microwave. This was found to improve the rehydration property of noodles during cooking and to decrease both dried noodle breakage and surface checking.

Rice (early Indica) ↓ Soak and ferment ↓ Grind to slurry ↓ Pour rice slurry on a canvas conveyor belt and steam in a steam tunnel (about 75% of degree of gelatinization) ↓ Extrude into noodles ↓ Steam the noodles (over 90% of degree of gelatinization) ↓ Wash and cool ↓ Dry and package ↓ Final product

FIGURE 16.25 Generalized production scheme for traditional fermented instant rice vermicelli. Source: Sun (2006).

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16.4.4.2. Instant Hefen The rehydration property of instant hefen is similar to the fried instant wheat noodles. Hefen is ready to eat after being soaked in boiling water for 2–3 minutes. The thickness of instant hefen is only 0.6–0.8 mm. The slurry used for instant hefen has a moisture content of 70% and it is cooked completely with a high degree of gelatinization. The best product is obtained from rice with amylose content of about 19%. Late Indica rice is the best rice variety used but a small amount of Japonica rice is often added to improve quality. Recently, corn starch, Konjak flour, modified starch, and potato starch have been added to improve appearance, mouthfeel, and texture of instant hefen. A generalized production scheme for instant hefen is presented in Figure 16.26. Slicing sheets manually is very labor intensive and produces inferior products during production. Automatic slicing machines are now being used along with continuous retrogradation machines, which have made it easier to handle sticky noodles. Nowadays, these two pieces of equipment are often installed in the processing line of

Rice wash and soak (1.5–2 h in summer and 2.5–3.5 h in winter) ↓ Coarse grind ← add gelatinized paste Fine grind (pass through a 50–60-mesh screen) ← dissolved Konjak solution ↓ Adjust slurry concentration (17–27 °Bé) ↓ Mix ↓ Spread slurry on canvas conveyor belt ↓ Steam (sheet thickness 0.5–0.7 mm) ↓ Coat oil ↓ Cool by strong wind and pre-dry to 35–38% of moisture content ↓ Retrogradation (1.5–2 h, 4 °C) ↓ Slice ↓ Weigh ↓ Load in molder to form a shape ↓ Dry to 13% of moisture content by hot air ↓ Package ↓ Final product

FIGURE 16.26

Generalized production scheme for instant hefen. Source: Sun (2006).

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hefen. Due to moisture variations in different parts of the sheet, the hefen strips often get entangled and are also not completely homogeneous in thickness. Consequently, automatic weighing for accurate packaging is always a problem. The schematic diagram of the processing equipment for instant hefen is presented in Figure 16.27.

16.4.4.3. Instant Fresh Rice Noodles Fresh rice noodles are a popular breakfast in South Asia and China. Because of their short shelf life and fast retrogradation rate, the producers usually make fresh rice noodles near local markets or sell the products next to their workplaces. Fresh rice noodle production is often done in small-scale operations and is labor intensive. Restaurants located far from processors are forced to cook dried products that lack the sensory attributes of fresh noodles. The scaling up of production and new development in the preservation technology for producing fresh-preserved instant rice noodles will resolve these problems. There are two types of instant fresh rice noodles—fermented fresh instant rice noodles and extrusion-cooked fresh instant rice noodles. Process Procedure of Fermented Fresh Instant Rice Noodles The processing procedure of fermented fresh instant rice noodles is shown as Figure 16.28. The early stage of processing is the same as fermented fresh rice noodles. Several processing breakthroughs, as explained below, have led to the commercialization of fresh instant noodles. spraying amylase solution After the steamed rice sheet is cooled by blowing strong, hot air (70 ◦ C), a certain concentration (0.1–0.4%) of β-amylase solution is sprayed on the sheet surface to inhibit starch retrogradation in the final noodle products during distribution and storage. preextruding

The enzyme in the rice sheet is mixed homogeneously.

incubation at constant temperature and relative humidity reaction is allowed to take place for 30 minutes at 70–100% of RH.

Enzymatic

extruding to threads A single screw extruder with an aperture size of the symbol for diameter, ø 1.2, 1.4, or 1.7 mm is used. cooking The threads come out from the extruder and fall down into boiling water and are cooked at 95–98 ◦ C for 10–20 seconds. steaming The cooked threads are steamed again for complete gelatinization. Steam pressure of 0.08–0.1 MPa is applied and steaming is done for 110–180 seconds. slicing weight.

Noodles are sliced to a certain length (usually 40 cm) to achieve target

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FIGURE 16.27 Processing line of instant hefen: (1) elevator, (2) de-sanding trough, (3) soaking tank, (4) conveyor, (5) rice tank, (6) grinder, (7) vibrating screen, (8) steaming tunnel, (9) conveyor, (10) drum, (11) tank, (12) pre-dryer, (13) rack, (14) retrogradation set, (15) conveyor, (16) cutter, (17) weighing machine, (18) feeding machine, (19) molding machine, (20) dryer, (21) cooler, and (22) tank. Source: Sun (2006).

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Rice ← Add inocula ↓ ↑ soak Inocula preservation ↓ ↑ Fermentation → Extract of inocula ↓ Wash and de-sand ↓ Recovered rice noodles Grind ↓ Mix ← Add additives ↓ Spread the slurry ↓ Steam the sheet ↓ Cool by fans ↓ Spray amylase ↓ Pre-extrude ↓ Slice sheet ↓ Equilibrium ↓ Extrude to threads ↓ Cook in boiling water

Steam threads ↓ Slice ↓ Wash ↓ Acid solution soak ↓ Package ↓ Metal detection ↓ Sterilization ↓ Cool ↓ First check ↓ Storage for 6 days ↓ Second check ↓ Package with seasoning pouches ↓ Final products

FIGURE 16.28 Processing technology of traditional fermented fresh instant rice noodles. Source: Sun (2006).

washing in cold water The surfaces of steamed noodles will become very sticky and may stick together. High-pressure water is used to flush the threads and disperse them. acid soaking The pH value of noodles is lowered to 3.8–4.0 by soaking in a 1% lactic acid solution for 30–60 seconds to inhibit the growth of microorganisms during product distribution and storage. noodles packaging A retort pouch that can tolerate high pressures and temperatures (>100 ◦ C) is used. It is made of polyethylene or nylon. weight checking and metal checking

A metal detector is used for this purpose.

sterilization A package containing 150 g of noodles is sterilized (95 ± 2 ◦ C, 35–40 minutes). cooling

The sterilized rice noodles are cooled by fan to around 38 ◦ C.

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Rice (aged for 6 months to 1 year) ↓ De-sand and wash ↓ Soak ↓ Grind and pass through a 60-mesh screen ↓ Rice flour (or rice dough formed by wet-milling and vacuum de-watering) ↓ Mix with other ingredients and adjust the moisture ↓ Extrusion-cook starch and form threads ↓ Retrogradation (12–24 h) ↓ Cook (98 °C, 10–20 min) or steam (100–121 °C, 25–30 min) ↓ Wash in cold water (0–10 °C, 15–25 min) ↓ Acid soak (1.5–2% lactic acid solution, pH 3.8–4.0, 25–30 °C, 1–2 min) ↓ Package ↓ Sterilization (93–95 °C, 40 min) ↓ Cool and check ↓ Package with seasoning pouches ↓ Final products

FIGURE 16.29 Diagram of processing technology of extrusion-cooked fresh instant rice noodles. Source: Sun (2006).

storage and checking Before storage, the packages are checked for defects (malsealing, foreign matter, etc.). After storage at 37 ◦ C for 6–7 days, products are checked again for spoilage.

Process Procedure of Extrusion-Cooked Fresh Instant Rice Noodles The processing procedure of extrusion-cooked fresh instant rice noodles is shown in Figure 16.29. The equipment for extrusion-cooked fresh instant rice noodles is presented in Figure 16.30.

16.4.5. Product Quality Evaluation The quality standards of rice noodles are listed in Table 16.4 (fresh-type) and Table 16.5 (dry and instant type).

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FIGURE 16.30

Sterilization equipment for fresh instant rice noodles. Source: Sun (2006).

16.5. INFLUENCE OF PROCESSES ON FINISHED PRODUCT QUALITY 16.5.1. Factors Affecting Product Quality of Rice Noodles The producer has to consider production cost, environmental issues, consumer preference, and market competition as well as appropriate formulations and practices. This makes it very complicated to compare quality of different types of noodle products. Table 16.6 is a summary of the major factors that could affect the quality of rice noodles. In the manufacture of rice noodles, one or more of the following common procedures are applied, depending on the products.

16.5.2. Milling Methods for Rice Flour Dry-milled rice flours contain a higher proportion of large particles compared with flours obtained from wet-milling methods. Noodles prepared from wet-milled flour gave more acceptable textural properties with slightly higher smoothness and higher deformation. Wet-milled flour has significantly lower starch damage but exhibits a higher retrogradation property, which is believed to be undesirable in noodle processing. The coarse flour from dry-milling gives lower peak viscosity and lower final viscosity. This could be attributed to the delayed swelling of granules embedded in large endosperm chunks of coarse flours compared with the earlier onset of swelling for smaller chunks or damaged individual granules in finer flours. The noodles prepared from dry-milled flours had a lower retrogradation rate measured by the

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Quality Evaluation of Fresh-Type Rice Noodles Nonfermented Rice Noodles

Quality Attributes Physicochemical properties Moisture (%) Acidity (%) pH value Sensory properties Appearance Color Odor

Taste

Fermented Rice Noodles

60–70 — 6.0–8.0

65–70 0.12–0.18 3.7–4.1

Smooth surface, uniform strips or threads, no air bubbles inside noodles, no bound strips Milky white, shiny, and Fermented type is a little translucent whiter Rice aroma, no off-flavor Characteristic smell and aroma of fermented rice products, with a little acid smell Smooth, pliable, and Smooth mouthfeel, elastic chewy, no gritty and chewy mouthfeel

Cooking properties Cooking loss (%) Percentage of broken noodles (%) Hygienic standards Aerobic plate count (cfu/g) Coliform (cfu/100 g) Mold (cfu/g) Pathogenic microbes

<8 <9 <1000 ≤30 ≤150 No pathogenic microbes detected

Source: Sun (2006).

TABLE 16.5

Quality Evaluation of Dry-Type and Instant Rice Noodles

Quality Attributes Moisture (%) Rehydration property

Sensory properties Other attributes Source: Sun (2006).

Normal Dry-Type Rice Noodles

Instant Rice Noodles Dry Type

Fresh Type

≤14 65–70 After being boiled for 2–4 min or soaked in 3–5 min. of boiling water for 6–8 min, the noodles are rehydration time, chewy, elastic, and smooth; percentage of clear soup broken noodles is less than 20% After being cooked or rehydrated for the required time, the noodles are chewy, elastic, and smooth Same as the fresh type (see Table 16.4)

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TABLE 16.6 Group I

Group II

Group III

Factors Affecting Product Quality of Rice Noodles Ingredients Amylose/amylopectin ratio of rice flour used Water quality Amount of salt used Amount of coating oil used Types and amount of additional ingredients used Dough quality Rheology of dough Viscosity of slurry Processing conditions Mixing of ingredients Kneading of dough Slicing actions for dough or noodle strips Steaming temperature and duration Sheeting actions Extruding conditions Cooking conditions Drying of final product

Source: Lu and Nip (2006).

texture profile analysis (TPA) and tensile test. The improvement of dry-milled flour for making noodles should be done by hydrating dry flour before processing. Moreover, dry-milling eliminates the cost of removal of excess water and waste treatment (Tungtrakul 1998). 16.5.3. Effects of Extrusion on Rice Noodle Quality Extrusion speed and feeding speed are key parameters for producing high-quality extruded rice noodles. A feeding speed that is too slow overheats the dough, causes brown color, and forms air bubbles in the noodle structure, whereas a feeding speed that is too fast causes insufficient cooking, poor appearance, and low tensile strength. A high screw speed is preferred for greater production efficiency. Because it has a higher shear stress output that mixes the rice flour more homogeneously and produces more heat, starch will gelatinize completely. Mold aperture size, shape, and number of mold apertures also affect the texture of noodles. 16.5.4. Effects of Fermentation on Rice Noodle Quality Lu et al. (2003) found that protein, lipid, and ash content decreased in fermented rice flour whereas free fatty acid increased. Fermentation had little effect on the crystalline structure of rice starch, but the ratio of the crystalline to the amorphous regions increased. The gelatinization temperature and the RVA peak viscosity of rice flour

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decreased while the gelatinization enthalpy increased after fermentation. Fermented rice starch granules had slight superficial corrosion (Lu et al. 2005). The chemical analysis of fermented rice starch suggests that the partial hydrolysis of amylopectin occurred during the fermentation process (Lu et al. 2007). The mechanism of textural improvement of fermentation is not fully understood. In industrial production, insufficient fermentation causes poor texture with perceptible loss of chewiness, whereas overfermentation causes off-flavor in the noodles. It is claimed that the success of fermentation is still fully dependent on the worker’s experience. 16.5.5. Other Starch Noodles Since the wide variety of other starch noodles and their production are still considered niche markets, studies on their processing and quality considerations are rather limited. Consequently, the information presented in this section is not as extensive as that presented for rice noodles. In the preparation of buckwheat noodles, the most common process involves combining buckwheat flour and wheat flour and adding water, the amount of which is dependent on the protein content of the flour mixture. The flour is mixed with a circular motion with gradual addition of water. The binding capacity of the flour is greatly improved by using boiling water during the initial mixing stages, which gelatinizes the starch. The addition of hot water to the flour has been observed in many other products. In jelly noodles made from sweet potato and potato, a batter with appropriate flow characteristics is required to enable smooth application on a metal plate covered with canvas cloth to form sheets. Hot water is mixed into the moist starch by continuous stirring for the development of the right viscosity and consistency in the dough or batter. In starch noodles, smooth balls are loaded into an extruder where they are forced through a die with a specified opening that corresponds to the noodle diameter or a viscous batter may be poured onto a metal or canvas sheet for steaming (Figure 16.31). In the production of starch noodles, processes are employed to enhance retrogradation such as the application of low-temperature conditioning after the gelatinization of noodle strands or sheets. Retrogradation sets the noodle structure so that the noodles can withstand normal cooking temperatures in soups and stir-fried dishes. This happens as noodles are washed in water after cooking such as in the preparation of rice, mung bean, and sweet potato noodles. Subzero storage after cooking is a normal practice in mung bean noodle preparation. It is interesting to note that in China this conditioning step is attained naturally since processing of noodles is an annual activity done during the months of October and November when the temperature in Sichuan and Shandong drops to below zero at night. After the overnight conditioning, the noodles are separated and sun-dried, and the drying is further hastened by the relatively low humidity during this time of the year. In many production systems in Asia, favorable conditions have to be provided artificially through appropriately designed processing equipment and facilities to ensure consistent product quality.

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Mixing starch batter

Starch sheet conditioning

Steaming starch batter

Slicing noodles

FIGURE 16.31 Potato starch noodle production in Changchun, People’s Republic of China (Collado and Corke 2004).

Most starch noodles are traditionally air-dried under the sun but much of commercial production is now dried in mechanized driers that are part of a continuous process (Figure 16.32). In the production of jelly-sheet noodles from potato and sweet potato, the gelatinized sheet is scraped and moved onto a fine wire screen conveyor that leads to a heating cabinet, after which the sheet comes out ready for conditioning followed by slicing, drying, and packing (Collado and Corke 2004). In the preparation of Chinese dimsum wrappers from starches, boiling water is added to wheat and cassava starches to enable the formation of dough that can be formed into a ball and rolled thin into a circular sheet and used to enclose the filling; otherwise, the sheet breaks easily when folded. Dimsum wrappers are formed by carefully picking up the flattened, soft, pliable, and circular dough on which a tablespoon of filling is placed, folding the wrapper 3 to 5 times on one side of the circle, pinching it to keep the folds in place, and then sealing it tightly with another pinch. Steaming not only sets the wrapper shape but also cooks the vegetable and meat filling. For dried starch wrappers, the shape is attained when the thin starch batter is poured into a shaped mold, normally a round shallow container. Rice spring roll wrappers usually have a delicate weave design that is picked up from the bamboo

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Mixing dough

Extruding noodles

Conditioning noodles

Drying noodles

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FIGURE 16.32 Sweet potato starch noodles production in Pinyin County, Shandong, People’s Republic of China (Collado and Corke 2004).

tray on which the wrappers are molded and dried. A Vietnamese dish uses this rice paper as a wrapper for steamed or fried spring rolls.

16.6. CURRENT AND FUTURE RESEARCH TOPICS The processing of rice noodles is mostly done by small- and medium-scale enterprises. Many areas of quality improvement exist in commercial production. The following research is proposed for future studies. 16.6.1. Inhibition of Starch Retrogradation in Final Products Inhibition of starch retrogradation in starch-based foods is an unresolved issue in the food industry and deserves further study. Sun (2006) reported that β-amylase had a

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significant effect on the inhibition of starch retrogradation of fermented rice noodles. Further research on this subject will benefit the development of desirable sensory properties for instant starchy foods. 16.6.2. Mechanism of Fermentation Process Effects on Fermented Rice Noodles Lu et al. (2003, 2005, 2007) have conducted pioneering work on the effect of natural fermentation of whole rice grains on texture improvements of fermented rice noodles. More research is needed to understand the relationship between fermentation and physical properties of rice noodles. This will facilitate the setting of process standards for consistent product quality. The adaptation of fermentation technology to other starchy crops, such as maize and potatoes, could contribute to the added value of these food resources. 16.6.3. Effect of Starch Granule Structure Amylose content is now widely recognized as the most important determinant of rice noodle quality. However, there are also studies that show the granule structure and component, followed by the amount of leached-out amylose in the process, have significant effects on the rheological property of the starch during heating (Lii et al. 1996). It is suggested that the integrity of swollen starch granules is the major factor determining the rheological properties of a starch paste or gel (Tsai et al. 1997). Tsai et al. (1997) reported that the formation of gel structure was governed by the rigidity of swollen granules and that the hot-water soluble component could strengthen the elasticity of the starch gel or paste. Basic research on granule structure, molecular components of rice varieties, and their effects on physicochemical properties of products may lead to the development of quality indices for processing. 16.6.4. Starch Digestibility of Rice Noodles Starchy foods are known to differ in the rates at which they are digested and at which they elicit blood glucose and insulin responses. This has been attributed to numerous factors, including amylose content. Because of the linear structure of amylose, starch granules rich in amylose are thought to have more extensive hydrogen bonding and hence more crystallinity in their structure than starch granules with very little amylose. Consequently, they do not swell or gelatinize as readily upon cooking and, therefore, are digested more slowly and result in lower blood glucose and insulin responses than those with low amylose content. For this reason, the intake of high-amylose food, such as rice noodles, has been considered more desirable for individuals with impaired carbohydrate and lipid metabolism. However, research on blood glucose and insulin responses to rice with similar chemical composition but different amylose content has shown conflicting results (Panlasigui et al. 1991, 1992). This indicates that amylose content alone may not be a good predictor of starch digestion rate and

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blood glucose and insulin response to rice; the physicochemical properties of the starch may also exert an influence. Rice noodles usually are produced from highamylose rice varieties (>28%). We think rice noodles should be an ideal material to elucidate the effect of physicochemical properties of rice starch on the starch digestibility. Starch noodles not only provide an alternative to wheat-based noodles for celiac patients but are now considered a source of dietary fiber from retrograded starch now recognized as a form of resistant starch. Other forms of enzyme-resistant starches include physically inaccessible starch, such as starch that is locked in plant cells, and the native granular starch in foods containing uncooked starch, chemically and thermally modified starches, and the indigestible starch fraction (Eerlingen et al. 1993) formed after heat-moisture treatment of starch such as those formed when starch noodles are produced. Retrograded starch is left undigested until it is fermented in the large intestine. In the past, retrograded amylose is considered to be nonnutritive; however, it has been demonstrated that amylases gradually degrade the structure. Glucose and oligosaccharides are released from retrograded starch over an extended period through the normal digestive process (Wolever and Jenkins 1985). The low digestibility and low glycemic response from noodles imply that these foods may have health benefits for both normal and diabetic individuals through sustained energy level and prolonged satiety. 16.6.5. Environmental Considerations Wet-milling is still a traditional process in the production of rice pulp or rice flour with a fine flour particle size; however, the large quantity of wastewater is a big environmental problem. An emerging process involves the use of dry-milling to minimize the liquid waste disposal problem. It should be noted that dry-milled rice flour is not the same as wet-milled rice flour, and the quality of the final product is perceived to be of lower organoleptic quality as compared to noodles produced from wet-milled flour. Wet-milled rice flour produces noodles with a smoother texture. Studies on techniques to improve the quality of noodles made from dry-milled rice flour are worth undertaking because the consequent lesser impact on the environment presents long-term benefit for the food company.

16.7. SUMMARY The origin, history, current status, and developing trends of rice and starch-based noodles are presented in this chapter. The processing technology, processing parameters, and equipment of fresh (wet) rice noodles, fermented rice noodles, dry rice noodles, instant rice noodles, and other starch-based noodles are described in detail. Meanwhile, the formulas and additives used in the production of starch-based noodles are introduced. The information contained in this chapter is intended as a comprehensive reference guide for researchers, engineers, and other professionals who are interested in starch-based noodles.

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REFERENCES Alden, L. 2005. The Cook’s Thesaurus: Asian Noodles. Available at http://www.foodsubs. com/Noodles.html. Chang, S. M. and Lii, C. Y. 1987. Characterization of some tuber starches and their noodle quality. Acad. Sinica Int. Bull. Chem. 34:9–15. Chen, Z., Sagis, L., Legger, A., Linssen, J. P. H., Schols, H. A., and Voragen, A. G. J. 2002. Evaluation of starch noodles made from three typical Chinese sweet-potato starches. J. Food Sci. 67:3342–3347. Chen, Z., Schols, H. A., and Voragen, A. G. J. 2003. Physicochemical properties of starches obtained from three varieties of Chinese sweet potatoes. J. Food Sci. 68:431–437. Cheng, M.-H. 2000. Study on the evaluation systems and processing technology of rice noodle. Department of Food Science, China Agricultural University, Beijing, China. Collado, L. S. and Corke, H. 1997. Properties of starch noodles as affected by sweetpotato genotype. Cereal Chem. 74:182–187. Collado, L. S. and Corke, H. 2004. Noodles/starch. In: C. Wrigley, H. Corke and C. E. Walkes (eds.), Encyclopedia of Grain. Science. Vol. 11. Elsevier. San Diego, CA, pp. 293–304. Collado, L. S., Mabesa, L. B., Oates, C. G., and Corke, H. 2001. Bihon-type noodles from heat-moisture-treated sweet potato starch. J. Food Sci. 66:604–609. Eerlingen, R. C., Deceuninck, M., and Delcour, J. A. 1993. Enzyme-resistant starch. II. Influence of amylose chain length on resistant starch formation. Cereal Chem. 70:345–350. FAO. 2007a. Field food crops: rice. FAO Crop and Grassland Service (AGPC), Rome. FAO. 2007b. Crop prospects and food situation. In: Global Cereal Production Brief , No. 4, July 2007. FAO, Rome. Hormdok, R. and Noomhorm, A. 2007. Hydrothermal treatments of rice starch for improvement of rice noodle quality. LWT Food Sci. Technol. 40:1723–1731. Hoseney, R. C. 1990a. Wet milling. In: Principles of Science and Technology. American Association of Cereal Chemists, St. Paul, MN, USA, pp. 153–165. Hoseney, R. C. 1990b. Pasta and noodles. In: Principles of Science and Technology. American Association of Cereal Chemists, St. Paul, MN, USA, pp. 277–291. Juliano, B. O. 2005. Overview of rice and rice-based products, Proceedings of the World Rice Research Conference. In: K. Toriyama, K. L. Heong, and B. Hardy (eds.), Rice Is Life: Scientific Perspectives for the 21st Century. International Rice Research Institute and Japan International Research Center for Agricultural Sciences, Tokyo and Tsukuba, Japan, pp. 268–270. Levine, H. and Slade, L. 1991. Water Relationships in Foods. Plenum Press, New York, NY, USA. Lii, C. Y. and Chang, S. M. 1981. Characterization of red bean (Phaseoulus radiatus var aurea) starch and its noodle quality. J. Food Sci. 46:78–81. Lii, C. Y., Tsai, M. L., and Tseng, K. H. 1996. Effect of amylose content on the rheological property of rice starch. Cereal Chem. 73:415–420. Lu, S. and Nip, W.-K. 2006. Manufacture of Asian (Oriental) noodles. In: Y. H. Hui (ed.), Handbook of Food Science, Technology, and Engineering. Taylor & Francis, Boca Raton, FL, USA. Lu, Z.-H., Li, L.-T., Cao, W., Li, Z.-G., and Tatsumi, E. 2003. Influence of natural fermentation on physico-chemical characteristics of rice noodles. Int. J. Food Sci. Technol. 38:505–510.

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Lu, Z.-H., Li, L.-T., Min, W.-H., Wang, F., and Tatsumi, E. 2005. The effects of natural fermentation on the physical properties of rice flour and the rheological characteristics of rice noodles. Int. J. Food Sci. Technol. 40:985–992. Lu, Z.-H., Yuan, M.-L., Sasaki, T., Li, L.-T., and Kohyama, K. 2007. Rheological properties of fermented rice flour gel. Cereal Chem. 84(6):620–625. Malcolmson, L. J. and Matsuo, R. R. 1993. Effects of cooking water composition on stickiness and cooking loss of spaghetti. Cereal Chem. 70:272–275. Matsuzaki, A. 1995. Trends of breeding and varieties. In: A. Hosokawa (ed.), Rice Postharvest Technology. The Food Agency, Ministry of Agricultural, Forestry and Fisheries, Tokyo, Japan, p. 108. Mestres, C., Colonna, P., and Buleon, A. 1988. Characteristics of starch networks within rice flour noodles and mungbean starch vermicelli. J. Food Sci. 53:1809–1812. Numfor, F. A., Walter, W. M., Jr., and Schwartz, S. J. 1995. Physicochemical changes in cassava starch and flour associated with fermentation: Effect on textural properties. Starch 47:86–91. Ohtsubo, K., Kobayashi, A., and Shimizu, H. 1993. Quality evaluation of rice in Japan. Jpn. Agric. Res. Q. 27:95–101. Ohtsubo, K., Yanase, H., and Ishima, T. 1987. Colorimetric determination of fat acidity of rice—relation between quality changes of rice during storage and fat acidity determined by improved Duncombe method. Report Natl. Food Res. Inst. 51:59–65. Panlasigui, L. N., Thompson, L. U., Juliano, B. O., Perez, C. M., Yiu, S. H., and Greenberg, G. R. 1991. Rice varieties with similar amylose content differ in starch digestibility and glycemic response in humans. Am. J. Clin. Nutr. 54:871–877. Panlasigui, L. N., Thompson, L. U., Juliano, B. O., Perez, C. M., Jenkins, D. J. A., and Yiu, S. H. 1992. Extruded rice noodles: starch digestibility and glycemic response of healthy and diabetic subjects with different habitual diets. Nutr. Res. 12:1195–1204. Perez, C. M. and Juliano, B. O. 1979. Indicators of eating quality for non-waxy rices. Food Chem. 4:185–195. Singh, N., Singh, J., and Sodhi, N. S. 2002. Morphological, thermal, rheological and noodlemaking properties of potato and corn starch. J. Sci. Food and Agric. 82:1376–1383. Sun, Q.-J. 2006. Theory and Technology of Rice Noodle Processing [in Chinese]. China Light Industry Press, Beijing, China, pp. 71–129. Tam, L. M., Corke, H., Tan, W. T., Li, J., and Collado, L. S. 2004. Production of Bihon-type noodles from maize starch differing in amylose content. Cereal Chem. 81 (4):475–480. Thitipraphunkul, K., Uttapap, D., Piyachomkwan, K., and Takeda, Y. 2003. A comparative study of edible canna (Canna edulis) starch from different cultivars. Part I. Chemical composition and physicochemical properties. Carbohydrate Polymers 53:317–324. Tsai, M. L., Li, C. F., and Lii, C. Y. 1997. Effects of granular structures on the pasting behaviors of starches. Cereal Chem. 74:750–757. Tungtrakul, P. 1998. Quality and physicochemical properties of rice related to rice noodle. Report Natl. Food Res. Inst. 0:19. Wolever, T. M. S. and Jenkins, D. J. A. 1985. Application of glycemic index to mixed meals. Lancet. 2 (8461):944–944.

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Acid value (AV), 368, 372–373, 384 Active packaging, 176 Air classification, 68, 71 Air drying of noodles, 101, 106, 110, 112–116, 131–134, 187, 191, 222, 253–254, 264, 340–341, 343, 415–416, 427 Alkaline noodles, 3, 27, 29, 39, 46, 57–62, 64–67, 75–76, 87, 91–92, 106, 109, 116–117, 127, 161, 228, 230, 235, 237–240, 245, 252–255, 257, 262, 264, 268, 273, 276, 299, 302, 304, 317–320, 341 Alkaline salt (alkali), 92, 100, 102, 117, 214, 252–253 Amylopectin, 35, 91, 272–275, 317–319, 424–425 Amylose, 32, 35, 42, 58–59, 91, 245, 268, 272–278, 316–320, 323, 395, 397–401, 417, 424, 428–429 Antimicrobial packaging, 176 Antioxidative packaging, 176–177 Arabinoxylans, 234, 313, 316, 323 Asian noodles browning (discoloration), 29, 32, 48, 65, 68, 87, 91, 102, 109, 114, 117, 161, 228–238, 254, 257, 262, 267, 285–289, 293 classification, 3, 251–253, 402 in China, 3 in Japan, 3, 8, 29, 57–58, 61, 66–67, 106, 115–117, 125, 194–197, 252–258, 261, 263, 269, 382–383, 397 in Korea, 30, 61, 111, 116, 134, 214–217, 221–223, 254, 258, 263, 270, 319, 397 in Taiwan, 75–76, 117

quality characteristics, 253–255 types, 106–138, 192–223, 253–255 Boiled noodles parboiled alkaline noodles (hokkien noodles), 116–119, 254 flour quality requirements, 76, 117 processing, 117–119 quality characteristics, 117, 119 long life (LL) noodles quality characteristics, 122 pH adjustment, 120–121 processing, 119–122, 342 steam pasteurization, 121–122 Boiler requirements in noodle manufacturing, 338, 345 feed water quality, 346 Breeding for hard white wheat cultivar release, 27, 36, 38–39, 43, 46–49 molecular markers, 3, 9, 12–15, 18, 22, 26 parental selection, 36–37 quality tests, 40–49 quality traits, 9–10, 12, 27, 30–36, 39, 43–48 selection parameters, 39 Buckwheat noodle (soba), 116, 137, 394, 397, 425 Chaomein noodle equipment, 342–343 processing, 134 quality characteristics, 135 Chinese instant fried noodles formulation, 212 processing, pilot-scale laboratory, 212–213

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Chinese instant fried noodles (Continued ) sensory evaluation, 214 TPA textural analysis, 213 Chinese noodles, 2–4, 6, 8, 11, 20, 61, 66 Chinese raw white noodle characteristics, 29, 106, 108–109 formulation, 106, 192 processing, 106–108, 192–193 sensory evaluation, 193–194, 258 TPA texture analysis, 193 Chinese wet noodles formulation, 197 general description, 117 processing, 117–119, 187, 197–198 quality characteristics, 117 sensory evaluation, 199–200 TPA textural analysis, 199 Chukka-men noodles formula, 199 processing, pilot-scale laboratory, 200–201 sensory evaluation, 201–202, 257–258 TPA textural analysis, 201 Compressed air, 347, 354 Cooking loss of noodles, 62, 65–66, 105, 242, 262, 264, 401, 423 Critical control point (CCP), 376–379 Dried noodles drying methods, 114–115 equipment, 341 flour requirements, 76, 116 freeze-dried noodles, 135–137 packaging, 175 processing, 112–115, 221–222 quality characteristics, 115–116, 223, 254 rice noodles, 411–412 shelf life, 254 storage, 164, 166, 172 water activity, 160 Eating quality of noodles, 91, 108, 133, 211, 256–257, 268, 271–272, 386, 398. See also Sensory evaluation Eggs, 109–110, 209 Electricity, 347 Extensograph, 11, 19, 90, 270

Farinograph, 4, 11, 15, 19, 21, 67, 89–91 Fatty acids, 93–95, 276, 323, 382, 399, 424 Fen, 4, 394, 402. See also Starch noodles Flour ash, 11, 13, 44, 47–48, 60–62, 64, 66, 70, 76, 87, 91–92, 227, 303, 380 color, 11, 14–17, 33, 62, 65, 68, 71, 77, 86–88, 240 enzymes, 93, 230–231, 236–237, 267, 285, 303–304 falling number, 85, 88 grading, 92–93 granulation, 88, 101 protein, 29, 44, 60, 87, 92, 101, 117, 241, 263–269, 276, 303, 313, 320–322, 324 starch damage, 62, 65, 70, 184, 228, 235, 240–242, 244–245, 317–318, 325 Flour quality requirements Asian noodles, 91–92 alkaline noodles, 65, 76 Chinese noodles, 30, 76, 120 instant noodles, 76, 93 Japanese noodles, 76 Korean noodles, 30 particle size, 62, 91, 101, 184, 241, 245, 265–266, 317, 429 protein content, 60, 87, 92, 101, 241, 264–266, 268–269, 276–322 Flour swelling volume (FSV), 39, 42, 319 Flour tests color grade, 68, 86, 88 image analysis, 68, 70 Pekar test, 68–69, 86–88 specks, 68, 70–71 Freeze-dried noodles equipment, 136 limitations, 137–138 processing, 135–136 quality characteristics, 137 Fresh raw noodles formulation, 106 processing, 106–108 quality characteristics, 108–109 Frozen noodles equipment, 123, 343–344 packaging, 170–171, 175 physical changes, 124 processing, 122–124

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quality characteristics, 123–124 quality factors, 124 rice noodles, 412 Frying oil, 131, 368, 372–373, 381–383 Genes flour extraction rate, 32–33 gluten quality, 13–14, 22, 32, 34 grain color, 26, 31–33 grain hardness, 13–14, 22, 31–32 noodle texture, 14 protein content, 32–34 polyphenol oxidase (PPO), 12–14, 22, 32, 34–35, 290–291 starch quality, 14, 22, 32, 35, 58–59, 272–273, 318 yellow pigment, 12–14, 22 Gluten development, 100–102, 104, 110, 264–266 Good Manufacturing Practice (GMP), 331, 358, 367–374, 391 Grain hardness, 28, 43–44, 77 Hard white wheat breeding targets, 27–28 market potential, 27 noodle flour, 30 quality traits, 30–35 Hazard Analysis and Critical Control Points (HACCP), 366, 374–381, 391 Hefen, 394, 396–397, 401–403, 417–419 Hokkien noodles equipment, 341–342 formulation, 202 general description, 116 processing, 117–119, 203–204 quality characteristics, 117, 119, 254 sensory evaluation, 204–205 TPA textural analysis, 204 Image analysis (IA) of noodle sheet specks effect of flour refinement, 237 effect of frost damage, 240 effect of fusarium head blight (FHB), 240 effect of salt and alkaline salts, 237–238 effect of sprout damage, 239–240 effect of wheat varieties and wheat color, 239 speck counts, 236–240

435

Indonesia yellow alkaline noodles formulation, 206 processing, pilot-scale laboratory, 206–207 sensory evaluation, 207–208 TPA textural analysis, 207 Instant noodles chaomein, 134, 342–343 hefen, 417–418 fat content, 161–162, 271, 276, 321 flour quality, 59, 61, 66–67, 75–76, 269 marketing, 360 markets, 3, 57 microbiological tests, 386–387 processing, 100–106, 339–340 quality characteristics, 76, 92–93, 134–135, 255, 274, 383–386 packaging, 156, 158, 163, 172–174, 176–177, 387–389 rice noodles, 412–415, 418–421 rice vermicelli, 415–416 steamed and fried, 128–131, 187–188 steamed and air-dried, 131–134 water activity, 160 Intelligent packaging, 174, 178 Interaction of starch and protein noodle texture, 276–278, 323–324 Inventory control, 354–356 Japanese noodles, 66, 197, 383 Korean dried noodles formulation, 221 processing, pilot-scale laboratory, 221–222 sensory evaluation, 222–223 TPA textural analysis, 222 Korean instant fried noodles formulation, 214 processing, 215–216 sensory evaluation, 216–217 TPA textural analysis, 216 Laboratory evaluation of noodles color, 68, 191, 228–229, 236–240, 254, 257–258, 298–302, 368, 380–382 cooking time, 274–275 cooking water, 120, 400 cooking weight gain, 200, 205, 386

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Laboratory evaluation of noodles (Continued ) eating quality, 192–223, 256–259 pH value, 120, 161, 368, 400 processing, 183–223 texture, 191, 268–269 Laboratory manufacture of Asian noodles dough makeup, 184–185 dough mixing, 185 dough sheeting, 186–187 guidelines, 184–188 noodle preservation, 187–188 Laboratory noodle testing equipment, 188–192 protocols, 192–223 Lighting noodle plant, 337, 349 sensory evaluation facility, 228, 256, 352 Lipids, 116, 124, 145, 162, 165, 275, 277, 322–323 Long life (LL) noodles equipment, 342 general description, 116–117 new products, 135 processing, 119–122, 342 quality characteristics, 122 Maintenance plant facility, 353 machinery, 353–354 Marketing, 359–360 Materials requirements planning (MRP), 355 Microbiological tests instant noodles, 386–387 instant noodle soup seasonings, 151 facility, 352 Milling break release, 86 break rolls, 63–64, 86 control, 85–86 mill flow, 63, 78 mill streams analysis, 82–84 noodle flour, 60–68, 76–81 process, 63–65, 78–81 reduction rolls, 80 wheat tempering, 62–63, 77–78

Mixing of noodle dough, 100–102, 110, 184–186, 188–189, 192, 197, 200, 203, 206, 209, 212, 215, 218, 221, 263–265, 371, 425–427 Modified atmosphere packaging (MAP), 174–177 Molecular markers of noodle quality, 12–18, 22 Noodle aging, 106 Noodle color darkening mechanisms, 302–304 effect of alkaline salts, 65–66, 92, 117, 230, 238, 252, 299 effects of peroxidase, 230, 234–235 effect of polyphenol oxidase (PPO), 11, 29, 41–42, 46, 230–233, 262, 267, 285–287, 300–303 measurement, 46–47, 191, 193, 195, 198, 201, 203, 206, 209, 212, 215, 218, 221, 228–230, 298–300 Noodle flour quality flour extraction rate, 4–5, 33, 67, 70, 81, 230, 262, 302 mill stream selection, 65–68, 82–84, 92–95 particle size, 62, 184 protein content, 11, 27, 30, 58, 60, 67–68, 87, 91–92, 109, 117, 120, 264, 267–269, 278–279, 304, 425 specifications in Taiwan, 76, 93 specifications in Japan, 62, 66 starch damage, 62, 65, 70, 228, 242, 245, 317–318 starch pasting properties, 29–30, 35, 58–60 Noodle flour milling, 62–70, 76–81 Noodle microstructure, 316–317 Noodle plant factory construction and design, 333–337, 367, 369 internal structures and fittings, 336–337 inventory control, 354–356 layout, 334–336 lighting, 337 location and general requirements, 332–333 machinery and tool requirements, 337–344, 369

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maintenance programs, 353–354 marketing, 359 organizational structure and employee requirements, 356–359 quality assurance programs, 351–353 sanitary facilities and controls, 347–350, 369–371 utilities and services, 344–347 warehouse and storage facilities, 350–351 Noodle processing basic (primary) processing unit, 99–106, 337–338 dough development, 265 dough resting, 102, 265 dough sheet forming and compounding, 102, 371–372 dough sheet resting, 103, 186 frying, 188, 372 mixing, 5, 8, 100–102, 185, 371 mixer, 5, 100–101, 183, 185, 188–189, 300 mixing moisture, 100–102 noodle sheet reduction, 103–105 machine settings, 103 reduction ratios, 104 secondary processing unit, 99, 138, 339–344 slitting, 105, 187, 190, 383 steaming, 125–131, 134, 190, 216, 219, 340, 342–343, 372, 405, 408, 418–419, 426 temperature mixing water, 102 noodle dough, 102, 105, 371 waving, 105–106 Noodle texture. See also Texture measurement of noodles arabinoxylans, 323 instrumental methods, 48, 191–193, 196, 199, 201, 204, 207, 210, 213, 216, 219, 222, 240–245, 268–269, 314–316 lipids, 322–323 microstructure, 316–317 physical flour properties, 317–318 protein, 28–30, 34, 60, 92, 268–270, 279, 320–322

437

sensory methods, 8–10, 193–194, 196–197, 199–202, 204–205, 207–208, 210–211, 214, 216–217, 220, 222–223, 258, 314–316, 383 starch properties, 29, 45, 58–59, 91, 271–274, 277–279, 318–320, 393–394, 399–401 starch and protein interactions, 276–278, 323–324 Organizational structure of noodle plant, 356–359 Oxygen-scavenging packaging, 177–178 Packaging of noodles components, 158–159 equipment, 340–343 factors, 159–165 functions, 156–158 materials and containers, 165–174, 387–389 technologies, 174–178 Packaging materials and containers Asian noodles, 165–174, 387–389 properties, 162–165 safety, 389 Pentosans, 101, 265–266 Peroxidase assay method, 234 distribution in millstreams, 93–94, 235 noodle color, 230, 293, 303–304 Peroxide value (POV), 373, 384 Pest control, 348–350, 357 Plumbing, 345 Polyphenol oxidase (PPO) biochemistry and biology in plants, 287–288 biochemistry and biology in wheat, 288–290 distribution in millstreams, 231 effect on noodle color (darkening), 11, 29, 32, 35, 231, 262, 286–287, 302–304 genetics and markers in wheat, 12–14, 22, 32, 290–291 inhibitors, 288–289, 303 measurement methods, 41–42, 231–233, 293–298 phenolic substrates, 291–293

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Preharvest sprouting (PHS), 25–26 quantitive trait loci (QTL), 26 Protein of wheat flour, quantity and quality fat content of instant fried noodles, 265, 271 noodle cooking quality, 264, 268 noodle color, 267 noodle processing, 263–264, 266–267 noodle quality, 265 noodle texture, 265, 268–271, 279, 320–322 water absorption of noodle dough, 265–266 Puroindolines, 31, 277, 318 Quality assurance (QA), 351–353, 358–359, 363, 366–367, 390 Quality control (QC) functions, 366–367, 380 instrument and methods, 368 noodle process control, 371–374 tests, 380–387 Quality management system (QMS), 351–353, 363–366, 390, 392 Radio frequency identification (RFID) packaging, 158, 178 supply chain management, 355–356 system, 355 Rice amylose, 398–399 fat acidity, 399 protein, 399 types, 395 viscosity and gel consistency, 399–400 Rice noodles additives, 400–401 equipment and processing, 401–421 history, 394 milling methods, 422, 424 processing, 402–421 quality evaluation, 423–424 types, 395–396 Rice noodle quality evaluation methods, 423–424 extrusion, 424

fermentation, 424 influencing factors, 424 Seasonings, instant noodles components, 127, 141–147, 376 manufacturing, 148–152 packaging, 169–170, 388 quality specifications, 385, 387 spice quality, 147–148 Sensory evaluation of noodles facilities, 256, 352 panelists, 255–256 preparation, 255 scoring systems/methods, 8–9, 193–194, 196–197, 199, 202, 204–205, 207–208, 210–211, 214, 216–217, 220, 222–223, 256–259, 382–384, 398 types, 251–252 Sewage disposal, 345 Shelf life alkaline noodles (hokkien), 119 chaomein, 135 dry noodles, 75–76, 112, 254 extrusion-cooked dry rice noodles, 411 fermented rice noodles, 403 fresh noodles, 75, 109, 402, 418 frozen noodles, 170, 412 influencing factors, 159, 162–165, 168–170, 172, 174–177, 372–373, 390 instant noodles, 75–76, 255, 383 long life (LL) noodles, 116–117, 120–122, 342 steamed noodles, 125, 128 wonton wraps, 110 Starch noodles processing, 425–427 raw materials, 394 retrogradation, 427–428 starch digestibility, 428–429 starch granule structure, 428 types, 396–398 Starch properties (characteristics) cooking time of noodles, 116, 268, 274–275, 279 eating quality (textural properties) of noodles, 29–30, 35, 58–60, 271–274, 276, 279, 318–321

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Steamed noodles high-moisture, 125, 127 low-moisture, 125–127 quality characteristics, 127–128 Swelling power, 29, 35, 273, 276, 319, 324–325 Textural measurement of noodles firmness or hardness, 242–243 rheometry, 245 noodle thickness, 241 sample preparations, cooking time, 241 stickiness, 245 tensile tests, 245 TPA, 191–192, 244–245, 268–269 uniaxial texture analyzer, 245 Texture profile analysis (TPA), 191–192, 244–245, 268–269 Thailand egg noodles formulation, 209 processing, pilot-scale laboratory, 209–210 sensory evaluation, 210–211 TPA textural analysis, 210 Thailand instant fried noodles formulation, 217 processing, pilot-scale laboratory, 218–219 sensory evaluation, 220 TPA textural analysis, 219 Toxic materials, 350

439

Udon noodles flour specifications, 29, 76, 120 formulation, 194 processing, 195–196 sensory evaluation, 108, 196–197, 256 TPA texture analysis, 196 Vacuum mixing of noodle dough, 100–101 Waste management, 350 Water boiler feed water, 346 noodle manufacturing, 333 requirements, 344–345 rice noodles, 400 Water absorption during cooking, 120 noodle dough, 4–5, 47, 101, 235, 265–266 Water activity Asian noodles, 159, 161–162, 164, 172 growth of microorganisms in foods, 160, 267, 352 Waxy wheat, 59, 272–275, 277–278, 316, 318–320, 324 Wonton wraps formulation, 109 processing, 109–112 quality characteristics, 110, 112

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FIGURE 2.3 Variation in polyphenol oxidase (PPO) enzyme activity among early generation hard white wheat experimental breeding lines. Lines with low PPO activity, as indicated by a lack of color intensity of the solution, are desirable for end-use products due to reduced enzymatic browning over time in noodle products.

FIGURE 3.5 Pekar color test for flour slicks immersed in cathecol solution to emphasize polyphenol oxidase activity in flour.

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FIGURE 12.1 Yellow alkaline noodle color in two hard white wheat cultivars after 24 hours at room temperature (noodle sheets and cut noodles are uncooked). “ID377s” (right) produces high-quality noodles with low discoloration and yellow tones, while “Klasic” (left) has high PPO levels that contribute to darkening and the grey tones seen here.

FIGURE 12.3 PPO staining of the bran layer of wheat. Wheat kernel cross section of high PPO cultivar “Penawawa” incubated in 10 mM tyrosine. In lower right is a piece of bran that has been detached from the kernel and rotated 90◦ .

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Tyrosine

L-DOPA

Ferulic

Vanillic

Sinapic

Caffeic

Chlorogenic

Catechin

Protochatechuic Aldehyde

FIGURE 12.4 Phenolic staining of wheat flour. Phenolic compounds (1 mM) were applied in an alkaline kansui wetting solution using “Klasic” refined white flour. “Klasic” is a high PPO cultivar. Flour layers were dried in a polyacrylamide gel electrophoresis gel drier after reaction. The check sample was wetted with kansui containing no added phenolic.

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B

C

D

FIGURE 12.5 Stained kernels of low PPO cultivars, “ID377s” (A) and “Eltan” (B), and high PPO cultivars, “Madsen” (C) and “Penawawa” (D), incubated in 1 mM phenol for 2 hours at room temperature.

FIGURE 12.6 The l-DOPA whole-kernel assay using the AACC International Approved Method 22-85. Five kernels per tube were incubated in 1.5 mL of 10 mM l-DOPA for 1 hour on an end-over-end mixer before measuring color change (absorbance) at 475 nm.

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FIGURE 12.7 Change in solution color from three cultivars following the procedure described in Figure 6: near-zero PPO cultivar “ID580” (left), low PPO cultivar “ID377s” (middle), and high PPO cultivar “Klasic” (right).

Kernels

Bran

Flour

Penawawa

ID377s

FIGURE 12.8 The l-DOPA assay using the AACC International Approved Method 22-85. Comparisons using five whole kernels, 100 mg bran, and 100 mg refined white flour from high PPO cultivar “Penawawa” and low PPO cultivar “ID377s.” Samples were incubated in 1.5 mL of 10 mM l-DOPA for 1 hour and then centrifuged.

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FIGURE 12.9 Three variations on PPO assays using methods similar to the AACC International Approved Method 22-85 in which five kernels of the indicated wheat cultivar were incubated in 1.5 mL of 10 mM l-DOPA for 1 hour. (A) Kernels were incubated in 2-mL deep-well microtiter plates on a rotary shaker. (B) Kernels were incubated in 2-mL deep-well microtiter plates on an end-over-end shaker. (C) Kernels were incubated in 2-mL microcentrifuge tubes on an end-over-end shaker. Aliquots (0.2 mL) were transferred to a standard 96-well microtiter plate and absorbance at 490 nm was recorded using a microtiter plate reader. Three replicate samples from the standard microtiter plate are shown above each bar. Error bars represent standard deviations. Langdon durum bars are barely visible above the zero axis. A

B

FIGURE 12.10 Thin-layer flour assay. A 1-mm thick layer of flour was spread on filter paper, moistened from below, and incubated 24 hours at room temperature. (A) White flour from low PPO cultivar “Eltan” (left) and high PPO cultivar “Madsen” (right) shows that darkening is mainly confined to spots in this assay, which involves no mixing after wetting. (B) A 10% whole-meal flour was blended with 90% (w/w) white flour from “ID377s” before wetting. Darkening spots had lower intensity with 10% whole-meal flour from the low PPO cultivar “ID377s” (left) and greater intensity with 10% whole-meal flour from the high PPO cultivar “Klasic” (middle). Ascorbate (1000 ppm) effectively inhibited much but not all of the darkening from “Klasic” (right).

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FIGURE 16.20

Waved rice noodles.

Mixing starch batter

Steaming starch batter

Starch sheet conditioning

Slicing noodles

FIGURE 16.31 Potato starch noodle production in Changchun, People’s Republic of China (Collado and Corke 2004).

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Mixing dough

Extruding noodles

Conditioning noodles

Drying noodles

FIGURE 16.32 Sweet potato starch noodles production in Pinyin County, Shandong, People’s Republic of China (Collado and Corke 2004).

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