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

25

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

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

57

Hideki Okusu, Syunsuke Otsubo, and James Dexter

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

75

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

183

Gary G. Hou

9. Objective Evaluation of Noodles

227

David W. Hatcher

10. Sensory Evaluation of Noodles

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Bin Xiao Fu and Linda Malcolmson vii


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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

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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

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Gary G. Hou, Syunsuke Otsubo, Verónica Jiménez Montaño, and Julio González

15. Quality Assurance Programs for Instant Noodle Production

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Sumonrut Kamolchote, Toh Tian Seng, Julio González, 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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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 González, 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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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, Verónica Jiménez Montano, Leandro Valle No. 404., Col. Reforma, Toluca, Edo de Mexico. México. 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

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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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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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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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NOODLE QUALITY TESTING AND CULTIVAR DEVELOPMENT

5

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

10:9

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

P1: OTA/XYZ P2: ABC c01 JWBS030-Hou August 5, 2010 Printer Name: Sheridan Books

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

10:9

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


7


8

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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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9

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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11

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,


12

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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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13

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


14

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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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BREEDING FOR BETTER NOODLE QUALITY

15

(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


16

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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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BREEDING FOR BETTER NOODLE QUALITY

17

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

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

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-Cádiz 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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INTRODUCTION

27

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

29

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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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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31

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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35

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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37

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 (Peña 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 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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403

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

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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421

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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INFLUENCE OF PROCESSES ON FINISHED PRODUCT QUALITY

TABLE 16.4

423

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

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