Barley for Food and Health: Science, Technology, and Products

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β-GLUCAN: THE CHALLENGE OF BARLEY AS FOOD 149 total available carbohydrates present. A consistent decrease in sugar release was noted in the breads with the β-glucan fraction relative to the percent inclusion. The decrease in sugar release was believed to be relative to reduction in starch availability for degradation. The relationship of this phenomenon to earlier events in the dough starch hydration and pasting, as well as the presence of β-glucan-rich fraction in the bread, was unclear. Cleary et al. (2006) investigated the influence on bread baking of commercially prepared, purified β-glucan of high and low molecular weight. Yeast breads were prepared with 4.5 g of β-glucan per 100 g of bread. Breads from both treatments had stiffer dough and lower loaf volume, but the high-molecular-weight product had the stiffest dough and lowest loaf volume. Breads with both high- and low-molecular-weight β-glucan exhibited attenuated reducing sugar release during in vitro digestion. This observation is comparable to slow or “lente” carbohydrate digestion, which has significance in glycemic control (discussed in Chapter 8). The high-molecular-weight β-glucan was more susceptible than the low-molecular-weight β-glucan to destruction during bread baking, leading the authors to conclude that the low-molecular-weight product would be a more desirable bread ingredient. Electron micrographs of bread and in vitro digestion provided a comparison and understanding of the microstructure of the products. There are numerous potential nutritional benefits of extracted barley β-glucans in food systems. Hecker et al. (1998) demonstrated the use of purified β-glucan to increase soluble fiber in tortillas. Hallfrisch et al. (2003) evaluated Nu-trimX, abarleyβ-glucan isolate, to lower glucose and insulin responses in healthy men and women. Glucagel, (GraceLinc Ltd., Christ Church, New Zealand), a purified β-glucan isolate from barley, forms a gelatinous precipitate that is water soluble and thermoreversible (Morgan and Ofman 1998). Brennan and Cleary (2007) prepared bread using Glucagel at the 2.5 and 5% inclusion levels. The bread with 5% isolate had increased resistance to extension compared to the control, and reduced volume. In vitro digestion of the bread indicated a decrease in reducing sugar release only from the bread with the 5% addition. The possible reasons for the lack of effect in the 2.5% product are discussed, stressing the necessity for careful consideration of the molecular and structural character of food mixtures containing starch and fiber. Glucagel has also been used in dairy products not only to add fiber but also to improve texture and microstructure. Tudorica et al. (2004) added Glucagel at several graduated levels to cheese made with milk of three different fat levels. Increased levels of the β-glucan product in milk significantly decreased coagulation time and coagulum cutting time, and appeared to form a gel network to reinforce the casein network. The most advantageous results in cheese quality occurred in the lower-fat cheeses. This same team also incorporated β-glucan at the 0.5% level into yogurt at various fat levels, with very successful results (Brennan and Tudorica 2008). β-Glucan extracted from waxy hulless barley was used successfully as a fat replacer in reduced-fat breakfast sausage (Morin et al. 2004). Another soluble fiber gel, Ricetrim, is a hydrocolloidal composite made from rice bran and barley flour (Inglett et al. 2004). Ricetrim has unique viscoelastic behavior and has been used as a fat replacer
150 BARLEY FOOD PRODUCT RESEARCH AND DEVELOPMENT in various Thai dishes. A novel use for barley β-glucan is in edible films for food products, investigated by Tejinder (2003). The films were translucent and smooth and remained intact during immersion in water. Other barley concentrates currently on the market are Barliv, containing 70% β-glucan (Cargill, Inc., Minneapolis, Minnesota) and Cerogen, available in β-glucan content from 70 to 90% (Roxdale Foods Ltd., Auckland, New Zealand). YEAST BREADS MADE WITH BARLEY FLOUR The history of barley bread dates long before writing began, as noted in Chapter 1. With the advent of improved wheat flour during the nineteenth century, barley began to lose favor as a source of bread flour. In the United States, the earliest “food science” report available to these authors on inclusion of barley in bread was that of Harlan (1925), who stated that barley flour could be combined up to 20% with wheat flour without detriment to the quality of a loaf of yeast bread. Harlan stated further that up to 80% of barley flour could be incorporated into chemically leavened bread, and in both cases, barley flour darkens the color of the bread and alters the flavor. These facts are still accurate after over 80 years, and as a result, considerable research in recent years has focused on quality improvement of breads containing barley flour. Evaluating the effects of barley flour or barley components such as high-fiber fractions on the mechanical properties of bread dough is essential for predicting product success. Dissemination of this information will be useful for manufacturers seeking new raw materials for development of products with enhanced health benefits. The results of these studies provide insight into relationships between ingredient components, processing parameters, and evaluation of the end products. Over 40 years ago, Niffeneger (1964) milled Compana barley with a laboratory Bühler mill to produce barley flour. This researcher prepared yeast bread (and other products) from 100% barley flour, 75% barley flour and 25% all-purpose wheat flour, 50% each barley and wheat flour, and 100% wheat flour. Loaf volume decreased progressively with increased proportion of barley flour. Sensory testing indicated poor texture and flavor in the breads with the higher (75 and 100%) barley levels. It was concluded that variations in the milling process, such as refined sieving methods, and a different barley variety, as well as a lower proportion of barley flour, may have produced more acceptable bread. Kim and Lee (1977) produced bread from hulless barley flour combined with hard white wheat flour in a ratio of 30% barley to 70% wheat, and included additives of 1% glyceryl monostearate and 1% calcium stearyl lactylate. The appearance, taste, and texture of the bread were very similar to those qualities of standard bread made from 100% wheat flour. R. S. Bhatty of the University of Saskatchewan, Saskatoon, Canada was a pioneer in the milling and utilization of hulless barley in North America (Bhatty 1986). Two Canadian cultivars, Scout and Tupper, were roller-milled into bran, shorts, break flour, reduction flour, and clear flour. The break, reduction, and
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BARLEY FOR FOOD AND HEALTH Science,
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On a Seed “This was the goal of t
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Cover design by Jean Rose Johnston.
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CONTENTS Preface xiii 1 Barley Hist
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CONTENTS ix Infrared Processing, 12
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CONTENTS xi Asia, 221 Barley Mixed-
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xiv PREFACE In the concluding two c
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2 RELATIONSHIP OF HUMANS AND BARLEY
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10 RELATIONSHIP OF HUMANS AND BARLE
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2 Barley: Taxonomy, Morphology, and
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20 BARLEY: TAXONOMY, MORPHOLOGY, AN
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3 Barley Biotechnology: Breeding an
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34 BARLEY BIOTECHNOLOGY: BREEDING A
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4 Barley: Genetics and Nutrient Com
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58 BARLEY: GENETICS AND NUTRIENT CO
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96 BARLEY PROCESSING: METHODS AND P
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200 HEALTH BENEFITS OF BARLEY FOODS
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202 HEALTH BENEFITS OF BARLEY FOODS
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9 Current Status of Global Barley P
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206 CURRENT STATUS OF GLOBAL BARLEY
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208 CURRENT STATUS OF GLOBAL BARLEY
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10 Barley Foods: Selected Tradition
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212 BARLEY FOODS: SELECTED TRADITIO
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APPENDIX 1 Glossary: Botany and Pla
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APPENDIX 2 Glossary: Food and Nutri
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APPENDIX 3 Glossary: Barley Terms T
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APPENDIX 4 Equivalent Weights and M
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SOURCES OF BARLEY AND BARLEY PRODUC
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Rancho Cucamonga, CA 91730 Ph: 888-
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SOURCES OF BARLEY AND BARLEY PRODUC
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E-mail:Tony.Steeper@csiro.au Web: h
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BARLEY RESOURCE ORGANIZATIONS 241 P
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INDEX Air classification, 102, 122-
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INDEX 245 Meat and barley casserole
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