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

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WHOLE-GRAIN PROCESSING 99 increased in the pearlings up to about 30% pearling and then remained stable, while the starch level showed a continued increase with pearling up to 80%. In a pearling study reported by Pedersen et al. (1989), the hull and seed coat were in the first pearling fraction (11% of the total), the germ and aleurone made up the second pearling fraction (11 to 25% of the total), and the remaining 75% found in the third pearling fraction was composed primarily of the endosperm. Nutrient composition of the pearling fractions represented the component parts of the kernel from which the fractions originated. Sumner et al. (1985) compared the pearling characteristics of waxy and nonwaxy hulled and hulless barley at three extraction rates—high, medium, and low—resulting in yields of 84, 7l, and 56% pearl barley, respectively. Protein percentages were decreased in the pearl barley and increased in the pearlings at each successive extraction level, with opposite effects on the percentage of starch. Percentages of ash and fat were also decreased in the pearled barley with concomitant increases in the pearlings, and were highest in pearlings obtained from 71% extraction. This was indicative of the mineral and oil contents of the outer layers of the kernel and germ, respectively. Bhatty and Rossnagel (1998) compared the composition of 12 Canadian and seven Japanese barleys pearled to 55% extraction in a Satake mill. The Canadian barleys were hulless, whereas only two of the Japanese barleys were hulless. Both groups of cultivars responded to pearling in a similar manner, although differences were found in the ratio of protein and starch between the Canadian and Japanese barleys. Fiber type and level differed due to the presence of hull in some of the Japanese barleys. Protein, ash, and total dietary fiber (TDF) decreased in the pearled barley kernel compared to the whole-grain kernels, whereas starch level and extract viscosity increased. Soluble dietary fiber (SDF) and β-glucan levels were essentially the same in whole and pearl barley. The data of Bhatty and Rossnagel (1998) shown in Table 5.1 are representative of those reported in most pearling studies (Norman et al. 1965; Bach Knudsen and Eggum 1984; Sumner et al. 1985; Pedersen et al. 1989). In this study, three of the 12 Canadian barleys were waxy, which had the highest levels of SDF and β-glucans in the pearled kernels of all barleys, including the Japanese cultivars. Zheng et al. (2000) and Yeung and Vasanthan (2001) compared pearling characteristics of nonwaxy and waxy hulless barleys. In both of these studies, β-glucan levels in the pearled kernels of nonwaxy barley showed a sharp increase up to about 25% pearling, followed by a gradual decrease toward the center of the kernel. These data suggested highest concentrations of β-glucan in aleurone, subaleurone, and outer starchy endosperm of nonwaxy barley. In contrast, a gradual increase in β-glucans in the pearled kernels of waxy barley indicated a positive concentration gradient of these compounds toward the center of the kernel. These data and those of others confirm earlier reports, such as those of Ullrich et al. (1986) and Xue et al. (1997), concerning the positive relationship between the waxy gene and β-glucan levels in barley. Pearled barley and pearling by-products were obtained from two commercial stocks of hulled nonwaxy barley of English and Italian origin (Marconi et al. 2000). The barleys were pearled using an industrial process in five consecutive
100 BARLEY PROCESSING: METHODS AND PRODUCT COMPOSITION TABLE 5.1 Composition of Japanese and Canadian Whole Barley Kernels (WK) and Pearled Barley Kernels (PK) and Extract Viscosity, Dry Matter Basis Japanese Barley (n = 7) Canadian Barley (n = 12) Item Mean Range Mean Range Protein (g/100 g) WK 10.5 8.7–12.6 15.5 12.8–17.8 PK 6.6 5.8–8.1 9.0 8.1–10.2 Ash (g/100 g) WK 2.1 1.7–2.8 2.0 1.8–2.2 PK 0.6 0.5–0.6 0.6 0.5–0.6 Starch (g/100 g) WK 71.5 67.4–77.3 67.5 60.1–74.5 PK 88.7 83.6–91.2 81.4 69.1–87.6 TDF a (g/100 g) WK 16.9 13.6–21.0 12.9 11.0–16.6 PK 8.8 7.5–9.8 7.3 6.5–9.6 SDF b (g/100 g) WK 4.1 3.6–5.2 3.6 3.1–6.4 PK 3.9 2.5–5.0 3.4 2.3–6.8 βG c (g/100 g) WK 4.6 3.8–5.4 5.0 4.1–8.0 PK 4.7 3.5–5.6 4.9 3.9–7.7 Viscosity (cP) WK 9.0 2.9–32.9 20.0 7.1–469.0 PK 14.0 3.4–49.8 35.9 18.9–786.9 Source: Bhatty and Rossnagel (1998). a TDF, total dietary fiber. b SDF, soluble dietary fiber. c βG, β-glucan. steps, removing a total of 37 and 46% of the kernel weight of the English and Italian barleys, respectively. The first two pearling fractions, representing about 10% of the kernel weight, were very high in TDF and insoluble dietary fiber (IDF) and low in β-glucans, components that are representative of fiber and β-glucan levels in the hull. Protein concentration in the first fraction of both barleys was the lowest of the five, but increased in fractions 2 to 4 with a slight decrease in the final fraction. Pearling did not always affect the β-glucan content of pearl barley significantly, although a general trend was found of increased β-glucan levels with each pearling in both the English and Italian barley. These data are shown in Table 5.2. These results are somewhat in contrast to the data reported by Zheng et al. (2000) for nonwaxy barley, although the latter research was with hulless barley, which may react differently from hulled barley. Protein, fat, ash, fiber, and digestible carbohydrate (starch and sugars) levels in pearlings, and pearled barley obtained with the industrial pearling process, followed the pattern reported
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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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Page 65 and 66: 48 BARLEY BIOTECHNOLOGY: BREEDING A
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Page 151 and 152: 134 EVALUATION OF FOOD PRODUCT QUAL
Page 161 and 162: 7 Barley Food Product Research and
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Page 165 and 166: 148 BARLEY FOOD PRODUCT RESEARCH AN
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150 BARLEY FOOD PRODUCT RESEARCH AN
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8 Health Benefits of Barley Foods I
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180 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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