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

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GLYCEMIC RESPONSE TO CARBOHYDRATE CONSUMPTION 193 The University of Lund researchers subsequently reported some methodology improvements of the second-meal technique applied to the effect of a low-GI evening meal on glycemic response to the following morning breakfast meal (Granfeldt et al. 2006). This study calculated available carbohydrate load as total carbohydrates minus the indigestible components DF and RS. The evening meals varied in GI and/or indigestible carbohydrates, and consisted of pasta, barley kernels, and white wheat bread. Serving sizes were adjusted to correspond with the DF and RS content. The test evening meals were found to substantially reduce the GI and insulinemic index of white wheat bread eaten at the subsequent breakfast meal. Following this study, Nilsson et al. (2007) expanded the study design to include four different low-GI evening meals and a white bread control. Tests following the subsequent breakfast meal were expanded to include measurement of free fatty acid levels, and the markers of colonic fermentation SCFAs in blood and urine and expired H 2 . The after-breakfast glucose response was significantly lower following consumption of barley kernels the previous evening than after white bread or spaghetti with wheat bran. Breath H 2 excretion and plasma SCFAs were higher at breakfast when subjects had previously consumed barley, and FFAs were lower, in accordance with earlier reports. These results indicate that colonic fermentation of the specific indigestible carbohydrates present as well as low-GI features may both influence the improved glucose tolerance at breakfast. A follow-up study (Nilsson et al. 2007) was conducted to elucidate the mechanism of improved glucose tolerance at breakfast. Test evening meals consisted of high-GI white bread (WWB), WWB + barley + barley DF corresponding to the DF of barley kernels, low-GI spaghetti + barley DF, spaghetti + double amounts of barley DF (2*DF), spaghetti + oat DF, or whole-grain barley flour porridge. The rationale of the treatment containing spaghetti + double the barley DF (2*DF) was to mimic the DF content of the whole barley kernels in the earlier studies. At breakfast the morning after the test meals, blood glucose, insulin, SCFAs, FFAs and breath H 2 were measured. The most effective evening meal for lowering glucose response was spaghetti + 2*DF. This meal also resulted in the highest breath H 2 excretion. The glucose incremental AUC after breakfast was correlated positively with fasting FFAs, suggesting colonic fermentation as a modulator of glucose tolerance through a mechanism leading to suppressed FFA levels. This study demonstrated that the low GI of a food per se is not attributable to slow digestion and absorption of sufficient magnitude to induce overnight benefits. These researchers suggested the possibility that the presence of abundant fermentable fiber in a food may be a more reliable indicator of potential low glycemic responses. More recently (Nilsson et al. 2008), this group repeated the study using both boiled barley kernels and WWB + barley fiber + RS at an evening meal. At breakfast, glucose response was negatively correlated with colonic fermentation and GLP-1 and positively correlated with fasting FFA. The levels of the pro-inflammatory marker IL-6 were lower at breakfast, and fasting adiponectin was higher after the previous barley kernel evening meals. These results support their hypothesis of high fermentable fiber as the definitive factor in physiological responses in carbohydrate metabolism.
194 HEALTH BENEFITS OF BARLEY FOODS BENEFICIAL EFFECTS OF RESISTANT STARCH IN BARLEY ON THE INTESTINAL TRACT The indigestible fiber components of barley, especially β-glucan,aswellasRS, progress through the digestive tract on into the large intestine. Fermentation of this material by microflora then occurs, resulting in formation of short-chain fatty acids (SCFA), especially butyrate and propionate (Topping and Clifton 2001).The benefits of these fatty acids in the large intestine are healthy colonic mucosa, and provision of an energy source for epithelial cells (Topping et al. 2003). Dongowski et al. (2002) investigated the effects of a high-amylose barley and PW barley, compared with maize starch, a high-RS commercial product, and a control diet with no barley. These materials were extruded to prepare experimental diets for rats. All of the animals fed barley diets thrived better and had greater intestinal mass than controls. SCFAs (i.e., acetic, propionic, and butyric) were higher in cecal and colon contents of animals fed the test diets. The more acid conditions indicated a smaller proportion of secondary bile acids, believed to be promoting factors in colon cancer. Bird et al. (2004b) fed stabilized whole-grain barley flours from Himalaya 292, the high-amylose barley cited previously (Bird et al. 2004a), with two other barleys, and either wheat or oat bran to rats, to determine the effects of these feeds on intestinal SCFAs. Although there were independent differences between animals fed different diets, colonic SCFAs were consistently higher and pH was lower in those fed Himalaya 292 barley than all other diets. Results were attributed to the greater RS content in this barley cultivar, due to its reduced amylopectin and increased amylose content as well as having a high β-glucan content. More recently, Bird et al. (2007) compared the effects of foods made from whole-grain Himalaya 292 with those made from whole-grain wheat or refined cereal. Biomarkers of bowel health in healthy subjects (fecal weight, fecal concentration of butyrate, SCFA excretion, and fecal p-cresol concentration) were all significantly different between groups and indicative of improved bowel health in subjects who consumed barley diets. The beneficial health benefits were attributed to the presence of resistant starch. SUMMARY Barley has been shown in animal studies and human clinical trials to be an ordinary food product that can effectively normalize blood cholesterol. β-Glucan, a significant part of the dietary fiber in barley, is the most important component for lowering blood cholesterol concentration. It is generally believed that this beneficial effect is the result of increased intestinal viscosity, delaying absorption of food fat and binding bile acids, which cycle with body cholesterol. Data from studies with extracted β-glucans have not been as consistent in cholesterollowering efficacy as with β-glucans in the natural state in the grain or grain products. Further research in extraction procedures to obtain semipurified β-glucan with intact physiochemical properties will no doubt improve the efficacy of the products.
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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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98 BARLEY PROCESSING: METHODS AND P
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100 BARLEY PROCESSING: METHODS AND
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134 EVALUATION OF FOOD PRODUCT QUAL
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Page 159 and 160: 142 EVALUATION OF FOOD PRODUCT QUAL
Page 161 and 162: 7 Barley Food Product Research and
Page 163 and 164: 146 BARLEY FOOD PRODUCT RESEARCH AN
Page 195 and 196: 8 Health Benefits of Barley Foods I
Page 197 and 198: 180 HEALTH BENEFITS OF BARLEY FOODS
Page 209: 192 HEALTH BENEFITS OF BARLEY FOODS
Page 221 and 222: 9 Current Status of Global Barley P
Page 223 and 224: 206 CURRENT STATUS OF GLOBAL BARLEY
Page 225 and 226: 208 CURRENT STATUS OF GLOBAL BARLEY
Page 227 and 228: 10 Barley Foods: Selected Tradition
Page 229 and 230: 212 BARLEY FOODS: SELECTED TRADITIO
Page 242 and 243: APPENDIX 1 Glossary: Botany and Pla
Page 244 and 245: APPENDIX 2 Glossary: Food and Nutri
Page 246 and 247: APPENDIX 3 Glossary: Barley Terms T
Page 248 and 249: APPENDIX 4 Equivalent Weights and M
Page 250 and 251: SOURCES OF BARLEY AND BARLEY PRODUC
Page 252 and 253: Rancho Cucamonga, CA 91730 Ph: 888-
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Page 256 and 257: E-mail:Tony.Steeper@csiro.au Web: h
Page 258 and 259: 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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