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

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WHOLE-GRAIN PROCESSING 115 kernel is thus modified over a period of four to five days and sometimes up to 10 days in traditional floor malting, which is performed at 13 to 16 ◦ C. In modern pneumatic malting houses, temperature is controlled typically over the range 16 to 20 ◦ C. Increasing the temperature to 25 ◦ C produces roots and enzymes more quickly; however, the rate of enzyme formation decreases such that grains germinating at lower temperatures ultimately contain higher enzymatic activity. Long, cool germination cycles maximize fermentability and also minimize malting loss (Bathgate et al. 1978). Native amylolytic and proteolytic enzymes in the kernel are activated by the moisture and temperature and enhanced by gibberellin, converting insoluble starch into soluble sugars and oligosaccharides. Proteins are converted to free amino acids and peptides by proteolysis. When this modification has reached the maltster’s desired stage, the greenmalt, asthematerial is now known, is transferred to the kiln for drying, the third and final stage of processing. Germination is arrested in the kiln, where warm air passes through the malted grain. The drying process causes withering and stabilization of the grain structure. Kiln drying is divided into four merging phases: free drying down to about 23% moisture, an intermediate drying stage to about 12% moisture, decreasing moisture from 12% to about 6%, and curing where moisture is taken down to 2 to 3%. During free drying, an air temperature of 50 to 60 ◦ C is attained along with an airflow of 5000 to 6000 m 3 /min, causing unrestricted removal of water. When moisture content reaches about 12%, the water in the malted kernel is said to be bound, requiring further increase in air temperatures and reduction of air fan speed. Lowering of moisture to about 6% allows the malt to be “cured” with the air temperature increased to 80 to 110 ◦ C, reducing moisture to 2 to 3%. Drying time and temperatures are essential in developing the flavor and color characteristics of the finished malt, this being a critical point in the malting process. Making specialty malts, as for use in food, differs from the basic malting process for beverage production in that batch sizes are smaller and constant monitoring is required to meet specifications (Kent and Evers 1994; Gibson 2001; Briess Industries). Malted kernels can be used directly in breads or other bakery products or processed further into flour extracts or syrup. A characteristic of malt products is the presence or absence of enzymes. Malt ingredients that contain diastatic enzymes are used in brewing. Nondiastatic malt products are processed at varying higher temperatures, which destroys some or all of the enzymatic activity. Diastatic malt flour is commonly used in bread baking in small amounts to act as a dough conditioner (Hansen and Wasdovitch 2005). Malt employed in the distilling industry to produce whiskey is made from maize, rye, and barley grains. Specifications placed on malt for distilling are comparable to those employed for brewing malt. Residual levels of unfermented dextrins are irrelevant to the flavor of whiskey, although they are desirable in beer and food malts. The goal is the maximum production of ethanol. Malt vinegars are produced by the bacterial oxidation of alcohol from wine, cider, or beer to acetic acid. Production of malt vinegars requires high fermentability of the grist so as to maximize ethanol production, as in distilling. Accordingly, high-diastatic
116 BARLEY PROCESSING: METHODS AND PRODUCT COMPOSITION malt may be employed that is capable of maximum conversion of starch in the adjunct. Acetic acid bacteria such as Acetobacter aceti are used to oxidize ethanol to acetic acid. Specifications applied to malt for vinegar manufacture relate to yield of soluble material and yield of fermentable material. The use of malt-based ingredients in foods is discussed briefly in Chapter 7. The effect of modification on nutrient composition in hulless and standard malting barley is described in Table 5.5 (Bhatty 1996). The absolute values shown for protein and starch are not indicative of the substantial enzymatic hydrolysis that occurs to these nutrients. Bhatty (1996) suggested that this abnormality was due to the analytical procedures used to measure these components. The average increases shown in soluble carbohydrates (3.5 to 10.3%, soluble protein (2.8 to 4.4%), and reducing sugars (0.3 to 3.1%) and decreases in β-glucans (4.7 to 1.5%) and viscosity (26.8 to 1.7 cP) present a truer indication of the hydrolytic activity occurring during modification. The soluble/total protein (S/T) ratio, known as the Kolbach index, is a measure of proteolysis. The higher the S/T ratio, the more extensive is the breakdown of protein. The lower β-glucan content was largely responsible for the greatly reduced viscosity. The major increases seen in α-amylase (ceralpha units), diastatic power, β-glucanase, and proteolytic activity are directly responsible for the changes. In comparing the hulless barley to the standard hulled malting barley, the major composition differences noted were in higher levels of α-amylase and diastatic power in the standard barley, but higher levels of β-glucanase in the hulless barley. Proteolytic activity was not greatly different between the two barley genotypes. Caution should be exercised in this area, due to the limited data available. Lipid constituents and their influence on the malting process and malt have not been investigated as extensively as have carbohydrates and protein. Kaukovirta- Norja et al. (1997) reported total lipids, including internal starch lipids, to be about 3.7% in the intact kernel prior to malting and about 3.3% in the resulting TABLE 5.5 Effect of Malting on the Composition, Viscosity, and Enzymatic Activity of Hulled and Hulless Barley, Dry Matter Basis Hulled Barley Hulless Barley Item Unmalted Malted Unmalted Malted Protein (%) 15.3 13.7 16.0 15.7 Ash (%) 2.4 2.2 1.8 1.4 Starch (%) 61.4 62.8 64.4 62.9 β-Glucan (%) 4.4 1.2 4.9 1.8 Viscosity (cP) 20.2 1.6 33.3 1.7 α-Amylase (ceralpha units/g) 0.1 258.4 0.1 288.0 Diastic power ( ◦ ASBC) 71.0 189.5 113.2 147.5 β-Glucanase (U/kg) 0 583.0 0 502.0 Proteolytic activity (mg NPN/kg) 42.0 112.0 46.0 105.0 Source: Bhatty (1996).
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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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Page 151 and 152: 134 EVALUATION OF FOOD PRODUCT QUAL
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166 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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