Effect of Cooking and Storage on the Amount and Molecular Weight of (1→3)(1→4)-β-d-Glucan Extracted from Oat Products by an In Vitro Digestion System

The extractability and molecular weight of β-glucan in oat bran, oat bran muffins, and oat porridge and the changes taking place during processing and storage were studied. The β-glucan was extracted using hot water and a thermostable α-amylase and by an in vitro system that simulated human digestion. Molecular weight (MW) of the extracted β-glucan was determined using high-performance size-exclusion chromatography. Hot-water treatment extracted 50–70% of total β-glucan in oat bran samples and rolled oats. The chromatographic peak MW of extracted β-glucan was in the 1.4–1.8 × 10⁶ range. Using the in vitro digestion system, 12–33% of total β-glucan in bran and rolled oats was solubilized, and peak MW was in the same range as β-glucan extracted by hot-water treatment. In muffins, 30–85% of total β-glucan was solubilized by in vitro digestion, with a major difference in extractability among muffins from different recipes. Peak MW of extracted β-glucan was lower in all muffins when compared to original bran. During frozen storage, extractable β-glucan decreased by >50% in all muffins, but no change in peak MW of extracted β-glucan was detected.     

Rheological Properties of (1→3),(1→4)-β-d-Glucans from Raw,Roasted, and Steamed Oat Groats

Effects of hydrothermal treatments (steaming, roasting) of oat grain on β-glucan extractability and rheological properties were tested on oat cultivars with low (Robert) and high (Marion) β-glucan content. Steaming of grain reduced the amount of β-glucan that could be extracted, compared with raw or roasted grain, but the extracts from steamed grain had much greater viscosity. Increased extraction temperatures increased the amount and the average relative molecular mass (M _r) value of β-glucan extracted. In boiling water extractions, the average M _r values among raw, roasted and steamed oat samples were equivalent, but extracts from steamed oat grain had significantly higher intrinsic viscosity than the extracts from roasted or raw oat grains. β-glucan solutions purified from steamed grain extracts were very viscous and highly pseudoplastic, as described by the power law equation. Oat β-glucan from steamed samples were more viscoelastic than β-glucan from roasted or raw oat samples. Because viscous properties of β-glucan from boiling water extracts are influencedhydrothermal treatments without affecting polymer molecular weight, polymer interaction with the solvent must be affected. Steaming may disrupt intramolecular cross-linkings in native β-glucan, allowing a linear chain configuration to generate greater viscosity.     

Waxy Starch Barley Genotypes with Reduced β-Glucan Contents

Random inbred lines were produced from a cross between the genotypes Chalky Glenn and Waxy Hector, and two-row lines were classified as waxy or nonwaxy by an iodine staining test. Mean nitrogen and β-glucan contents of the waxy types were higher than those of the nonwaxy types but, in contrast to previous data, mean milling energies of the two groups were not significantly different. Waxy lines with low milling energy had much lower β-glucan levels than those with high milling energy, and they also demonstrated much more extensive cell wall modification during malting. From a trial grown the following season, the waxy types with low milling energy were again identified and had levels of β-glucan content similar to those of nonwaxy types. β-Glucan contents and, particularly, milling energies showed good agreement between seasons. It is suggested that, although waxy starch is usually associated with high β-glucan content, a genetic factor from Chalky Glenn that confers low levels of β-glucan can express in a waxy background.     

Comparisons of β-Glucan Content of Barley and Oat

The cholesterol-lowering effect of cereal grains has been associated with the soluble fiber component of dietary fiber. β-Glucan is the major soluble fiber component of barley (Hordeum vulgare L.) and oat (Avena sativa L.). Much research has been conducted to determine the β-glucan content of barley and oat genotypes from many different countries. However, genotypes of both crops always were grown in separate experiments, making direct comparisons between the two crops difficult. This study compares in the same experiment the β-glucan content of nine barley and 10 oat genotypes grown at two locations in each of two years (i.e., four environments) in North Dakota. Averaged across genotypes, total β-glucan content of barley and oat groat was similar. Soluble β-glucan content of oat groat was greater than barley, and oat groat had a greater ratio of soluble-to-total β-glucan than barley. The soluble β-glucan content and ratio of soluble to total β-glucan content of the “best” barley genotypes were less than that of oat genotypes with the highest levels of these two traits.     

Effect of Extraction Conditions on Yield,Composition, and Viscosity Stability of Barley β-Glucan Gum

Cereal β-glucan can function as a thickener, but endogenous β-glucanase enzymes of the grain cleave β-glucan, reducing its viscosity. Although different extraction techniques have been developed, the viscosity stability of β-glucan gum has not been reported. The objective of this study was to investigate the effect of extraction treatments on the yield, purity, and viscosity stability of barley β-glucan (BBG) gum. A regular barley cultivar, Condor, and a waxy cultivar blend were extracted at pH 7–10 and 55°C for 0.5 hr. Four extraction conditions were evaluated: 1) extraction at high pH with no additional heat treatment; 2) boiling of extract; 3) prior refluxing of flour with 70% ethanol; and 4) treatment of extract with thermostable α-amylase for purification. Viscosity of extracts was monitored for ≥24 hr at 25°C. The highest β-glucan purities were achieved with a boiled Condor extract at pH 7 (81.3% db, 4.1% yield) and with refluxed waxy barley extracted at pH 8 and treated with α-amylase and (79.3% db, 5.1% yield). Gums extracted without subsequent heat treatment or prior refluxing of flour had high protein (>17%) and starch (>24%) impurities, respectively. The viscosity of gums obtained without heating was unstable. Prior refluxing treatment was not sufficient to stabilize final extracts. Boiling extracts resulted in stable but low viscosity. Reflux followed by purification treatment produced the highest stable viscosity for 0.5% solutions of both Condor (64 mPa sec^-1, pH 7) and waxy (48.8 mPa sec^-1, pH 8) extracts. Stable BBG gum with high viscosity can be obtained using thermal treatments in combination with high pH. The potential use of such gums as thickeners in food systems needs to be assessed.     

Quality of Flours from Waxy and Nonwaxy Barley for Production of Baked Products

One nonwaxy (covered) and two waxy (hull-less) barleys, whole grain and commercially abraded, were milled to break flour, reduction flour, and the bran fraction with a roller mill under optimized conditions. The flour yield range was 55.3–61.8% in whole grain and increased by 9–11% by abrasion before milling. Break flours contained the highest starch content (≤85.8%) independent of type of barley and abrasion level. Reduction flours contained less starch, but more protein, ash, free lipids, and total β-glucans than break flours. The bran fraction contained the highest content of ash, free lipids, protein, and total β-glucans but the lowest content of starch. Break flours milled from whole grain contained 82–91% particles <106 μm, and reduction flours contained ≈80% particles <106 μm. Abrasion significantly increased the amount of particles <38 μm in break and reduction flours in both types of barley. Viscosity of hot paste prepared with barley flour or bran at 8% concentration was strongly affected by barley type and abrasion level. In cv. Waxbar, the viscosity in bran fractions increased from 428 to 1,770 BU, and in break flours viscosity increased from 408 to 725 BU due to abrasion. Sugar snap cookies made from nonwaxy barley had larger diameter than cookies prepared from waxy barley. Cookies made from break flours were larger than those made from reduction flours, independent of type of barley. Quick bread baked from nonwaxy barley had a loaf volume similar to that of wheat bread, whereas waxy barley bread had a smaller loaf volume. Replacement of 20% of wheat flour by both waxy and nonwaxy barley flour or bran did not significantly affect the loaf volume but did decrease the hardness of quick bread crumb.     

β-Glucanase Activity and Molecular Weight of β-Glucans in Barley After Various Treatments

β-Glucanase activity interferes with molecular characterization of mixed-linkage (1→3)(1→4)-β-d -glucans (β-glucans). Reductions in β-glucanase activity were determined after barley cvs. Azhul, Waxbar, and Baronesse were treated with autoclaving (120°C, 45 min), calcium chloride (0.05M, 1 hr), 70% ethanol (80°C, 4 hr), hydrochloric acid (0.1N, 1 hr), oven heating (120 and 140°C, 40 min), sodium hydroxide (0.0025M, 1 hr), and 5% trichloroacetic acid (TCA) (40°C, 1 hr). High-performance size-exclusion chromatography (HPSEC) of α-amylase-treated aqueous extracts was used to demonstrate the effects of treatments on the molecular weights of β-glucans. The HPSEC system included multiple-angle, laser light scattering, refractive index, and fluorescence detectors. β-Glucanase activities, ranging from 52 to 65 U/kg of barley, were reduced by autoclaving (50–75%), hot alcohol (67–76%), oven heating (40–96%), CaCl₂ (75–95%), NaOH (76–89%), and TCA (92–96%). Some malt β-glucanase activity remained after most treatments. HCl and TCA treatments reduced extraction and molecular weights of β-glucans. Weight-average molecular weights (M_w) for β-glucans extracted with water at 23°C were low (most <8 × 10⁵). Base treatment (pH 9) and extraction at 100°C for 2.5 hr resulted in the greatest extraction of β-glucans and highest M_w. As a result, the conditions seem appropriate for measurement of physical characteristics of β-glucans in cereal products.     

Extraction and Physicochemical Characterization of Rye β‐Glucan and Effects of Barium on Polysaccharide Molecular Weight

Use of saturated Ba(OH)₂ to extract rye β‐glucan led to a depolymerized product. Similar depolymerization of β‐glucan was observed when oat bran was extracted with this reagent. Isolated oat β‐glucan, detarium xyloglucan, guar galactomannan, and wheat and rye arabinoxylan were also depolymerized by treatment with the barium reagent. The degree of depolymerization was related to time of contact with, and concentration of, the barium. Rye β‐glucan of two different molecular weights (MW) were isolated and characterized. The structure of rye β‐glucan, as evaluated from the ratio of (1→3)‐linked cellotriosyl to (1→3)‐linked cellotetraosyl primary structural units, most closely resembles barley β‐glucan. Analytical variability of this ratio is discussed. A freshly prepared solution (2%) of the higher MW sample showed shear thinning behavior typical of cereal β‐glucans. The lower MW sample at 2% was not shear thinning, but on further purification, after storage for seven days, a 6% solution had gelled as shown by the mechanical spectrum.     

Comparison of Waxy vs. Nonwaxy Wheats in Fuel Ethanol Fermentation

Fermentation performance of eight waxy, seven nonwaxy soft, and 15 nonwaxy hard wheat cultivars was compared in a laboratory dry‐grind procedure. With nitrogen supplements in the mash, the range of ethanol yields was 368–447 L/ton. Nonwaxy soft wheat had an average ethanol yield of 433 L/ton, higher than nonwaxy hard and waxy wheat. Conversion efficiencies were 91.3–96.2%. Despite having higher levels of free sugars in grain, waxy wheat had higher conversion efficiency than nonwaxy wheat. Although there was huge variation in the protein content between nonwaxy hard and soft wheat, no difference in conversion efficiency was observed. Waxy cultivars had extremely low peak viscosity during liquefaction. Novel mashing properties of waxy cultivars were related to unique pasting properties of starch granules. With nitrogen supplementation, waxy wheat had a faster fermentation rate than nonwaxy wheat. Fermentation rates for waxy cultivars without nitrogen supplementation and nonwaxy cultivars with nitrogen supplementation were comparable. Ethanol yield was highly related to both total starch and protein content, but total starch was a better predictor of ethanol yield. There were strong negative relationships between total starch content of grain and both yield and protein content of distillers dried grains with solubles (DDGS).     

Structure and Functionality of Barley Starches

Amylose contents of prime starches from nonwaxy and high-amylose barley, determined by colorimetric method, were 24.6 and 48.7%, respectively, whereas waxy starch contained only a trace (0.04%) of amylose. There was little difference in isoamylase-debranched amylopectin between nonwaxy and high-amylose barley, whereas amylopectin from waxy barley had a significantly higher percentage of fraction with degree of polymerization < 15 (45%). The X-ray diffraction pattern of waxy starch differed from nonwaxy and high-amylose starches. Waxy starch had sharper peaks at 0.58, 0.51, 0.49, and 0.38 nm than nonwaxy and high-amylose starches. The d-spacing at 0.44 nm, characterizing the amylose-lipids complex, was most evident for high-amylose starch and was not observed in waxy starch. Differential scanning calorimetry (DSC) thermograms of prime starch from nonwaxy and high-amylose barley exhibited two prominent transition peaks: the first was >60°C and corresponded to starch gelatinization; the second was >100°C and corresponded to the amylose-lipid complex. Starch from waxy barley had only one endothermic gelatinization peak of amylopectin with an enthalpy value of 16.0 J/g. The retrogradation of gelatinized starch of three types of barley stored at 4°C showed that amylopectin recrystallization rates of nonwaxy and high-amylose barley were comparable when recrystallization enthalpy was calculated based on the percentage of amylopectin. No amylopectin recrystallization peak was observed in waxy barley. Storage time had a strong influence on recrystallization of amylopectin. The enthalpy value for nonwaxy barley increased from 1.93 J/g after 24 hr of storage to 3.74 J/g after 120 hr. When gel was rescanned every 24 hr, a significant decrease in enthalpy was recorded. A highly statistically significant correlation (r = 0.991) between DSC values of retrograded starch of nonwaxy barley and gel hardness was obtained. The correlation between starch enthalpy value and gel hardness of starch concentrate indicates that gel texture is due mainly to its starch structure and functionality. The relationship between the properties of starch and starch concentrate may favor the application of barley starch concentrate without the necessity of using the wet fractionation process.     

Effects of Different Cereal Fibers on Cholesterol and Bile Acid Metabolism in the Syrian Golden Hamster

This study examined the effects of various cereal fibers and various amounts of β-glucan on cholesterol and bile acid metabolism. Hamsters were fed semisynthetic diets containing 0.12% cholesterol, 20% fat, and either 16% total dietary fiber (TDF) from wheat bran (control) or 10% TDF from oat bran, 13% TDF from oat bran concentrate or barley grains, 16% TDF from oat fiber concentrate, barley flakes, or rye bran. After five weeks, plasma total cholesterol and liver cholesterol concentrations were significantly lower (20 and 50%, respectively) only in hamsters fed rye bran. Diets containing any of the oat ingredients or barley had no effect on total cholesterol. Changes in the pattern of biliary bile acids occurred in hamsters fed 16% TDF from barley flakes or 10% TDF from oat bran. Hamsters fed rye bran had a significantly higher fecal bile acid excretion when compared with controls fed wheat bran. Because rye bran caused the most pronounced lowering effect of total cholesterol despite the lowest content of β-glucan and soluble fibers, components other than β-glucan and soluble fibers seem to be involved in its hypocholesterolemic action. Since the effects of the oat and barley ingredients were not solely correlated to the β-glucan content, structural changes occurring during processing and concentrating of the products may have impaired the hypocholesterolemic potential of the β-glucans, and other factors such as solubility and viscosity of the fiber components seem to be involved.     

Effect of Extrusion Cooking on the Primary Structure and Water Solubility of β‐Glucans from Regular and Waxy Barley

Water‐soluble β‐glucan from native and extrusion‐cooked barley flours of two barley cultivars, Candle (a waxy starch barley) and Phoenix (a regular starch barley), was isolated and purified. The purity of β‐glucan samples was 85–93% (w/w, dry weight basis) for Candle and 77–86% (w/w, dry weight basis) for Phoenix. The water solubility of β‐glucan (at room temperature, 25°C) in the native and extruded flours (primary solubility) was different from that of the purified β‐glucan samples (secondary solubility). The solubility of β‐glucan in the native and extruded Candle flour was substantially higher than that of β‐glucan in Phoenix. For both cultivars, β‐glucan in the extruded flours had solubility (primary solubility) values higher than in their native counterparts. The solubility of β‐glucan in the purified β‐glucan samples differed depending on the barley cultivar and the extrusion conditions employed. The glycosidic linkage profiles of purified soluble β‐glucan from native and extruded barley flours were determined in order to understand the changes in the primary structure of β‐glucan and the effect of extrusion on the β‐glucan structure‐solubility relationship.     

Observations on the Quality Characteristics of Waxy (Amylose‐Free) Winter Wheats

Previous investigations have suggested waxy (amylose‐free) wheats (Triticum aestivum L.) possess weak gluten properties and may not be suitable for commercial gluten extraction. This limitation could prevent the use of waxy wheat as a source of unique starch, because gluten is a by‐product of the wheat starch purification process. Fifty waxy wheat lines were used to determine the extent to which gluten protein and other grain quality related traits might vary and, consequently, allow the development of waxy wheat with acceptable gluten properties. Among the waxy lines, significant variation was observed for all measured quality traits with the exception of flour protein concentration. No waxy entries statistically equaled the highest ranking nonwaxy entry for grain volume weight, falling number, flour yield, or mixograph mix time. No waxy lines numerically exceeded or equaled the mean of the nonwaxy controls for falling number, flour yield, or mixograph mix time. For grain and flour protein related variables, however, many waxy lines were identified well within the range of acceptability, relative to the nonwaxy controls used in this study. Approximately 50% of the waxy lines did not differ from the highest ranking nonwaxy cultivar for grain and flour protein concentrations. Forty‐three (86%) of the tested waxy lines were not sig‐nificantly different from the nonwaxy line with the highest mixograph mixing tolerance, 22/50 (44%) of the waxy wheat lines did not differ from the highest ranking nonwaxy line in gluten index scores, and 17/50 (34%) did not differ from the highest ranking nonwaxy line in extracted wet gluten. All waxy experimental lines produced gluten via Glutomatic washing. The quality of the gluten, as measured both by mixograph and gluten index, varied widely among the waxy lines tested. These observations suggest that weak gluten is not a natural consequence of the waxy trait, and waxy cultivars with acceptable gluten properties can be developed.     

Recovery and Purity of Isolated Barley Starch and Protein as Affected by Fractionation Water Temperature

Wet fractionation of barley flours was conducted to identify appropriate fractionation water temperature considering the recovery and purity of starch and protein. In abraded hulless regular barley, yield of starch fraction, starch recovery, and purity of the protein fraction increased from 43.3 to 45.7%, from 61.7 to 64.8%, and from 37.6 to 65.2% when water temperature in fractionation was increased from 23 to 60°C. In abraded hulless waxy barley, recovery of starch with 40°C water was much greater (67.7%) than that at other temperatures (<61.7%). Starch recovery and protein purity of regular barley cultivars were higher than those of waxy barley cultivars with fractionation water of 60°C. In whole hulless barley flours fractionated with 60°C water, waxy barley flours showed similar to or higher protein purity (44.8–48.9%) than regular barley flours (42.8– 44.6%), while regular barley flours exhibited higher starch recovery (>60.6%) than waxy barley flours (<57.3%). The purity of isolated starch was >97.7%, regardless of water temperature and barley type. Considering yield and recovery of the isolated starch, and purity of the isolated protein, 60°C water for hulless regular barley and 40°C for hulless waxy barley seem to be appropriate for fractionation of barley flour for isolation of starch and protein.     

Effect of Processing on Viscosity and Molecular Weight of (1,3)(1,4)‐β‐Glucan in Western Australian Oat Cultivars

Six Australian milling oat cultivars grown over two growing seasons were characterized for differences in (1,3)(1,4)‐β‐glucan (β‐glucan) viscosity, solubility, molecular weight (M_w), and the effect of processing. Oat cultivars grown in 2012 had significantly higher extracted β‐glucan viscosity from oat flour than the same oat cultivar grown in 2011 (P < 0.05, mean 137 and 165 cP, respectively). Noodle β‐glucan mean viscosity for 2012 (147 cP) was significantly higher than for 2011 (128 cP). β‐Glucan from ‘Williams’ and ‘Mitika’ oats had the highest viscosity (P < 0.05) in flour (5.92 and 5.25%, respectively) and noodles (1.64 and 1.47%, respectively) for both years, compared with the other oat cultivars. β‐Glucan (M_w) of Williams for 2012 and ‘Kojonup’ for both years were the least affected by processing, with an average drop of 33% compared with a maximum of 63% for other cultivars. Therefore, Williams showed superior β‐glucan properties to other oat cultivars studied, and can potentially provide improved health benefits. High and low β‐glucan M_w populations were found in the same elution peak after processing. Oat cultivars chosen for processing should be those with β‐glucans that are more resistant to processing, and that maintain their physiochemical properties and, therefore, bioactivity.     

The Potential of Hull-less Barley

Hull-less barley (HB) has been investigated in many countries for use in feed, food, and industry since the publication of the last review in 1986. Literature published since 1990 on various aspects of HB utilization, other than in monogastric feeds, has been reviewed. Several HB cultivars containing low or β-glucan, low or high extract viscosity, and waxy (0–5% amylose) or normal starch are now available. Interest in HB utilization in the food industry developed largely due to its high β-glucan content, particularly in the waxy cultivars. β-Glucan is a major component of soluble fiber implicated in hypocholesterolemia, hypoglycemia, and in reducing incidence of chemically induced colon cancer in experimental animals. However, large-scale clinical trials using human subjects are needed to corroborate these effects. The zero amylose HB starch had low syneresis or a high freeze-thaw stability suitable for use in frozen foods. Single- or double-modified waxy HB starch may replace corn starch in some food applications, and cationized HB starch can replace corn and potato starches in the pulp and paper industry. HB may be milled using conventional wheat milling equipment to yield bran and flour for multiple food uses. Hull-less barley may also be used as a feed stock for fuel alcohol production, for the preparation of food malt with low or high enzyme activities, and for brewer's and distiller's malts.     

Structure of (1→3)(1→4)‐β‐d‐Glucan in Waxy and Nonwaxy Barley

The endosperm cell walls of barley are composed largely of a (1→3)(1→4)‐β‐d ‐glucan commonly known simply as β‐d ‐glucan (Wood 2001). There has been much research into the characteristics of barley β‐glucan because of the influence of this polysaccharide on performance of barley in malting and subsequent brewing of beer, and in feed value, especially for young chicks (MacGregor and Fincher 1993). The potential for β‐glucan to develop high viscosity is a problem in these uses, but from the perspective of human nutrition, this characteristic may be an advantage. The glycemic response to oat β‐glucan is inversely related to (log)viscosity (Wood et al 1994a) and there is evidence to suggest that the lowering of serum cholesterol levels associated with oat and barley products (Lupton et al 1994; Wood and Beer 1998) is at least in part due to the β‐glucan (Braaten et al 1994) and probably also its capacity to develop viscosity in the gastrointestinal tract (Haskell et al 1992).     

Effect of Barley β-Glucan in Durum Wheat Pasta on Human Glycemic Response

High-fiber, high-carbohydrate diets, including foods with low glycemic index, have been associated with prevention and treatment of diseases such as coronary heart disease and diabetes. β-glucan, a soluble, viscous polymer found in oat and barley endosperm cell wall, was incorporated into pasta test meals. Five fasted adult subjects were fed test meals of a barley and durum wheat blend pasta containing 100 g of available carbohydrate, 30 g of total dietary fiber (TDF) and 12 g of β-glucan, or an all durum wheat pasta containing the same amount of available carbohydrate, 5 g of TDF, and negligible β-glucan. The β-glucan and durum wheat pasta resulted in a lower glycemic response as measured by average total area and maximum increment of the blood glucose curves. Lower insulin response to the β-glucan and durum wheat pasta was also indicated by lower average area and increment characteristics of the insulin curves. Barley β-glucans may be an economical and palatable ingredient for processed food products formulated to modify glycemic and insulin response.     

Composition,Microstructure, Water Imbibition,and Thermal Properties of Abraded Barley

Barley, nonwaxy hull (cvs. Crystal and Meltan) and waxy hull-less (cvs. Merlin and Waxbar), was abraded at 10, 20, and 40% of kernel weight on a laboratory scale and commercially abraded at two levels: fine and coarse. In 40% abraded kernels of Crystal, protein, ash, and free lipids contents decreased by 1.6, 1.4, and 1.4%, respectively, and starch and β-glucans contents increased by 16 and 1.2%, respectively, compared to nonabraded kernels. Merlin showed smaller changes in the levels of these components, except for proteins. Changes in starch and protein in laboratory abraded barley were used to estimate the level of barley abrasion on a commercial scale. Scanning electron microscope pictures revealed that in nonwaxy barley at 10% abrasion the hull and part of the seed coat were absent, whereas waxy barley lost all of the seed coat and most of the aleurone layer. Maximum water imbibition of 40% abraded waxy barley was reached after 5 hr of soaking, whereas nonwaxy barley needed 8 hr to level off. Nonwaxy barley kernels at 20% abrasion and cooked for 10 min required 52 N to compress to 50% thickness, whereas waxy barley needed only 28 N. Changes in chemical composition and microstructure due to abrasion had a strong effect on the thermal properties of kernels during cooking. The extent to which barley starch was gelatinized during cooking was evaluated by differential scanning calorimetry. Crystal and Merlin showed significant decreases in enthalpy value for 40% compared to 10% abraded barley. These results indicate that when a large portion of the outer layer of barley is removed, water and heat penetrate more quickly into kernels during cooking, causing more starch to be gelatinized. The results obtained in this study indicate that changes in composition and microstructure due to abrasion affect the rate of water imbibition, hardness of cooked kernels, and enthalpy value of starch. Composition and properties of laboratory abraded barley could be used to predict the level of abrasion and properties of barley abraded on a commercial scale within the same cultivar.     

Preparation and Characterization of Films Using Barley and Oat β‐Glucan Extracts

Films for potential food use were prepared from aqueous solutions of β‐glucan extracted from hulled barley, hull‐less barley, and oats. The extracts (75.2–79.3% β‐glucan) also contained proteins, fat, and ash. Glycerol was used as a plasticizer. The films were translucent, smooth, and homogeneous in structure on both sides. Water vapor permeability of films prepared from 4% solutions of β‐glucan extracts were higher than those from 2% solutions, despite similar values for water vapor transmission rate. Mechanical properties were influenced by both β‐glucan source and concentration. The oat β‐glucan films showed higher tensile strength and water solubility, and lower color, opacity, and deformation values than those of barley. Films prepared from hull‐less barley cv. HLB233 remained intact upon immersion in water for 24 hr.