Benny E. Knuckles

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

ABSTRACT 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 pr...

Effect of dietary fats and barley fiber on total cholesterol and lipoprotein cholesterol distribution in plasma of hamsters

Abstract Dietary saturated fatty acids and cholesterol elevate blood lipids, promote hypercholesterolemia and lead to elevation of circulating very low density (VLDL) and low density lipoproteins (LDL). Dietary fiber is suggested to ameliorate hypercholesterolemia. This study was undertaken to determine if dietary fiber would alter the quantity and distribution of cholesterol among plasma lipoproteins in the well-described model of dietary fat-induced hypercholesterolemia, the golden Syrian hamster. Hamsters were fed a basal high fat diet with 2.5% safflower oil and 10% butterfat to which had been added either 2.5% olive oil or 2.5% fish oil. Fiber was provided as cellulose or beta-glucan-enriched barley fiber at 10% of the diet. In hamsters fed 10% butterfat, 2.5% olive oil and cellulose, plasma cholesterol content was 237 mg/100 mL, with 65% of the total plasma cholesterol distributed in high density lipoproteins (HDL) and 35% in LDL plus VLDL. In hamsters fed 10% butterfat and 2.5% fish oil and cellulose, total cholesterol was 297 mg/100 mL, and 32% of the cholesterol was associated with HDL and 68% with LDL plus VLDL. These data indicated a significant redistribution of cholesterol from the HDL to the LDL and VLDL in fish oil fed animals. Substitution of barley fiber for cellulose in diets tended to decrease plasma cholesterol, however, it did not significantly affect the distribution of cholesterol among the lipoprotein classes. Serum triglycerides were higher in plasma of hamsters fed fish oil, and fiber did not alter either total triglycerides or distribution of triglycerides among lipoprotein classes. This study suggested that cholesterol distribution in plasma of hamsters fed cholesterolemic diets is more responsive to dietary fat than fiber and is due to mechanisms additional to hepatic LDL-receptor binding activity.

Molecular Characterization of Barley β-Glucans by Size-Exclusion Chromatography with Multiple-Angle Laser Light Scattering and Other Detectors

ABSTRACT Molecular characteristics were determined for mixed-linkage (1→3) (1→4)-β-d-glucans (β-glucans) extracted from Azhul, Crystal, Waxbar, and Prowashonupana barleys. β-Glucans in extracts (with or without α-amylase, protease, hemicellulase, or xylanase treatment) were separated from other components by high-performance size-exclusion chromatography and detected with multiple-angle laser light scattering, refractive index, and fluorometry following postrefractive index treatment with Calcofluor. Pretreatment of barley with 70% ethanol (80°C, 4 hr) reduced β-glucanase activity by ~20%. Hot-alcohol treatment also reduced β-glucan extraction at 23 and 65°C by 42 and 14%, respectively. Molecular weights of β-glucans in the first water extract were generally higher than in succeeding water and alkali extracts. Weight average molecular weights ranged from 0.44 × 106 to 2.34 × 106 g/mol after α-amylase treatment to remove interfering starch. Interference due to pentosans was not demonstrated using enzyme tr...

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

ABSTRACT 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 ...

Health-promoting Properties of a High Beta-glucan Barley Fraction

Barley, a cereal high in dietary fiber, can be milled into a high-fiber flour that has favorable effects on blood cholesterol and possibly also on insulin sensitivity.