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

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 treatments.