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 (0.05 M , 1 hr), 70% ethanol (80°C, 4 hr), hydrochloric acid (0.1 N , 1 hr), oven heating (120 and 140°C, 40 min), sodium hydroxide (0.0025 M , 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%), CaCl 2 (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 × 10 5 ). 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.