MOLECULAR CHARACTERIZATION OF BARLEY BETA-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)-beta-D-glucans (beta-glucans) extracted from Azhul, Crystal, Wax bar, and Prowashonupana barleys. beta-Glucans in extracts (with or wit hout alpha-amylase, protease, hemicellulase, or xylanase treatment) we re 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 tre atment with Calcofluor. Pretreatment of barley with 70% ethanol (80 de grees C, 4 hr) reduced beta-glucanase activity by similar to 20%. Hot- alcohol treatment also reduced beta-glucan extraction at 23 and 65 deg rees C by 42 and 14%, respectively. Molecular weights of beta-glucans in the first water extract were generally higher than in succeeding wa ter and alkali extracts. Weight average molecular weights ranged from 0.44 x 10(6) to 2.34 x 10(6) g/mol after alpha-amylase treatment to re move interfering starch. Interference due to pentosans was not demonst rated using enzyme treatments.