MOLECULAR-WEIGHT DISTRIBUTION AND (1-]3)(1-]4)-BETA-D-GLUCAN CONTENT OF CONSECUTIVE EXTRACTS OF VARIOUS OAT AND BARLEY CULTIVARS

The content and molecular weight (MW) of beta-glucan in extracts from a selection of oat and barley cultivars were compared using flow-injec tion analysis and high-performance size-exclusion chromatography From 60 to 75% of the beta-glucan was extracted from oat and waxy barley by hot water (90 degrees C) containing heat-stable alpha-amylase, wherea s just 50-55% was extracted from nonwaxy barley. Consecutive extractio ns with hot water and dimethylsulfoxide (DMSO) extracted 65% (nonwaxy barley) or 75-80% (oat and waxy barley) of the total beta-glucan. An e xtraction with sodium hydroxide and sodium borohydride (NaOH/NaBH4) in creased the percentage of beta-glucan extracted to 86-100% but decreas ed the MW. The MW of beta-glucan in the oat cultivars selected was sig nificantly higher than those in the barley cultivars. The beta-glucan extracted from the nonwaxy barley cultivars showed significantly highe r peak MW than that from the waxy barley cultivars.