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-injection 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, whereas just 50-55% was extracted from nonwaxy barley. Consecutive extractions with hot water and dimethylsulfoxide (DMSO) extracted 65% (nonwaxy barley) or 75-80% (oat and waxy barley) of the total beta-glucan. An extraction with sodium hydroxide and sodium borohydride (NaOH/NaBH4) increased the percentage of beta-glucan extracted to 86-100% but decreased the MW. The MW of beta-glucan in the oat cultivars selected was significantly higher than those in the barley cultivars. The beta-glucan extracted from the nonwaxy barley cultivars showed significantly higher peak MW than that from the waxy barley cultivars.