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Molecular Weight Distribution and (1→3)(1→4)-β-D-Glucan Content of Consecutive Extracts of Various Oat and Barley Cultivars¹

¹Contribution 2413 of the Centre for Food and Animal Research, Agriculture and Agri-Food Canada, Ottawa. ²Centre for Food and Animal Research, Agriculture and Agri-Food Canada, Ottawa, Ontario, K1A 0C6, Canada. ³Corresponding author. E-mail: WoodP@EM.AGR.CA

The content and molecular weight (MW) of β-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 β-glucan was extracted from oat and waxy barley by hot water (90°C) containing heat-stable α-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 β-glucan. An extraction with sodium hydroxide and sodium borohydride (NaOH/NaBH₄) increased the percentage of β-glucan extracted to 86–100% but decreased the MW. The MW of β-glucan in the oat cultivars selected was significantly higher than those in the barley cultivars. The β-glucan extracted from the nonwaxy barley cultivars showed significantly higher peak MW than that from the waxy barley cultivars.