Linkage Structure Analysis of Barley and Oat β-Glucans by High Performance Anion Exchange Chromatography

Cereal β-glucans, linked essentially by mixed β-(1,4/1,3) glycosidic bonds, were extracted, purified, and structurally identified. Previously chemical structure of barley β-glucans was characterized from 3 varieties of ‘Gang’, ‘Ohl’, and ‘Gwangan’, and the (1,4)/(1,3) linkage ratio of the β-glucans was identical. In this study, β-glucans from 1 barley (‘Chal’) and 3 oat (‘Ohl’, ‘Samhan’, and ‘Donghan’) varieties were structurally scrutinized, and the linkage pattern of total 7 cereal β-glucans was compared. The amount of 2 major 3-O-β-cellobiosyl-D-glucose (DP3) and 3-O-β-cellotriosyl-D-glucose (DP4) from barley and oat accounted for only 66.6-73.3 and 68.12-81.89% of water-extractable β-glucan fractions, and the (1,4)/(1,3) linkage ratios of both barley and oat β-glucans were within very narrow range of 2.27-2.31 and 2.38-2.39, respectively, among the cultivars tested. Structural difference in the cereal β-glucans was evident when DP3:DP4 ratio in the β-glucan structure was compared. As a result, this ratio was significantly greater for barley β-glucan (2.26-2.74) than for oat (1.54-1.66). Chal-B had the greatest DP3 to DP4 ratio among the samples, which in turn reflected the least amount of (1,4)-linkages.