2020 Volume 67 Issue 11 Pages 430-441
Herein, proton quantitative nuclear magnetic resonance (1H qNMR), an absolute quantification method, was used to identify the types of glycosidic bonds contained in glucans and to quantify them individually. In this study, glucan quantities were determined using signals arising from an anomeric proton of the glucose unit, which showed a signal at δ 4.2 to 5.3 ppm and was well separated from the other signals. The signal area derived from the anomeric proton in the major α- and β-glucans measured by 1H qNMR exhibited good linearity (r＝0.999) in a sample concentration range of 0.1 to 2 w/v %. 1H qNMR correctly fulfilled the conditions of purity of β-glucan standards obtained from barley and baker’s yeast, with an accuracy of within 1 %. Furthermore, the quantity of glucans in dietary supplements determined by 1H qNMR was largely consistent with the quantitative value obtained by a conventional method employed to determine glucose generated from glucans by sulfate hydrolysis. 1H qNMR enabled non-destructive quantification of glucans, and was particularly effective for glucans consisting of a single unbranched glycosidic bond, such as pustulan and curdlan.
