Comparison of distribution and physicochemical properties of β-glucan extracted from different fractions of highland barley grains

Highland barley grains were roller-milled to produce five different fractions (B-1, B-2, B-3, B-4, and B-5). The distribution and physicochemical properties of β-glucans from five roller-milled fractions were investigated. The B-4 fraction contained the highest concentration of β-glucan (4.40%), and the outermost bran (B-1) had the lowest β-glucan content (1.01%). Besides, β-glucans from inner core B-5 (BG-5) had higher Mw (6.482 × 105 g/mol), whereas β-glucans from outer bran B-1 (BG-1) showed lower Mw (5.859 × 104 g/mol) than those from other fractions. Accordingly, the viscosity of BG-5 was highest (0.038-0.365 Pa·s), and the water solubility index of BG-1 was highest (50.43-90.71%). BG-5 showed stronger foam stability and emulsifying properties but weaker foaming capability, while BG-1 exhibited stronger foaming capability. The foaming capability and emulsifying properties of β-glucan samples were better under the neutral condition (pH = 7). The foam capabilities of all β-glucan samples displayed higher values at 65 °C, and emulsifying properties exhibited higher values at 45 °C. This study is expected to promote the application of highland barley β-glucans in food industry.