Extraction of β-Glucan from Oat Bran in Laboratory Scale

Effects of various enzymes and extraction conditions on yield and molecular weight of beta-glucans extracted from two batches of commercial oat bran produced in Sweden are reported. Hot-water extraction with a thermostable alpha-amylase resulted in an extraction yield of approximate to 76% of the beta-glucans, while the high peak molecular weight was maintained (1.6 x 10(6)). A subsequent protein hydrolysis significantly reduced the peak molecular weight of beta-glucans (by pancreatin to 908 x 10(3) and by papain to 56 x 10(3)). These results suggest that the protein hydrolyzing enzymes may not be pure enough for purifying beta-glucans. The isolation scheme consisted of removal of lipids with ethanol extraction, enzymatic digestion of starch with alpha-amylase, enzymatic digestion of protein using protease, centrifugation to remove insoluble material, removal of low molecular weight components using dialysis, precipitation of beta-glucans with ethanol, and air-drying.