Hydrolysis of beta-glucan in oat flour during subcritical-water extraction

Oat (Avena sativa L.) β-glucan is bound tightly to other components of the endosperm cell wall, which means that β-glucan extraction processes are complex and involve many different stages. Subcritical-water extraction (SWE) has emerged as a promising method for extracting β-glucan under high temperature and pressure conditions. This study investigated the efficiency of the SWE of β-glucan from oat flour. The yield of β-glucan was optimized under the following conditions: extraction temperature of 200 °C, solvent pH of 4.0, extraction time of 10 min, and particle size of 425-850 μm. The extraction yield under the optimal condition was 6.98 ± 1.17 g/100 g oat flour, which was more than twofold higher than when using hot-water extraction at 60 °C for 3 h. β-glucan degradation to 5-hydroxymethyl-2-furaldehyde was increased under high-temperature conditions. SWE is a feasible alternative for extracting β-glucan in a single-step process, and could be developed into an effective industrial process.