Enzymatic Preparation and Characterization of Soybean Oligosaccharides from Okara

The objective of this study was to investigate the enzymatic preparation method of soybean oligosaccharides (S0S) from okara by using Viscozyme L, characterize the physicochemical properties as well as antioxidant activity of S0S. The effect of Viscozyme L treatment on the preparation of S0S from okara was researched by orthogonal test. Under the fixed extraction time of 2.5 h and the ratio of okara to water of 1:15 (w/v), the optimal enzymatic preparation conditions of S0S by using Viscozyme L were identified as pH of 3.5, temperature of 45 °C, enzyme dosage of 3% (w/v) with a maximum yield of 10% (w/w). S0S were found to be crude oligosaccharides containing 56.5% neutral sugar, having a low molecular weight distribution range between 860 and 9380 Da, composing of galactose, xylose, rhamnose, arabinose, mannose and glucose. Furthermore, S0S showed the free radical scavenging activity with IC50 value of 1.81 mg/mL. These results suggest that S0S are novel oligosaccharides derived from okara, and could be improve value-added utilization of okara as antioxidants in functional foods and nutraceuticals.