Abstract:Okara was used as materials to determine the optimum parameters to improve the soluble dietary fiber（SDF）content in okara of β-mannanase enzymatic method and its composition were determined.The results showed that the optimum parameters of further improved the SDF content of extruded okara with cellulase enzymatic method were：enzymatic temperature 50℃，enzymatic time 3 h，enzyme amount（the mass ratio of enzyme and the substrates）1∶500. In this condition，the SDF content of enzymolysis okara was（30.10±0.17）%. The optimum parameters of preparation of high oligosaccharides content SDF according to β-mannanase enzymatic method were：enzymatic temperature 60℃，enzymatic time 4 h，enzyme amount（the mass ratio of enzyme and the substrates）1∶50. After enzymatic hydrolysis，the mixture was subjected to ultrafiltration by Hollow fiber ultrafiltration membrane. The filtrate was concentrated and lyophilized，the yield of crude oligosaccharide was 37.67 %. High performance liquid chromatography（HPLC）analyze showed that the crude oligosaccharide had four kinds of oligosaccharide with different degree of polymerization，total amount was 40.31 %. The content of the best group is divided into molecular weight 1 349 Da，its content is 27.65 %. The degree of the oligosaccharide may be eight when speculated based on the molecular weight. A major oligosaccharide component was obtained when separated the oligosaccharide fractions with dextran gel Sephadex G25. The purity of the main component was verified by Sephadex G15，the results showed that the separated component was a single component oligosaccharide. After calculation，the okara oligosaccharides content obtained through this research was 3.7 g/100 g（in dry okara）.