Dietary fiber preparation from sweet potato by combined technology of enzymolysis with alkaline hydrolysis

In order to develop an optimal preparation procedure of dietary fiber from sweet potato that was red picea yellow heart by combined technology of enzymolysis with alkaline hydrolysis， single factor and orthogonal array design experiments were carried out and the properties of dietary fiber product were studied. The results showed that the optimum preparation procedure was based on enzymolysis with addition of lipase of 0.5%， mixing enzyme （α-maylase and glucoamylase）dose of 0.6%， papain of 0.2% alkaline hydrolysis for 1.5 h at 60℃with pH 8.5. Under such conditions， the yield of dietary fiber could reach 66.31%， the contents of dietary fiber could increase from 24.21% in the raw materials to 83.74% in the soluble product. The swelling capacity， water holding capacity and oil holding capacity of dietary fiber product was 6.23 mL/g， 9.33 g/g and 3.96 g/g respectively， the functional properties were good.