Study on the Enzyme Based Extraction of Soluble Dietary Fiber from Sweet Potato Dregs

Objective: To increase the yield of soluble dietary fiber (SDF) in sweet potato dregs. Method: The dried and smashed sweet potato dregs were used as the raw materials. First, the insoluble dietary fiber (IDF) was converted to SDF by cellulase in the materials. And the impurity in the sample was removed by treating with amylase, diastatic enzyme and Na2CO3 and then precipitated by adding ethanol. The precipitate was collected and the soluble dietary fiber (SDF) was obtained. Result: The optimized conditions to extract the SDF, explored through singer factors and orthogonal experiment, were 100 μl of amylase, 90 μl of cellulase, reaction time of 3 h, temperature of 40℃, and pH of 5.6. The contents of the SDF in sweet potato dregs could be increased from 10.06% to 25.52% compared with the enzyme-gravimetric method, which raised by 15.46%. Conclusion: The yield of SDF in sweet potato dregs is affected by multiple factors, such as the quantity of amylase or cellulase, the reaction time, the pH value and reaction temperature.