Optimization of High-temperature Steaming Combined with Snail Enzymatic Modification of Insoluble Dietary Fiber from Grape Peel and Its in Vitro Hypoglycemic Effect

The insoluble dietary fiber (IDF) of grape skins was modified by high-temperature steaming combined with the snail enzyme method using grape skins as raw material, the aim of this study was to increase the yield of soluble dietary fiber (SDF) and improve the physicochemical properties of SDF and IDF. The effects of different factors on the yield of SDF were studied, and the physicochemical indexes of dietary fiber before and after modification were determined. The experimental results were as follows: Steaming time of 60 minutes, steaming temperature of 120 ℃, the material to liquid ratio was 1:25 g/mL, enzyme addition of 3.50%, enzymatic hydrolyswas temperature of 34.0 ℃, and enzymatic hydrolysis time of 55 minutes. Under these conditions, the yield of SDF was 10.25%. The water holding capacity, oil holding capacity, and swelling capacity of modified SDF were increased by 1.74, 1.53, and 1.13 times, respectively. The water holding capacity, oil holding capacity, and swelling capacity of the modified IDF were increased by 1.01, 1.26, and 1.27 times, respectively. Compared with the unmodified SDF and IDF, the structure of the modified SDF and IDF became more loose, and the glucose adsorption capacity, glucose dialysis retardation index, and α-amylase inhibition were significantly improved. Among them, the modified SDF had the strongest glucose adsorption capacity, and the glucose dialysis delay index was also higher than other dietary fiber samples. When the addition amount was 8 mg/mL, the inhibition rate of the modified SDF on α-amylase reaches its maximum value (54.71%). In summary, the modified SDF and modified IDF had better characteristics, which would provide a theoretical basis for modified grape skin dietary fiber.