The invention relates to a method for preparing an
antioxidant for oil and fat, and belongs to the preparation technology of food additives. The method comprises the following steps: (1) after washing grape
skin residue with water and removing impurities, conducting
freeze drying, and then
grinding and ultramicro-pulverizing for modified treatment to obtain grape
skin residue
powder; (2) successively conducting enzymolysis treatment with alpha-
amylase and
protease on the grape
skin slag powder, and conducting
centrifugal separation after enzymolysis to obtain a supernatant; (3) dialyzing the supernatant to obtain a dialyzate, conducting
freeze drying for the dialyzate and then conducting decolorization, conducting esterification modification treatment after decolorization, and then neutralizing and conducting
centrifugal separation to obtain a supernatant; (4) after conducting dialyzation and
alcohol precipitation on the supernatant, conducting
centrifugal separation to obtain precipitate, conducting
freeze drying on the precipitate to obtain modified
antioxidant dietary fiber, namely a novel
antioxidant. According to the method, simple equipment is needed and the operation is safe, and the obtained antioxidant can be used alone or be compounded with other antioxidants or auxiliaries and is widely applied to oil and fat,
fatty foods, aquatic products, fried foods and the like.