Abstract: Wheat bran was used as raw material to extract protein, water-insoluble fiber and water-soluble fiber, respectively. Wheat bran protein and water-soluble dietary fiber were extracted simultaneously by alkaline ethanol extraction-salting out. The removal of water-insoluble dietary fiber was conducted using α-amylase hydrolysis. Based on single factor tests, the optimal extraction process was determined by using central composite design combined with response surface methodology. The results indicated that the optimal extraction process was enzyme addition amount of 270 U/g, enzymatic reaction temperature of 56 ℃, material/liquid ratio of 1:12, ethanol/alkali ratio of 1:4, extraction temperature of 51 ℃, and ammonium sulfate saturation degree of 33%. Under the optimal conditions, the extraction rate of wheat bran protein, water-insoluble dietary fiber and water-soluble dietary fiber were 5.23%, 88.76% and 3.08%, respectively. The fitted mathematical models for the extraction rates of wheat bran protein and insoluble dietary fiber had a good feasibility.

Key words: wheat bran, protein, water-insoluble fiber, water-soluble fiber, response surface