关键词: 母乳乳清蛋白；酶解；响应面优化；抗氧化活性；分离纯化

Abstract: Breast milk is the best source of food for infants and young children, and the whey proteins contained in the milk are the base of nutritional and bioactive substances including bioactive peptides, which play an important role in promoting human health. In this research, the antioxidant activities of peptides prepared by enzymatic hydrolysis of breast milk whey proteins with four different proteases, i.e., neutral protease, alkaline protease, papain and trypsin, were assessed and compared. The hydrolysis conditions were optimized using combination of one-factor-at-a-time method and response surface methodology. Neutral protease was found to be the most suitable enzyme for the production of antioxidant peptides from breast milk whey proteins. The optimal hydrolysis conditions were established as follows: pH 7.21, 50.03 ℃, an enzyme/ substrate ratio of 4 486.68 U/g and 5 h. The effect of hydrolysis parameters on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity was in the decreasing order: enzyme/substrate (E/S) ratio > temperature > initial pH. Fraction I with the highest antioxidant activity was separated chromatographically with macroporous resin, Sephadex G-25 and Sephadex G-15, which could scavenge 60.31% of DPPH radical.

Key words: breast milk whey proteins; enzymatic hydrolysis; response surface optimization; antioxidant activity; purification