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

摘要： 母乳是婴幼儿的最佳食物来源,而乳清蛋白是营养和活性物质的基础,其中生物活性肽对人体健康具有重要促进作用.为研究母乳乳清蛋白抗氧化活性肽,采用中性蛋白酶、碱性蛋白酶、木瓜蛋白酶和胰蛋白酶4种酶制备抗氧化活性多肽,通过单因素试验和响应面分析对乳清蛋白酶解工艺进行优化.结果表明:中性蛋白酶最适于母乳乳清蛋白抗氧化肽的制备,此时的最佳工艺参数为pH 7.21、反应温度50.03℃、酶与底物比(E/S)4 486.68 U/g、酶解时间5h;影响1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基清除率的因素大小为:酶与底物比＞温度＞pH值.利用大孔树脂、葡聚糖凝胶过滤色谱G-25、G-15分析得出组分峰Ⅰ抗氧化活性最强,其DPPH自由基清除率达到了60.31％.

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