以牦牛（Bos grunniens）乳酪蛋白为原料，用胃蛋白酶、胰蛋白酶、碱性蛋白酶、木瓜蛋白酶和风味蛋白酶制备酪蛋白酶解产物，分别测定其DPPH自由基清除活力，发现碱性蛋白酶酶解产物的清除活力显著高于其他酶解产物（p＜0.05）。测定不同水解时间点酪蛋白酶解产物的DPPH自由基清除活力，发现第7 h酶解产物的清除活力显著高于其它水解时间点的样品（p＜0.05）。还分析了碱性蛋白酶7 h酶解产物的理化指标，发现其水解度、三氯乙酸氮溶解指数和蛋白质回收率均较高，表明此时大部分酪蛋白已降解，且酶解产物中短肽段的含量较高，用碱性蛋白酶制备具有DPPH自由基清除能力的酪蛋白酶解产物时得率较高，而其氨基氮含量相对较低，适宜作为保健食品功能性基料。

The DPPH radical scavenging activity of enzymatic hydrolysate of yak casein by different enzymes was studied. It was found that hydrolysates catalyzed by Alcalase showed the highest scavenging effect (p<0.05). Its scavenging effect varied with the hydrolysis time. When the hydrolysis time was 7 h, the obtained hydrolysate had the highest antioxidation property (p<0.05).Besides，the hydrolysis degree, TCA-soluble nitrogen index, short chain peptide content and protein recovery rate of casein hydrolysate by Alcalase for 7 h were very high, indicating a degradation of the most yak casein. In addition, the amino acid content of this hydrolysate was much lower than 15%.

国家863计划资助项目（2008AA10Z320）；国家科技支撑计划（2006BAD04A06）；中国农业大学青年启动基金（2006020）