高活性酪蛋白抗氧化肽的制备方法研究

采用木瓜蛋白酶对酪蛋白进行水解，得到抗氧化活性较好的酪蛋白水解物，并且水解物在木瓜蛋白酶作用下进行类蛋白反应制备出高活性酪蛋白抗氧化肽。第一步制备酪蛋白水解时酶添加量为500 U/g酪蛋白、温度45℃、底物浓度5%、反应时间2 h。第二步类蛋白反应的最优条件为：酶添加量为500 U/g水解物、温度30℃，底物浓度50%、作用时间5.5 h。毛细管电泳结果确认，类蛋白反应修饰后抗氧化肽的组成情况发生变化。抗氧化活性分析结果表明，类蛋白反应修饰后的酪蛋白抗氧化肽对两种自由基的清除能力显著提高。

Preparation of Casein Peptides with High Antioxidant Activity

Peptides with high antioxidant activity were prepared from casein by a two-step method, i.e., first preparation of casein hydrolysates by papain-catalyzed, and then modification of these hydrolysates by plastein reaction with papain. The antioxidant activities of casein hydrolysates and their modification products were evaluated by DPPH assay and ABTS assay. The optimum conditions for casein hydrolysis were casein concentration 5%, papain concentration 500 U/g casein, pH 4.5, temperature 45 for a hydrolysis duration of 2 h, and the optimal plastein reaction conditions were substrate concentration 50%, papain concentration 500U/g substrate, and temperature 30 for 5.5 h reaction. Capillary electrophoresis analysis confirmed that the compositions of antioxidant peptides were changed as a result of plastein reaction. The DPPH and ABTS scavenging activity of casein peptides were remarkably enhanced after enzymatic modification.