水牛奶乳清蛋白制备抗氧化活性肽工艺的研究

实验是以水牛奶为原料,分离纯化后得到乳清蛋白。利用碱性蛋白酶、中性蛋白酶、胰蛋白酶、木瓜蛋白酶和胃蛋白酶5种不同的蛋白酶对水牛奶乳清蛋白酶解以制备抗氧化活性多肽。酶筛选结果显示,中性蛋白酶是最适宜酶解水牛奶乳清蛋白制备抗氧化活性肽,其酶解液的还原能力和DPPH自由基清除率较其他4种酶高。探讨酶解反应时pH、温度、时间、酶浓度对酶解反应的水解度、酶解液的还原能力和DPPH自由基的清除率的影响,在单因素试验基础上,采用响应面法对酶解工艺进行优化。结果表明,中性蛋白酶酶解乳清蛋白的最佳工艺参数为:pH为7.4,温度为50.5℃,酶与底物浓度比为2.1%,酶解时间5.0h,此时2mg/mL酶解物的DPPH自由基清除率为32.58%。实测结果与预测值吻合效果良好。

Preparation of antioxidant peptides of whey protein from the buffalo milk

The whey protein was separated from the buffalo milk.The whey protein of the buffalo milk was hydrolyzed with neutrase to prepare antioxidant peptide.Studying the effects of pH,temperature,time and enzyme-to-substrate ratio on degree of hydrolysis,DPPH radical-scavenging capacity and reducing power with neutrase.It was found that the hydrolysates with neutrase had the best effect of reducing ability and scavenging to DPPH free radical.Hydrolysis conditions for preparing protein hydrolysates from whey protein was used single factor experiments and response surface methodology(RSM) to optimize the enzymatic processes.An enzyme to substrate level of 2.1%,temperature of 50.5 ℃,a hydrolysis time of 5.0 h and the pH of 7.4 were found to be the optimum conditions to obtain a higher DPPH radicalscavenging capacity of hydrolysis,which the DPPH radical-scavenging capacity was up to 32.58%.Therefore,there was a good accordance between the predicted and observed values.