棉籽多肽的制备及其自由基清除能力研究

Preparation of cottonseed peptide and its free radical scavenging capacity

以碱溶酸沉法提取的棉籽蛋白为原料,分别用碱性蛋白酶、中性蛋白酶、胃蛋白酶、木瓜蛋白酶对其进行水解,比较4种蛋白酶水解棉籽蛋白的水解度及棉籽多肽自由基清除能力。结果表明:中性蛋白酶水解所得棉籽多肽自由基清除能力较强。在单因素试验基础上,采用正交优化试验,得到中性蛋白酶水解制备棉籽多肽最佳条件为:水解时间5 h,水解温度45℃,pH 7.5,加酶量8 000U(100 mL 5%棉籽蛋白溶液)。在最佳条件下棉籽蛋白的水解度为11.23%,制备的棉籽多肽对超氧阴离子自由基清除率为72.48%,对羟自由基清除率为89.01%,其10倍稀释液对DPPH自由基清除率为84.67%,与0.5 mg/mL VC的自由基清除能力相当。

The cottonseed protein prepared by alkali extraction and acid precipitation was hydrolyzed respectively by Alcalase, Neutrase, Pepsin and Papain, and the degrees of hydrolysis of cottonseed protein and scavenging capacities on free radicals of cottonseed peptide obtained were compared. The results showed that the cottonseed peptide produced by Neutrase presented stronger free radical scavenging activi- ty. On the basis of single factor experiment, the preparation conditions of cottonseed peptide by Neutrase hydrolysis were optimized by orthogonal experiment as follows： hydrolysis time 5 h, hydrolysis temperature 45℃, pH 7.5, enzyme dosage 8 000 U（ 100 mL 5% of cottonseed protein solution）. Under these conditions, the degree of hydrolysis of cottonseed protein reached 11.23%, the scavenging rates of cottonseed peptide on superoxide anion free radical and hydroxyl free radical were 72. 48% and 89. 01% respectively, and the scavenging rate of ten times - diluted cottonseed peptide solution on DPPH free radical was 84. 67%. The free radical scavenging capacity of cottonseed peptide was similar to that of 0. 5 mg/mL vitamin C.