谷氨酰胺转氨酶对酸奶乳清蛋白抗氧化活性的影响

Effect of Transglutaminase on Antioxidant Activity of Whey Protein in Yoghurt

以酸奶乳清为原料,将添加或不添加谷氨酰胺转氨酶(TG)分为TG组和空白组,通过3种截流分子质量的超滤膜对酸奶乳清蛋白进行分级分离,各自得到4种分子质量的超滤酸奶乳清蛋白(UFMP)。以DPPH·及还原力抗氧化体系研究各组分的抗氧化活性,采用SDS-PAGE和氨基酸自动分析技术研究各组分肽组成和游离氨基酸组成及其含量变化。结果表明:TG组各UFMP组分的抗氧化活性大于空白组;一些乳清蛋白肽组成和游离氨基酸种类及含量的显著变化(P<0.05),这是导致组间抗氧化活性提高的主要原因。在空白组和TG组内,UFMP的抗氧化活性与其分子质量呈显著负相关(P<0.05),这可能与小分子蛋白质活性基团的暴露及其空间结构的反应灵活性有关。

Effect of adding transglutaminase（TG） on the antioxidant activity of yoghurt whey protein was studied in this paper. Whey protein in yoghurt with TG treatment or not was fractionated by centrifugal ultrafiltration, and ultrafiltration fermented milk protein（UFMP） was obtained. The methods of DPPH radical scavenging and reducing power were used to measure the antioxidant activity of UFMP. The changes of composition and quantity of molecular weight and free amino acids were analyzed by SDS-PAGE and amino acid automatic analyzing technology. The results suggested that the antioxidant activity of UFMP from TG group was significantly stronger than the control group（P0.05）, which indicated that adding TG contributed to enhance antioxidant ability of whey protein. The change of peptide composition and significant differences of the composition and quantity for some amino acids were the main cause of the change of the antioxidant activity between groups. In addition, the negative correlation between molecular weight of UFMP and antioxidant activity was verified in all fractions. It might be concluded that the molecular weight and compositions of peptide and free amino acids in UFMP affected by TG were closely related to its antioxidant capability.