美拉德反应对乳清分离蛋白及其水解物抗氧化性的影响

Effect of Maillard Reaction on Antioxidant Activity of Whey Protein Isolate and Its Hydrolysate

以乳清分离蛋白及其蛋白水解物为原料分别与半乳糖发生美拉德反应,研究两者美拉德反应的褐变程度、接枝度及产物荧光光谱的变化,同时以乳清分离蛋白和蛋白水解物作对照,研究两者美拉德反应产物的抗氧化性。结果表明:乳清分离蛋白及其水解物美拉德反应的褐变程度、接枝度及产物的抗氧化性均在4 h达到最大。其中,乳清分离蛋白及其水解物与半乳糖美拉德反应的褐变程度和接枝度最大值分别为1.114、18.431%和1.413、28.273%;两者美拉德反应产物的还原力、2,2’-联氨-二(3-乙基-苯并噻唑-6-磺酸)二铵盐自由基清除能力和1,1-二苯基-2-三硝基苯肼自由基清除能力分别为0.605、46.29%、61.77%和0.923、69.81%、78.43%,均显著高于对照组(P<0.05)。同时,内源荧光光谱发现,美拉德反应改变了乳清分离蛋白及其水解物的构象,使二者的结构更加松散。

Maillard reaction products (MRPs)were prepared from whey protein isolate (WPI) and its hydrolysate (WPH) with galactose (Ga), respectively. Changes in the degree of browning, degree of glycation and fluorescence spectrum of MRPs were investigated during reaction periods. The antioxidant activity of MRPs was evaluated by comparing with that of WPI and WPH. The results showed that the degree of browning (DB), degree of glycation (DG), and antioxidant capacity ofMRPs from WPI and WPH reached the maximum values at 4 h of reaction. The maximum DB and DG values of MRPs fromWPI and WPH with Ga were 1.114, 18.431%, and 1.413, 28.273%, respectively, and the reducing power, 2,2’-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS+) radical scavenging percentages and 1,1-diphenyl-2-picrylhydrazyl (DPPH)radical scavenging percentages of both MRPs were 0.605, 46.29%, 61.77%, and 0.923, 69.81%, 78.43%, respectively, which were significantly higher than those of the controls (P < 0.05). Meanwhile, the intrinsic fluorescence spectra indicated that the structure of WPI and WPH became loose after Maillard reaction.