超声-离子液体处理对乳清蛋白酶解动力学及其产物抗氧化活性的影响

为了阐明超声-离子液体处理后乳清蛋白酶解动力学特性,研究初始底物质量浓度、酶质量浓度和酶解时间对乳清蛋白水解度的影响,在此基础上建立了乳清蛋白-碱性蛋白酶酶解动力学模型,并通过清除1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基法、螯合Fe~(2+)法和还原力法研究了超声-离子液体处理对乳清蛋白酶解产物抗氧化活性的影响。结果表明:超声-离子液体处理后,乳清蛋白的酶解动力学模型发生了改变,其酶解反应所需的临界酶质量浓度降低了43.1%,这表明超声-离子液体处理促使了乳清蛋白酶解。抗氧化实验表明,超声-离子液体处理后,乳清蛋白酶解产物清除DPPH自由基活性和螯合Fe~(2+)能力分别提高了14.4%和28.4%,其还原力也得到了改善。体积排阻色谱分析表明,超声-离子液体处理显著提高了乳清蛋白酶解产物中1~5 ku组分的含量(P0.05),比未处理组提高了12.2%。

Effect of Ultrasound-Ionic Liquid Treatment on Kinetics of Enzymatic Hydrolysis and Antioxidant Activities of Hydrolysates from Whey Protein

In order to elucidate the kinetic characteristics of the enzymatic hydrolysis of whey protein that had been subjected to ultrasound-ionic liquid (UIL) treatment, the effects of initial substrate concentration, enzyme concentration and hydrolysis time on the degree of hydrolysis of whey protein were studied, and a kinetic model for the hydrolysis of whey protein by alcalase was established. In addition, the effect of UIL treatment was evaluated on antioxidant activities of whey protein hydrolysates such as 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, Fe2+ chelating activity and reducing power. Results showed that UIL treatment changed the kinetic model for enzymatic hydrolysis of whey protein. After UIL treatment, the critical enzyme concentration was decreased by 43.1%, suggesting that UIL treatment could promote the enzymatic hydrolysis of whey protein. Antioxidant assays showed that UIL treatment caused a 14.4% increase in the DPPH radical scavenging activity and a 28.4% increase in the Fe2+ chelating capacity of whey protein hydrolysate. Moreover, the reducing power was improved after UIL treatment. Size exclusion chromatography analysis showed that UIL treatment significantly increased the > 1-5 ku fraction from whey protein hydrolysate by 12.2% compared to untreated whey protein (P < 0.05).