响应面试验优化裙带菜蛋白酶解工艺及酶解液抗氧化活性

运用响应面分析方法对裙带菜蛋白酶解工艺条件进行优化。经单酶筛选,在单因素试验基础上,以亚铁离子螯合率和1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基清除率为主要指标,水解度为辅助指标,研究酶解时间、酶解温度、p H值、底物质量浓度、加酶量对裙带菜蛋白酶解产物抗氧化活性和水解度的影响,并比较优化条件下的酶解液与常用天然抗氧化剂抗坏血酸、合成抗氧化剂丁基羟基茴香醚(butyl hydroxyanisole,BHA)的抗氧化活性。结果表明:复合蛋白酶是裙带菜蛋白酶解的最适用酶,酶解液螯合亚铁离子能力和清除DPPH自由基的最优条件为酶解时间8.1 h、酶解温度50℃、p H 7.0、底物质量浓度15 g/L、加酶量0.2%(0.3 AU/g裙带菜粉末)。在此条件下,酶解液的亚铁离子螯合率为88.58%,DPPH自由基清除率为59.22%,水解度为29.72%。对比常用抗氧化剂,在亚铁离子螯合能力方面,酶解液显著高于0.01%抗坏血酸和0.01%BHA(P0.05),而在DPPH自由基清除能力和还原能力方面,酶解液低于0.01%抗坏血酸和0.01%BHA(P0.05)。

Optimization of Enzymatic Hydrolysis of Undaria pinnatifida Protein and Antioxidant Activity of Its Hydrolysate

This paper deals with the optimization of the process conditions for the enzymatic hydrolysis of Undaria pinnatifida protein using response surface methodology (RSM). With this aim in mind, after selection of an appropriate enzyme, the effects of hydrolysis time, pH, hydrolysis temperature, substrate concentration and enzyme dosage on the degree of hydrolysis and the antioxidant activity of hydrolysates were investigated using RSM based on one-factor-at-atime experiments. The optimized hydrolysate was compared with the natural antioxidant ascorbic acid and the synthetic antioxidant butyl hydroxyanisole (BHA) in regard to their antioxidant activity. The results showed that protamex was the best enzyme for the hydrolysis of U. pinnatifida protein. The optimal conditions that provided ferrous ion-chelating ability and 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity were determined as follows: hydrolysis time, 8.1 h; pH, 7.0; hydrolysis temperature, 50 ℃; substrate concentrate, 15 g/L; and enzyme dosage, 0.2% (0.3 AU/g). Under these conditions, the rate of chelation of ferrous ion by the hydrolysate was up to 88.58%, which was significantly higher than that by 0.01% ascorbic acid and BHA (P < 0.05). However, in terms of DPPH free radical scavenging percentage (59.22%) and reducing power, the hydrolysate was inferior to 0.01% ascorbic acid and BHA (P < 0.05).