Rational approach to sequential optimization of antioxidative whey protein hydrolysate production
Keywords:Hydrolysis of protein, Whey protein hydrolysate, Sequential optimization, Degree of hydrolysis, Antioxidant activity, Reducing power
AbstractA two-step method for sequential optimization was designed based on the role of hydrolytic factors in the preparation of antioxidative whey protein hydrolysates (WPH). In the first step, the rates of reaction- related variables such as pH, temperature and the enzyme/substrate (E/s) ratio (w/w) were optimized to 1.5, 37°C and 1:100 for pepsin, 8, 42°C and 1:100 for trypsin, and 7.8, 37°C and 1:50 for pancreatin, respectively, with maximum degrees of hydrolysis of 4.5%, 14% and 15.2%, respectively. In the second step, hydrolysis was performed at the optimum conditions determined in the first step. The optimum hydrolysis times were 1.5 h for pepsin and 2 h each for trypsin and pancreatin based on their maximum reducing powers of 0.31, 0.55 and 0.62, respectively. In sequential hydrolysis, the optimized pepsin hydrolysates with subsequent action of trypsin and pancreatin individually were optimized at their respective E/s ratios of 1:50 and 1:100 (w/w) based on their respective degrees of hydrolysis of 13.6% and 14.8%, while the optimum hydrolysis times were 4.5 h and 2.5 h for reducing powers of 0.66 and 0.75, respectively. This study indicates that sequential optimization for the production of antioxidative WPH could be better than the traditional one factor at a time (OFAT) method.