Use of response surface methodology to describe the combined effects of pH, temperature and E/S ratio on the hydrolysis of dogfish (Squalus acanthias) muscle

Response surface methodology was used to study the effects of pH, temperature and enzyme – substrate ratio (E/S) on the degree of hydrolysis (DH) of dogfish muscle protein. The effect of the hydrolysis variables was described using a three-level Box–Behnken factorial design giving a mathematical model that shows the influence of each variable and their interactions. Based on degree of hydrolysis (DH) of the original substrate, the hydrolysis variables were optimized at a pH of 8.3, a hydrolysis temperature of 53.6°C and an E/S of 3.6% (w/w). The coefficient of determination (R2ad) was greater than 95%, and a lack-of-fit test revealed a non-significant value for the DH model equation, indicating that the regression equation was adequate for predicting the degree of hydrolysis under any combination of values of the variables.