Enzymatic hydrolysis of protein isolate from hull-less pumpkin oil cake: Application of response surface methodology

Enzymatic hydrolysis of protein isolate from hull-less pumpkin (Cucurbita pepo L.) oil cake was studied by response surface methodology, using a central-composite experimental design. The hydrolysis was carried out with an acid protease, at temperature of 30 °C and pH 3.00. Second-order polynomial model was proposed with regard to of effect of time, enzyme and NaCl concentration. The mathematical model showed good fit with the experimental data, since the R2 of 0.946 indicated that 94.6% of the variability within the range of values studied could be explained by the model. A hydrolysis time of 32.5 h, enzyme concentration of 0.137% (v/v) and NaCl concentration of 0.84% (w/v) were found to be the optimal conditions to achieve the highest value of degree of hydrolysis (DH).