Optimization of Enzymatic Hydrolysis Conditions for Hydrolysate Production from Indian Squid (Uroteuthis duvauceli)

Abstract

This study optimized the enzymatic hydrolysis for producing antioxidant-potent protein hydrolysate from Indian squid (Uroteuthis duvauceli) using pepsin, papain, and trypsin, applying response surface methodology. A Box–Behnken design comprising fifteen experimental runs was employed, and the resulting data were used to develop a second-order response surface model. The model adequacy was tested using the coefficient of determination (R² = 0.84). Based on the ridge analysis and response surface plots, the ideal hydrolysis conditions for pepsin, papain, and trypsin were 1:100 enzyme-to-substrate ratio, pH: 2, time: 3.15 h, and temperature 37 °C; 1.5:100 enzyme-to-substrate ratio, pH: 6.25, time: 5.15 h, and temperature 60 °C; and 1.4:100 enzyme-to-substrate ratio, pH: 7.25, time: 6 h, and temperature 37 °C, respectively. DPPH activity (0.1 mM) of papain-aided hydrolysate was found to be maximum, 66.34% against trypsin (52.24%) and pepsin (29.49%) aided hydrolysate, which can be attributed to its high content of antioxidant-rich amino acids. The findings support the reliability of the developed model in predicting the antioxidant characteristics of Indian squid protein hydrolysate produced via enzymatic hydrolysis.