Abstract: Tilapia waste was used as the material to conduct hydrolysis by alkaline protease. The degree of hydrolysis (DH) of protein from tilapia waste was determined to explore the optimal enzymatic hydrolysis conditions. The results indicated that the optimal hydrolysis conditions for tilapia waste were hydrolysis temperature of 50 ℃, substrate concentration of 20 g/L, enzyme concentration of 0.067 g/L, hydrolysis pH of 9.50 and hydrolysis time of 180 min. Under the optimal hydrolysis conditions, the DH of tilapia waste was 22%. Meanwhile, a kinetic model of hydrolysis was established, which revealed an inactivation constant (Kd) of 37.9 min-1 for enzyme, enzymatic reaction rate constant (K2) of 244.2 min-1, Michaelis-Menten constant (KM) of 29.27 g/L, and the maximum reaction rate (Vmax) of 28.41 g/(min·L) at 50 ℃. The kinetic equation of enzymatic hydrolysis of tilapia waste protein was derived. The proposed kinetic model exhibited a convenient determination of kinetic parameters by a few experiments.

Key words: tilapia waste, alkaline protease, enzymatic hydrolysis, kinetics