Kinetics of hydrolysis of egg white protein by pepsin

Taking into account the enzyme inactivation and substrate inhibition, the bioreaction mechanism and kinetics characteristic of egg white protein (EWP) enzymatic hydrolysis by pepsin were investigated. A logarithmic equation h = (1/b) ln (1 + abt) indicating the relationship between the degree of hydrolysis (DH) and time was established. For EWP-pepsin system, the reaction mechanism could be deduced from a series of experimental results at different temperatures, pH values, substrate concentrations, and enzyme concentrations. The reaction kinetics and thermodynamic constants (KS = 3916.5 g/l, k2 = 17 202.86 min-1, kd = 21 962.03, Ea = 56.89 kJ/mol, Ed = 51.99 kJ/mol) were responsible for the empirical equations. The results of nonlinear regression of the proposed kinetic model agreed with the experimental data, i.e. the average relative error was less than 5%. As a conclusion, the kinetic equations can be used to fit the enzymatic hydrolysis process of egg white protein and to optimise the operating parameters of bioactive peptides preparation for the bioreactor design.