Preparation of Antihypertensive Peptide from Hydrolyzing Peanut Protein by Trypsin Covalently Immobilized on Chemically Modified Chitosan-coated Fe3O4 Particles

The aim of this study was mainly on apply immobilized trypsin which covalently linked with chemically modified chitosan-coated Fe3O4 particles to producing the antihypertensive peptide by hydrolyzing peanut protein. Response Surface Methodology (RSM) was employed to optimize the hydrolysis conditions, including Enzyme/substrate ratio, temperature, pH and time. Results showed that enzyme immobilization technology improved the thermal and pH stability of trypsin. The minimum IC50 value for Angiotensin Converting Enzyme (ACE) inhibitory activity (0.76 mg/mL) was obtained at the E/S ratio of 3.52, the temperature of 54.65°C, the time of 2.95 h and pH of 8.43, which was agreement with the predicted value (0.77 mg/mL) estimated by RSM within a 95% confidence interval. Moreover, a modest increase in the degree of hydrolysis promoted the ACE inhibitory activity of the hydrolysates, but excessive hydrolysis would lead to a decrease in ACE inhibitory activity.