Abstract:

Egg white proteins were hydrolyzed by Alcalase to prepare antihypertensive peptides. The effects of four crucial factors on the degree of hydrolysis (DH) of egg white proteins were analyzed by single-factor method. Subsequently, a three factor/three-level Box-Behnken experimental design combining with response surface methodology (RSM) and quadratic programming (QP) was employed for maximizing the Alcalase-catalyzed hydrolysis of egg white proteins and a quadratic regression model was obtained using the Design-Expert software. The optimal hydrolysis conditions were determined as follows: substrate concentration 1.14 %, temperature 58 ℃, pH 10.10, and ratio of enzyme to substrate 6%. Under these conditions, the angiotensin-converting enzyme (ACE) inhibitory activities of 1 mg/ml peptide hydrolysates after hydrolysis for 1, 1.5, 2, 2.5 and 3 h were determined by HPLC to be 25.72% , 66.85%, 36.00% , 43.31% , 50.84%, respectively. It is very clear that the peptide hydrolysate after 1.5 h of hydrolysis has the highest ACE inhibitory activity among the 5 peptide hydrolysates.

Key words: egg white proteins, angiotensin-converting enzyme inhibitory peptides, response surface methodology