Abstract: Effects of separation pressure, temperature, pH and the ratio of E/s on enzymic activity and separation of ACE (angiotensin converting enzyme) inhibitory peptides were investigated. The combination system of hydrolysis-membrane separation to separate ACE inhibitory peptides from hydrolysates was established. The results showed that the effects of separation parameters of membrane separation on enzymic activity and separation of ACE inhibitory peptides are prominent. The combination system of two-times hydrolysis-two-ranks membrane separation possesses the high yield of ACE inhibi-tory peptides as 5.73%, while IC50 (half inhibit concentration) as 0.088 mg/ml. The yields of ACE inhibitory peptides of the two combination system. Such as were one-time hydrolysis-two-ranks membrane separation and of one-time hydrolysis-one-rank membrane separation, are 3.19% and 2.31% respectively, while IC50 values are 0.081 mg/ml and 0.078 mg/ml, respectively.

Key words: membrane separation, angiotensin converting enzyme (ACE), active peptide, hydrolysis