Abstract:In order to develop the angiotensin converting enzyme （ACE）inhibitory peptides of loach protein，the amino acid composition of loach protein was first determined by high performance liquid chromatography.Then，the effects of single enzymatic hydrolysis of loach protein and compound enzymatic hydrolysis on the production of ACE inhibitory peptide were investigated systematically，and tricine sodium dodecyl sulfatepolyacrylamide gel electrophoresis was used to further verify the hydrolysis effects of loach protein by different enzymatic hydrolysis methods. The results showed that loach protein was rich in hydrophobic amino acids（39.823%），branched chain amino acids （18.102%）and aromatic amino acids （8.216%），and was a good source for the preparation of ACE inhibitory peptides. Proline protease，α-chymotrypsin and alkaline protease single enzymatic hydrolysis loach protein，the highest ACE inhibition rate of enzymatic hydrolysis products were 81.01%，64.91% and 87.84%，the highest degree of hydrolysis were 1.48% and 9.04% and 28.29%. Alkaline protease and proline protease were used to carry out stepwise enzymolysis and simultaneous enzymolysis of loach protein. Simultaneous enzymolysis could produce more active ACE inhibitory peptides. The highest ACE inhibition rate was 90.14%，and the IC50 was 0.491 mg/mL.