Isolation and Identification of Angiotensin Converting Enzyme Inhibitors from Fermented Milk

To produce fermented milk that can inhibit the activity of angiotensin converting enzyme(ACE), then the angiotensin converting enzyme inhibitor(ACEI) can be purified from the fermented milk. Skim milk was sterilized at 115℃ for 15min, inoculated with 4%(V/V)starter containing L. helveticus, and fermented at 37℃ for 24h. Finally, the fermented milk was obtained with rather high inhibitory activity to ACE. From the whey of fermented milk, two kinds of ACEI pepetides of most functions were purified by using ultrafilter, cation exchange with shanghai 732, gel filter with Sephadex G-15 and several step HPLC. The structures of two peptides were Phe-Pro and Ala-Glu-Glu respectively determined by LC/MS and amine acid composition, and the concentrations of peptides needed to inhibit 50% of ACE activity (IC50) were 12.05μmol/L and 12.42μmol/L, respectively.