The ACE-inhibitory Preparation Derived From Fermented Milk

Angiotensin-converting enzyme (ACE) perhaps produces a big change in blood pressure due to converting angiotensin I to the potent vasoconstrictor angiotensin II and inactivating the vasodilator bradykinin. Currently, various ACE inhibitors are being used as antihypertensive agents. The ACE-inhibitor(s) obtained out of fermented milk were prepared by ultrafiltration.The effects of proteolytic activity of proteinase from lactic acid bacteria and their growth properties on ACE inhibitor were studied. The more proline or short peptides containing proline in fermented milk, the stronger the ACE activity was inhibited . The value of titratable acidity was higher, the stronger the ACE-inhibitory activity. The 5 strains of lactic acid bacteria (L. helveticus H-l , H-2, LH and 1. easel C, LC) showed the ability in reducing ACE activity when they was used as starters for the fermentation of skim milk. It was seen that the skim milk cultured with L. helveticus H-l and fermented at 37癈 for 1 8h had the strongest ACE-inhibitory activity.To promote the ACE-inhibitory activity, ultrafiltration was applied to concentrate antihypertensive product. The product, after ultrafiltration had cut off molecular weight near to 1 0000 under 1 .38 X 1 05Pa pressure at about 20 癈 .The fermented milk with ACE inhibitory activity showed a decline inhibition towards ACE activity as cold storage increased. However, the whey before ultrafiltration had less loss in the ACE-inhibitory activity. The ACE-inhibitory activity of the product kept stability during cold storage or freezing storage as well as incubation at 90 癈 for 1 hour. The ACE inhibitory activity of the ultrafiltration product after adjusting pH to 8.3 declined at about 20癈, but there was no loss for ACE inhibitory activity under refrigerated storage conditions.