Abstract: Preparing the Angiotensin Converting Enzyme (ACE) inhibitory peptides fermented by probiotic has become a new hot pot in recent years, and it was significant to the development of the functional food market. Proteolytic activity of Lactobacillus helveticus was studied in this article and the ACE-inhibitory activity of the products was also researched. It showed that the products harvested in the period of logarithm growth have better performance. After 16h fermentation, the ACE -inhibitory activity reached to 44.17% and cell count was 107CFU/ml in the products. The ACE-inhibitory activity of the product ultrafiltratedby 10000D molecular weight membrane is 2.5 times higher than is the product that not ultrafiltrated. The IC50 reaches to 19.63μg/ml. Finally two methods of dryness are studied, one is spray- dry and the other is freez- dry. ACE-inhibitory activity of the products is not affected by these two methods. Output of the product made by the freeze-dried method is higher: it reaches to 106.08g/L, and IC50 of the product is 50.28μg/ml.

Key words:  , Lactobacillus helveticus； whey protein； proteolytic activity； ACE-inhibitory activity；