Screening And Fermentation Characteristics Of Lactobacillus Helveticu With ACE Inhibitory Activity S In Traditional Fermented Milk

Lactobacillus helveticus is one of human-origin probiotics from intestinal tract, and a variety of biologically active peptides such as angiotensin-converting enzyme inhibitory peptides can be produced by milk protein hydrolysis via these strains. ACE inhibitory peptides play a significant role in the treatment of hypertension, heart failure, myocardial ischemia, protecting vascular endothelial cells, correcting lipid disorders and anti-atherosclerosis. In this paper, 208 strains of Lactobacillus helveticus which isolated from traditional fermented koumiss, fermented camel milk, fermented bovine milk, sour porridge, Rushan cake, sour milk whey, fresh goat milk, fresh goat cheese and mixed cheese in the Xinjiang, Qinghai, Inner Mongolia, Yunnan, Mongolia and other regions, were screened for ACE inhibitory activity. And then the selected strains were subjected to research of fermentation properties. The main results were as follows:11% sterilized skim milk was fermented by each strain of L. helveticus with a inoculation of 5×106 cfu/g at 37℃and stoped at about pH value to 4.5. Through the determination of ACE inhibitory activity, L. helveticus IMAU30005 was screened out with higher ACE inhibitory activity.Fermentation characteristics (temperature, inoculum and fermentation time) of L. helveticus IMAU30005 was investigated in skim milk or casein and/or whey protein supplement skim milk by the determination of ACE inhibitory activity and content of VPP and IPP. The results showed that the highest ACE inhibitory activity and concentration of VPP and IPP was repectively observed at 30h and 42h while 11% sterilized skim milk supplemented with 1.2% casein was fermented by L. helveticus IMAU30005 at 37℃with an inoculation of 5×106 cfu/g. ACE inhibition rate was 58.47% at 30h and the concentration of VPP and IPP could be as much as 1.278μmol / L and 0.735μmol / L at 42h.It suggested that L. helveticus IMAU30005 could be applied in fermented milk and provide a theoretical foundation for the fulture increase in ACE inhibitory activity of a reference value with the ability to reduce blood pressure in the development of functional dairy products.