Study On The Growth Characteristics And ACE Inhibitory Activity Of Lactobacillus Delbrueckii QS701in The Reconstituted Skim Milk

Not only the growth characteristic, proteolytic activity and ACE (angiotensin converting enzyme) inhibitory activity of the Lactobacillus delbrueckii QS701in the reconstituted skim milk was measured, but also discusses acid tolerance, bile salt tolerance and artificial gastrointestinal fluid resistance. The results show that Lb. delbrueckii QS701in10%reconstituted skim milk was growing slowly at37℃in the early culture, growth faster after12h. Their biomass, the content of free amino nitrogen and ACE inhibitory activity reached the highest value were11.2(OD410nm×10),512.8μg/mL Tyr and62.7%at48h. This strain has a certain acid tolerance and bile salt resistant ability through simulated gastrointestinal digestion the viable growth rate of37.04%. Fermented milk produced by Lb.delbrueckii QS701, which was separated into15fractions by Sephadex G25, the ACE of the component3and4had the highest inhibition rate that was up to43.38%and40.52%. It means that the fraction3and4isolated and purified had higher inhibitory activity of ACE component. That bacterial strain had the ability of anti-enzyme digestion by gastrointestinal digestion test in vitro, after hydrolyzation of pepsin and Trypsin respectively, the inhibitory activity of ACE decreased into87.73%and92.72%compared with the original. After continuous digestion, it decreased to90.49%.Strain has a good heat-resisting property, it reached82.67%and69.84%respectively with the heat from100℃to110℃for20min. After collection and concentration, the higher ACE fractions by Sephadex G25separated into25components with RP-HPLC method, the components14and15had the highest ACE inhibition rate of50.66%and.55.75%.