Screening Of ACE Inhibitory Peptide Strains From Fermented Milk And Optimization Of Peptide Production Conditions

In today's society,hypertension has become a common chronic disease.Elevated blood pressure causes 7.6 million deaths each year.Angiotensin-converting enzyme plays an important role in regulating blood pressure.ACE inhibitory peptides can effectively reduce ACE activity and regulate blood pressure,which can effectively reduce blood pressure.In recent years,researches on ACE inhibitory peptides and its fermented milk has become a hot spot.There is "koumiss Therapy" in China which can assist in the treatment of hypertension.Although the effect is significant,the price of the koumiss is higher.The experiment in this paper uses Inner Mongolia's superior resource—cow milk as raw milk,and the lactic acid bacteria and yeasts strain isolated from traditional koumiss,which exerts high-yielding ACE inhibitory peptides properties in order to obtain low-cost functional hypotensive yogurt with high ACE inhibitory activity.It provides a reference for further development of probiotic-containing antihypertensive peptide yogurt.In this experiment,koumiss was purchased from herdsmen live in Xilinguole League of Inner Mongolia Autonomous Region.10 strains of lactic acid bacteria and 3 strains of yeast chosen from al]strains that screened from the original koumiss were used in this experiment.One strain of Lactococcus lactis L8 with high ACE inhibition and one strain yeast with high ACE inhibition Yarrowia lipolytica Y2 were obtained by fermenting milk alone with each of 13 strains.Optimizing peptide production conditions of L8 and Y2 co-fermented milk by single factor experiment and orthogonal experiment yogurt with an ACE inhibition rate of 83%was obtained.The yogurt was subjected to in vivo gastrointestinal digestion experiments to determine whether its ACE inhibitory activity was stable or not.The following conclusions are drawn:(1)The lactic acid bacteria and yeast screened from koumiss had good ACE inhibitory activities,among which Lactococcus lactis L8 and Yarrowia lipolytica Y2 had the highest ACE inhibitory activities(40%and 57%,respectively).(2)Through single factor and orthogonal experiment,it was found that the optimal fermentation conditions of high-yielding ACE inhibitory peptide yoghurt were as following:the inoculation amount of bacterial strains L8 and Y2 was 4%,the inoculation ratio was 1:1,and the static fermentation at 26? was conducted for 60 hours.The inhibitory activity of ACE was 83%.(3)High-yielding yield ACE inhibitory peptide yogurt has good stability,and gastrointestinal digestion has little influence on it.After gastric juice treatment,the ACE inhibitory activity was 75%,and after gastric juice treatment,the ACE inhibitory activity was 74%.High-yielding ACE inhibitory peptide yogurt may have the effect of helping to lower blood pressure.