ACE-inhibitory activity of lactic acid bacteria in fermented milks

Twenty-two strains of lactic acid bacteria were screened in vitro for the inhibition of Angiotensin Converting Enzyme (ACE). Amongst these, Lactobacillus delbrueckii ssp. bulgaricus and Lb. helveticus whey fractions exhibited the highest extent of ACE inhibition amounting to 72 and 78%, respectively. Further, processing conditions were optimized for maximizing the liberation of these peptides by Lb. delbrueckii subsp. bulgaricus. Different types of milk, rates of inoculation, temperatures of incubation and duration of incubation, respectively, were tested. Cow standardized milk gave higher extent of inhibition than cow skim, buffalo skim and buffalo standardized milk at 37degreesC. With this, 1 % rate of inoculum suited most rather than 0.5, 2.0 and 3.0%. An incubation temperature of 37degreesC yielded more ACE inhibition than 20, 25, 30 and 42degreesC. With these, incubation up to 8 h was better than longer ones of 12 and 24 h. The final extent of ACE inhibition employing these standardized conditions amounted to 88%. These results find an application in preparing functional Dahi with anti hypertensive property.