Purification and Production of Novel Angiotensin I-Converting Enzyme (ACE) Inhibitory Bioactive Peptides Derived from Fermented Goat Milk

In the study, five different Lactobacillus cultures i.e. L. rhamnosus (NK2) (KR080695), L. casei (NK9) (KR732325), L. fermentum (M5) (KU366365), L. paracasei (M16) (KU366368), L. fermentum TDS030603 (MTCC 25067) (LF) were studied for their growth behavior, PepX and ACE-inhibitory activities and peptides production from fermented goat milk (Capra aegagrus hircus). The acidity, pH and lactic counts were evaluated for 0, 6, 12, 24 and 48 h at 37 degrees C. During their growth in heat treated goat milk (90 degrees C for 10-15 min), M5 significantly showed maximum titratable acidity (3.25%LA) and highest pH reduction (pH 3.10), while M16 exhibited highest lactic counts (9.35 log cfu/ml) up to 12 h of incubation (P < 0.05). LF significantly produced the highest PepX activity (0.667 O.D.) after 48 h of incubation than other cultures (P < 0.05). NK9 also significantly exhibited highest ACE-inhibitory activity (66.99%) after 24 h of incubation than other cultures (P < 0.05). However, M5 and M16 exhibited the second highest X-prolyl-dipeptidyl aminopeptidase (PepX) and angiotensin converting enzyme (ACE) inhibitory activity than other cultures during fermentation of goat milk. Purified peptides from fermented goat milk were isolated and characterized by amino acids profiling by searching on BIOPEP database, Protein information resource (PIR) database and Database of Antihypertensive peptides (AHTPDB). However, L. fermentum (M5) and L. paracasei (M16) could be explored for the production of ACE inhibitory peptides from fermented goat milk. Fermented goat milk produced by Lactobacillus cultures could be a novel source of ACE-inhibitory peptides.