Effects of fermentation conditions on the potential anti-hypertensive peptides released from yogurt fermented by Lactobacillus helveticus and Flavourzyme®.

This study investigates the effects of fermentation conditions on the production of angiotensin-converting enzyme inhibitory (ACE-I) peptides in yogurt by Lactobacillus helveticus 881315 ( L. helveticus) in the presence or absence of Flavourzyme®, which is derived from a mould, Aspergillus oryzae and used for protein hydrolysis in various industrial applications. Optimal conditions for peptides with the highest ACE-I activity were 4% (v/w) inoculum size for 8 h without Flavourzyme® supplementation, and 1% inoculum size for 12 h when combined with Flavourzyme®. The yogurt fermented by L. helveticus resulted in IC50 values (concentration of inhibitor required to inhibit 50% of ACE activity under the assayed conditions) of 1.47 ± 0.04 and 16.91 ± 0.25 mg mL−1 with and without Flavourzyme® respectively. Seven fractions of ACE-I peptides from the yogurt incorporated with L. helveticus and Flavourzyme® were separated using the preparative high-performance liquid chromatography. Fraction (F3) showed the highest ACE-I activity with an IC50 of 35.75 ± 5.48 μg mL−1. This study indicates that yogurt may be a valuable source of ACE-I peptides, which may explain the outcomes observed in the experimental and clinical studies and foresee the application of fermented milk proteins into functional foods or dietary supplements. [ABSTRACT FROM AUTHOR]