Fermentation characteristics and angiotensin I-converting enzyme-inhibitory activity of Lactobacillus helveticus isolate H9 in cow milk, soy milk, and mare milk.

This research investigates the fermentation characteristics and angiotensin I-converting enzyme-inhibitory activity of Lactobacillus helveticus isolate H9 in cow milk, mare milk and soy milk. The findings suggest that the bacteria has promising probiotic properties, specifically in cow milk, which make it suitable for the production of probiotic foods.

Objective and Method

• The objective of the study was to evaluate the properties of L. helveticus H9 when fermented in different types of milk namely cow, mare, and soy milk.
• The characteristics monitored were pH, titratable acidity, free amino nitrogen, and viable bacterial counts – the number of live bacteria present in the milk after fermentation.
• The level of Angiotensin I-converting enzyme (ACE)-inhibitory activity of L. helveticus H9 along with the content of Val-Pro-Pro (VPP) and Ile-Pro-Pro (IPP) peptides were also assessed. These components are noted for their ACE inhibition, which can help in lowering blood pressure.

Findings

• Throughout storage, the pH and titratable acidity stayed stable in yogurts produced from all milk types and all inoculation amounts. This indicates that different types of milk and various concentrations of the bacteria don’t affect the pH or acidity of the fermented product greatly.
• There was a range of 10(6.72) to 10(8.59) cfu/g of live bacterial counts in all stored yogurts, showing that a good amount of bacteria survived during storage, ensuring the benefits of the probiotic would be present over a long period of time.
• The research found that the highest ACE-inhibitory activity (70.9-74.5%) was achieved at inoculation concentrations of 5×10(6) cfu/mL. For this concentration of bacteria, the ACE inhibition was at its highest, which would make it the most beneficial for anyone needing to lower their blood pressure.
• However, none of the VPP and IPP tripeptides were produced in yogurt made from soy milk or mare milk, suggesting that the L. helveticus H9 strain doesn’t elicit the same beneficial properties in these types of milk.

Conclusion

• The study concludes that L. helveticus H9 has promising probiotic properties, particularly when fermented in cow milk. Its high ACE-inhibitory activity makes it a good contender for the production of probiotic foods, especially for those having high blood pressure.