Fermentation of milk and soymilk by Lactobacillus bulgaricus and Lactobacillus acidophilus enhances functionality for potential dietary management of hyperglycemia and hypertension

The health-relevant functional benefits of Lactobacillus bulgaricus and Lactobacillus acidophilus fermented milk and soymilk were investigated and targeted for management of hyperglycemia and related complication of hypertension using in vitro models. Free radical scavenging-linked antioxidant activity and enzyme inhibitory activities linked to hyperglycemia (alpha - amylase and alpha-glucosidase) and hypertension (angio-tensin - I converting enzyme, ACE) of fermented substrates were evaluated using in vitro assays. These activities were correlated to phenolic and lactic acid contents. In spite of total phenolic content decreasing over 24 h, the free radical scavenging-linked antioxidant activity increased. alpha-Glucosidase inhibitory activity increased with fermentation, with higher activity in soymilk substrate. alpha-Amylase inhibitory activity was high in milk substrate throughout the fermentation and in soymilk it increased from a lower initial activity. Initial ACE inhibitory activity was high in soymilk and was maintained following fermentation. In milk, initial ACE inhibitory activity was low, which increased following fermentation, especially for L. bulgaricus fermentation. The enhancement of ACE inhibitory activity in milk was correlated to the lactic acid contents with the range of 0.5-1% having the highest activity. This study provides insights that fermentation of milk and soymilk with specific lactic acid bacterial strains can potentially enhance functional properties relevant for hyperglycemia management linked to type 2 diabetes and related complication of hypertension.