Antioxidative and ACE-inhibitory activities of skim milk fermented with thermophilic <i>Lactobacillus</i> isolated from traditional Indian sweet curd of West Bengal

Fermentation and storage are known to enhance the production of natural antioxidative and angiotensin-I converting enzyme (ACE)-inhibitory components in dairy products. In this study, the antioxidative potential (% ABTS and % DPPH inhibition) and ACE-inhibitory activity of fermented skim milk (fermented at 42°C for 24 h) using 10 <i>Lactobacillus</i> isolates, previously isolated and characterized from the traditional sweet curd of West Bengal, India were evaluated over a storage period of 7 days at 7 ± 2°C. Among all isolates, <i>Lactobacillus delbrueckii</i> subsp. <i>indicus</i> (JSL₂P₂) exhibited the highest functional activity, with ABTS and DPPH inhibition levels of 14.57 ± 0.67% and 14.43 ± 0.72%, respectively, and ACE inhibition of 47.86 ± 1.95% after 24 h of fermentation. These bioactivities further increased during storage. The findings scientifically validate the health-promoting properties of traditional Indian sweet curd prepared with <i>Lactobacillus delbrueckii</i> subsp<i>. indicus</i>, highlighting its potential for commercial application in functional dairy product development and its role in reducing the risk of lifestyle-related diseases.