V. ALEKSANDROVA, G. CHIKOV, G. VELIKOVA, M. DIMITROV and S. G. DIMOV
Sofia University „St. Kliment Ohridski“, Faculty of Biology, BG – 1164 Sofia, Bulgaria
Aleksandrova, V., G. Chikov, G. Velikova, M. DimItrov and S. G. Dimov, 2013. In vivo antioxidant activity evaluation of peptides produced during the fermentation of yoghourt-like dairy products. Bulg. J. Agric. Sci., Supplement 2, 19: 90–100
A collection of few dozens Lactobacillus strains belonging to different species was previously screened for proteolytic activity by polyacrylamide gel electrophoresis during cultivation in skim milk (data not shown). Four Lb. delbrueckii strains were selected based on their good proteolytic activity. They all belonged to the subspecies bulgaricus and lactis, and were used in combination with the commercial yoghourt starter LBB BY D4 (“LB Bulgaricum” PLC, Sofia, Bulgaria) for the production of yoghourt-like dairy products, which were further analyzed for in vivo antioxidant activity caused by the peptides obtained during the fermentation of the milk proteins. It was found that the concentration of the reactive oxygen species (ROS) within living yeast cells (used as indicator for the test) was lower when treated with samples obtained by the combined starters in comparison with the commercial starter only. Differences between the strains were also observed, thus suggesting that different strains possess different levels of probiotic antioxidant properties in vivo. To the authors knowledge this is the first study of the antioxidant activity of the fermented milk protein using an in vivo testing system.