Assessment of the antioxidant and ACE-inhibitory activities and some quality characteristics of Kaşar cheese produced by probiotic Lactobacillus acidophilus

In this study, four types of Kaşar cheese were produced using raw milk (C), starter culture (Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus) (S), starter culture + probiotic Lactobacillus acidophilus ATCC 4356 (SLA), and probiotic L. acidophilus ATCC 4356 (LA) were produced and ripened at 6 ± 2 °C for 150 days. The physicochemical, microbiological, proteolysis, electrophoretic (Urea-PAGE), ACE-inhibitory, and antioxidant activity analyses of vacuum-packed Kaşar cheeses were performed on 5, 30, 60, 90, 120, and 150 days of ripening. During ripening, no significant differences (p > 0.05) were detected in total solids, fat, and protein values of Kaşar cheeses. Titratable acidity, water-soluble nitrogen (WSN), ripening index (RI), and electrophoresis results of cheese samples showed an increase while pH values decreased. Also, the degradation products of αs1-casein were higher than those of β-casein. The number of probiotic L. acidophilus ATCC 4356 after scalding decreased by an average of 1.57 log cfu/g. However, probiotic bacteria count increased during ripening and maintained their viability. The addition of L. acidophilus ATCC 4356 improved the bioactivity, electrophoresis, titratable acidity, and ripening index results of Kaşar cheese. ACE-inhibitory activity of Kaşar cheeses increased during ripening and had the highest value on the 150th day of ripening. Furthermore, antioxidant activity of Kaşar cheeses increased on the 60th day of ripening and then decreased. Consequently, the combination of probiotic bacteria and starter culture had a positive effect on the physicochemical, microbiological, and proteolytic properties of Kaşar cheese.