Abstract: Our study evaluated the acid and salt tolerance of 9 strains of probiotics to screen them for cheese production. We selected one strain with higher hydrolysis activity and another strain with higher antioxidant activity, and added them to cheddar cheese, respectively. Cheddar cheese without probiotics was used as the control. We studied the viability and antioxidant activity of all samples to determine the effect of various probiotics on antioxidant properties of cheese. The results showed that Lactobacillus helveticus 1.0612 possessed better hydrolysis activity while Lactobacillus rhamnosus 1.0911 possessed better antioxidant activity. During the ripening period, viable counts in the probiotic cheeses were significantly higher than those in the control (P < 0.05), but there was no significant difference between the probiotic cheeses (P > 0.05). For all three cheeses, antioxidant properties were increased first, then decreased, and finally leveled off. The scavenging capacities against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radicals reached the maximum at the 4th month while reducing power reached the maximum at the 5th month. The DPPH and hydroxyl radical scavenging capacity and reducing power (51.05%, 49.97% and 0.66) of the cheese with L. helveticus 1.0612 were significantly higher than those (47.30%, 46.19% and 0.56) of the cheese with L. rhamnosus 1.0911, respectively (P < 0.05). Therefore, we concluded that compared with the strain with good antioxidant activity, adding the strain with high hydrolysis activity to cheese can promote protein breakdown into antioxidant short-chain peptides and amino acids, consequently enhancing antioxidant activity in cheese.

Key words: probiotics, Cheddar cheese, hydrolysis activity, antioxidant activities, ripening period