Screening of lactic acid bacteria with antioxidant capacity and its effect on quality of quark cheese.

The addition of adjunct culture has a significant impact on the quality of cheese. To screen adjunct culture with high protein hydrolysis and antioxidant capacity, this study evaluated 12 strains of lactic acid bacteria based on the acid production, protease activity, proteolysis, and antioxidant capacity. The potentially beneficial strain was used as adjunct culture to make quark cheese. The effect of adjunct culture on cheese quality was assessed by examining physicochemical indices, titration acidity changes, lactic acid bacteria count, texture alterations, and antioxidant activity during storage. Results showed that Lactobacillus kefiranofaciens XZ-54, which had a weak acid-producing capacity, high protease activity, protein hydrolysis, and antioxidant capacity, had the potential to be used as an adjunct fermenter for quark cheese. The addition of XZ-54 had no significant effect on the physicochemical parameters, hardness, and spread ability of quark cheese (P > 0. 05), and the viable counts of XZ-54 in the cheese were maintained above 107 CFU/ g during the 21-day storage period. Additionally, it significantly enhanced the DPPH free radical, ABTS cationic radical, and hydroxyl radical scavenging activities of the cheese. Therefore, Lactobacillus kefiranofaciens XZ-54 could be effectively employed as an adjunct culture in quark cheese, improving its antioxidant qualities and demonstrating significant potential for development and application. [ABSTRACT FROM AUTHOR]