Effect of mixed fermentation with Lacticaseibacillus paracasei SMN-LBK and Limosilactobacillus reuteri LBK on the flavor precursor and flavor formation of Kazak cheese

Previous research has demonstrated that Lacticaseibacillus paracasei notably enhances flavor stability with the cost of diminishing the inherent milk flavor in cheese, which may be rescued by the incorporation of Limosilactobacillus reuteri . To investigate the effects of mixed fermentation with Lacticaseibacillus paracasei SMN-LBK and Limosilactobacillus reuteri LBK on the formation of taste during the ripening period of kazak cheese, this study determined its sensory attributes, flavor precursors, volatile flavor components (VFCs), and Odorant Activity Value (OAV). The mixed fermentation increased the levels of organic acids, aromatic and umami amino acids, saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs), ultimately intensifying the concentration of aldehydes and ketones. Importantly, 2,3-butanadione, 1-octane-3 ketone, 2-undecone and 1-octane-3 alcohol were prominently enriched in the mixed fermented cheese, which were contributing to the distinctive milk aroma. This study provided insights into the mechanism of flavor formation during mixed fermentation of Kazak cheese. • Mixed fermentation yields a richer milk flavor than single bacterial fermentation. • Key ketone volatile compounds in mixed fermentation contributed to milk flavor. • Mixed fermentation increased the content of organic acids, SFAs and MUFAs. • Mixed fermentation led to a reduction in the content of bitter amino acids.