Integrated metabolomics and sensory analysis reveal the potential roles of glutamate and lipid metabolism in taste formation during the ripening of Monascus-fermented cheese.

The intrinsic mechanisms underlying taste formation during the ripening of a novel mold-ripened Monascus-fermented cheese (MC) remain poorly understood. This study aimed to provide preliminary insights into the mechanisms of taste formation in MC during ripening by integrating electronic tongue (e-tongue) analysis, quantitative descriptive analysis (QDA), targeted metabolite profiling, and non-targeted metabolomics. The combined results of e-tongue analysis and QDA demonstrated that saltiness and sourness intensities significantly increased as ripening progressed. Targeted analysis revealed a substantial accumulation of free amino acids (particularly glutamic acid and branched-chain amino acids), accompanied by marked alterations in free fatty acid and organic acid compositions. These changes reflect intensified proteolysis and lipolysis during ripening. Non-targeted metabolomics identified a total of 99 significantly differential metabolites (variable importance in projection (VIP) > 1 based on OPLS-DA, p < 0.01, |Log2FC| > 2), and multivariate analysis clearly discriminated samples at different ripening stages. Pearson correlation analysis further demonstrated significant associations between key metabolites, such as glutamic acid, amino acid derivatives, and lipid-related compounds, and specific taste attributes, especially umami and saltiness. Pathway enrichment analysis highlighted glutamate metabolism, unsaturated fatty acid biosynthesis, and polyketide biosynthesis as potential primary metabolic pathways underlying taste formation in MC. Overall, this integrated approach expands our understanding of the metabolic profiles associated with taste evolution in MC, providing a valuable biochemical reference for future flavor evaluation of fungal-fermented dairy products.