Characterization of unique metabolites in γ-aminobutyric acid-rich cheese by metabolome analysis using liquid chromatography-mass spectrometry.

Fermented dairy products comprise many functional components. Our previous study using fermented milk showed that the γ-aminobutyric acid (GABA)-producing Lactococcus lactis 01-7 strain can produce unique metabolites such as antihypertensive peptides, whereas this study was designed to find the unique metabolites in GABA-rich cheese using the 01-7 strain. Metabolites between cheese ripening with the non-GABA-producing L. lactis 01-1 strain (control) and GABA-rich cheese ripening with a mixture of 01-1 and 01-7 strains were compared. GABA and ornithine were detected in GABA-rich cheese using an amino acid analyzer and citrate was detected in the control cheese using HPLC. Metabolome analysis using LC-MS showed that peptides with unknown function and those with antihypertensive activity were higher in the GABA-rich cheese than in the control cheese. Further analysis of the amount of the YLGY derivatives showed that the amount of YL in the GABA-rich cheese was lower than that in the control. PRACTICAL APPLICATIONS: Clarification of metabolites in cheese contributes to the improvement of cheese ripening, thereby providing consumers with unique cheese with good nutritional and functional characteristics. The use of the 01-7 strain as a cheese starter might provide a functional cheese with antihypertensive-, antioxidative-, and anxiolytic-like activities.