Abstract:[Objective] This study aims to reveal the biotransformation patterns and metabolic pathways of polyphenols in blueberry juice during mixed fermentation with Leuconostoc mesenteroides R2, Lactobacillus plantarum 9sh, and Lactobacillus fermentum SR2-6. [Method] Blueberry juice underwent mixed fermentation with Leuconostoc mesenteroides R2, Lactobacillus plantarum 9sh, and Lactobacillus fermentum SR2-6 selected in a previous study. Non-targeted metabonomics was conducted based on ultra-performance liquid chromatography-electrospray ionization-quadrupole-time of flight-mass spectrometry (UPLC-ESI-Q-TOF-MS), and the maps of polyphenols and their differential metabolites were drawn. The polyphenols that changed significantly before and after fermentation were analyzed, and the metabolic pathways of polyphenol bioconversion were analyzed via Kyoto Encyclopedia of Genes and Genomes (KEGG). [Result] The fermented blueberry juice contained 726 polyphenols, which included 44.77% flavonoids, 41.32% phenolic acids, 11.98% lignins and coumarins, 0.83% tannins, and 1.10% others. In addition, there were many bioconversion pathways of polyphenols during fermentation, among which tyrosine metabolism, phenylalanine metabolism and other metabolic pathways were significantly enriched. [Conclusion] Mixed fermentation of blueberry juice with Leuconostoc mesenteroides R2, Lactobacillus plantarum 9sh, and Lactobacillus fermentum SR2-6 can produce a variety of polyphenols including flavonoids and phenolic acids. The metabolic pathways mainly involve tyrosine metabolism, phenylalanine metabolism and others. This study can provide a reference for the bioconversion of polyphenols in blueberry juice fermented by lactic acid bacteria.
