Abstract: In this study, phenyllactic acid (PLA) was isolated and purified from Chinese vinegar and identified by nuclear magnetic resonance (1H-NMR and 13C-NMR). Furthermore, a rapid method was established to analyze PLA in 72 vinegar products marketed in China by ultra-high performance liquid chromatography-triple quadrupole tandem mass spectrometry (UPLC-MS/MS). The results showed that PLA was detectable in all samples. The concentration of PLA in cereal vinegar was significantly higher than that in fruit vinegar, with average and maximum values of 227.89 and 618.69 mg/L, respectively. The concentration of PLA was closely related to the raw material and fermentation mode. Vinegar made from glutinous rice through solid-state fermentation showed the highest PLA concentration. The time-killing curve method and scanning electron microscopy (SEM) were used to evaluate the antibacterial effect of PLA combined with acetic acid, and the results showed that they had a synergistic antibacterial effect on a variety of spoilage and pathogenic bacteria in foods, and the combined application of PLA and acetic acid could damage the morphology of Staphylococcus aureus and Salmonella typhimurium, leading to the leakage of intracellular contents from S. aureus and the shrinkage of S. typhimurium cells. This study provides a new scientific basis for elucidating the health benefits of vinegar, and a theoretical basis for the application of PLA in food bio-preservation.

Key words: phenyllactic acid; vinegar; ultra-high performance liquid chromatography-triple quadrupole tandem mass spectrometry; antibacterial activity; foodborne pathogenic bacteria