Effect of quorum sensing signal molecular analog 4-hydroxy-5-methyl-3(2H)-furanone on the microbial diversity and flavor characteristics of Sichuan Paocai.

Sichuan paocai, a distinctive type of Chinese fermented vegetable, is highly favored by consumers for its unique flavor. Microbial metabolism plays a crucial role in the fermentation process and flavor development of paocai. This study explored the effects of the Quorum sensing (QS) molecular analog 4-hydroxy-5-methyl-3(2H)-furanone (MHF) on the spoilage microorganisms in Sichuan paocai, as well as the microbial diversity and flavor characteristics during fermentation. The results showed that MHF functioned as an AI-2 signaling molecule at a concentration of 100 μmol/L, inducing bioluminescence in Vibrio harveyi BB170. Additionally, MHF effectively inhibited biofilm formation of Klebsiella trevisanii, Providencia ewingii, Enterobacter cloacae, Pichia sp., and Candida tropicalis, while delaying pellicle formation. No significant differences were observed in the total bacterial counts, lactic acid bacterial (LAB) counts, or pH during fermentation with or without MHF. However, the addition of MHF significantly increased the relative abundance of Lactiplantibacillus while decreasing those of Enterobacter and Bacillus. Moreover, MHF supplementation effectively reduced nitrite and butyric acid production, while increasing the content of free amino acids (FAAs) such as aspartic acid (Asp) and glutamic acid (Glu), as well as volatile organic compounds (VOCs), including eucalyptol, linaloolmol and phenylethyl alcohol. Therefore, MHF can delay Sichuan paocai spoilage, increase the relative abundance of Lactiplantibacillus, and enhance Sichuan paocai flavor.