This study was carried out in order to clarify the antifungal activity and mechanism of the essential oil of Litsea cubeba against Candida albicans. The major components of the essential oil were analyzed, and changes in the cell morphology, surface hydrophobicity, surface charge, intracellular nucleic acid and protein leakage of Candida albicans isolated from contaminated pickles were evaluated after being treated with the essential oil. The results showed that the major components of Litsea cubeba essential oil were citral, limonene, and citronellal. The minimum inhibitory concentration (MIC) was 0.25 mg/mL, and the minimum bactericidal concentration (MBC) was 1 mg/mL. The addition of Litsea cubeba essential oil to yeast extract peptone dextrose (YPD) medium delayed cell growth, impaired cell membrane integrity, and increased cell membrane permeability, indicating that Litsea cubeba essential oil has good membrane permeability, and can disrupt cell structure, disorder cell membrane permeability, and result in leakage of intracellular materials, thus leading to cell death. This study provides a theoretical basis for the application of Litsea cubeba essential oil to inhibit the growth of Candida albicans during the storage of fermented vegetable juice and dairy products.

Umami peptides play important roles in the flavor of fermented broad bean paste (FBBP), and proteases produced by microorganisms contributed to the production of umami peptides. In order to reveal the formation of umami peptides and their relationships with protease-producing microorganisms during the natural fermentation of FBBP, peptidomics and virtual screening were used to identify and screen umami peptides. Meanwhile, macrogenomics was used to analyze the abundance of microbial-derived protease genes during FBBP fermentation. Then, based on the Pearson correlation coefficient, the correlation network diagram of each protease-producing microorganism with umami peptides was constructed. The results showed that a total of two exopeptidases and four endopeptidases were annotated from FBBP. Staphylococcus, Lactobacillus, Aspergillus, and Weissella can produce most proteases. The species Lactobacillus curvatus, Dyella jiangningensis, Erythrobacter sp., and unclassified_g_Pantoea had strong correlation with umami peptides, and they may contribute to the process of protein hydrolysis to produce umami peptides. This study is expected to reveal the formation mechanism of umami peptides in FBBP, and the results of this study provided a better understanding of the relationship between proteases, microbiota, and core umami peptides in FBBP, which could help to improve the umami taste of Pixian Douban paste during fermentation.