Exploring Dynamic Changes in Microbial Succession and Flavor-Active Metabolites During Pickled and Dried Mustard Fermentation of Traditional Fermented Vegetables

Pickled and dried mustard (PDM) is a traditional dish of the Hakka people that is well-known in many parts of the world. However, past scientific studies on PDM provide little information on the relationship between the microbiome composition of the PDM fermentation process and flavor formation, which restricts the industrialization and improved quality control of PDM. Therefore, this study investigated the microbiome composition, flavor metabolites, physicochemical properties, and the relationships among them in PDM from Shaoxing. During fermentation, the main aromas of PDM are similar to pine and orange oils, with a strong fat aroma, and are mainly contributed by dodecanal in the early and middle stages of fermentation. As the fermentation progressed, the phenolic and aldehyde contents increased markedly; the major aldehydes in PDM were dodecanal, nonanal, and phenylacetaldehyde. The microbial succession during PDM fermentation was a gradual transition from Weissella sp. and Basidiomycota to Latilactobacillus, Lactiplantibacillus, and Ascomycota. We identified candidate core microorganisms potentially related to characteristic flavor development in PDM: Debaryomyces sp., Weissella cibaria, Lactiplantibacillus pentosus, Weissella sp. NBRC 107272, Latilactobacillus sakei, Cryptococcus sp., Filobasidium magnum, Cystofilobasidium macerans, Weissella hellenica, Levilactobacillus brevis, and Weissella sp. NBRC 107245. The findings of this study will be an important guide to optimizing the production process and quality of PDM.