Flavor formation and microbial community dynamics in Dong ethnic fermented Anyu

Traditional Dong-fermented Anyu exhibits a distinct organoleptic profile, with microbial metabolic activities driving the development of its characteristic flavor. To elucidate the relationship between characteristic flavor compounds and microbial communities during Anyu fermentation, flavor precursor conversion, volatile compound profiles, and microbial community succession were systematically tracked. During fermentation, the concentrations of umami amino acids (Asp, Glu) and unsaturated fatty acids (EPA, DHA, linoleic acid) increased significantly(P < 0.05), while IMP levels (0.14 mg/g) peaked at 150d. Gas chromatography-ion mobility spectrometry (GC-IMS) analysis identified 60 volatile flavor compounds, including 14 key compounds such as ethyl 2-methylbutyrate and ethyl 2-methylpropionate. Following a 150d fermentation period, esters (61.92 %) exhibited a significant increase and became the predominant volatile compounds in Anyu. 16S rRNA sequencing revealed distinct structural shifts in the bacterial community compared to the fungal community (P < 0.05), with Firmicutes becoming the predominant phylum at 95.02 % relative abundance. At the genus level, Tetragenococcus, Staphylococcus, Bifidobacterium, and Lactobacillus were identified as the dominant genera. Correlation analysis found that Tetragenococcus (a dominant bacterium) was negative associated with most bacteria, while Tetragenococcus and Staphylococcus were strongly linked to key flavor precursors and key aroma compounds in the fermentation. In addition, KEGG functional annotation revealed the metabolic pathways underlying flavor compounds formation, including carbohydrate metabolism, lipid metabolism, amino acid metabolism, and nucleotide metabolism.