Correlation between metabolite changes and microbial succession in millet vinegar produced via traditional solid‐state fermentation

Abstract BACKGROUND Millet vinegar (MV), a type of vinegar obtained by the solid‐state fermentation of millet grains, has a unique production process and flavor. This study investigated the dynamics of microbial succession and flavor compounds during MV fermentation. RESULTS The analysis revealed that MV contains substantial concentrations of acetic acid, oxalic acid, and lactic acid, which were identified as the principal organic acids (OAs), as well as glutamic acid (Glu), alanine (Ala), and valine (Val), which were the principal free amino acids (FAAs). These compounds contributed substantially to the taste of MV. The ratio of essential to nonessential amino acids (AAs) was 74.09%, approaching the benchmark recommended by the World Health Organization/Food and Agriculture Organization (WHO/FAO) for high‐quality protein sources. Lactobacillus , Pediococcus , Pantoea , Staphylococcus , Massilia , and Candidatus phytoplasma emerged as the principal microbial groups positively correlated with lactic acid and oxalic acid accumulation in MV. Acetobacter , Wallemia , Saccharomyces, Xylaria, and Alternaria were found to contribute positively to the production of Glu, Ala, Val, and acetic acid. Finally, Bradyrhizobium and Mesorhizobium were found to be unique to MV. CONCLUSION This study identified the principal metabolites found in MV and highlighted the core microbes present during the traditional solid‐state fermentation of MV. These insights provide valuable guidance for the optimization of MV production. © 2025 Society of Chemical Industry.