Characteristic Flavor Compounds and Microbiota during the Fermentation of Changsha Stinky Tofu Brine and Correlation between Them

In this study, the volatile composition and characteristic flavor compounds of Changsha stinky tofu brine during fermentation were analyzed and identified by headspace solid phase microextraction coupled to gas chromatography-mass spectrometry (HS-SPME-GC-MS) with internal standards based on odor activity values (OAV). The dominant microbiota was investigated by shotgun metagenomic sequencing, and the correlation between the dominant microbiota and the characteristic flavor substances was analyzed by calculating Pearson’s correlation coefficients. Results showed that a total of 75 volatile flavor compounds were identified during the 120-day fermentation period, including phenols, indoles, alcohols, acids, aldehydes, ketones, esters, and ethers. Phenol, p-cresol, indole, 3-methylindole, butyric acid, isovaleric acid, 4-ethylphenol, trimethylamine, 3-methyl-1-butanol, 2-heptanol, 1-hexanol, 3-octanol, 1-octen-3-ol, 2-undecanol, phenethyl alcohol, (E,E)-farnesol, ethyl 3-phenylpropionate, 4-dodecanolide and 1-nonanal were identified as the characteristic flavor substances in the whole fermentation process. The predominant microorganisms identified were Clostridium bacterium SYSU GA17129, Clostridiales unclassified, Clostridium ultunense, Sporanaeromonas acetenes, Keratinibaculum paraultunense, Massiilibacterium senegalense, Aneurinibacillus aneurinilyticus, Pseudogracilibacillus auburnensis, Paencaligenes hominis, Ignatzschineria sp. F8392, and Ignatzschineria indica. Moreover, C. bacterium SYSU GA17129, A. aneurinilyticus, and S. acetigenes had significant correlations with 12 characteristic flavor components (P < 0.05), which were the major microbiota associated with the flavor of Changsha stinky tofu brine. This study provides a theoretical basis for promoting the stability of the flavor quality of Changsha stinky tofu.