## 3 Results and Discussion
### Correlation between the Microbial Community and Flavor Substances during Fermentation
#### 3.5.3 Correlation between the Microbial Community and Volatile Flavor Substances  
In CF (Figure 9a), _Saccharomyces_ of the dominant fungal genera, and _Achromobacter_ and _Lactobacillus_ of the dominant bacterial genera were significantly and negatively correlated with 2-(4-Methoxyphenyl)ethyl acetate (A9), Hexanoic acid,3-hydroxy-,ethyl ester (A14), 1-Pentanol,4-methyl- (A31), 2-Buten-1-one, 1-(2,6,6-trimethyl-1,3-cyclohexadien-1-yl)- (A42), 4(3H)-Pyrimidinone, 3-methyl- (A47) et al., and significantly and positively correlated with Decanoic acid, ethyl ester (A1), Dodecanoic acid, ethyl ester (A6), Butylphosphonic acid, di(2-phenylethyl) ester (A11), Ethylene glycol acetate formate (A15), 2-Pentanol, acetate (A17), Hexanoic acid, ethyl ester (A19), Phenylethyl Alcohol (A26), 1-Butanol,3-methyl- (A30), p-Tolylacetic acid (A54), Acetic acid,(aminooxy)- (A55), Tricarbomethoxyethyl  
Figure 7: Venn diagram of differential volatile flavor substances during fermentation. (**a**) CF group; (**b**) NF group.  
lene (A59), Ethane, 1,1-diethoxy- (A63) et al. _Cladosporium_, _Meyerozyma_ and _Paucibacter_ showed the opposite results. There was a significant correlation between _Saccharomyces_, _Achromobacter_, _Lactobacillus_ and a variety of esters and alcohols, indicating that _Saccharomyces_ played an important role in the production of volatile flavor substances in CF. Studies have shown that _Lactobacillus_ and _Saccharomyces_ are important contributors of flavor substances in the fermentation process of Chinese liquor [56].  
In NF (Figure 9b), _Wickerhamomyces_, _Achromobacter_, _Bifidobacterium_ and _Lactobacillus_ show a significant positive correlation with Ethylene glycol acetate formate (A15), 2-Pentanol, acetate (A17), Phenylethyl Alcohol (A26), 1-Butanol, 3-methyl-(A30) and Acetic acid,(aminooxy)-(A55), and show a significant negative correlation with Ternpily formate (A3), 2-(4-Methoxyphenyl)ethyl acetate (A9), Hexanoic acid,3-hydroxy-,ethyl ester (A14), Cyclohexanol, 3-(acetyloxymethyl)-2,2,4-trimethyl-(A29), 1-Pentanol,4-methyl-(A31), 2-Buten-1-one,1-(2,6,6-trimethyl-1,3-cyclohexation-1-yl)-(A42), 4(3H)-Pyrimidinone,3-methyl-(A47) and 3-Propoxy-benzoic acid (A52). It can be seen that _Wickerhamomyces_, _Achromobacter_, _Bifidobacterium_ and _Lactobacillus_ are significantly related to a variety of esters, and have a great influence on the flavor substances in the NF. Studies have shown that _Wickerhamomyces_ has a promoting effect on ester synthesis and contributes to the formation of flavor substances [57].  
Figure 8: _Cont_.  
Figure 8: Heatmap of the correlation between the microbial community and the nonvolatile differential. The microorganisms selected in the CF and NF were fungal genera and bacterial genera, with relative abundances \(>5\%\); \({}^{***}p<0.05\), \({}^{***}p<0.01\), \({}^{***}{}^{**}p<0.001\). (**a**) CF group; (**b**) NF group.  
Figure 9: Heatmap of the correlation between the microbial community and differential volatile flavor substances. “_\"\"_” \(p<0.05\), “_\"\"_” \(p<0.01\), “_\"\"_” \(p<0.001\). **(a)** CF group; **(b)** NF group.