## 3 Results
### Effects of Pre-Fermentative Addition of UFAs Mixture on Volatile Compounds Production
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Treatments** & **E\_Control** & **E\_L** & **E\_H** & **B\_Control** & **B\_L** & **B\_H** & **\_p Value** \\ \hline \multicolumn{1}{c}{Fermentation duration time (h)} & 326 & 326 & 446 & 326 & 446 & 446 \\ Maximum biomass (g DCW/L) & 2.44 \(\pm\) 0.09 a & 2.59 \(\pm\) 0.06 a & 2.77 \(\pm\) 0.14 b & 2.36 \(\pm\) 0.09 a & 2.65 \(\pm\) 0.04 b & 2.80 \(\pm\) 0.09 b & * \\ Maximum growth rate & 0.028 \(\pm\) 0.001 a & 0.028 \(\pm\) 0.001 a & 0.000 \(\pm\) 0.002 a & 0.035 \(\pm\) 0.001 b & 0.036 \(\pm\) 0.001 b & 0.033 \(\pm\) 0.002 & * \\ (g DCW/L/h) & & & & & & & & \\ Maximum fermentation rate & 1.94 \(\pm\) 0.05 a & 1.96 \(\pm\) 0.03 a & 1.61 \(\pm\) 0.03 b & 1.93 \(\pm\) 0.10 a & 1.86 \(\pm\) 0.06 a & 1.61 \(\pm\) 0.05 b & * \\ \(\delta\)/L/h & 9.32 \(\pm\) 0.3 a & 10.23 \(\pm\) 0.2 b & 10.57 \(\pm\) 0.18 c & 8.78 \(\pm\) 0.27 a & 10.26 \(\pm\) 0.06 b & 10.45 \(\pm\) 0.21 c & * \\ Ethanol (\(\approx\)\(v\)/\(v\)) & 13.94 \(\pm\) 0.25 a & 14.38 \(\pm\) 0.05 b & 14.57 \(\pm\) 0.05 b & 13.86 \(\pm\) 0.46 a & 14.49 \(\pm\) 0.08 b & 14.72 \(\pm\) 0.13 b & * \\ Cliric acid (g/L) & 0.22 \(\pm\) 0.01 b & 0.21 \(\pm\) 0.01 a & 0.21 \(\pm\) 0.01 a & 0.21 \(\pm\) 0.01 a & 0.21 \(\pm\) 0.02 a & 0.21 \(\pm\) 0.03 a & * \\ Malic acid (g/L) & 3.10 \(\pm\) 0.06 a & 3.28 \(\pm\) 0.22 a & 3.52 \(\pm\) 0.03 b & 3.58 \(\pm\) 0.03 b & 3.48 \(\pm\) 0.07 a & 3.93 \(\pm\) 0.29 a & * \\ Succinic acid (g/L) & 3.60 \(\pm\) 0.04 a & 3.79 \(\pm\) 0.22 ab & 3.87 \(\pm\) 0.01 ab & 4.39 \(\pm\) 0.23 c & 3.93 \(\pm\) 0.05 b & 4.48 \(\pm\) 0.20 c & * \\ Acetic acid (g/L) & 0.51 \(\pm\) 0.07 a & 0.42 \(\pm\) 0.02 b & 0.43 \(\pm\) 0.01 b & 0.39 \(\pm\) 0.03 b & 0.31 \(\pm\) 0.01 c & 0.24 \(\pm\) 0.04 d & * \\ \hline \multicolumn{1}{c}{Values (mean \(\pm\) SD, \(n\) = 3) of the same compound followed with the same lowercase letters indicate no significant difference (\(p\) \(<\) 0.05, Duncan’s test). Abbreviations: E\_Control, E\_L, and E\_H represented the control, low-UFAs, and high-UFAs added wines fermented by EC1118 strain, respectively; B\_Control, B\_L, and B\_H represented the control, low-UFAs, and high-UFAs added wines fermented by BDX strain, respectively. * means the least significant difference \(<\) 0.05.} & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Effects of different levels of unsaturated fatty acids (UFAs) mixtures on yeast fermentation activity and major fermentation products of EC1118 and BDX strains. BDX strain fermented wines, respectively (Table S7). Methyl octanoate showed similar trends (decreasing in EC1118 strain wine and increasing in BDX strain wine with the improvement of UFAs addition). These distinct profiles suggested that the effect of UFA on ethyl esters syntheses is strain-specificity. To reveal the mechanism at the molecular level, we determined the relative expression levels of _EHT1_ and _EEBI_ encoding acyl-CoA: ethanol O-acyltransferases, which are responsible for the biosynthesis of MCFA ethyl esters, at different stages of fermentation (including mid-exponential phase, the early-stationary phase, and the mid-stationary phase) by real-time PCR. The results shows that UFAs addition had no clear effect on _EHT1_ expression, while the _EEBI_ expression level was up-regulated by 1.2-1.4 fold in BDX strain while down-regulated by 1.8-3.3 fold in EC1118 strain compared to the control trials. Principal Component Analysis (PCA) (Figure 2) was applied using major fermentation products (Table 1) and all aromatic compounds listed in Table S7, to explore the distinct effect and identify the chemical and volatile compounds that discriminate these treatments. The first and second accounted for 42.4% (PC1) and 21.4% (PC2) of the total variation, respectively. The PC1 distinguished the high-UFAs added wines with no-UFAs addition wines. The wines without UFAs addition (E_control and B_control) were positioned on the negative part of PC1, separated by volatile fatty acids (octanoic acid, decanoic acid, and total fatty acids).