## 3 Results and Discussion
### Accumulation of Ester Compounds during the Simulated Fermentation of Blueberry Wine
\begin{table}
\begin{tabular}{l c c c c c c c c c c} \hline \hline \multicolumn{1}{c}{**Compounds**} & \multicolumn{1}{c}{**Coaleset (log/H)**} & \multicolumn{1}{c}{**Coaleset (log/H)**} & \multicolumn{1}{c}{**Coaleset (log/H)**} & \multicolumn{1}{c}{**Coaleset (log/H)**} & \multicolumn{1}{c}{**Coaleset (log/H)**} & \multicolumn{1}{c}{**Coaleset (log/H)**} \\ \hline
**Academic column** & & & & & & & & & & & & \\ \hline High-acute & \(\approx\) 2.1\({}^{\circ}\) & 38.8\(\pm\) 1.2\({}^{\circ}\) & 38.8\(\pm\) 1.48\({}^{\circ}\) & 30.27 \(\pm\) 1.5\({}^{\circ}\) & 107.1 \(\pm\) 2.05\({}^{\circ}\) & 15.09 \(\pm\) 0.1\({}^{\circ}\) & 21.36 \(\pm\) 1.12\({}^{\circ}\) & 11.0 \(\pm\) 1.5\({}^{\circ}\) & 44.7 \(\pm\) 3.3\({}^{\circ}\) & 33.76 \(\pm\) 6.4\({}^{\circ}\) & 33.69 \(\pm\) 6.4\({}^{\circ}\) \\ Improved Acute & 240.3\({}^{\circ}\) 1.2\({}^{\circ}\) & 800.1 \(\pm\) 1.9\({}^{\circ}\) & 250.5\({}^{\circ}\) & 362.2 \(\pm\) 3.9\({}^{\circ}\) & 263.2 \(\pm\) 3.9\({}^{\circ}\) & 73.1 \(\pm\) 2.3\({}^{\circ}\) & 29.1 \(\pm\) 1.2\({}^{\circ}\) & 186.0 \(\pm\) 2.4\({}^{\circ}\) & 14.53 \(\pm\) 3.3\({}^{\circ}\) & 106.6 \(\pm\) 10.4\({}^{\circ}\) & 27.91 \(\pm\) 3.3\({}^{\circ}\) \\ Phenod/1.4\({}^{\circ}\) & 70.6\(\pm\) 2.3\({}^{\circ}\) & 70.1\(\pm\) 2.5\({}^{\circ}\) & 322.2 \(\pm\) 3.8\({}^{\circ}\) & 501.5 \(\pm\) 8.1\({}^{\circ}\) & 202.8 \(\pm\) 1.4\({}^{\circ}\) & 435.2 \(\pm\) 0.8\({}^{\circ}\) & 224.49 \(\pm\) 0.7\({}^{\circ}\) & 224. As for ethyl esters, medium-chain fatty acid ethyl esters were the main ethyl esters, such as ethyl hexanoate, ethyl octanoate, and ethyl decanoate. Ethyl octanoate has a fruity flavor and is found in many fruits, while ethyl decanoate imparts a fruity and brandy-like flavor to wine [43]. Additionally, the contents of these compounds both significantly increased in the co-fermentation samples of CS and PS, while their contents only significantly increased in the WS5 sample. These results were consistent with the result of a previous study, i.e., that the co-fermentation of _T. delbrueckii_ and _S. cerevisiae_ had higher contents of ethyl hexanoate, ethyl octanoate, and ethyl decanoate than those of _S. cerevisiae_ pure fermentation [44]. In addition, the results also showed that the content of ethyl laurate also increased in the co-fermentation samples of CS and PS. As for other esters, the content of 3-methylbutyl hexanoate increased in the co-fermentation samples of WS, and the content of 3-methylbutyl decanoate increased in the co-fermentation samples of CS. All of these compounds could give the wine more complex flavor characteristics. These results indicated that different ratios and strains of ester-producing yeast co-fermentation with _S. cerevisiae_ could lead to wines with a wide range of ester compounds, which was similar to the results of [PERSON] et al. [45]. Principal Component Analysis (PCA) of Ester Compounds during the Simulated Fermentation of Blueberry Wine  
PCA was used to reveal the correlation and separation of ester compounds in different samples (Figure 6). The variance of 64.8% was explained by 29 different ester compounds, and PC1 and PC2 accounted for 38.8% and 26.0% of the variance, respectively. The PCA results showed that the co-fermentation samples of PS1, WS1, and WS10 were close to S sample, suggesting that they had similar ester compound profiles. In these samples, the effects of ester-producing yeast were not obvious, and the characteristics of ester compounds were not prominent. The co-fermentation samples of CS1, CS5, PS5, and WS5 were separated from the S sample and had their own characteristic ester compounds. For example, the sample of CS1 was characterized by phenethyl acetate and isoamyl acetate, the samples of CS5 and PS5 were characterized by propyl octanoate and ethyl decanoate, and the sample of WS5 was characterized by 3-methylbutyl hexanoate, which provided the potential for creating a distinctive flavor of blueberry wine. Figure 6: PCA of ester compounds during the simulated fermentation of blueberry wine.