## 3 Results and Discussion
### Correlation between Volatiles and Sensory Attributes in Passion Fruit Wines Using PLSR  
Partial least squares regression analysis (PLSR) was further utilized in the present study to elucidate the correlation between the volatile compounds (OAV > 1 for volatiles or OAV > 0.1 for esters) and sensory features (GM% > 20%) in these passion fruit wine samples (Figure 3). The correlation loading in the PLSR analysis included 44 volatiles determined by GC-Orbitrap-MS and GC-qMS (Table 4) and 5 aromatic features (passion fruit, mango, green apple, lemon and floral). It was found that the floral note was positively correlated with phenyl ethyl alcohol and phenethyl acetate (Figure 3). Both phenyl ethyl alcohol and phenethyl acetate were described as the rose flavor note. The biosynthesis of phenyl ethyl alcohol and phenethyl acetate is performed mainly by yeasts (Saccharomyces cerevisiae) through the L-phenylalanine biotransformation system, which is mainly concentrated in the deep fermentation process. Phenyl ethyl alcohol and phenethyl acetate are obtained in two forms, where each has its own advantages and disadvantages. One was obtained by chemical synthesis; however, these processes tend to produce undesirable by-products and give off odors. The other was extracted from the essential oil contained in flowers such as rose or jasmine, but their low concentration makes the recycling process complicated and expensive. In this study, phenyl ethyl alcohol and phenethyl acetate were produced by alcohol fermentation. Similarly, a positive correlation of the mango descriptor in these passion fruit wines was established with octanoic acid, ethyl 9-decenoate, TDN and benzothiazole. Terpenoids and esters, such as cis-rose oxide, \(\beta\)-damascone, isopentyl acetate and ethyl butanoate, exhibited a positive correlation with the green apple aroma in these wine samples. The passion fruit descriptor in these wines was strongly correlated with sulfur volatiles, especially 2-methyltetrahydrodrothiophen-3-one, 2-methyl-4-propyl-1,3-oxathiane and 3-(methylthio)propyl acetate, whereas 9-decenoic acid appeared to exhibit a correlation with the leemon sensory attribute in these passion fruit wines. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Compound** & **Volatile Compound** & **Odor Series** & **ES** & **BV** & **VI** & **CY** \\ \hline
1 & **Isovaleric acid** & 8 & 1.53 & 1.01 & 1.56 & 1.85 \\
2 & **Hexanoic acid** & 8 & 33.28 & 27.1 & 45 & 43.93 \\
3 & **Octanoic acid** & 8 & 108.81 & 117.54 & 141.99 & 148.55 \\
4 & **Decanoic acid** & 8 & 118.78 & 157.16 & 147.79 & 150.57 \\
5 & **9-Decenoic acid** & 7,8 & 3.81 & 8.69 & 4.92 & 5.76 \\
6 & **Lauric acid** & 8 & 7.64 & 5.47 & 7.32 & 8.38 \\
7 & **Isobutanol** & 3,7 & 1.19 & 0.84 & 1.46 & 0.59 \\
8 & **Isopentanol** & 7,5,8 & 6.33 & 4.39 & 6.69 & 6.73 \\
9 & **2-Hepranolol** & 1,6 & 2.15 & 1.83 & 2.19 & 2.2 \\
10 & **2-Nonanol** & 7 & 3.64 & 2.87 & 3.62 & 3.81 \\
11 & **Phenyl ethyl alcohol** & 2 & 0.87 & 2.49 & 3.63 & 6.86 \\
12 & **Ehylly butanoate** & 1 & 5.48 & 4.33 & 5.6 & 6.6 \\
13 & **Ethyl hexanoate** & 1 & 20.23 & 12.63 & 23.28 & 22.59 \\
14 & **Ethyl caprylate** & 1,2 & 8.05 & 4.27 & 10.43 & 8.59 \\
15 & **Ethyl caprate** & 1 & 0.96 & 0.85 & 0.99 & 1 \\
16 & **Ethyl 9-decenoate** & 1 & 2.64 & 2.34 & 2.52 & 2.99 \\
17 & **Ethyl cinnamate** & 2 & 8.27 & 7.74 & 8.94 & 9.73 \\
18 & **Ethyl acetate** & 1,2 & 3.4 & 2.36 & 3.67 & 3.54 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Volatile compounds in passion fruit wine fermented by commercial yeast strain ES488 (ES), BV818 (BV), VIC (VI) and CY3079 (CY) selected for partial least squares regression analysis (volatiles with OAV > 1 and esters with OAV > 0.1). Figure 2: Sensory attributes of passion fruit wine fermented by commercial yeast strain ES488 (ES), BV818 (BV), VIC (VI) and CY3079 (CY) using a professional panel. The geometric mean (GM%) was used to assess the aromatic features of these passion fruit wine samples.