## 3 Results and Discussion
### Aroma Profile  
The aromatic profile of these passion fruit wine samples was evaluated using the aroma series features. Each aroma feature was calculated by summing up the OAV of each volatile compound with the same aromatic note and its OAV above 1 (Table 3). These passion fruit wines fermented by different yeast strains were featured with strong fruity, floral, herbaceous, caramel, chemical, earthy and fatty aromas, with a lack of roasted, nutty and spice scents (Table S2). The floral aroma played a dominant role in the aroma profile of these passion fruit wines. The major floral aroma contributors included one alcohol (phenyl ethyl alcohol), four esters (ethyl cinnate, ethyl caprylate, ethyl acetate and phenethyl acetate), seven terpenes (\(\alpha\)-terpineol, linalool, citronello, geranyl acetone, cis-rose oxide, trans-rose oxide and geraniol), and three norisoprenoids (\(\beta\)-damascone, \(\beta\)-ionone and TDN). It is worth noting that other fruit wines, such as mulberry and Airen macerated wines, exhibited a fruity aroma as the dominant aromatic feature as well [8; 20; 43]. Among these passion fruit wine samples, the CY wine exhibited the highest floral aroma intensity, followed by the VI and ES wine. The least floral aroma was found in the BV wine. Besides the floral aroma, the passion fruit wines were also abundant in fruity and fatty aromas. The fruity aroma in the passion fruit wines was primarily determined by 20 volatile compounds, including 2-heptanol, ethyl butanoate, ethyl hexanoate, ethyl caprylate, ethyl caprate, ethyl 9-decenoate, ethyl acetate, ethyl laurate, isopentyl acetate, isobutyl acetate, phenethyl acetate, hexyl butyrate, isoamyl caprylate, \(\beta\)-myrcene, \(\beta\)-damascone, \(\alpha\)-ionone, ethyl 3-(methylthio)propionate, 3-mercaptoethanol, 3-mercaptoethanol acetate and 2-methyl-4-propyl-1,3-oxathiane. The varietal thiols, such as 3-mercaptoethanol and 3-mercaptoethanol acetate, with desirable citrus and tropical fruit flavor notes, were of particular importance to the fruity aroma of the passion fruit wines [9]. The ES-fermented passion fruit wine exhibited the highest intensity in the fruity aroma since 3-mercaptoethanol acetate was only found in the ES wine with an extremely high OAV (1332.66). The fatty aroma in these passion fruit wines was mainly attributed to isovaleric acid, hexanoic acid, octanoic acid, decanoic acid, 9-decenoic acid, lauric acid, isopentanol, ethyl laurate and isoamyl caprylate. The ES-fermented passion fruit wine sample was found to possess the lowest intensity in the fatty aroma. The caramel aroma in these passion fruit wine samples mainly consisted of one alcohol (isopentanol), one ester (isoamyl caprylate), two terpenes (\(\alpha\)-terpineol and linalool) and one norisoprenoid (\(\beta\)-damascone). These strain-fermented passion fruit wines displayed a similar intensity in the caramel aroma. The chemical aroma in these passion fruit wines mainly resulted from the accumulation of fused alcohols (higher alcohols). It has been reported that isobutanol and isopentanol primarily determined the chemical flavor in Cabernet Sauvignon wines [21]. In the present study, these two fused alcohols were the critical chemical aroma contributors in these passion fruit wines. These different strain-fermented passion fruit wines also showed a different intensity in the chemical aroma, which mainly resulted from the content difference in 2-methyltetrahydrodrothiophene-3-one in these wines. The herbaceous flavor has been reported to be mainly determined by the alcohols' presence in wine, and this aromatic note was normally considered as a negative factor in the overall amora in wine [23]. In the present study, isobutanol was the main alcohol to bring a herbaceous aroma to the passion fruit wines. This volatile compound had a higher concentration than its odor threshold in the ES and VI passion fruit wines, leading the ES and VI wines to have strongest herbaceous aroma.