# Flavor Profile Evolution of Bottle Aged Rose and White Wines Sealed with Different Closures
## 2 Results and Discussion
### Flavor Profile Analysis of Wines after an 18-Month Bottle Aging
#### 2.3.1 Flavor Compounds  
In rose wines, principal component 1 (PC1) and principal component 2 (PC2) accounted for 56.4% of the total variance (Figure 5a). According to variable importance in projection values (VIP > 1) of the first two PCs from the PLS-DA model and \(P\) values (_p_ < 0.05) from a one-way ANOVA test, differentiated flavor compounds in rose wines sealed with natural corks and their alternatives were selected (Table 1). Closures seemed to have more effect on volatile compounds than  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**No. \({}^{\text{a}}\)**} & \multirow{2}{*}{**CAS**} & \multirow{2}{*}{**Compounds \({}^{\text{b}}\)**} & \multicolumn{3}{c}{\({}^{\text{*}}\)**Cabernet Sauvingon’ Rose Wines**} & \multicolumn{3}{c}{\({}^{\text{*}}\)**Chardonasy**} & \multicolumn{1}{c}{\({}^{\text{*}}\)**Dry White Wines**} \\ \cline{4-9}  & & & **VIP1** & **VIP2** & \(p\) **values** & **VIP1** & **VIP2** & \(p\) **values** \\ \hline C10 & 104-76-7 & 2-Ethylhexanol & 1.145 & 1.055 & **0.024** & 1.045 & 1.229 & **7.07 \(\times\) 10\({}^{-7}\)** \\ C12 & 112-30-1 & 1-Decanol & 0.286 & 0.617 & 0.001 & 1.443 & 1.022 & **0.035** \\ C24 & 106-30-9 & Ethyl heptanoate & 1.876 & 1.720 & **0.022** & 0.348 & 1.025 & 0.992 \\ C29 & 124-06-1 & Ethyl tetradeanoate & 1.404 & 1.245 & **0.022** & 0.155 & 0.944 & 0.029 \\ C33 & 111-11-5 & Methyl octanoate & 1.266 & 1.187 & **0.021** & 0.711 & 1.121 & 0.954 \\ C38 & 2023-59-6 & Isoamyl octanoate \({}^{\text{*}}\) & 1.136 & 1.111 & **0.002** & 0.117 & 1.44 & 0.678 \\ C48 & 142-62-1 & Hexanoic acid \({}^{\text{**}}\) & 1.655 & 1.464 & **0.022** & 0.717 & 0.917 & 0.975 \\ C55 & 1450-72-2 & 2-Hydroxy-5-methylacetophenone & Trace & Trace & Trace & 1.673 & 1.218 & **0.013** \\ C60 & 18794-84 & \(\beta\)-Farnese & Trace & Trace & Trace & 1.053 & 0.963 & **0.000** \\ C64 & 8013-90-9 & \(\alpha\)-lonone \({}^{\text{**}}\) & 0.341 & 0.851 & 0.003 & 1.464 & 1.039 & 0.037 \\ C65 & 23726-93-4 & \(\beta\)-Damascenone \({}^{\text{**}}\) & 1.301 & 1.274 & **0.014** & 0.428 & 0.883 & 0.749 \\ C68 & 100-42-5 & Styrene & 0.691 & 0.934 & 0.001 & 1.121 & 0.847 & **0.010** \\ C69 & 90-5-1 & Guaica-phenolic compounds because those differentiated flavor compounds were all volatile compounds. Only rose wines with natural corks were in the quadrant where PC1 and PC2 were both positive. PC1, which accounted for 34.5% of the total variance, could distinguish wines sealed with natural corks from those with a polymer synthetic plug (SP) (Figure 5a). As shown in Figure 5b, the positive direction of PC1 was mostly driven by esters, such as ethyl octanoate (C25), methyl octanoate (C33), isopentyl hexanoate (C34), and isoamyl octanoate (C38). Except for 2-ethylhexanol (C10), the other differentiated compounds all lay in the positive part in PC1. Ethyl heptanoate (C24), hexanoic acid (C48), \(\beta\)-damascenone (C65), and guaiocal (C69) had a higher concentration in wines with natural corks (see Table S2). All phenolic compounds, especially 4-hydroxycinnamic acid (P4) and catechin (P1), drove PC2 in the negative direction, where wines with a screw cap lay. As for white wines, PC1 and PC2 accounted for 55.1% of the total variance (Figure 5c). Since phenolic compounds are quite limited in white wines, aroma properties play a more important role from an organoleptic perspective. According to the loading plot, the quadrant where PC2 was positive and PC1 was negative contained the most types of volatile compounds (alcohols, esters, aliphatic acids, terpen, and norisoprenoids) (Figure 5d). Wines sealed with a screw cap lay in this quadrant. The most differentiated compounds (VIP > 1, \(P\) < 0.05) in white wines were 2-ethylhexanol (C10), 1-decanol (C12), 2-hydroxy-5-methylacetophenone (C55), \(\beta\)-francesene (C60), \(\alpha\)-ionone (C64), and styrene (C68). Those volatile compounds characterized the negative direction of PC1 (Table 1, Figure 5d) to distinguish wines sealed with a screw cap from those with natural corks.