## 3 Results and Discussion
### Aroma Compounds
Previous studies reported that aliphatic lactones are associated with a variety of aroma characteristics in wine, such as peach, apricot, coconut, and dried fruits [8]. In this study, concentrations of \(\delta\)-octalactone, \(\gamma\)-undecalactone, and \(\gamma\)-butylrolactone were higher in the Cabernet Sauvignon wines than Marselan wines. This result may be ascribed to complex factors, such as the harvesting date, the thickness of the skin, and the degree of dehydration [19], which could not be concluded in this study. For example, a previous study showed that red Merlot and Cabernet Sauvignon wines made from berries infected and withered by _Plasmopara vitticola_ contained large amounts of \(\gamma\)-lactones [20]. For fermentation-derived aroma compounds, three higher alcohols (isoamyl alcohol, 2-phenylethyl alcohol, and methionol), isoamyl hexanoate, ethyl hexadecanoate, and isovaleric acid had significantly higher mean concentrations in Cabernet Sauvignon wines than those of Marselan wines. However, the mean concentrations of isoamyl hexanoate, ethyl hexadecanoate, were lower than those of Marselan dry red wine. These compounds mainly originated from yeast and bacterial metabolism on grape compositions, such as sugar, amino acids, and fatty acids [21]. The variation in these grape compositions could contribute to the differences in fermentation-derived aroma compounds between the two varieties. However, further comprehensive studies are needed to investigate the differences in these chemical components. PCA exploratory data analysis was carried out and found that the volatile compounds were more influenced by the variety (Figure S1). Then, an overview of the differences in aroma compounds between Cabernet Sauvignon and Marselan was obtained by partial least squares-discriminant analysis (PLS-DA). The optimal number of factors for the calibration was selected based on the PRESS. As a result, a total of 16 factors of the PLS model were selected. As shown in Figure 1, a clear separation between the two varieties was obtained by a reliable PLS-DA model. As shown in Figure 1, the Cabernet Sauvignon wines were mainly located on the positive axis of the t1. The Marselan wines were mainly located on the negative axis of the t1. The distribution of the target metabolites can reflect the contribution between the two varieties of wines. The first and second components (t1 and t2), accounting for 32.7% of the total variance (total amount of variance explained in the x matrix [R2\({}^{2}\)X] [cumulative] = 0.326, the total amount of variance explained in the y matrix [R2\({}^{2}\)Y] = 0.932, and Q2 [cumulative] = 0.551). Isoamyl alcohol, 2-phenylethyl alcohol, isovaleric acid, methionol, \(\gamma\)-butylrolactone, and 1-nonanol revealed a high positive correlation with the first component (t1), whereas \(\delta\)-octalactone, \(\alpha\)-terpineol, methyl salicate, linalool, ethyl hexadecanoate, \(\gamma\)-decalactone, \(\delta\)-decalactone, and 4-terpineol revealed a strong negative correlation with t1. All Marselan wines are located on the negative axis of t1, and all Cabernet Sauvignon wines are located on the opposite axis of t1. Based on the variable influence on projection (VIP) score above 1, the predominant aroma compounds responsible for the discriminations were isoamyl alcohol, followed by methionol, isovaleric acid, \(\delta\)-octalactone, 2-phenylethyll alcohol, \(\alpha\)-terpineol, \(\gamma\)-butylrolactone, isoamyl hexanoate, ethyl hexadecanoate, linalool, \(\gamma\)-decalactone, 1-nonanol, 4-terpineol, ethyl cinnamate, phenol, methyl salicate, 1-hexanol, ethyl nonanoate, and ethyl heptanoate. Among these compounds, the varietal aroma compounds, especially terpenoids, could be considered marker aroma compounds to distinguish Marselan wines from Cabernet Sauvignon, which could explain the distinct floral note in young Marselan wines.