## 3 Results and Discussion
### Wine Characterization
#### 3.3.4 Volatile Compounds  
A total of 46 volatile compounds were identified in the wines (Figure S1 and Table 5). Alcohols and esters were the most abundant classes of compounds, deriving from fermentation. Isoamyl alcohol and 2-phenylethanol were the alcohols found in highest amounts, while the most abundant esters were isoamyl acetate and phenylethyl-acetate (among acetates), ethyl hexanoate, and octanoate and decanoate (among ethyl esters). Similar volatile profiles were reported in the literature [27; 36; 41; 42]. Several significant differences were however observed in the levels of volatile compounds, due to both _Cultivar_ and _Yeast_ variables. Wines from Jolly Red were richer in esters. Further research is needed to assess whether these differences could underlie different sensory properties related to fruity perception. The effects of yeast strains also involved differences in the amounts of several esters, suggesting quite different flavor profiles. A comprehensive evaluation of the volatile patterns was obtained by applying multivariate analysis. Figure 4A reports the biplot of the principal components analysis (PCA). The first two principal components deriving from the PCA accounted for 52.4% of total variability. The twelve pomergnate wines were grouped on the plane of PC1 and PC2, according to both cv. and yeast. Fermentation by EC1118 seemed to emphasize the varietal differences: the wines fermented by Clos, in fact, clustered closer on the plane of the PCA. In Figure 4B, a polar heatmap with a circular dendrogram deriving from a hierarchical cluster analysis is reported and allows to characterize the volatile patterns. In fact, wines were clusterized in four homogeneous groups, indicating that both cv. and yeast conferred specific features to the volatile profile. Moreover, volatile compounds were clusterized in seven groups characterized by a certain homogeneity related to the chemical nature and origin of volatiles. The first two clusters (analyzing clockwise the circular heatmap) included acetate esters (also known as _fruit esters_[43]), fatty acid ethyl esters, and the two ketones found in the wines. This cluster characterized the wines fermented with EC1118, particularly from Jolly Red. Esters are typical products of fermentation related to secondary aroma of wines [44; 45] and are mainly responsible for fruity notes. The compounds in this cluster have been related to perceptions such as apple (isobutyl-acetate, ethyl-2-methylbutyrate, ethyl-hexanoate, hexyl-acetate, isoamyl-hexanoate), banana (isoamyl-acetate, isobutyl-acetate, isoamyl-butyrate, ethyl-hexanoate), pineapple (ethyl-acetate, ethyl-butyrate, isoamyl-hexanoate), and pear (isobutyl-acetate, isoamyl-acetate, ethyl-decanoate) [42; 45]. The possible effect on the sensory properties of the wines needs to be assessed by further research. The third and fourth clusters of volatiles characterized the wines obtained from cv. Smith, and particularly those fermented with Clos yeasts. The volatile compounds belonging to these clusters included unsaturated six-carbon alcohols and esters together with two aldehydes (i.e., octanal and nonanal). Both C6 unsaturated compounds and C8/C9 aldehydes derive from enzymatic and chemical fatty acid oxidation [43; 46]. This could be the reason why they characterized wines from cv. Smith, in which juice extraction could have also caused the release of lipids from the seeds. On the contrary, this did not happen in wines from Jolly Red, which is a seedless cultivar. The effect of unsaturated fatty acids deriving from pomergnate seeds is confirmed by studies investigating the effect of unsaturated fatty acid supplementation during winemaking. Recently, [PERSON] et al. [47] reported that unsaturated fatty acid supplementation determined an increase of C6 alcohols and a decrease of medium-chain fatty acids and acetate esters. Moreover, they observed some strain-related effects, as observed in our study.