## 3 Results and Discussion
In fact, the authors showed that Aglianico wines, compared to Primitivo, were characterized by a higher amount of the major fermentation compounds (i.e., esters, fatty acids and phenylethyl alcohol). In addition to these major compounds, mostly related to fermentation conditions and nutrient availability, other minor classes such as terpenols, lactones, and other miscellaneous compounds showed some significant differences for specific VOCs. Terpenols, which are grape aromas, included three identified compounds: beta-linalool, alpha-terpineol, and beta-citronellol. Beta-citronellol showed a significant difference with a higher trend (\(p<0.01\)) in Aglianico wine, while for beta-linalool and alpha-terpineol no significant differences were found. Three lactones were detected: gamma-butyrolactone, (E)-whiskeylactone, and gamma-nonlactone, showing no significant differences between the two types of wines. However, a trend for a higher amount of gamma-nonlactone and (E)-whiskeylactone in Primitivo wine samples was observed, in line with [PERSON] et al. [18], which observed a higher concentration of gamma-nonlactone in Primitivo wines compared to Aglianico. Finally, regarding miscellaneous compounds, seven compounds were identified in the two wine types, with benzaldehyde and an unknown furanone compound showing significant differences between the two varieties. While benzaldehyde displayed a significantly higher amount in Aglianico wines (\(p<0.01\)), the unknown furanone compound showed a greater amount in Primitivo wine samples (\(p<0.05\)). Regarding this latter compound, it was tentatively identified as 5-hydroxymethyldihydrofuran-2-one, which was previously detected in Madeira wines [36; 37]. Results suggest a potential discriminability between Aglianico and Primitivo wines based on their VOCs profiles, as shown by the Principal Component Analysis (Figure 1). The PCA was performed to study the relationships between the thirteen wine samples (observations) and the volatile composition (variables). Moreover, a Hierarchical Clustering Analysis (HCA) (Ward algorithm, Euclidean distance) was conducted on a subset of eight samples (four Aglianico and four Primitivo wines) to investigate the relationships between the entire set of data (wines, volatile compounds, and sensory attributes) (Figure 2). Figure 1 shows the biplot where wines and volatiles are plotted on the first two components, representing 50.21% of the total variance (PC1: 30.83% and PC2: 19.39%). Looking at Figure 1a, it can be observed that, while the first component (PC1) separates the two types of wines, the second component (PC2) would seem to describe the heterogeneity within Primitivo wines into two groups: PRI001, PRI002, PRI003, and PRI004; PRI005, PRI006 and PRI007. All Aglianico wines are mostly correlated to fermentative alcohols such as phenylethyl-, isobutyl alcohols, and 2+3-methyl-1-butanol, and even to the varietal terpen beta-citronellol, alpha-terpineol and beta-linalool (Figure 1b), all compounds reported as impacting wine aromas because they are key players of the alcoholic-solvent and fowery aroma vectors, respectively [38; 39]. The first group of Primitivo wines (PRI001, PRI002, PRI003, and PRI004) seems to be related to gamma-butyrolactone, (E)-whiskeylactone, and gamma-nonlactone, together with syringol, furfural (Figure 1b), and a pool of VOCs responsible for woody, spicy, liquorice, toasty, smokoy, cocoa, coconut, leather, and vanilla nuances [40]. The second group, formed by PRI005, PRI006, and PRI007 shows correlations with beta-phenethyl acetate and isoamyl acetate, decanoic acid, and, to a lesser extent, beta-ionone and 1-butanol. Among these compounds, both beta-phenethyl acetate and beta-ionone are relevant VOCs for the floral aroma vector in wine, as well as isoamyl acetate for the fruity one [38; 39]. Figure 1: Principal component analysis (PCA) plots of (**a**) wines—observations (six Aglianico: AGL; seven Primitivo: PRI) and (**b**) volatile compounds—variables.