## 4 Discussion
In the case of proanthocyanidins for both wines, different non-cyclic and cyclic PAC differentiated the origins, but not clearly. This result was also found in previous work published by [PERSON] et al., 2022 [6], where only some differences due to the origins were found according to this variable. Instead, c-PAC variables and the related %-ratio indexes featured in that study were more prominent as varietal markers, an aspect not investigated in this study. However, interestingly for both Pinot Gris and Pinot Noir, the %-ratio chemical indexes %C-4 and %C-5 separated one origin, which was Italy (Sicily/Puglia), from all therest of the samples. The correlations between these indexes and the phenolic compounds were also observed. The conditions that favored the accumulation of c-PAC possibly also favored the higher abundance of the phenolic compounds present in these samples. Furthermore, regression models have been reported, in which the relationship between the overall quality score (OQJ) and sensory attributes are shown, for both varieties. In Pinot Gris wines, the descriptors with large effect on the regression model (VIP > 1) were \"yellow\" color, \"tropical fruit\" aroma, \"floral\" aroma, \"stone fruit\" flavor, \"caramelized\" aroma, and \"pome tree fruit\" flavor, while for Pinot Noir, unfortunately, there was no significant model that could describe which sensory attributes contributed to the overall quality of the wines. Various other regression models were also tested, and the model with the best results has been reported, with the focus being solely on the relation between the volatile compounds and the sensory aroma attributes. However, a PLS-1 regression was performed again with the volatile compounds as explanatory variables and each sensory olfactory variable as the dependent variable for both varieties. Identification of the volatile compounds in both Pinot Gris [56; 57] and Pinot Noir [58; 59; 60] wines have been reported by many authors; however, little information regarding the relationship between the volatile compounds and the sensory attributes is available. The results from this study showed that in Pinot Gris wines, for the \"floral\" aroma, the volatile compounds isobutyl alcohol, linalool, ethyl phenylacetate, and decanoic acid showed a positive effect. Indeed, previous studies have shown that volatile compounds, such as hexanoic acid, octanoic acid, linalool, and decanoic acid (volatile fatty acids), were identified in Pinot Gris wines, which were responsible for imparting a floral aroma [29; 53]. For Pinot Noir, volatile compounds, such as isopentanol, 1-hexanol, benzaldehyde, ethyl phenylacetate, and ethyl isopentyl succinate, showed a positive influence on the \"green bell pepper\" aroma. Indeed, 1-hexonal has been reported in many studies as a compound with a strong positive influence on imparting vegetal notes in wines [61; 62; 63]. For \"cherry\" aroma, the compounds were furfuryl ethyl ether, 1-hexanol, benzaldehyde, ethyl19-decenoate, and also 4-ethylphenol. The \"licorice\" aroma was positively influenced by a combination of volatile compounds, namely furfural, benzaldehyde, isoamyl lactate, 4-tert-butylcyclohexanol, hexanoic acid, benzyl alcohol, and trans-whiskey lactone. Very few compounds appeared to have a positive effect on the \"fresh wood aroma\" but included ethyl 9-decenoate, ethyl 2- furoate, and \(\beta\)-damascenone. Along with this investigation, there are studies where the relation between flavor and aroma with the volatile compounds, and the relation between visual and gustatory with the non-volatile phenolic compounds, have been studied, which could provide information regarding the interplay of these analyzed compounds with the sensory variables [6]. Although the identity of single-varietal Pinot Gris and Pinot Noir wines from different countries has been studied in this work, it should be emphasized that the number of samples is far from representative of a particular country's wine style.