## 3 Results and Discussion
### Classification of Greek Distillates According to Geographical Region
Samples of Crete were differentiated from those of Northern Greece, since the climate of Crete is warmer and drier, favoring the cultivation of varieties with less aromatic metabolites; however, they produce spirits with higher alcohol content, explaining the abundance of higher alcohols and carbonyl compounds in these beverages. Figure 5: PCA scores plot presenting the discrimination of analyzed samples according to their geographical origin. Fatty acid ethyl esters, and especially long-chain fatty acid ethyl esters, were found in higher concentrations in Thessaloniki, Macedonia, and Thessaly samples, whilst ethyl isovalerate and ethyl 2-methylbutanoate were more abundant in Crete spirits. An interesting observation is that ethyl lactate was found in higher concentrations in Thessaloniki spirits compared with any other region, and as mentioned in Section 3.1, this metabolite is an indicator of bad fermentation or storage conditions of a spirit or a long-time ensilage. On the other hand, phenethyl acetate, and acetate esters generally, were more abundant in Limnos and Thessaly grape marc spirits, followed by Thessaloniki, while similar behaviors were followed by terpenes and fatty acids. Macedonia is at a higher altitude than the Thessaly plain and this often affects the composition of the grapes and thereby the aromaticity of the produced distillates. On the other hand, Limnos is an island with a Mediterranean climate and volcanic soil, so although all the distillates from these areas were produced from Muscat pomaces, the products showed several differences in their aromatic composition. Terpenes, as is shown from _alpha_-pinene and 4-carene in Figure 2, were in higher concentrations in Limnos and Macedonia distillates compared with the other regions, while terpen were more abundant in Macedonia, Thessaloniki, Thessaly, and Limnos spirits. More specifically, hotrienol was found to be characteristic in Limnos samples, while linalool and nerol oxide were more abundant in Limnos and Thessaloniki samples, _alpha_-terpineol and geraniol in Thessaloniki and Thessaly, and terpinen-4-ol in Macedonia and Thessaly samples. Higher alcohols and aldehydes were more abundant in Limnos, Macedonia, and Thessaly samples, produced from Muscat and Muscat of Alexandria grapes, with the exception of 2-methylpropan-1-ol and benzaldehyde, which were detected in higher concentrations in Thessaloniki and Crete spirits (Table S2 and Figure S2). While numerous factors affect the aromatic profile of grape marc spirits, such as the grape's varietal origin, pomace storage methods, fermentation duration, distillation technology, and characteristics of the barrels used in the aging process [13; 14], there is no established relationship between the geographical origin and the volatile composition of tisopuro distillates. Since, in most cases, the distillation process is empirical and based on distinctive local traditions, the influence of the geographic origin can be multifactorial, as in different regions, apart from the unique raw materials, there are different storage, fermentation, and distillation practices that are followed, making it very hard to distinguish the influence of each origin-based variable. In this study, we discussed the observed differentiation among samples from different geographical origins, assessing their aromatic profile, and as in the case of Northern Greece tisopuro samples, whilst they were all produced from Muscat pomaces with a similar production process (addition of arise), they presented great differences in their volatile compositions and especially in their abundances of terpenes and terpenoids, ethyl esters, and fatty acids. The samples of this study were examined as products with a holistic approach, as they were produced from several grape cultivars, with various traditional processes (as many of them are PDO products), and in many different regions.