# Aromatic Characterization of Grasevina Wines from Slavonia and Podunavlje Sub-Regions
## 3 Results and Discussion
### Potential Markers of Grasevina Wines' Regionality  
Different statistical approaches led to the same conclusion, suggesting that it was not easy to discriminate between Grasevina wines from both studied sub-regions based on the targeted volatiles. Nevertheless, a group of wine samples exclusively from the Kutjevo district in the Slavonia sub-region were systematically correlated to some norisoprenoids and a wide range of monoterenes, including the four compounds potentially involved in Grasevina aromatic signature, namely 4-terpineol, 1,4-cineole, and \(\alpha\)- and \(\gamma\)-terpinene. In contrast, wines from the Podunavlje sub-region were grouped together when PLS-DA was applied, and seemed to be correlated with the levels of vitispirane isomers (Figures 3 and 5). This consistent result highlights that appropriate statistical analyses can unravel some subtle differences in the composition of wines from different geographical origins. For instance, this approach has recently been used to characterize the regional aromatic signature of Australian Shiraz wines [15; 16]. More recently, [PERSON] et al. [17] managed to predict the origin of Bordeaux red wines from simple GC/MS data with the help of a Machine Learning tool. Figure 5: The PLS-DA score scatter plot (**top**) and the correlation circle plot (**bottom**) for 22 VOCs associated with 32 samples from 2 geographical regions, Podunavljé (P) and Slavonia (S). In the case of Grasevina wines from northeastern Croatia, as shown in Figure 6, it seems that the Kutjevo district in the Slavonia sub-region is more prone to favor higher levels of terpenoids. The Podunavlje sub-region has a more continental climate than the Slavonia sub-region, with warmer days and slightly colder nights during the ripening season. Rain precipitation is slightly more abundant during summer and autumn in Slavonia (www.meteoblue.com, 28 January 2024). This climatic difference is even more pronounced when considering the Kutjevo district, which is located on the slope of the Papuk mountains. Interestingly, Grasevina wines from different areas of the Slavonia sub-region, namely Pozega Pleternica, and Djakovo, were rather grouped with wines from the Podunavlje sub-region. This was particularly the case for samples from the Djakovo area, located at the border with the Podunavlje sub-region, which has a more continental climate than Kutjevo. Different studies have reported contradictory results regarding the effects of temperature on norisoprenoids and monoterepenes [18]. The influence of abiotic factors on these volatiles also depends on the compound [18]. For norisoprenoids, there is consensus that warmer and sunnier climate favors higher levels of TDN [18]. This was not the case in the present study, because samples from the cooler Kutjevo district displayed higher levels than those from the warmer Podunavlje sub-region (Figure 5). \(\beta\)-Damascenone and \(\alpha\)-ionone were also associated with samples from Kutjevo area. For these compounds, there is a lack of consensus in the literature regarding the impact of abiotic factors on their contents in grapes and wine [18]. In contrast, both vitispirane isomers were correlated with wines from the Podunavlje sub-region, indicating that warmer temperatures could potentially stimulate their synthesis in grapes. However, this topic is poorly documented in the literature and further studies are required to confirm this assumption. Monoterpenes were all associated with different degrees of correlation with wines from Kutjevo area. According to [PERSON] et al. [18], the influence of air temperature on monoterepene concentrations in grape and wine is difficult to predict and depends on other factors. In contrast, [PERSON] et al. [15] found in Shiraz wines that monoterepenes were associated with cooler regions  
Figure 6: Slavonia and Podunavlje sub-regions are divided by a red line with the geographical positions of wine producers marked in blue and violet, respectively. Producer labels are listed in Table S1.