## 2 Results and Discussion
This indicates that the cultivar, seasonal dynamics, and growing conditions influence the volatiles emitted by the same fruit, but there are some specific compounds that can be found in all cultivars. Among the seven identified hydrocarbons, the amount of tetradecane stood out from the others. It was also observed that the nectarine samples were richer in tridecane compared to flat peaches and peaches. These results comply with and extend the ones published about peach volatile emissions from Chinese samples [50]. Aroma is very valuable for the consumer, and specific attention should be paid to odor-important compounds. Thus, if key odor-active compounds for peaches have to be identified, lactones will be among them [51]. Although past research [52] on the relative VOC concentrations and sensory attributes of peaches found higher concentrations of monoterenes and esters compared to lactones in peaches, the latter are major contributors to the specific fruity, peach-like aroma [53]. Terpenoids and aldehydes are seen as insignificant contributors [53]. The sensory quality of peaches and fruit in general is also dependent on the odor threshold [54]. This may be the reason for odor-active substances' inability to produce flavor intensity among the overall volatile compounds. With reference to the abovementioned knowledge, fruit skin is identified as an extremely important contributor to the overall sensory experience in terms of lactone content. Consumption of peaches with their skin will not only contribute to the zero-waste approach promoted nowadays but will also maximize the sensory experience of the consumer. _Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) of HS-SPME-GC-MS Data_  
PCA is a commonly used dimensionality-reduction method that provides visualizations of data. As is evident from Figure 2, the studied cultivars were divided into different groups when the WF or only the FP was being evaluated. This undoubtedly proves the importance of the fruit skin to the overall volatile contribution. The applied multivariable analysis aided in the identification of the volatiles that contribute to the differentiation of the peach varieties' WFs and FPs. High positive load scores in PC1, which distinguish the \"Flat Queen\" from the other studied peaches, are shown by dodecane, nonanal, and ethyl octanoate. The high negative scores in PC1 clearly differentiate the \"July Lady\" and \"Laskava\" whole fruits from the others. When the fruit pulp is assessed, high positive load scores in PC1 distinguish again the \"Flat Queen\" from the other studied varieties in terms of 1-octen-3-yl-butanoate. The \"Uto 4\" pulp appeared different from the rest due to the negative scores of several compounds in PC2. Figure 2: _Cont._  
PC1 and PC2 explain 44.4% of the total variation in the peaches' whole fruits, while the differences in the pulps when considering PC1 and PC2 account for 58.1% of the variation. The clustering results also confirm the differences when taking into account the WF or only the FP. The conducted analysis of the data revealed that peaches, flat peaches, and nectarines can fall into the same cluster when the contribution of their volatiles is being assessed. Considering the clade arrangement in Figure 2A,B, it can be concluded that when the fruit pulp is being evaluated, more differences are visible between cultivars compared to evaluation of the whole fruit. In both dendrograms, there are seven clades consisting of different arrangements when evaluating the WF and FP. For example, the fruit pulp leaves the \"Morsiani 90\" and \"July Lady\" as clustered together, being the most different from the others. On the other hand, the whole fruit reveals the \"Filina\" and \"Flat Queen\" as the most different from the others, but similar to each other. Here, once more, the importance of the skin is observed in the differences of the data visualization.