## 3 Results and Discussion
### Geographical Variability of Tuber borchii and Tuber mesentericum
[8] detected significant differences in the proportion of volatile compounds from white truffles of the _Tuber magnatum_ species collected from different regions of Italy. [PERSON] et al. [30] found a low level for random amplified polymorphic DNA and microsatellite polymorphism of _T. melanosporum_ collected from different areas of Italy and France. This low genetic variation led the authors to explain the observed morphological and organoleptic differences to environmental variables, such as pedoclimatic conditions. Similarly, a discriminant analysis was also conducted on the E-nose data pattern of the different harvesting zones of _Tuber mesentericum_, and the confusion matrix is reported in Table 4.  
In this case, the \"Picentini\" collection area obtained the best % correct classification, 64%, followed by \"Alburni\" and \"Eremita-Marzano\" areas, both of which obtained 56% correct classification (Table 4). Figure 5 illustrates the results of the cluster heatmap analysis performed on VOCs identified in the _Tuber mesentericum_ truffle samples collected in different areas of Campania, in order to effectively visualise their distribution and clustering patterns. All samples exhibited a peculiar pattern of VOCs, although, at the same time, they showed some similarities that caused their partial grouping. For example, \"Alburni\" and \"Eremita-Marzano\" collection sites had in common the abundance of certain VOCs, such as a higher presence of 3-methylanisole, pyrrole, 2,5-dimethoxyytoluene, 3,4-dimethoxyytoluene, and 3,4,5-trimethoxytoluene, and a lower quantity of some ketones and unsaturated aldehydes, thereby causing their clustering. Subsequently, the \"Picentini\" site, due to the sharing of volatile phenols such as 6- and 4-methylguaiacol and some aromatic compounds, was partially grouped with the previous two groups. However, the greater abundance of 8-carbon alcohols and ketones also contributed to its similarity with the \"Partenio-Taburno\" site, which still maintained a modest diversity in the composition of VOCs, such as a higher quantity of unsaturated aldehydes and 2-ketones (Figure 5). Previously, differences in the abundance of VOCs helped discriminate the black truffle _Tuber indicum_ harvested from seven different regions of China, despite some regions showing very similar profiles [9]. Moreover, within the sample groups from the Mudanjiang and Linzhi (Tibet) regions, authors observed intra-group variations in VOCs, indicating differences across various collection sites within the same region. Similar results were obtained by [PERSON] et al. [31] who observed differences in the VOCs of Chinese truffles of different origins, even within the same region, attributing these differences to the metabolic activity of the associated microorganisms and to the different pedoclimatic conditions [31]. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**From\textbackslash{}To** & **Alburni** & **Eremita-Marzano** & **Partenio-Taburno** & **Picentini** & **Total** & **\% Correct** \\ \hline
**Alburni** & 14 & 1 & 7 & 3 & 25 & 56\% \\
**Eremita-Marzano** & 3 & 10 & 3 & 2 & 18 & 56\% \\
**Partenio-Taburno** & 6 & 4 & 20 & 9 & 39 & 51\% \\
**Picentini** & 5 & 0 & 4 & 16 & 25 & 64\% \\ \hline \hline \end{tabular}  
See Table 1 for further sample details.  
\end{table} 
Table 4: Confusion matrix obtained from the discriminant analysis performed on the data pattern constructed considering the different harvesting areas of _T. mesentericum_. Although this study recognises the limitation of non-robust quantitative analysis of volatile compounds based on relative percentage areas, it aims to pave the way for future research focused on combined E-nose and GC/MS analysis for rapid discrimination of truffles and the identification of key volatile molecules responsible for these differences. Overall, these results suggest that environmental factors could be crucial in affecting the VOC profile of the truffle, although the species remains the main determinant.