## 4 Conclusions  
Through the analysis of the E-nose data pattern, _T. mesentercium_ was effectively discriminated from _T. borchii_. SPME-GC/MS analysis revealed qualitative-quantitative differences in volatile compounds between the two truffle species. This study provided, for the first time, a comprehensive list of volatile compounds identified in _T. mesentercium_, which included aromatic compounds like 3-methylanisole and volatile phenols like m-cresol. On the contrary, 8-carbon ketones and alcohols, such as 3-octanone, 1-octen-3-one, and 1-octen-3-ol, prevailed in _T. borchii_. While volatile phenols (m-cresol) were exclusively identified in _T. mesentercium_, thiophene derivatives qualitatively characterised _T. borchii_. The abundance of these compounds is responsible for more pronounced floral and smoky odours for _T. mesentercium_, and mushroom and earthy notes for _T. borchii_.  
Considering the E-nose data pattern of different collection sites for the same species, the differences were smaller, leading to an average 60% correct classification rate. However, for _T. borchii_, the correct classification rate increased when it was divided into two groups depending on the harvesting altitude (at sea level or >350 m above sea level) of the provinces of Caserta and Salerno, suggesting an important role of environmental factors on the composition of truffle volatile compounds. In fact, quantitative differences in volatile compounds were mainly observed between these areas based on the collection altitude. Overall, the abundance of volatile compounds of the same truffle species varied quantitatively within the collection sites, as observed for the different harvesting areas of _T. borchii_ and _T. mesentercium_. These findings suggest that environmental factors could be crucial in affecting the VOC profile of the truffle, although the species remains the main determinant.  
Our results are a first step to pave the way for further works that employ the electronic nose as a rapid, solvent-free, and reliable method to authenticate different truffle harvesting areas, by combining the E-nose with GC/MS to identify and quantify the volatile organic compounds responsible for these differences. Therefore, the relationship between E-nose responses and the amount of specific volatile compounds, as well as the environmental and microbial factors that influence them, would require further investigation.  
Conceptualisation, E.D.F., M.C. and L.B.; methodology, A.G., E.D.F. and L.B.; formal analysis, A.B.; investigation, A.B.; resources, A.G. and R.S.; data curation, A.B. and M.C.; writing--original draft preparation, A.B.; writing--review and editing, A.G., E.D.F. and R.S.; funding acquisition, E.D.F. and L.B.; visualisation, A.B.; supervision, A.G. All authors have read and agreed to the published version of the manuscript.  
This research was funded by Assessorato all'Agricoltura, Regione Campania, Project \"Research activity on aroma compounds of Campania truffles\" entrusted to the Osservatorio Appennino Meridionale (CUP B45C22021070002).  
The data presented in this study are contained within the article. Raw data are available from the corresponding author upon reasonable request.  
The authors would like to thank the truffle hunters of Campania for collecting the samples. We would also like to thank [PERSON] of the Assessorato all'Agricoltura, Regione Campania, and [PERSON] of the Osservatorio Appennino Meridionale, for their collaboration.  
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.