## 2 Materials and Methods
### Volatile Compounds Analysis--GC-MS Methods  
All standards were purchased from Merck KgaA (Darmstadt, Germany); methanol and dichloromethane (HPLC grade) were purchased from Carlo Erba Reagents (Rodano, Milan, Italy). Ultrapure water was obtained using a Milli-Q gradient A10 instrument (Millipore Corporation, Billerica, MA, USA). The solid-phase extraction (SPE) cartridges used for sample preparation were polymeric reversed-phase cartridges (Strata X; Phenomenex, Torrence, CA, USA).  
The method described by [PERSON] et al. (2016) for xylovolatile analysis was used, with the following changes: 1-heptanol (250 uL of 78 mg/L) and 3,4-dimethyl phenol (250 uL of 50 mg/L) were added, as internal standards, to 5 mL of distillate; then, 20 mL of water was added to reduce the concentration of alcohol to less than 5%. SPE cartridges were activated with 5 mL of dichloromethane, 5 mL of methanol and then 5 mL of ultrapure water without drying the cartridges between passages.  
The sample was passed through the activated cartridge at a maximum flow rate of 2 mL/min on a 24-port SPE vacuum manifold; the cartridge was then washed with 5 mL of ultrapure water and was dried at room temperature. The volatile compounds were extracted with 5 mL of dichloromethane, dehydrated with anhydrous sodium sulphate and then partially concentrated to a volume of 2 mL. Samples were stored at \(-\)18 \({}^{\circ}\)C until GC analyses. The initial volume was further reduced, immediately before analysis, to approximately 500 uL using a slight stream of nitrogen. The analysis was performed with a GC 7890A system coupled to a 5975 MSD detector (Agilent Technologies, Santa Clara, CA, USA). A volume of 1 uL of extract in dichloromethane was injected in splitless mode. The split/splitless injection port was heated to 250 \({}^{\circ}\)C, and the split vent was opened after 2 min. The column used was a 60 m HP-Imowax (Agilent J&W GC Columns, Santa Clara, CA, USA) fused silica capillary column 60 m in length \(\times\) 0.25 mm in internal diameter \(\times\) 0.25 um in polyethylene glycol film thickness. Helium was used as the carrier gas with a linear flux of about 1.1 mL/min.  
Some selected key aromatic compounds derived from wood (e.g., acetophenone, acetovanillone, eugenol, isoeugenol, guaiacol, maltol, p-cresol, vanillin, \(\beta\)-methyl-y-octadecone) were quantified using appropriate calibration curves. Commercial analytical standards were dissolved in a model solution (40% ethanol) to prepare the different levels of concentrations for each compound. Each calibration level was analysed using the same method previously described, and the regression analysis method was applied for quantification. All the other compounds (including varietal and fermentative compounds) for which the calibration curve was not made were reported as equivalents of the internal standard, 1-heptanol. The analysis of the volatile compounds, both the semiquantitative (general aromatic profile) and quantitative evaluation (xylovolatiles) were performed acquiring the chromatogram in Total Ion Current mode (TIC). Mass spectra were recorded across the range of 30-300 \(m/z\). As regards the analytes considered in this paper, any coelution phenomenon with other compounds was excluded.  
The tentative identification of volatile compounds was performed by comparing the recorded mass spectra with those of the NIST15 and WILEY275 databases. Moreover, the retention index calculated for each compound was compared with those available in the literature [17].