## 2 Volatile Wood Composition
### _Q. pyrenaica_ Wild
pyrenaica_ wood undergoes changes during the drying process, which may seem limited compared to the toasting process as well as traditional woods [58]. The dry wood of _Q. pyrenaica_, as in green wood, showed higher _cis_ lactone than _trans_ lactone (Table 3). In general, both isomers were found in concentrations within the range of traditional oaks. The seasoned wood from Gata/Pena de Francia forest, an origin that already showed a high concentration when green (Table 2), stood out for its high _cis_ lactone  
Figure 1: Graphical representation of the averages of the sum of the compounds in wood volatile phenols, franatic compounds, lactones and phenolic aldehydes/phenyl ketones by wood species, after the different cooperate treatments: (**a**) green, without treatment; (**b**) seasoned (carried out in oven and in open air); (**c**) light-toasted (light toasting, 190 \({}^{\circ}\)C for 10 min, 160–170 \({}^{\circ}\)C for 20 min and for 35 min); (**d**) medium-toasted (medium toasting, 180 \({}^{\circ}\)C for 45 min, 200 \({}^{\circ}\)C for 15 min and 35 min, 210 \({}^{\circ}\)C for 20 min and 45 min, and medium plus toasting); (**e**) heavy-toasted (heavy toasting and 250–260 \({}^{\circ}\)C for 27 min). content, even higher than that of _Q. alba_ (Table 3). Meanwhile, the wood from the Salamanca region (Spain) had the highest _trans_ lactone content (33.8 \(\upmu\)g/g) [23], being six times higher than the other _Q. pyrenaica_ woods and even more than twice as high as the traditional ones. However, _trans_ lactone was not detected in wood from the Geres forest in Portugal [63]. The average lactone concentration of seasoned wood from _Q. pyrenaica_ was very similar to _Q. alba_ and higher than _Q. petraea_ (Figure 1b). The highest vanillin contents were found after oven drying in both _Q. pyrenaica_ and traditional woods. Oven-dried and generally air-seasoned woods of _Q. pyrenaica_ had lower vanillin concentrations than _Q. petraea_ and _Q. alba_, with the exception of those from the Salamanca and Alava provinces in Spain. The content of volatile phenols and furanic compounds in the seasoned _Q. pyrenaica_ woods was between the values of _Q. petraea_ and _Q. alba_ (Figure 1b). It was observed that the concentration of eugenol, isoeugenol and 5-HMF in some seasoned woods of _Q. pyrenaica_ were even higher than those found in traditional woods (Table 3). [PERSON] et al., 2012 [61] placed the dry wood of _Q. pyrenaica_ aromatically closer to _Q. alba_, especially because of the low content of furanic compounds, which did not correlate with that observed by most authors, and the high content of lactones. These authors [61] indicated that this species is very rich in terpenic and norisoprenoid compounds, with particularly higher levels of \(\upalpha\)-terpineol and methyl dihydroajmonate than traditional _Quercus_ and chestnut woods. [PERSON] et al., 2011 [60] studied the influence of geographical location on the aroma of dried wood and found that altitude was the most influential parameter, with geographical location also having an important impact on extraction. Thus, higher altitudes and/or clay-textured soils showed lower concentrations of some volatiles [60]. Therefore, the content of all volatile compounds in Ourense's forest wood was lower than in the wood from forests from Lugo and Pontevedra (Spain) [60]. On the other hand, the way _Q. pyrenaica_ wood was dried, in a traditional or accelerated way, had less influence on the volatile composition than the size of the piece of wood and the intensity of the toasting [40]. This is probably due to the fact that this wood undergoes less volatile compound formation than traditional wood during this drying process. [PERSON] et al., 2005 [63] showed that _Q. pyrenaica_ wood was poor in total volatile composition after being seasoned, presenting about 30-40 \(\upmu\)g/g compared to more than 50 \(\upmu\)g/g for the traditional ones. However, after toasting, _Q.