# The Application of Wood Species in Enology: Chemical Wood Composition and Effect on Wine Quality
## 2 Chemical Composition of Wood Species
On the other hand, [PERSON] et al. [68] detected several compounds characteristic of false acacia wood, like fustin, robinetin, and butin, that were not found in the cherry and oak woods. Other researchers described only a few procyanidins and no hydrolysable tannins [65; 66; 74]. Other wood species with very limited enological applications, such as ash wood, the occurrence of phenylethanolamine glycosides, sesoriidoids, or di- and oligoligionols could be a good identifier for the application of this wood species. [65; 66]. Lastly, for mulberry wood, mainly for the two species that have been studied by [PERSON] et al. [75], high antioxidant activity and polyphenolic concentration were achieved in wood extracts from _Morus nigra_ L. and _Morus alba_ L. in contrast with the phenolic concentration achieved for extracts of _Robinia pseudoacacia_ L and. _Quercus robur._ \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{6}{c}{**Wood Species**} \\ \cline{2-7}  & \multicolumn{3}{c}{**Oak Species**} & \multicolumn{3}{c}{**Fabaceae**} & **Cherry** \\ \cline{2-7}
**Phenolic** & _Quercus_ & _Quercus_ & _Quercus_ & _Robinia_ & _Pruuns_ & **Reference** \\
**Compounds** & _petraea_ & _alba_ & _Wiprena_ & _Wiprena_ & _Wiprena_ & _Avium_ & **L.** & \\ \hline Total polyphenols [1] & 1269 & – & – & 786 & 898 & [76] [2] \\ \hline Total polyphenols [3] & 61.39 & 61.51 & 65.03 & 51.23 & 46.82 & [77; 78] [7] \\ \hline Protocatechic aldehyde [4] & nd & nd & nd & 1.40 & nd & \\ Gallic acid & 1.25 & nd & 1.44 & nd & nd & \\ Vanillic acid & 0.14 & 0.33 & 0.128 & nd & nd & \\ Syringic acid & 0.44 & 0.83 & 0.22 & nd & nd & \\ (+)-Catechin & nd & nd & nd & nd & 18.51 & \\ Robinetin & nd & nd & nd & 118.94 & nd & \\ Fustin [5] & nd & nd & nd & 0.86 & nd & \\ Butin [6] & nd & nd & nd & 3.52 & nd & \\ _p_-Cumaric acid & 153.4 & nd & 84.3 & nd & 172.5 & \\ Quercetin & 5.45 & 5.49 & 2.48 & nd & nd & \\ Naringenin & nd & nd & nd & nd & 5.54 & \\ Vescalagin [6] & 19.21 & 6.21 & 25.74 & nd & nd & \\ Castalagin [6] & 24.97 & 5.43 & 32.45 & nd & nd & \\ Ellagic acid & 3.49 & 1.17 & 4.91 & 0.049 & 0.72 & \\ \hline Vescalagin [8] & 9.87–10.6 & 5.41–8.24 & – & – & – & \\ Castalagin [8] & 12.56–19.8 & 2.34–3.54 & – & – & – & [58] [9] \\ Ellagic acid & 6.91–12.56 & 2.34–3.42 & – & – & – & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Individual phenolic compounds are found in different wood species. Table 2 shows the content of some of the most typical volatile compounds quantified in oak, false acacia, and cherry wood species. In oak wood species existent, a high quantity of volatile compounds with a significant influence on the wine sensory profile, especially in olfactive wine characteristics and also in some descriptors of the wine taste profile. Generally, wood belonging to genus _Quercus_ has \(\beta\)-methyl-\(\gamma\)-octadecones (_cis_ and _trans_ forms), frequently in higher quantities in American species, like _Quercus alba_. Nevertheless, also in European oak species, it is possible to find these compounds. The lactones are related to sensory descriptors such as coconut and fresh oak. The literature describes that the _cis_ isomer is more aromatic than the _trans_ isomer (11; 80; 81). Rendering to numerous authors (82; 83), the _cis_ to _trans_-oak lactone ratio is specific to the wood's source, where this ratio is greater for American oak wood species than European oak species. [PERSON] et al. (11) reported values of _cis/trans_ ratio of 5.7, 4.2, and 0.63 for _Q. alba_, _Q. petraea_, and _Q. pyrenaica_, respectively. These authors also quantified twelve distinct volatile compounds, comprising _cis_- and _trans_-\(\beta\)-methyl-\(\gamma\)-octadecones, in toasted oak woods from these species and diverse geographical origins. Rendering to the outcomes achieved the highest concentration for \(\beta\)-methyl-\(\gamma\)-octalactones were detected in _Q. alba_, followed by _Q. petraea_. For all of these oak species, the _cis_ form was the most abundant \(\beta\)-methyl-\(\gamma\)-octalactone.