## 3 Results and Discussion
### Multidimensional Approach of the Similarity/Dissimilarity of Aged Wine Spirit Samples  
Based on the previous results, the variables that significantly influenced the variability were used for to a multidimensional analysis through heatmap and PCA to help evaluating the relationship between the sensory and the chemical results, and to assess if the set of variables (sensory and chemical) could be helpful to discriminating the samples from different ageing modalities. Figure 2 depicts two heatmaps illustrating the multifactorial relationship between volatile compounds or sensory attributes and the different aged wine spirits at 365 days of ageing. Regarding the volatile compounds, the heatmap clustered three groups of wine spirit modalities: barrel (CB), nitrogen modality (CN) and a group consisting of MOX modalities (CO15, CO30 and CO60). The wine spirit aged in the modalities CO15, CO30 and CO60 have a quite similar volatile composition but with the aforementioned variation showed by the ANOVA results. This result confirms the influence of the different oxidative media in the aged wine spirit's volatile composition. The cluster of CO15, CO30, and C060 seems to also be related to higher levels of some volatile compounds, such as volatile phenols, acetovanillone, and vanillin. It was also possible to identify two important subgroups responsible for the observed differences in the studied modalities. The first subgroup comprises the ethyl hexanoate, acetic acid, ethyl acetate, eugenol, vanillin and acetaldehyde and the second one includes guaiacol, syringol, 4-methylguaiacol, 4-methylsyringol, and acetovanillone. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Sensory Attribute**} & \multirow{2}{*}{_Sigificance Level_} & \multirow{2}{*}{Control} & \multicolumn{2}{c}{CB} & **CO15** & **CO30** & **CO60** & **CN** \\ \hline Alcohol & _0.048_ & 2.4 & 1.9 \({}^{\text{a}}\) & 1.8 \({}^{\text{a}}\) & 2.3 \({}^{\text{b}}\) & 2.2 \({}^{\text{a,b}}\) & 2.2 \({}^{\text{a,b}}\) \\ Vanilla & _0.010_ & 0.0 & 1.9 \({}^{\text{a,b}}\) & 2.3 \({}^{\text{b,c}}\) & 1.6 \({}^{\text{a}}\) & 2.5 \({}^{\text{c}}\) & 1.9 \({}^{\text{a,b}}\) \\ Spicy & _0.009_ & 0.0 & 1.6 \({}^{\text{a}}\) & 2.1 \({}^{\text{b}}\) & 1.8 \({}^{\text{a,b}}\) & 2.2 \({}^{\text{b}}\) & 1.6 \({}^{\text{a}}\) \\ Burning & _0.041_ & 2.4 & 2.0 \({}^{\text{a}}\) & 1.9 \({}^{\text{a}}\) & 2.5 \({}^{\text{b}}\) & 2.3 \({}^{\text{a,b}}\) & 2.0 \({}^{\text{a}}\) \\ Body & _0.014_ & 2.0 & 3.0 \({}^{\text{b,c}}\) & 3.1 \({}^{\text{b,c}}\) & 2.8 \({}^{\text{a,b}}\) & 3.2 \({}^{\text{c}}\) & 2.6 \({}^{\text{a}}\) \\ Unctuous & _0.000_ & 1.1 & 2.7 \({}^{\text{b}}\) & 2.8 \({}^{\text{b}}\) & 2.2 \({}^{\text{a}}\) & 3.1 \({}^{\text{c}}\) & 2.6 \({}^{\text{b}}\) \\ Flavor evolution & _0.000_ & 1.3 & 3.2 \({}^{\text{b}}\) & 3.3 \({}^{\text{b}}\) & 2.6 \({}^{\text{a}}\) & 3.5 \({}^{\text{b}}\) & 2.7 \({}^{\text{a}}\) \\ Flavor complexity & _0.001_ & 1.8 & 3.1 \({}^{\text{b}}\) & 3.2 \({}^{\text{b}}\) & 2.6 \({}^{\text{a}}\) & 3.3 \({}^{\text{b}}\) & 2.7 \({}^{\text{a}}\) \\ Retronasal aroma & _0.002_ & 2.4 & 3.3 \({}^{\text{b}}\) & 3.3 \({}^{\text{b}}\) & 2.9 \({}^{\text{a}}\) & 3.6 \({}^{\text{b}}\) & 2.9 \({}^{\text{a}}\) \\ Overall quality & _0.001_ & - & 14.5 \({}^{\text{b,c}}\) & 14.6 \({}^{\text{c}}\) & 13.1 \({}^{\text{a}}\) & 15.1 \({}^{\text{c}}\) & 13.6 \({}^{\text{a,b}}\) \\ \hline \hline \end{tabular} For each sensory attribute of aged wine spirit samples, means within the same row followed by different uppercase letters (\({}^{\text{a}}\), \({}^{\text{b}}\), \({}^{\text{c}}\)) are significantly different (\(p<0.05\)).  
\end{table} 
Table 3: Sensory attributes intensity (average values) determined by the sensory panel in the wine spirits sampled from different ageing modalities at the end of the ageing experiment (365 days) and the ANOVA summary.