## 3 Results and Discussion
### Multivariate Statistical Analysis  
The dendrogram obtained by the hierarchical cluster analysis (HCA), performed on the complete chemical composition of the Cascade hop EO and the HSs of the starting plant materials and the beverages (Figure 3), evidenced a partition of the samples in two macro-cluster. The hop HS (SPME Hop) was clustered by itself in the pink group, confirming the chemical differences with all the other samples. The second cluster was further divided into two sub-groups, green and blue, whose samples presented a composition closer to each other than to the pink sample. The green cluster comprises the hop EO and the HS of the hibiscus flowers (SPME Hibiscus), clustered together in a further sub-group, and the HS of the hibiscus liqueur (SPME Hibiscus Liqueur). The HSs of the two beer samples (SPME CTR Beer and SPME Hibiscus Beer) were clustered in the blue group, evidencing the compositional similarity reported by the GC-MS analysis.  
Figure 3: Dendrogram of the hierarchical cluster analysis (HCA) performed on the complete composition of the Cascade hop EO and the headspaces of the plant materials and the beverages.  
\begin{table}
\begin{tabular}{l c c c} \hline \hline
**Compounds** & **l.r.i. 1** & **Class.** & \multicolumn{2}{c}{**Relative Abundance**} \\  & & & **(\%) \(\pm\) SD** \\ \hline _trans-\(\alpha\)-bergamotene_ & 1436 & sh & 0.4 \(\pm\) 0.06 \\ \(\alpha\)-humulene & 1453 & sh & 0.5 \(\pm\) 0.07 \\ (E)-\(\beta\)-farnesene & 1458 & sh & 0.2 \(\pm\) 0.03 \\ germacrene D & 1481 & sh & 0.3 \(\pm\) 0.05 \\ \(\beta\)-selinene & 1486 & sh & 0.1 \(\pm\) 0.00 \\ \(\beta\)-bisabolene & 1509 & sh & 0.3 \(\pm\) 0.04 \\ \(\delta\)-cadene & 1524 & sh & 0.3 \(\pm\) 0.05 \\ ethyl dodecanoate & 1596 & nt & 0.2 \(\pm\) 0.02 \\ \hline Total identified (\%) & & & 100.0 \(\pm\) 0.01 \\ \hline Monoterpene hydrocarbons (mh) & & & 86.3 \(\pm\) 0.96 \\ Oxygenated monoterpenes (om) & & & 0.3 \(\pm\) 0.04 \\ Sesquietrpene hydrocarbons (sh) & & & 4.8 \(\pm\) 0.69 \\ Other non-terpene derivatives (nt) & & & 8.5 \(\pm\) 0.29 \\ _Alcohols_ & & & 2.7 \(\pm\) 0.06 \\ _Esters_ & & & 4.9 \(\pm\) 0.15 \\ _Aldehydes_ & & & 0.8 \(\pm\) 0.15 \\ \hline \hline \end{tabular} \({}^{\dagger}\) Linear retention index on a HP 5-MS capillary column.  
\end{table}
Table 5: _Cont._The score and the loading plots of the principal component analysis (PCA) are reported in Figure 4.  
The distribution of the samples in the score plot was comparable to the clustering of the PCA analysis. SPME Hop was plotted by itself in the leftmost area of the bottom left quadrant (PC1 and PC2 \(<\) 0): greater distance to all other analyzed samples evidenced low compositional similarities. Both beer samples were positioned close to each other in the lower right quadrant (PC1 \(>\) 0 and PC2 \(<\) 0), probably due to their relevant content in non-terpene esters, whose vectors were directed towards the rightmost area of the bottom right quadrant. Finally, the samples of the green cluster of the HCA analysis were plotted in the upper quadrants (PC2 \(>\) 0), near the separation line between the left and the right ones. The positioning of the sample hop EO in the upper left quadrant was probably due to the \(\alpha\)-humulene and \(\beta\)-caryophyllene vectors, whilst the hibscus liqueur was plotted in the middle area of the upper quadrant because of the high relative content in limonene, whose vector pointed towards the same area of the score plot.