## 3 Results and Discussion
### Headspaces Chemical Composition
#### 3.2.1 Plant Materials
\begin{table}
\begin{tabular}{l c c c c} \hline \hline \multirow{2}{*}{**Compounds**} & \multirow{2}{*}{**l.r.i. 1**} & \multirow{2}{*}{**Class.**} & \multicolumn{2}{c}{**Relative Abundance (\%) \(\pm\) SD**} \\ \cline{3-5}  & & & \multicolumn{2}{c}{**SPME Hop**} & \multicolumn{2}{c}{**SPME Hibiscus**} \\ \hline \(\beta\)-pinene & 977 & mh & 2.7 \(\pm\) 0.07 & 0.5 \(\pm\) 0.12 \\
6-methyl-5-hepten-2-one & 986 & nt & - & 1.0 \(\pm\) 0.07 \\ myrcene & 991 & mh & 64.9 \(\pm\) 2.19 & 1.2 \(\pm\) 0.06 \\ octanal & 1003 & nt & - & 0.9 \(\pm\) 0.05 \\ \(\alpha\)-phellandrene & 1006 & mh & 0.1 \(\pm\) 0.02 & - \\ _iso_amyl isobutanoate & 1015 & nt & 0.3 \(\pm\) 0.04 & - \\
2-metylbutyl _iso_butyrate & 1016 & nt & 0.5 \(\pm\) 0.06 & - \\ \(\alpha\)-terpinene & 1017 & mh & 0.1 \(\pm\) 0.01 & - \\ methyl heptanoate & 1023 & nt & 0.7 \(\pm\) 0.02 & - \\ \(p\)-cymene & 1025 & mh & - & 2.1 \(\pm\) 0.33 \\
3-ethyl-1-hexanol & 1027 & nt & - & 1.0 \(\pm\) 0.20 \\ limonene & 1029 & mh & 2.1 \(\pm\) 0.09 & 2.4 \(\pm\) 0.35 \\
1,8-cineole & 1031 & om & - & 19.1 \(\pm\) 2.67 \\ (Z)-\(\beta\)-ocimene & 1036 & mh & 0.2 \(\pm\) 0.02 & - \\ phenylacetaldehyde & 1043 & nt & - & 0.4 \(\pm\) 0.04 \\ (\(E\)-\(\beta\)-ocimene & 1047 & mh & 0.8 \(\pm\) 0.05 & - \\ \(\gamma\)-terpinene & 1058 & mh & 0.1 \(\pm\) 0.00 & 0.6 \(\pm\) 0.15 \\
1-ocanol & 1069 & nt & - & 0.3 \(\pm\) 0.07 \\
2,3,5,6-tetramethyl pyrazine & 1088 & pyrr & - & 0.6 \(\pm\) 0.02 \\
2-nonanone & 1092 & nt & 0.2 \(\pm\) 0.01 & 0.2 \(\pm\) 0.03 \\ linalool & 1101 & om & 0.5 \(\pm\) 0.03 & 1.1 \(\pm\) 0.02 \\ nonanal & 1105 & nt & - & 3.3 \(\pm\) 0.17 \\ phenylethyl alcohol & 1114 & nt & - & 0.7 \(\pm\) 0.09 \\ methyl octanoate & 1129 & nt & 0.3 \(\pm\) 0.02 & - \\ camphor & 1145 & om & - & 0.4 \(\pm\) 0.12 \\ citronellal & 1153 & om & - & 0.5 \(\pm\) 0.01 \\ borneol & 1165 & om & - & 0.6 \(\pm\) 0.07 \\ menthol & 1173 & om & - & 1.0 \(\pm\) 0.04 \\
4-terpineol & 1177 & om & - & 1.1 \(\pm\) 0.13 \\ \(\alpha\)-terpineol & 1191 & om & - & 1.2 \(\pm\) 0.17 \\ decanal & 1206 & nt & - & 1.1 \(\pm\) 0.13 \\ carvone & 1244 & om & - & 0.8 \(\pm\) 0.11 \\ nonanoic acid & 1269 & nt & - & 0.8 \(\pm\) 0.13 \\ thymol & 1292 & om & - & 0.3 \(\pm\) 0.04 \\
2-undecanone & 1294 & nt & 0.1 \(\pm\) 0.00 & - \\ carvacrol & 1302 & om & - & 1.2 \(\pm\) 0.04 \\ methyl 4-decenoate & 1312 & nt & 0.3 \(\pm\) 0.03 & - \\ methyl gernate & 1324 & om & 0.2 \(\pm\) 0.02 & - \\ \(\alpha\)-terpinyl acetate & 1350 & om & - & 0.9 \(\pm\) 0.08 \\ naryl acetate & 1365 & om & - & 0.6 \(\pm\) 0.08 \\ \(\alpha\)-ylangene & 1372 & sh & 0.2 \(\pm\) 0.03 & - \\ \(\alpha\)-copaene & 1376 & sh & 0.6 \(\pm\) 0.08 & 0.3 \(\pm\) 0.05 \\ \(\beta\)-caryophyllene & 1419 & sh & 6.6 \(\pm\) 0.32 & 7.5 \(\pm\) 0.61 \\ \(\beta\)-copaene & 1429 & sh & 0.2 \(\pm\) 0.02 & - \\ _trans_-\(\alpha\)-bergamotene & 1436 & sh & 0.3 \(\pm\) 0.03 & 0.7 \(\pm\) 0.11 \\ aromadendrene & 1442 & sh & - & 0.4 \(\pm\) 0.11 \\ \(\alpha\)-humulene & 1453 & sh & 12.0 \(\pm\) 1.39 & 10.1 \(\pm\) 0.78 \\ (\(E\))-\(\beta\)-farmesene & 1458 & sh & 1.5 \(\pm\) 0.08 & 2.6 \(\pm\) 0.00 \\ \(\gamma\)-muviolene & 1477 & sh & 0.3 \(\pm\) 0.03 & 0.7 \(\pm\) 0.06 \\ \(\beta\)-selineine & 1486 & sh & 0.6 \(\pm\) 0.04 & 1.4 \(\pm\) 0.07 \\ \(\alpha\)-seineme & 1495 & sh & 0.7 \(\pm\) 0.08 & 1.1 \(\pm\) 0.01 \\ \(\alpha\)-muvirolene & 1500 & sh & 0.1 \(\pm\) 0.05 & 0.3 \(\pm\) 0.04 \\ \(\beta\)-bisabolene & 1509 & sh & - & 0.1 \(\pm\) 0.01 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: _Cont._The volatilome of the hop cones was characterized by a predominance of terpenes in their hydrocarbon form. In particular, monoterepene hydrocarbons were the most abundant chemical class, as they accounted up for 71.6%, followed by sesquiterpene hydrocarbons, which represented 23.7% of the whole headspace composition. Among the former class, myrcene (64.9%) was the main detected chemical, whilst among the latter, \(\alpha\)-humulene (12.0%), \(\beta\)-caryophyllene (6.6%) and (E)-\(\beta\)-farmesene (1.5%) were predominant, confirming what has been previously reported [36; 37].