## 3 Results and Discussion
### Key Volatile Compounds Identified in OOT and TOT
O-Cymene is a collinear component of the five fragrance types of oolong tea [25; 34; 35]. Generally, the content of \(\alpha\)-cedrene decreases during the processing steps of withering, rolling and roasting [35; 36; 37]. \(\alpha\)-Curcumene is a sesquiterpene rarely detected in tea, and only some samples of longjing tea from different regions contained \(\alpha\)-curcumene [38]. The finding suggests that the synthesis of \(\alpha\)-cedrene, \(\alpha\)-curcumene and o-cymene might be induced by certain environmental factors of the plateau. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**No.**} & \multirow{2}{*}{**Compounds**} & \multicolumn{2}{c}{**Relative Contents \({}^{\mathbf{a}}\)**} & \multirow{2}{*}{**Aroma Description \({}^{\mathbf{b}}\)**} & \multirow{2}{*}{**RI (Cal) \({}^{\mathbf{c}f}\)**} & \multirow{2}{*}{**I Method \({}^{\mathbf{e}}\)**} \\ \cline{3-3} \cline{5-6}  & & & **TOT** & & & \\ \hline \multicolumn{6}{c}{**Alcohols**} \\
**1** & Benzyl alcohol & 2.60 \(\pm\) 0.10 & 1.04 \(\pm\) 0.13 & Sweet, floral, rose-like, & \\  & & & & & \multicolumn{1}{c}{} \\  & & & & & \multicolumn{1}{c}{} \\
**2** & Linalool oxide I & 1.19 \(\pm\) 0.12 & 1.52 \(\pm\) 0.23 & Sweet, floral, creamy \({}^{1}\) & 1075/1078 & MS, RI \\
**3** & Linalool oxide II & 1.38 \(\pm\) 0.15 & 1.46 \(\pm\) 0.30 & Floral \({}^{2}\) & 1090/1094 & MS, RI \\
**4** & Linalool & 1.27 \(\pm\) 0.12 & 2.51 \(\pm\) 0.36 & Wood \({}^{1}\) & 1101/1101 & MS, RI \\
**5** & Hotrienol & 9.22 \(\pm\) 0.79 & 7.26 \(\pm\) 1.07 & Fresh, floral, fruity \({}^{1}\) & 1107/1107 & MS, RI \\
**6** & Linalool oxide III & 1.26 \(\pm\) 0.14 & 1.82 \(\pm\) 0.24 & Musty, wood, sweet, & \\  & & & & \multicolumn{1}{c}{} \\  & & & & \multicolumn{1}{c}{} \\
**7** & Geraniol & 0.75 \(\pm\) 0.05 & 0.69 \(\pm\) 0.09 & Rose-like, sweet, \\  & & & & \multicolumn{1}{c}{} \\
**8** & Nerolidol & 1.09 \(\pm\) 0.33 & 3.92 \(\pm\) 0.47 & Floral, apple, green \({}^{1}\) & 1567/1535 & MS, RI \\
**9** & Cedrol & 0.15 \(\pm\) 0.08 & 0.09 \(\pm\) 0.02 & Wood, floral \({}^{1}\) & 1609/1593 & MS, RI \\
**10** & \(\tau\)-Muurolololol & 0.23 \(\pm\) 0.08 & 0.21 \(\pm\) 0.00 & Herb, weak spice \({}^{2}\) & 1648/1640 & MS, RI \\
**11** & \(\alpha\)-Cadinol & 0.14 \(\pm\) 0.05 & 0.16 \(\pm\) 0.01 & Herb, wood \({}^{2}\) & 1660/1663 & MS, RI \\  & **Total alcohols** & **19.28 \(\pm\) 0.83** & **20.68 \(\pm\) 2.88** & \\ \hline \multicolumn{6}{c}{**Alkene**} \\
**1** & 1,3,5,7- & 0.28 \(\pm\) 0.08 & 1.48 \(\pm\) 0.17 & Solvent-like \({}^{1}\) & -/- & MS \\
**2** & Glycrene & 0.31 \(\pm\) 0.06 & 0.65 \(\pm\) 0.11 & Balsamic, gasoline \({}^{2}\) & 913/898 & MS, RI \\
**3** & \(\beta\)-Myrcene & 1.24 \(\pm\) 0.25 & 2.28 \(\pm\) 0.34 & Wood, resinous, musty \({}^{1}\) & 992/988 & MS, RI \\
**4** & D-Limonene & 0.78 \(\pm\) 0.16 & 0.45 \(\pm\) 0.03 & Citrus, lemon, \\  & & & & \multicolumn{1}{c}{} \\  & & & & \multicolumn{1}{c}{} \\
**5** & \(\beta\)-Ocimene & 1.74 \(\pm\) 0.18 & 2.64 \(\pm\) 0.39 & Warm, floral, herbal, \\  & & & & \multicolumn{1}{c}{} \\ \end{tabular}
\end{table} 
Table 2: Summary of volatile compounds in TOT and OOT.