## 3 Results and Discussion
### Combination of GC-IMS and HS-SPME-GC-Ms
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**No.**} & \multirow{2}{*}{**Volatile Compounds**} & \multirow{2}{*}{**Odor Description *} & \multirow{2}{*}{**Threshold \(\Psi\) (\(\text{ug/L}\))**} & \multicolumn{2}{c}{**ROAV**} \\  & & & & **FTL** & **BT** & **GT** \\ \hline
1 & Hexanal & Grassy, green, fresh, fatty & 4.5 & 10.82 & 1.33 & 0.98 \\
2 & Heptanal & Green, oily, grassy & 2.8 & 1.21 & 0.08 & 0.94 \\
3 & Octanal & Fruity & 0.7 & 9.71 & \textless{}0.01 & \textless{}0.01 \\
4 & (E,E)-2,4-Heptdienal & Fatty, green & 10,000 & \textless{}0.01 & \textless{}0.01 & \textless{}0.01 \\
5 & Benzeneacetaldehyde & Floral, green, sweet & 4 & 5.70 & 0.65 & \textless{}0.01 \\
6 & Nonanal & Floral, green, lemon-like & 1.1 & 18.18 & 1.79 & 1.98 \\
7 & Decanal & Orange, sweet & 0.1 & 80.00 & 15.63 & 14.09 \\
8 & Safranal & Herbal, fruit & 3 & 0.23 & 0.40 & \textless{}0.01 \\
9 & \(\beta\)-Cyclocitral & Herbal, clean, rose-like, fruits & 3 & 3.20 & \textless{}0.01 & \textless{}0.01 \\
10 & \(\beta\)-Homocycloctiral & Camphor, cool wood & 0.2 & 15.00 & 0.47 & \textless{}0.01 \\
11 & (E,E)-2,4-Decaelan & Cucumber, melon & 0.07 & \textless{}0.01 & \textless{}0.01 & 14.29 \\
12 & Linalool oxide I & Sweet, floral, creamy & 190 & \textless{}0.01 & 0.02 & 0.04 \\
13 & Benzyl alcohol & Sweet, floral, rose-like, caramel & 20,000 & \textless{}0.01 & \textless{}0.01 & \textless{}0.01 \\
14 & Linalool oxide II & Sweet, floral, creamy & 190 & \textless{}0.01 & 0.03 & \textless{}0.01 \\
15 & Linalool & floral, fruit, green, orange-like & 0.22 & 100 & 100 & 100 \\
16 & Phenylethyl Alcohol & Floral, rose-like & 390 & 0.05 & 0.02 & \textless{}0.01 \\
17 & linalool oxide III & Floral, honey-like & 3000 & \textless{}0.01 & \textless{}0.01 & \textless{}0.01 \\
18 & \(\alpha\)-terpineol & Pleasant, floral & 330 & \textless{}0.01 & \textless{}0.01 & \textless{}0.01 \\
19 & Geraniol & Rose-like, sweet, honey-like & 7.5 & \textless{}0.01 & 2.61 & 0.60 \\
20 & Sulcatone & Green, fruity & 50 & \textless{}0.01 & 0.05 & 0.16 \\
21 & Isophorone & Cooling, woody, sweet, green, fruity & 11 & 0.09 & \textless{}0.01 & 0.03 \\
22 & Geranyl acetone & Fresh, rose-like, floral, green, fruity & 60 & 0.24 & 0.06 & 0.13 \\
23 & \(\beta\)-Ionone & Floral, woody, sweet, fruity, berry & 8.4 & 3.32 & 1.65 & 3.12 \\
24 & Methyl salicate & Minty, wintergreen-like, grass & 40 & \textless{}0.01 & 0.76 & 0.73 \\
25 & Thyroidacidinolide & Sweet, faint floral, herbal & 3.8 & 6.47 & 0.77 & 0.68 \\
26 & D-Limonene & Citrus, lemon, orange-like, green & 200 & 0.70 & 0.13 & 0.06 \\
27 & 2-pentyl-Furan & Bean, fruity, earth, green, vegetable & 6 & 1.45 & 0.21 & 0.26 \\
28 & p-Cymene & Aromatic & 11.4 & 1.64 & \textless{}0.01 & \textless{}0.01 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The ROAV values of the main volatile compounds by GC-MS.  
geraniol, geranyl acetone, \(\beta\)-ionnone, and methyl salicylate. All these major flavor compounds can be detected simultaneously by combining the two methods. The results of the methods were complementary with little difference. The compounds with high content were detected mainly by GC-MS, and the compounds with low content were detected mainly by GC-IMS. Therefore, the combination of the two technologies expanded the scope of volatile compounds detected in the samples in terms of content. The research reflected chemical changes in volatile compounds associated with the different tea processing methods comprehensively. By using a combination of the two methods, we can detect more compounds, in order to promote the quality of summer tea toward that of spring tea.