## 3 Results and Discussion  
The volatiles from fresh tea leaves, green tea, oolong tea, and black tea were extracted in diethyl ether, then separated from non-volatile substances and analyzed by GC-MS and GC-FID (Supplementary Figures S2 and S3). In total; 31, 32, 27, and 31 volatiles were identified from respective samples (Table 1). Among the 31 EVs of fresh tea leaves, there were 19, 15, and 14 volatiles detected from green tea, oolong tea, and black tea, respectively. Among the 32 green tea volatiles, there were 17 and 15 volatiles commonly detected from oolong tea and black tea, respectively. There were 14 volatiles commonly detected between oolong tea and black tea (Table 1, Supplementary Figure S4). Among the 31 EVs detected from fresh tea leaves, nine volatiles were below the detection threshold from these three types of made tea: phenylethyl alcohol, germacrene D, meridolol isobutyrate, \(\gamma\)-cadinene, trans-calamenene, _cis_-cadina-1(2),4-diene, and three unidentified volatiles. Meanwhile, nine volatiles from fresh tea leaves were commonly detected from these three types of made teas. In four of them, \(\beta\)-_cis_-ocimene, _cis_-linalo oxide (furanoid), _trans_-linalo oxide (furanoid), and linalool, their contents from made teas only accounted for 0.8-14% of that from fresh tea leaves. The other five volatiles, including \(E\)-nerolidol, (\(Z\))- 3-hexenyl benzoate, hexyl benzoate, neophytadiene, and caffeine, were not significantly different from that of fresh tea leaves except that the \(E\)-nerolidol contents from green tea and oolong tea as well as the neophytadiene and caffeine contents from black tea were significantly higher than that of the fresh tea leaves. The remaining 13 volatiles were either detected from only one or two types of made teas; their contents were significantly lower than that of fresh tea leaves except _cis_-jasmone and \(\beta\)-caryophyllen, which were similar between fresh tea leaves and green tea or oolong tea (Table 1). The total volatile contents for fresh tea leaves, green tea, oolong tea, and black tea were 76.13 \(\pm\) 11.66, 7.73 \(\pm\) 0.71, 5.77 \(\pm\) 0.74, 7.80 \(\pm\) 1.83 \(\upmu\)g. g\({}^{-1}\) dry weight (DW), respectively. These data demonstrated that the tea making processes were characterized by the significant loss for most of the EVs. Thus, their synthesis during postharvest tea making processes would not contribute significantly to the aroma quality of made tea products. It remains unclear why and how these EVs were lost during tea making processes. A detailed quantitative volatile measurement at each processing step is required to resolve this issue. It is obvious that the abundant volatiles from fresh tea leaves were lost more compared to less abundant volatiles (Table 1). We speculated that there are two factors that could affect volatile retention. One was that the leaf cell structure was disrupted by the tea making process, which may reduce the leaf's volatile holding capacity, and thus result in the evaporation of the abundant volatiles. On the other hand, drying should result in significant volatile loss since it was performed at 90-100 \({}^{\circ}\)C, which was above the boiling points for many tea volatiles. Under this pathway, the amounts of volatile loss would depend on the drying temperature, time, and the volatility of individual tea aroma. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**EXT ratio** & **R\({}_{\text{Min}}\)** & **R\({}_{\text{Min}}\)** & **Identification** & **Bailing Point C** & **Aroma Descriptions** & \multicolumn{4}{c}{**Coates (ng.