## 2 Results and Discussion
### Tea infusion Volatile Profiling by IS-SPME-GC-MS
Qualitative profiling results show that some volatiles are ubiquitous in all tea infusions, although quantitative differences deserve some comments. Of those detected in all samples, Strecker aldehydes (_2-methyl butanal_ and _3-methyl butanal_) and volatile terpenes (_linalool_ and its related _3,6-oxides_, and _genaniol_) are the most relevant in the aroma definition. Phenyl propanoid derivates, a group of characteristic components in tea, followed a slightly different behavior; _phenylacetaldehyde_ and _benzaldehyde_ were detected in all samples, while _benzyl alcohol_ and _2-phenyl alcohol_ were present only in some products (both for Ceylon and Darjeeling TV, _benzyl alcohol_ in Assam tea, the others in tea from Kenya). Within the entire set of volatiles, an important role is played by saturated and unsaturated aldehydes, which originate from the oxidation of fatty acids and contribute to defining the aroma of tea infusions. In this case, it is interesting to point out that some short-chain linear aldehydes (_hexanal_, _heptanal_) are present in all infusions, while unsaturated C7-C10 aldehydes have characteristic patterns in Ceylon, Assam, Darjeeling TV, and Kenya samples. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline  & **Compound Name** & \(\mathbf{f_{R}}\) & \(\mathbf{l^{T}s}\) & **Odor** & **Ceylon** & **Assam** & **Azores** & \
\begin{tabular}{c} **Darjeeling** \\ **Castleton** \\ **Valley** \\ \end{tabular} &
\begin{tabular}{c} **Darjeeling** \\ **Testa** \\ **Valley** \\ \end{tabular} & **Kenya** & **Yunnan** \\ \hline
16 & Limonene & 14.17 & 1026 & Citrus & d & nd & nd & d & d & d \\
17 & 2,2,6-Trimethyl & & & & & & & & & \\ cyclohexance & & & & & & & & & \\
18 & Benzyl alcohol & 14.73 & 1035 & Sweet, fruity & d & d & nd & nd & d & nd \\
19 & Phenyl acetaldehyde * & 14.90 & 1039 & Honey-like & d & d & d & d & d & d \\
20 & (E)-2-Octenal & 15.67 & 1055 & Green, nut, fat & d & d & nd & d & d & nd \\
21 &
\begin{tabular}{c} Trans-linalo-3,6- \\ oxide \\ \end{tabular} & 16.98 & 1071 & Sweet, floral, & d & d & d & d & d & d & d \\
22 & Cis-linalo-3,6- & & 17.13 & 1087 & citrus & d & d & d & d & d \\
23 & Linalool * & 17.67 & 1101 & Citrus & d & d & d & d & d \\
24 & Nonanal & 18.03 & 1103 & Fatty, waxy & d & nd & nd & d & nd & d \\
25 & 2-Phenyl alcohol & 18.30 & 1111 & Honey-like & d & nd & nd & d & d & nd \\
26 & (E,Z)-2-6-Nonnadial * & 20.12 & 1151 & Cucumber-like & d & d & nd & d & d & nd \\
27 & (E)-2-Noncal * & 20.43 & 1157 & Fatty, green & d & d & nd & nd & d & d \\
28 & _cis_-Linalo-3,7- & & 20.93 & 1168 & Sweet, floral, & d & d & nd & d & d & nd \\
29 & _trans_-Linalo-3,7- & & & & & & & & & & \\ oxide & & & & & & & & & & & \\
30 & Methyl salicylate & 21.95 & 1192 & - & d & d & d & d & d & d \\
31 & Safranal & 22.25 & 1196 & Safron & d & nd & nd & nd & d & d & nd \\
32 & Decanal & 22.45 & 1200 & Penetrating, & & & & & & & & \\
33 & (_E,E)-2,4-Nonnadial * & 22.93 & 1215 & Fatty, green & d & d & d & nd & d & d \\
34 & Geranial * & 24.79 & 1254 & Rose-like & d & d & d & d & d & d \\
35 & Geranial & 25.55 & 1267 & Citrus & d & nd & nd & d & d & nd \\
36 & Trans anethole & 26.35 & 1280 & Sweet & nd & d & d & d & nd & nd \\
37 & (_E,Z)-2,4-Decadical & 26.54 & 1291 & Deep-fried & d & d & nd & d & d & nd \\
38 & (_E,Z)-2-Decadical * & 29.64 & 1319 & Fatty, fried & d & d & nd & d & d & nd \\
39 & \(\beta\)-Damascenone & 30.48 & 1381 & Fruity & d & d & nd & d & d & nd \\
40 & (Z)-Jasmone & 31.01 & 1400 & Florat, sweet, & d & nd & d & d & nd & nd \\  & & & & & & & & & & & \\
41 & \(\alpha\)-Ionone & 32.24 & 1424 & Violet-like & d & d & d & d & d & d \\
42 & Geranyl acetone & 33.31 & 1450 & Magnolia, green & d & d & nd & d & d & d \\
43 & \(\beta\)-Ionone * & 34.62 & 1483 & Violet-like & d & d & nd & d & d & d \\
44 & Caffeine & 43.77 & 1841 & - & d & d & d & d & d & d \\ \hline \hline \end{tabular}
\end{table}