## 3 Results and Discussion
### VOC Flavor Profile of Commercial Tea  
Compared to the VOC flavor profile of concentrated apple juice, a considerably lower number of target compounds were identified in samples of commercial tea, but also a different structure of the proportions between the classes of compounds. Also, in this case, the flavor profile was dominated by compounds from the medium-chain ester class, with a \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Peak No.** & **RT (min)** & **Compound** & **CAS No.** & **Probability (\%)** & **Flavor/Fragance** \\ \hline
1 & 4.428 & Pentyl acetate & 628-63-7 & 66.8 & Banana/apple \\
2 & 7.562 & trans-2-Pentene & 646-04-8 & 65.2 & - \\
3 & 7.898 & Ethyl butyrate & 105-54-4 & 73.0 & Pineapple \\
4 & 8.250 & Tetramethylene diacetate & 628-67-1 & 70.6 & Pineapple \\
5 & 8.775 & Ethyl 2-methylbutyrate & 7452-79-1 & 65.1 & Strawberries \\
6 & 9.490 & 2-Methylbutyl acetate & 624-41-9 & 68.7 & Sweet banana \\
7 & 10.044 & 3,3-Dimethyl-1-pentene & 3404-73-7 & 66.8 & - \\
8 & 10.200 & 3-Furaldehyde & 498-60-2 & 67.6 & Woody \\
9 & 11.568 & Butyl butyrate & 109-21-7 & 69.0 & Sweet pineapple \\
10 & 11.930 & Hexyl acetate & 142-92-7 & 75.4 & Sweet pear/banana \\ \hline \hline \end{tabular}
\end{table} 
Table 1: VOCs identified in the concentrated apple juice. majority of four compounds, namely pentyl acetate (rt = 4.428 min; \(m/z\) = 55, 61, 43), ethyl butyrate (rt = 7.898 min; \(m/z\) = 43, 73,88), isopentyl acetate (rt = 9.449 min, \(m/z\) = 70, 55, 43), and pentyl butyrate (rt = 12.607, \(m/z\) = 70, 43, 89). The other compounds were identified as terpen/terpenoids: two compounds (A-terpineol; rt = 12.756 min; top-priority \(m/z\) = 91, 93, 121) and A-pinene (rt = 13.839; top-priority \(m/z\) = 91, 93, 77)) and the alkene 1-methyl-cyclopentene (rt = 11.928, \(m/z\) = 67, 82, 41, Table 2). VOCs qualitatively identified by the proposed method have a probability higher than 67% and, respectively, a match factor score higher than 750. MS profiles of the VOCs identified in the commercial tea are given in Figure S3. Pentyl acetate and ethyl butyrate were previously detected in the concentrated apple juice, giving the profile the sweet and intense flavor of apple and pineapple. Compared to pentyl acetate, its superior counterpart, isopentyl acetate is an ester with a strong and pungent smell similar to banana and pear [30]. It is found naturally in the banana plant, but it is also obtained synthetically through a condensation reaction, and the product is commercially also called banana oil. Isopentyl acetate is found naturally in the species of Vitis rotundifolia, but there are studies on its formation through the microbial proliferation of _C. albicans_ and _S. aureus_[31]. A final ester detected in commercial tea that contributes to banana-like flavors is pentyl butyrate (amyl butyrate). It is found naturally in bananas, apples, and common apricot species. It has a smell reminiscent of pears and apricots, which makes it ideal in food flavoring and as an additive in cigarettes [10]. The alkene 1-methyl-cyclopentene is the only component in commercial tea. There are a lot of studies in the literature on 1-methyl-cyclopentene, but none attest to its use in the food or beverage industry. However, according to the PubChem database, it is a compound detected naturally in camphor (_Cinnamomum camphora_) and rice (_Oryza sativa_). A-terpineol is a terpenoid with an intense woody odor, used most intensively in the flavors and fragrances industry and in medicine due to its multiple properties reported as biological agents (ant antimicrobial, anticarcinogenic, etc.). In nature, it is identified in many sources, such as flowers, fruits, vegetables, and herbs, but this compound is present in low concentrations (generally less than 1%). Moreover, although it can be extracted from natural sources by fractional distillation, in terms of commercial production, a-terpineol is generally obtained by chemical synthesis [32]. A-pinene completes the profile of intense woody aromas.