## 3 Results and Discussion
### VOC Flavor Profile of Flavored Sparkling Water  
The total ion chromatogram (TIC) recorded for flavored sparkling water showed an impressive number of peaks: 15 were identified according to Figure S5 and are exemplified in Table 4. According to the retention time and the three most important peaks of the MS spectrum, the volatile organic compounds detected were esters such as methyl butyrate (rt = 6.423 min; \(m/z\) = 43, 74, 78), ethyl isobutyrate (rt = 6.978 min; \(m/z\) = 88, 43, 73), methyl 2-methyl butyrate (rt = 7.411 min; 88, 57, 101), ethyl butyrate (rt = 7.893 min; \(m/z\) = 43, 73, 88), ethyl 2-methyl butyrate (rt = 8.773 min; \(m/z\) = 74, 102, 87), ethyl hexanoate \begin{table}
\begin{tabular}{c c c c c} \hline
**Peak No.** & **RT (min)** & **Compound** & **CAS No.** & **Probability (\%)** & **Flavor/Fragance** \\ \hline
1 & 10.916 & (+)-Sabinene & 3387-41-5 & 77.9 & Herb \\
2 & 11.770 & (+)-Limonene & 5989-27-5 & 73.1 & Fruity \\
3 & 12.058 & p-Cyrene & 535-77-3 & 83.4 & Fruity \\
4 & 12.175 & cis-Sabinene hydrate & 15537-55-0 & 77.5 & Herb \\
5 & 12.274 & \(\gamma\)-Terpinene & 99-85-4 & 71.2 & Turpentine odor \\
6 & 15.723 & 3-Carene & 13466-78-9 & 72.2 & Piney \\
7 & 12.756 & \(\alpha\)-Terpineol & 586-62-9 & 81.3 & Pine/Woody \\ \hline \end{tabular}
\end{table} 
Table 3: VOCs identified in the carbonated lemon drink. (rt = 11,606 min; \(m/z\) = 73, 61, 55), propyl 3-methyl butyrate (rt = 12.417 min; \(m/z\) = 103, 57, 85), and trans-methyl cinnamate (rt = 18.700 min; \(m/z\) = 103, 131, 77). Other compounds identified were alcohols such as cis-2-hexenol (rt = 8.473 min; \(m/z\) = 67, 77, 72), trans-verbenol (rt = 13.397 min; \(m/z\) = 79, 91, 81), and cis- verbenol (rt = 13.713 min; \(m/z\) = 79, 91, 81); aldehydes such as trans-2-hexenal (rt = 10.032 min; \(m/z\) = 83, 69, 55); alkenes, for example, 3-menthene ( rt = 15,407 min, \(m/z\) = 81, 95, 67) and 2-menthenes (rt = 16.569 min, \(m/z\) =95, 81, 67); and terpen such as 3-carene (rt = 15.720 min, \(m/z\) = 93, 91, 79). All VOCs were detected in the headspace air of the flavored sparkling water with a probability > 70% and a match factor score higher than 700. Like many other esters, methyl butyrate and ethyl hexanoate have a fruity apple or pineapple smell. Methyl butyrate was identified by GC-MS in strawberries [42], and ethyl hexanoate was isolated by HS-SPME-GC/MS [43]. It can be produced by distilling essential oils but also chemically synthesized for use in perfumes [44] and as a food flavor. Ethyl isobutyrate has a fruity smell and is used in the following products: disinfectants, washing and cleaning products, paints, and waves, but also in the cosmetic and food industry as a flavoring agent [45]. Regarding Methyl 2-methyl butyrate, numerous brands of fresh and processed apple juices with a pungent, ethereal, and fruity smell use it. Specific strawberry and pineapple flavors for Ethyl butyrate and Ethyl 2-methyl butyrate esters were identified and discussed for the concentrated apple juice samples. Another compound that contributes to the fruity aroma of flavored sparkling water is propyl 3-methyl butyrate. It was isolated and detected from sea bucklhorn juice by HS-SPME-GC/MS [46]. Moreover, the profile of ethereal aromas is completed by trans-Methyl cinnamate-ester derived from aromatic cinnamic acid. According to the PubChem database, it is found in olive oil, used in the perfume industry, and used as a food flavoring due to its intensely aromatic volatile component. Trans-2-hexenal is one of the aldehydes similar in aroma to green apples. It is found naturally in other fruits, such as cherries and wild strawberries. It is only formed when crushed or chewed by very rapid enzymatic conversion of fatty acids. In addition to its usefulness as a flavoring agent, 2-hexenal is used in manufacturing brake fluid and motor lubricants and as a refrigerator cooling agent [47]. 3-menthene and 2-menthene are alkenes structurally similar to monoterpenes.