## 3 Results and Discussion
### Volatile Compounds
#### 3.4.6 Ethyl Esters
\\ EE11 & Ethyl 3-ethoxypropionate & B, C & 1336 & 1320 & n.d. & n.d. & **0.37 \({}^{\text{a}}\)** & **0.00 \({}^{\text{b}}\)** & - & - & - \\ EE12 & Ethyl heptanoate & B, C & 1340 & 1342 & **8.84 \({}^{\text{a}}\)** & **6.09 \({}^{\text{b}}\)** & 9.59 \({}^{\text{c}}\) & 7.54 \({}^{\text{c}}\)** & n.s. & n.s. \\ EE13 & Ethyl 2-hexenoate I & B, C & 1350 & 1357 & 14.68 \({}^{\text{a}}\) & 12.80 \({}^{\text{a}}\) & 21.45 \({}^{\text{a}}\) & 22.60 \({}^{\text{a}}\) & n.s. & **22** & n.s. \\ EE14 & Ethyl 2-hexenoate II & B, C & 1361 & 1357 & 0.17 & 0.18 \({}^{\text{a}}\) & n.d. & n.d. & - & - & - \\ EE15 & Ethyl _trans_-4-heptenoate & B, C & 1378 & 1377 & n.d. & n.d. & 0.18 \({}^{\text{a}}\) & 0.18 \({}^{\text{a}}\) & - & - & - \\ EE16 & Ethyl 2-hydroxyisovalerate & B, C & 1426 & 1426 & n.d. & n.d. & 0.01 \({}^{\text{a}}\) & 0.09 \({}^{\text{a}}\) & - & - & - \\ EE17 & Ethyl octanocate (mg/L) \(\ddagger\) & A, B, C & 1462 & 1466 & **0.41 \({}^{\text{a}}\)** & **0.04 \({}^{\text{b}}\)** & **0.05 \({}^{\text{b}}\)** & **SCE** & n.s. & n.s. \\ EE18 & Ethyl acetylacate & B, C & 1462 & 1486 & **2.14 \({}^{\text{a}}\)** & **0.78 \({}^{\text{b}}\)** & n.d. & n.d. & - & - & - \\ EE20 & Ethyl _trans_-2-4-hexadiene & B, C & 1510 & 1505 & n.d. & n.d. & 0.11 \({}^{\text{a}}\) & 0.12 \({}^{\text{a}}\) & - & - & - \\ EE21 & Ethyl _trans_-4-octoneate & B & 1516 & - & n.d. & n.d. & 0.09 \({}^{\text{a}}\) & 0.08 \({}^{\text{a}}\) & - & - & - \\ EE22 & Ethyl 3-hydroxybutyrate & B, C & 1520 & 1524 & **2.48 \({}^{\text{a}}\)** & **0.91 \({}^{\text{b}}\)** & 4.61 \({}^{\text{b}}\) & 5.15 \({}^{\text{a}}\) & n.s. & **22** & **n.s. \\ EE23 & Ethyl nonanoate & B, C & 1537 & 1535 & 7.98 & 10.42 \({}^{\text{a}}\) & 12.21 \({}^{\text{a}}\) & 11.08 \({}^{\text{a}}\) & n.s. & n.s. & n.s. \\ EE24 & Ethyl 2-hydroxy-4-methylvalerate & B, C & 1542 & 1547 & **13.95 \({}^{\text{a}}\)** & **9.89 \({}^{Some other linear-chain ethyl esters were more prevalent in SCE wines. These included ethyl propanoate and ethyl _trans_-2-butenoate in both years, ethyl heptanoate and ethyl 7-octenoate in 2021, and ethyl pentanoate in 2022 (Table 10). Higher levels of other ethyl ester derivatives, such as oxo-, hydroxy-, and acetoxy-esters, were also characteristic of SCE fermentation. These included ethyl acetylacetate and ethyl 4-hydroxybutyrate in both years; ethyl 3-hydroxybutyrate, ethyl 2-hydroxy-4-methylvalerate, and ethyl 3-acetoxyhexanoate in 2021; as well as ethyl 5-oxohexanoate and ethyl 3-hydroxydecanoate in 2022. Among branched-chain fatty acid esters linked to the Ehrlich pathway, SCE wines contained higher levels of ethyl 3-methylbutyrate, whereas SPA wines contained more ethyl 2-methylbutyrate. Additionally, _S. paradoxus_ produced more ethyl pyruvate, suggesting possible differences in the initial metabolic processes between the two yeasts. Ethyl esters of certain medium-chain unsaturated fatty acids, such as ethyl _trans_-4-decenoate and two isomers of ethyl 9-decenoate, were found in higher concentra-tions in SPA-21 than in SCE-21 wines. In most instances where significant differences were noted, the 2021 wines contained higher concentrations of ethyl esters compared to those from 2022.