## 3 Results and Discussion
### Relevance for the Production of Volatile Compounds during Alcoholic Fermentation
#### 3.3.1. Biotin Influence on Wine Volatile Compounds  
Out of the 31 analyzed, 13 volatile compounds were significantly influenced by the initial biotin concentration in the synthetic must medium (Table 6, Figure 2A-C), offering the first evidence for the relevance of biotin in the production of wine volatiles, on a substantial scale of analyzed compounds. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Compound (ug/L)**} & \multicolumn{2}{c}{**Initial Biotin Concentration (ug/L)**} \\ \cline{2-3}  & **0** & **0.5** & **3** \\ \hline Benzaldehyde & 52.57 \(\pm\) 16.76 \({}^{\text{a}}\) & 36 \(\pm\) 10.69 \({}^{\text{ab}}\) & 29.56 \(\pm\) 4.93 \({}^{\text{b}}\) \\ Diethyl succinate & 0.34 \(\pm\) 0.05 \({}^{\text{a}}\) & 0.47 \(\pm\) 0.1 \({}^{\text{ab}}\) & 0.44 \(\pm\) 0.05 \({}^{\text{b}}\) \\ Ethyl dec-9-enoate & 0.69 \(\pm\) 0.16 \({}^{\text{a}}\) & 1.77 \(\pm\) 30.0 \({}^{\text{ab}}\) & 1.19 \(\pm\) 0.4 \({}^{\text{b}}\) \\ Ethyl hexanoate & 38.29 \(\pm\) 4.54 \({}^{\text{a}}\) & 41.67 \(\pm\) 7.95 \({}^{\text{a}}\) & 52.56 \(\pm\) 4.33 \({}^{\text{b}}\) \\ Ethyl octanoate & 51.43 \(\pm\) 4.76 \({}^{\text{a}}\) & 54.22 \(\pm\) 6.7 \({}^{\text{a}}\) & 71.56 \(\pm\) 9.03 \({}^{\text{b}}\) \\
1-Heptanol & 9.14 \(\pm\) 1.57 \({}^{\text{a}}\) & 14.22 \(\pm\) 4.29 \({}^{\text{b}}\) & 14.22 \(\pm\) 2.44 \({}^{\text{b}}\) \\ Isoamyl acetate & 83 \(\pm\) 18.15 \({}^{\text{a}}\) & 81.44 \(\pm\) 28.85 \({}^{\text{ab}}\) & 59.78 \(\pm\) 13.46 \({}^{\text{b}}\) \\ Isoamyl alcohol & 75,173.43 \(\pm\) 8173.63 \({}^{\text{a}}\) & 67,532.22 \(\pm\) 19,964.24 \({}^{\text{a}}\) & 49,623.22 \(\pm\) 4767.42 \({}^{\text{b}}\) \\ Isovaleric acid & 2787.86 \(\pm\) 156.47 \({}^{\text{a}}\) & 3095.96 \(\pm\) 401.25 \({}^{\text{ab}}\) & 347.22 \(\pm\) 327 \({}^{\text{b}}\) \\
1-Nonanol & 8.14 \(\pm\) 1.46 \({}^{\text{a}}\) & 11.33 \(\pm\) 4.06 \({}^{\text{b}}\) & 10.44 \(\pm\) 1.59 \({}^{\text{b}}\) \\ Octanoic acid & 6334 \(\pm\) 695.2 \({}^{\text{a}}\) & 6620.89 \(\pm\) 1678.83 \({}^{\text{a}}\) & 8288.22 \(\pm\) 730.84 \({}^{\text{b}}\) \\
1-Octanol & 37.71 \(\pm\) 5.59 \({}^{\text{ab}}\) & 35.78 \(\pm\) 11.02 \({}^{\text{a}}\) & 48.56 \(\pm\) 8.9 \({}^{\text{b}}\) \\ Propy1 acetate & 2.26 \(\pm\) 0.36 \({}^{\text{a}}\) & 3.3 \(\pm\) 0.81\({}^{\text{ab}}\) & 4.06 \(\pm\) 0.94 \({}^{\text{b}}\) \\ \hline \hline \end{tabular} Note: different letters in the same line indicate significant differences between conditions (Scheire–Ray–Hare and Dunn tests, \(p<0.05\)).  
\end{table} 
Table 6: Biootin-dependent volatile contents in the final wines. Figure 2: Hierarchical clustering of the biotin (**left**) and thiamine (**right**) significantly impacted volatile compounds in the final wines: effect of both vitamins on their profiles. (**A–C**): Biotin-impacted volatile compounds (**(A)**: Fatty acid metabolites, (**B**): Ehrlich pathway metabolites, (**C**): Central carbon metabolites). (**D–F**): Biotin-impacted volatile compounds (**(D)**: Fatty acid metabolites, (**E**): Ehrlich pathway metabolites, (**F**): Central carbon metabolites). A clear effect held by the vitamin on fatty acid metabolism appeared here, since 7 of the 13 fatty acids, fatty alcohols, and fatty acid ethyl esters (FAEEs) displayed significant (\(p>0.05\)) dose-related variations in their contents (Figure 2A). Notable increases in all the fatty acid-related compounds appeared when increasing the initial biotin concentration in the medium, therefore highlighting a strong stimulatory effect of the vitamin on those compounds. Interestingly, it must be noted that such increases do appear for all derived compounds of a given fatty acid, with its associated alcohol and ethyl esters being heightened in a similar fashion, suggesting that the stimulatory influence of the vitamin on those compounds appears at the previous stages of the fatty acid synthesis pathway.