## 3 Results
### Fermentation Temperature Impacts the Volatile Compound Profile in S. eubayanus Strains
\begin{table}
\begin{tabular}{l l l l l l l} \hline \hline  & & \multicolumn{6}{c}{**Relative Abundance (\(\times 10^{6}\)) and SEM**} \\ \cline{3-6}  & & \multicolumn{6}{c}{**Strain**} \\ \hline \multicolumn{6}{c}{**CL905.1**} \\ \hline
**Chemical Group** & **Compound** & **RI** & **12 °C** & **20 °C** & **12 °C** & **20 °C** \\ \hline
**Aliphatic esters** & Ethyl octanoate & 1192.63881 & 483.1 \(\pm\) 250.2 & 1566.67 \(\pm\) 251.66 & 228.8 \(\pm\) 76 & 1566.67 \(\pm\) 120.19 \\  & Ethyl 9-decanoate & 1384.56268 & 448.5 \(\pm\) 165.1 & 622.93 \(\pm\) 232.23 & 137.5 \(\pm\) 63.5 & 622.93 \(\pm\) 116.55 \\  & Ethyl decanoate & 1391.7014 & 1700 \(\pm\) 734.6 & 3666.67 \(\pm\) 101.60 & 141.7 \(\pm\) 38.3 & 3666.67 \(\pm\) 490.61 \\  & Isoamyl decanoate & 1644.73154 & 1021.2 \(\pm\) 28.9 & 162.40 \(\pm\) 44.51 & N/D & 162.40 \(\pm\) 21.72 \\  & Ethyl tetradecanoate & 1786.82537 & 228.2 \(\pm\) 38.9 & 267.33 \(\pm\) 52.60 & 49.7 \(\pm\) 6.8 & 267.33 \(\pm\) 23.47 \\  & Ethyl hexadecanoate & 1991.92208 & 666 \(\pm\) 179.7 & 553.43 \(\pm\) 59.25 & N/D & 553.43 \(\pm\) 48.51 \\ \hline
**Aromatic esters** & Phenethyl acetate & 1250.12471 & 522.4 \(\pm\) 233.1 & 687.80 \(\pm\) 328.51 & N/D & 687.80 \(\pm\) 189.00 \\ \hline
**Aromatic alcohols** & Phenethyl Alcohol & 1116.18753 & 3800 \(\pm\) 971.5 & 8600.00 \(\pm\) 346.41 & 2900 \(\pm\) 805 & 8600.00 \(\pm\) 851.14 \\ \hline
**Aromatic aldehydes** & Benzaldehyde, 4-methyl & 1083.5138 & N/D & 170.50 \(\pm\) 85.41 & 42.1 \(\pm\) 6 & 170.50 \(\pm\) 21.10 \\ \hline
**Carboxylic acids** & Octanoic acid & 1171.36867 & 633.5 \(\pm\) 101.3 & N/D & 12.5 \(\pm\) 2.4 & 131.80 \(\pm\) 13.44 \\  & Decanoic acid & 1556.73878 & 38.3 \(\pm\) 3.4 & 1866.67 \(\pm\) 404.15 & N/D & 1866.67 \(\pm\) 135.36 \\ \hline
**Phenols** & 4-vinyl[quaiacol] & 1317.44761 & 238.7 \(\pm\) 39.4 & 308.03 \(\pm\) 76.01 & 98.8 \(\pm\) 11.4 & 290.93 \(\pm\) 38.64 \\ \hline \end{tabular} Compounds detected in S. _exhausum_ fermentation by HS-SPME-CG-MS. SEM standard error of the mean; CAS Chemical Abstracts Service: N/D. Not detected; RI Kovats retention indices.  
\end{table} 
Table 2: Main Volatile Compounds detected in CL905.1 and CL602.1. We next selected the compounds with the highest area percentage (representing approximately 65% of the area of the whole peak) in CL905.1 and CL602.1 strains (Figure 5, Table 2). In this way, we identified 12 main compounds at 12 \({}^{\circ}\)C and 20 \({}^{\circ}\)C, for which relative areas were compared between both strains. As previously mentioned, not only the number of VCs changed with temperature, but we also found differences in the relative amount produced depending on the fermentation temperature. For example, ethyl octanoate (aliphatic ester) and phenethyl alcohol (aromatic alcohol, higher alcohol) (Figure 5, Table 2) significantly increased at 20 \({}^{\circ}\)C (\(p\)-value \(>\) 0.001, ANOVA), independently of the strain. On the other hand, higher levels in the relative amount of 4-VG at 20 \({}^{\circ}\)C compared to 12 \({}^{\circ}\)C was only observed in CL602.1 (\(p\)-value \(>\) 0.001, ANOVA) and not in CL905.1 (Figure 5). Similarly, other ester compounds significantly increased with temperature solely in CL602.1, such as: ethyl 9-decanoate, ethyl decanoate, isoamyl decanoate, and phenethyl acetate (\(p\)-value \(>\) 0.001, ANOVA). Depending on the strain, a higher fermentation temperature allowed us to find novel compounds undetected at 12 \({}^{\circ}\)C. For example, benzaldehyde 4-methyl (aromatic aldehyde) was exclusively detected in CL905.1 at 20 \({}^{\circ}\)C, but not at 12 \({}^{\circ}\)C. In contrast, in CL602.1, this compound was detected at both temperatures (\(p\)-value \(<\) 0.001, ANOVA). These results demonstrate that fermentation temperature results in different profiles in both strains in terms of the number of compounds, but also in their relative amounts, representing a strain \(\times\) temperature specific interaction.