## 2 Results and Discussion
### VOCs Produced during Fermentation
\begin{table}
\begin{tabular}{c c c c c} \hline
**No** & **VOCs** & **Formula** & **RT** & **RLcal** & **RLlit** \\ \hline \multicolumn{5}{c}{Acids} \\  
Tridecanol & C\({}_{13}\)H\({}_{28}\)O & 25.9 & 1933 & 1903 \\
21 & P-cresol & C\({}_{7}\)H\({}_{8}\)O & 29.452 & 2051 & 2080 \\  & Aldehydes & & & \\
22 & Butanal & C\({}_{4}\)H\({}_{8}\)O & 2.752 & 911 & 877 \\
23 & 2-Methyl-butanal & C\({}_{5}\)H\({}_{10}\)O & 2.898 & 922 & 914 \\
24 & 3-Methyl-1-butanol & C\({}_{5}\)H\({}_{10}\)O & 2.958 & 926 & 918 \\
25 & 2-Methyl-2-butenal & C\({}_{5}\)H\({}_{8}\)O & 6.174 & 1114 & 1095 \\
26 & 3-Methyl-2-butenal & C\({}_{5}\)H\({}_{8}\)O & 8.765 & 1216 & 1215 \\
27 & 2-Methyl pentanal & C\({}_{6}\)H\({}_{12}\)O & 13.655 & 1403 & - \\
28 & Benzaldehyde & C\({}_{7}\)H\({}_{6}\)O & 17.154 & 1542 & 1520 \\
29 & Benzeneacetaldehyde & C\({}_{8}\)H\({}_{8}\)O & 20.033 & 1663 & 1640 \\  & Esters & & & \\
30 & Ethyl acetate & C\({}_{4}\)H\({}_{8}\)O\({}_{2}\) & 2.608 & 901 & 888 \\
31 & Isoamyl acetate & C\({}_{7}\)H\({}_{14}\)O\({}_{2}\) & 6.811 & 1139 & 1122 \\
32 & 2-Phenylethyl acetate & C\({}_{10}\)H\({}_{12}\)O\({}_{2}\) & 23.892 & 1836 & 1813 \\  & Furans & & & & \\
33 & Furfural & C\({}_{5}\)H\({}_{4}\)O\({}_{2}\) & 15.723 & 1484 & 1461 \\
34 & 2-Furanmethanol & C\({}_{5}\)H\({}_{6}\)O\({}_{2}\) & 20.403 & 1679 & 1660 \\  & Ketones & & & & \\
35 & Acetone & C\({}_{3}\)H\({}_{6}\)O & 1.971 & 823 & 819 \\
36 & 2-Heptanone & C\({}_{7}\)H\({}_{14}\)O & 8.285 & 1198 & 1182 \\  & Sulphur compounds & & & & \\
37 & Dimethyl disulfide & C\({}_{2}\)H\({}_{6}\)S\({}_{2}\) & 5.727 & 1095 & 1077 \\
38 & Methonal & C\({}_{4}\)H\({}_{8}\)OS & 15.467 & 1474 & 1454 \\
39 & Cyclohexyl isothiyanate & C\({}_{7}\)H\({}_{11}\)NS & 20.607 & 1687 & 1667 \\
40 & 3-(methylthio)-1-propanol & C\({}_{4}\)H\({}_{10}\)OS & 21.644 & 1734 & 1719 \\  & (methanol) & Pyrazine & & & \\
41 & Pyrazine & & & & \\
42 & Unknown 1 & & & & \\
43 & Unknown 2 & & & & \\ \hline \end{tabular} Retention time (RT). Retention indices (RI).  
\end{table} 
Table 2: VOCs detected after 14 days of LB672 fermentation in DM with either added glucose or fructose at either 25 or 35 \({}^{\circ}\)C by HS-SPME-GC-MS.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline  & & \multicolumn{3}{c}{**Sum Formula**} & \multicolumn{3}{c}{**P-Value**} \\
**No** & **m/z** & **(Phounded Iend)** & **Tentative Identification** & \multicolumn{3}{c}{**M**} & **T** & **Temp**} & \multicolumn{3}{c}{**M** \(\times\) **T**} & **M** \(\times\) **Temp**} & \multicolumn{3}{c}{**T** \(\times\) **Temp**} \\ \hline
1 & 26.016 & C\({}_{3}\)H\({}^{*}\) & Common fragment & -0.0001 & -0. \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**No**} & \multicolumn{3}{c}{**Sum Formula**} & \multicolumn{3}{c}{**P-Value**} \\  & \multicolumn{3}{c}{**mV/z**} & \multicolumn{3}{c}{**(Protonated Ion)**} & **Tentative Identification**} & \multicolumn{3}{c}{**M**} & **T** & **Temp** & \multicolumn{1}{c}{**M** \(\times\)**T**} & **M** \(\times\)**Temp** & \multicolumn{  
To understand how glucose or fructose addition to the defined medium and fermentation conditions impacted on VOCs generation during LB672 fermentation, principal component analysis (PCA) was performed using the 104 \(m/z\) detected by PTR-ToF-MS. To ensure that the PCA was focusing on variation in the data from different medium compositions and fermentation conditions, data from the control (uninoculated) treatments were excluded from the PCA. As shown in Figure 1a, the PCA score plot of the DM and DMFr samples explained 60.8% of the total variance, comprising 46.8% from the first principal component (Dim 1) and 14% from the second principal component (Dim 2). The explained variance was mainly attributed to the separation of DM samples at 35 \({}^{\circ}\)C from the 0 day samples (Figure 1a). The DMFr at either 25 or 35 \({}^{\circ}\)C and DM at 25 \({}^{\circ}\)C samples showed a minor separation from the 0 day samples.