## 2 Results
### Optimized Tube Scale Production and Scalabilty  
Combining the optimized factors allowed a product concentration of up to 50 g/L of SL at the tube scale to be reached. Interestingly, to demonstrate the scalability of the production in a batch STR, we ended up with a \(\sim\)2-fold decrease of both titer and yield, as shown in Table 5, suggesting that the reaction is sensitive to the effect of the reactor. Presumably, the chosen parameters such as stirring speed and stirring did not match the performance of orbital shaking and resulted in lower performance. Albeit we demonstrated in the present work the scalability of our process. More investigation specific on this reactor system that would focus on these parameters is needed.  
In Figure 5, we observe directly this blatant two-fold decrease in titer. However, it is interesting to notice an equivalent titer in the early stage of the reaction being reached in the STR and the orbitally shaken tubes with comparable initial velocities. After 24 h, the difference in titer increases drastically while the specific productivity dropped in both reactors with a 1:2.5 ratio between the two systems. Finally, at 48 h, reaction velocities decreased again by roughly 2-fold, conserving a similar ratio as previous. Thus, it is suspected that, comparatively, the enzyme was inhibited due to mass transfer limitations in the STR.  
We propose thereafter a discussion making a parallel between our results and pre-existing ones in literature. Allowing us to give a broader aspect of the role of immobilized enzymes, DESs and reactor technologies in sustainable processes such as, but not only limited to, sugar ester synthesis.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Observed _m/z_ Value** & **Corresponding Adduct** & **Relative Abundance (\%) * \\ \hline
329.232 & [M\({}_{\text{SL}}\) + H]\({}^{+}\)-2H\({}_{2}\)O & 7.27 \\
347.243 & [M\({}_{\text{SL}}\) + H]\({}^{+}\)-H\({}_{2}\)O & 100 \\
365.253 & [M\({}_{\text{SL}}\) + H]\({}^{+}\) & 34.05 \\
382.280 & [M\({}_{\text{SL}}\) + NH\({}_{4}\)]\({}^{+}\) & 0.92 \\
387.235 & [M\({}_{\text{SL}}\) + Na]\({}^{+}\) & 18.57 \\ \hline \hline \end{tabular}  
* Calculated from the abundance of the ionic fragments on the y-axis, which was produced by in source fragmentation.  
\end{table}
Table 4: Adducts determined from the observed _m/z_ obtained via ElectroSpray Ionization-Quadrupole (ESI-Q) experiment for the purified Sorbitol-6-O-Laurate (SL).  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Scale/Stirring** & **Titer (g/L)** & **Yield *** (\%)** & \multicolumn{3}{c}{**Specific Reaction Velocity *** (\(\mathbf{\mathbf{\mu}}\)mol/h/g)**} \\ \cline{3-5}  & & & **4 h** & **24 h** & **48 h** \\ \hline Tube/Orbital Shaking & 50 \(\pm\) 3 * & 28 \(\pm\) 2 * & 151 \(\pm\) 13 * & 91 \(\pm\) 4 * & 54 \(\pm\) 5 * \\ Stirred-Tank/3-bladed spiral propeller & 25 \(\pm\) 8 ** & 14 \(\pm\) 4 ** & 134 \(\pm\) 10 ** & 40 \(\pm\) 8 ** & 29 \(\pm\) 4 ** \\ \hline \hline \end{tabular}  
* \(n\) = 3, _p_-value \(<\) 0.05. **\(n\) = 2, _p_-value \(<\) 0.1. *** Calculated from Equations (1) and (2), Section 4.9.  
\end{table}
Table 5: Impact of optimized factors on SL titer after 48 h in Sorbit DES with 5 wt.% water, using Novozym 435® at tube and stirred-tank scales. Reaction conditions: 0.5 M vinyl laurate, 50 \({}^{\circ}\)C and 50 g/L enzyme formulation.