## 3 Results and Discussion
### Product Identification and Quantitative Analysis  
The percent conversion, which was taken as a scale to determine the optimum conditions, was quantified via in situ NMR monitoring (Figure 3). The \({}^{1}\)H NMR noted new multiple signals at 4.17 and 4.41 ppm, which matched the CH2 OCO and grew concurrently with a decline in the intensity of the glucose protons of C6 signals at 3.39 and 3.52 ppm. The latter signals disappeared after 50 h of reaction when the FAME:glucose 1:3 ratio was used, which means that 100% conversion was achieved (Figure 3). The main product obtained was identified as Glc (C-6)-OCOR, as indicated by 2D (\({}^{1}\)H-\({}^{13}\)C HMDC) NMR (Figure 4a),  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Entry**} & \multirow{2}{*}{**Substrate**} & **Immobilized Enzyme** & **Olive Oil: Glucose Ratio** & **Product** & **Conversion (\%)** \\ \hline
1 & & & 1:1 & Still contains FFAs & 50.5 \(\pm\) 2.5 \\
2 & FFAs & & 1:2 & Still contains FFAs & 70.7 \(\pm\) 3.5 \\
3 & & & 1:3 & Almost 100\% ester & 95.2 \(\pm\) 4.8 \\
4 & & & 1:1 & Still contains FAMEs & 70.1 \(\pm\) 3.5 \\
5 & FAMEs & & 1:2 & Still contains FAMEs & 96.1 \(\pm\) 3.5 \\
6 & & & 1:3 & 100\% ester & 100.0 \(\pm\) 5.0 \\ \hline
7 & & & 1:1 & Still contains FFAs & 30 \(\pm\) 1.5 \\
8 & FFAs & & 1:2 & Still contains FFAs & 63 \(\pm\) 3.2 \\
9 & & & 1:3 & Still contains FFAs & 89 \(\pm\) 4.5 \\
10 & & & 1:1 & Still contains FAMEs & 64 \(\pm\) 3.2 \\
11 & FAMEs & & 1:2 & Still contains FAMEs & 87 \(\pm\) 4.4 \\
12 & & & 1:3 & Still contains FAMEs & 92 \(\pm\) 4.6 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Comparison of GE synthesis using two immobilized liposomes and olive oil-derived FFAs or FAMEs as substrates at different molar ratio of the reactants.  
\begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Entry**} & \multicolumn{2}{c}{**CA Lipase**} & **Conversion (\%)** \\  & **(g/25 mL)** & **(\%)** \\ \hline
1 & 0.10 & 80.3 \(\pm\) 4.0 \\
2 & 0.15 & 92.1 \(\pm\) 4.6 \\
3 & 0.20 & 96.3 \(\pm\) 4.8 \\
4 & 0.25 & 100.3 \(\pm\) 5.0 \\
5 & 0.30 & 100.2 \(\pm\) 5.0 \\ \hline \hline \end{tabular}
\end{table}
Table 2: GE synthesis using olive oil-derived FAMEs (at a FAMEs:Glc ratio of 1:3), utilizing \(C\). _antarctica_ (CA) lipase as catalyst at different concentrations, in a solvent mixture consisting of 80% DMSO and 20% tert-amyl alcohol and for an incubation duration 50 h.  
showing a correlation between the peak assigned to the proton C-6 glucose ester and the carbonyl function in olive oil FAMEs (Figure 4b). The structure of the obtained GEs was additionally confirmed by FTIR analysis, showing the appearance of a broad band at 3380 cm\({}^{-1}\) due to the hydroxyl groups of glucose and the two stretching bands of O-C bond at 1316 cm\({}^{-1}\) and 1015 cm\({}^{-1}\), in parallel with the disappearance of the band at 1743 cm\({}^{-1}\), due to the consumption of the carbonyl group of FAMEs (Figure 5).  
Figure 4: Identification of the ester produced as Glc (C-6)-OCOR by 2D (\({}^{1}\)H-\({}^{13}\)C heteronuclear multiple bond correlation (HMBC)) NMR (**a**) and correlation between the protons of C-6 glucose ester and the carbonyl function in olive oil FAMEs (**b**).  
Figure 3: NMR monitoring of glucose ester synthesis. The signal intensity at 4.17 and 4.41 ppm derived from the CH\({}_{2}\)OCO group increased simultaneously with a decrease in the signal intensity derived from the glucose protons of C6 at 3.39 and 3.52 ppm.