## 3 Results
### Characterization of Microcapsules
#### 3.2.4 Thermogravimetric Analysis (TGA)  
The thermal stability of the dried powders was determined using thermogravimetric analysis (Figure 2). The powders' weight loss data are summarized in Table 4. All dried power samples generally exhibited the same dehydration trend and decomposition phases as the conventional thermogravimetric profile of carbohydrates. Weight loss occurred in three main stages. The initial weight loss up to 100 \({}^{\circ}\)C corresponds to the evaporation of water and adsorbed volatile compounds or non-encapsulated oil from the powders. The weight loss of this first stage varied between 6.31% and 7.07%. There is no significant difference between the different powders. The second stage of thermal degradation corresponds to the decomposition of the carrier. It coincides with the loss of essential oil. The powders prepared at pH 3 presented higher temperatures in this step. This could be due to the higher concentrations of H\({}^{+}\) ions in acidic solutions that could cause more hydrogen-bonding interactions. Finally, the third stage of thermal degradation corresponds to the thermal decomposition of the organic compounds or inert carbonaceous residues. The principal weight loss occurred during this last step for all samples. The average weight loss for all powders was 58.72 \(\pm\) 0.68%. These results are similar to the data reported by [PERSON] et al. [33], who encapsulated thyme essential oil via freeze-drying using whey protein nanocarriers. They observed the weight loss over three stages, of which the third stage corresponded to a weight loss of about 80% of their mass. \begin{table}
\begin{tabular}{c c c c c c} \hline \multirow{2}{*}{**Sample**} & \multicolumn{2}{c}{**Step 1**} & \multicolumn{2}{c}{**Step 2**} & \multicolumn{2}{c}{**Step 3**} \\ \cline{2-7}  & **T** (\({}^{\circ}\)**C) & **Mass Loss (\%)** & **T** (\({}^{\circ}\)**C) & **Mass Loss (\%)** & **T** (\({}^{\circ}\)**C) & **Mass Loss (\%)** \\ \hline L3S & 100.62 & 6.53 \(\pm\) 0.02 \({}^{\mathrm{d}}\) & 245.37 & 16.49 \(\pm\) 0.7 \({}^{\mathrm{a}}\) & 297.95 & 57.58 \(\pm\) 0.21 \({}^{\mathrm{f}}\) \\ L7S & 100.67 & 7.07 \(\pm\) 0.02 \({}^{\mathrm{a}}\) & 194.46 & 12.46 \(\pm\) 0.37 \({}^{\mathrm{d}}\) & 313.12 & 59.37 \(\pm\) 0.06 \({}^{\mathrm{b}}\) \\ P3S & 100.47 & 6.92 \(\pm\) 0.02 \({}^{\mathrm{b}}\) & 257.93 & 18.56 \(\pm\) 0.18 \({}^{\mathrm{a}}\) & 311.16 & 59.83 \(\pm\) 0.08 \({}^{\mathrm{a}}\) \\ P7S & 100.57 & 6.79 \(\pm\) 0.01 \({}^{\mathrm{c}}\) & 192.95 & 13.12 \(\pm\) 0.04 \({}^{\mathrm{d}}\) & 308.04 & 59.10 \(\pm\) 0.07 \({}^{\mathrm{b}}\) \\ L3L & 100.47 & 6.80 \(\pm\) 0.02 \({}^{\mathrm{c}}\) & 242.88 & 15.21 \(\pm\) 0.03 \({}^{\mathrm{c}}\) & 313.16 & 58.10 \(\pm\) 0.14 \({}^{\mathrm{e}}\) \\ L7L & 100.49 & 6.29 \(\pm\) 0.02 \({}^{\mathrm{c}}\) & 197.46 & 14.50 \(\pm\) 0.37 \({}^{\mathrm{c}}\) & 308.11 & 58.16 \(\pm\) 0.45 \({}^{\mathrm{e}}\) \\ P3L & 100.49 & 6.87 \(\pm\) 0.08 \({}^{\mathrm{b}}\) & 242.85 & 16.75 \(\pm\) 0.11 \({}^{\mathrm{b}}\) & 305.46 & 58.60 \(\pm\) 0.23 \({}^{\mathrm{d}}\) \\ P7L & 100.57 & 6.60 \(\pm\) 0.02 \({}^{\mathrm{d}}\) & 192.41 & 14.88 \(\pm\) 0.14 \({}^{\mathrm{c}}\) & 300.52 & 58.95 \(\pm\) 0.11 \({}^{\mathrm{c}}\) \\ \hline \end{tabular}
\end{table} 
Table 4: The weight loss temperature (Tm) and mass loss (%) of microcapsules. For results with the same letter, the difference between the means is not statistically significant. Figure 2: TG curves of microcapsules of _trans_-cinnamaldehyde (SD and FD powders). The total weight loss of all powders ended at 600 \({}^{\circ}\)C. At the end, all powders completely degraded and turned into gray ash. As we observed, the drying method and the different emulsifying agents did not cause a considerable change in the thermal stability of the dried powders. Thermal stability varied only slightly with the pH at which the emulsions were prepared prior to drying, with thermal stability being higher at pH 3 than at pH 7.