## 3 Results and Discussion
### FT-IR Analysis of Microcapsules
The FT-IR spectrum of gelatin (Figure 8: GE) shows a broad peak at 3453 cm\({}^{-1}\) that reflects the combined contributions of functional groups characteristic of gelatin's complex structure, such as the N-H stretching of amide bonds and -NH\({}_{2}\) groups [67; 68] and O-H stretching vibrations from hydroxyl groups in amino acid side chains [68]. The peak at 2924 cm\({}^{-1}\) is due to stretching vibrations of C-H bonds in the aliphatic chains of the amino acid residues, while the one observed at 1385 cm\({}^{-1}\) is associated with the bending vibrations of C-H bonds in methyl groups [59], indicating the presence of amino acids with methyl-containing side chains. The prominent peak at 1632 cm\({}^{-1}\) is primarily due to the C=O stretching vibrations of the amide groups in the protein backbone, a characteristic feature of proteins and polypeptides that reflect the peptide bond structure. Lastly, the peak at 1032 cm\({}^{-1}\) can be attributed to the C-N stretching vibrations of amine groups or the C-O stretching of hydroxyl groups, indicative of the complex structure of amino acid residues and peptide bonds in gelatin [64; 65; 66]. During complex coacervation, the free negatively charged carboxylic groups of polysaccharides are expected to interact with the positively charged amino groups of proteins, forming complexes. Figure 8 (PL) shows the FT-IR spectrum of the coacervates, which contains the characteristic peaks of both GA and GE, such as at 3570 cm\({}^{-1}\), 2926 cm\({}^{-1}\), and a broader peak at 1638 cm\({}^{-1}\), which arises from the overlap and slight shift of the GE peak at 1632 cm\({}^{-1}\) and the GA peak at 1617 cm\({}^{-1}\). However, the characteristic peak of the GA spectrum at 1425 cm\({}^{-1}\) was absent. Similar observations have been reported by other authors for GA--GE coacervates and attributed to the involvement of GA's carboxylic groups in electrostatic interactions with the amino groups of the protein. The appearance of new peaks at 1240 cm\({}^{-1}\) and 1029 cm\({}^{-1}\) indicates the presence of N-H groups that can form hydrogen bonds and participate in electrostatic interactions when protonated (NH\({}_{3}\)\({}^{+}\)) and C-O stretching in arabic gum, supporting the presence of carboxylate groups (COO\({}^{-}\)) contributing to negative charges [65]. To investigate the intermolecular interactions between the wall materials and the core material, the spectrum of AMO-loaded microcapsules (Figure 8: MC) was compared with the FTIR spectrum of the essential oil (Figure 8: AMO) and that of unloaded microcapsules (Figure 8: PL). The spectrum of the AMO-containing microcapsules exhibits the same characteristic peaks as the essential-oil-free microcapsules (PL), except for a more intense peak at 2926 cm\({}^{-1}\) and the appearance of a new peak at 1450 cm\({}^{-1}\), both associated with the C-H stretching and bending vibrations in the aliphatic hydrocarbons found in the composition of the essential oil. These findings suggest that the essential oil was successfully encapsulated and there was no significant interaction between AMO and wall materials [64,66].