## 3 Results
### Optical Properties  
The optical properties of food packaging materials play an important role in the appearance and acceptance of packaging by consumers [40]. Table 4 presents the optical properties (gloss at an angle of incidence of 85\({}^{\circ}\) and internal transmittance at 650 nm) of yarn starch films with and without essential oils. The gloss values obtained were between 32.1 and 38.7\({}^{\circ}\), so they can be considered low gloss. In F3, the gloss decreased significantly (\(p>0.05\)) compared to the other formulations. This property is related to the surface roughness of the films. The more homogeneous the surface, the brighter it will be. Therefore, the analyzed films had surface roughness, possibly due to the drying process and the retrogradation of the starch chains on the surface of the films. In addition, essential oils have been reported to reduce the transparency and increase the opacity of starch films due to a modification in the crystalline structure and increased light scattering generated by the oil droplets in the polymer matrix [41]. For instance, [PERSON] et al., 2020 reported a reduction in corn starch films' optical properties (e.g., transparency) due to the presence of thyme essential oil microcapsules [36]. All the films here developed mean  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Formulations** & **Xw** & **Solubility in Water** & **Water Absorption Capacity** & **Water Contact Angle (\({}^{\circ}\))** \\ \hline F1 & 0.067 \(\pm\) 0.005 \({}^{\text{a}}\) & 0.182 \(\pm\) 0.005 \({}^{\text{a}}\) & 0.81 \(\pm\) 0.02 \({}^{\text{a}}\) & 56 \(\pm\) 2 \({}^{\text{c}}\) \\ \hline F2 li & 0.042 \(\pm\) 0.003 \({}^{\text{b}}\) & 0.142 \(\pm\) 0.004 \({}^{\text{b}}\) & 0.95 \(\pm\) 0.03 \({}^{\text{b}}\) & 62 \(\pm\) 2 \({}^{\text{b}}\) \\ \hline F3 fe & 0.045 \(\pm\) 0.005 \({}^{\text{b}}\) & 0.141 \(\pm\) 0.002 \({}^{\text{b}}\) & 0.98 \(\pm\) 0.04 \({}^{\text{b}}\) & 67 \(\pm\) 2 \({}^{\text{a}}\) \\ \hline F4 la & 0.043 \(\pm\) 0.005 \({}^{\text{b}}\) & 0.148 \(\pm\) 0.005 \({}^{\text{b}}\) & 0.94 \(\pm\) 0.03 \({}^{\text{b}}\) & 63 \(\pm\) 2 \({}^{\text{b}}\) \\ \hline F5 lifela & 0.042 \(\pm\) 0.004 \({}^{\text{b}}\) & 0.145 \(\pm\) 0.003 \({}^{\text{b}}\) & 0.96 \(\pm\) 0.02 \({}^{\text{b}}\) & 64 \(\pm\) 2 \({}^{\text{ab}}\) \\ \hline \hline \end{tabular}  
* Different superscript letters within the same column indicate significant differences among formulations (\(p<0.05\)).  
\end{table}
Table 3: Mean values and standard deviation of moisture content (Xw, (g water/g dried film)), solubility in water (g solubilized film/g initial dried film), water absorption capacity (g water/ g dried film), and contact angle with water (\({}^{\circ}\)) of the different films after one week of storage at 53% relative humidity and 25 \({}^{\circ}\)C.  
internal transmittance values associated with greater internal homogeneity of the film. As expected, the dispersed phase of essential oil causes the internal homogeneity of the material to decrease as a consequence of higher diffraction of the light 33. From a food preservation point of view, reduced transparency in food packaging materials can also be a positive feature because light scattering can help prevent photo-oxidation and degradation of organic compounds in food products [42].