## 3 Results
### Interaction with Water  
Table 3 shows the moisture content, water-solubility, absorption capacity, and contact angle values for the studied films. As expected, the addition of hydrophobic molecules to the material significantly modified the properties related to the interaction with water.  
Regarding the moisture content, no significant differences (\(p<0.05\)) were observed between the yarn flour films in addition to essential oil. However, a higher moisture content (0.0067) was observed for F1 compared to the other formulations. This fact suggests that the amylose interaction favoured the hydrophilicity of the material. Finely dispersed oil molecules between the starch chains could occupy intermolecular spaces, preventing the water molecules from easily interacting with the starch hydroxyls [33]. This fact would favour a decrease in the moisture content of the material, given that the incorporation of hydrophobic substances throughout the polysaccharide matrix tends to reduce possible interactions between water and functional groups of the polymer [34].  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Formulations** & **Thickness** & **WVP** & **OP** \\ \hline F1 & 244 \(\pm\) 4 \({}^{\text{a}}\) & 19.2 \(\pm\) 1.2 \({}^{\text{a}}\) & 2.4 \(\pm\) 0.3 \({}^{\text{a}}\) \\ F2 li & 175 \(\pm\) 4 \({}^{\text{b}}\) & 11.8 \(\pm\) 0.5 \({}^{\text{b}}\) &  
The results of the solubility of the films are related to the moisture content, so the higher value of solubility (F1) indicates a lower water resistance. Possibly the presence of oil molecules between the starch chains can weaken the intermolecular forces between the amylose and amylopectin chains, promoting the system's instability in an aqueous medium [31]. As have been reported, the addition of essential oil significantly changes the water solubility of starch films. In some cases, essential oils increase this property, and in other cases, a reduction is observed, suggesting that hydrophilic compounds increase the film solubility while hydrophobic compounds decrease it [35]. [PERSON] et al., 2020 found that the solubility of starch films increased with increasing thyme essential oil microcapsule content due to the hydrophilicity of the microcapsules [36]. The high-water solubility of biomaterials can be advantageous for the biodegradation process of the films [37].  
Water absorption is a critical film factor, especially for packaging applications, demonstrating the film's sensitivity to liquid water contact [38]. Films in the presence of essential oil did not show significant differences between them (\(p<0.05\)), with a maximum value for F3 fe of 0.98, while F1 showed the minimum value of 0.81. Therefore, all films achieved medium absorption. The decrease in the intermolecular forces of the starch chains could make it easier for the liquid water molecules to penetrate the matrix more easily. Interestingly, the opposite case would be given for water vapour molecules (moisture content and permeability to water vapour) [36].  
Table 3 shows that the yarn films presented values between 56 and 62\({}^{\circ}\) of contact angle with water. The contact angles were higher in the films containing essential oils, due to the presence of oils molecules that increase the surface tension of the water droplets on the surface of the film. Other authors also observed similar water contact angle values for yarn starch-based films ranging from 44.0\({}^{\circ}\) to 63.3\({}^{\circ}\), indicating that the higher the contact angle value, the more hydrophobic the material [39].