# Rosehip Seed Oil-Incorporated Chitosan Films for Potential Fruit Packaging Applications
## 3 Results and Discussion
### Chitosan/RSO Film Morphology
The puncture modulus was also affected by the oil addition and dropped from (5.46 \(\pm\) 0.78) N/mm down to (3.30 \(\pm\) 0.37) N/mm. A measure of the elasticity in the puncture test is the deformation at break. It shows a linear increase in the full concentration interval from (0.70 \(\pm\) 0.09) mm to up to three times higher at (2.21 \(\pm\) 0.27 mm). Similar to the tensile energy, the puncture energy increased with increasing oil content from (14.46 \(\pm\) 1.76) N\(\cdot\)mm to (28.78 \(\pm\) 3.82) N\(\cdot\)mm. The decrease in strength and the increase in deformability and fracture energy are associated with a change in film properties from stiffer to more elastic. One possible explanation for the observed dependence is the plasticizing effect of the oil [47]. The hydrogen bonds within and between the chitosan chains undergo partial disruption, leading to a decrease in film strength. Similar results were reported by [PERSON] et al., who investigated a chitosan-PLA film containing cinnamon and ginger essential oil [48]. Based on their investigation, oil incorporation into the film can induce the replacement of stronger polymer-polymer interaction by a weaker polymer-oil interaction. This interaction may have caused embrittlement of the network structure, hence decreasing film tensile strength. The other possible reason is the increase in the polyphenol content, which also results in the formation of more hydrogen bonds between the polyphenol and polysaccharide molecules [49]. Consequently, there is an increase in molecular mobility and polymer flexibility. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**RSO cc, \%**} & **Tensile** & **Strain at** & **Tensile** & **Tensile** & **Tensile** & **Puncture** & **Deformati-** & **Puncture** & **Puncture** & **Puncture** & **Pacey** & **Modulus**, \\  & **MPa** & **Break, \%** & **Energy, N-mm** & **Modulus, GPa** & **Force, N** & **mn** & **N-mm** & **N/mm** & **N/mm** \\ \hline
0 & 62.27 \(\pm\) 6.75 \({}^{\rm c}\) & 2.87 \(\pm\) 0.33 \({}^{\rm a}\) & 4.22 \(\pm\) 0.62 \({}^{\rm a}\) & 1.016 \(\pm\) 0.547 \({}^{\rm c}\) & 20.53 \(\pm\) 1.17 \({}^{\rm d}\) & 0.70 \(\pm\) 0.09 \({}^{\rm a}\) & 14.46 \(\pm\) 17 \({}^{\rm g}\) & 5.46 \(\pm\) 0.78\({}^{\rm c}\) \\
1 & 19.27 \(\pm\) 1.90 \({}^{\rm b}\) & 6.89 \(\pm\) 0.21 \({}^{\rm b}\) & 12.85 \(\pm\) 2.68 \({}^{\rm b}\) & 0.588 \(\pm\) 0.432 \({}^{\rm b}\) & 16.99 \(\pm\) 0.61 \({}^{\rm c}\) & 1.09 \(\pm\) 0.17 \({}^{\rm b}\) & 18.53 \(\pm\) 2.36 \({}^{\rm b}\) & 4.77 \(\pm\) 0.72 \({}^{\rm c}\) \\
2 & 19.08 \(\pm\) 3.36 \({}^{\rm b}\) & 9.15 \(\pm\) 1.54 \({}^{\rm c}\) & 16.00 \(\pm\) 2.57 \({}^{\rm b}\) & 0.556 \(\pm\) 0.913 \({}^{\rm ab}\) & 15.89 \(\pm\) 1.06 \({}^{\rm b}\) & 1.24 \(\pm\) 0.15 \({}^{\rm c}\) & 19.38 \(\pm\) 3.82 \({}^{\rm b}\) & 4.03 \(\pm\) 0.42 \({}^{\rm b}\) \\
3 & 19.74 \(\pm\) 2.21 \({}^{\rm b}\) & 11.58 \(\pm\) 1.89 \({}^{\rm d}\) & 18.82 \(\pm\) 3.19 \({}^{\rm c}\) & 0.544 \(\pm\) 0.725 \({}^{\rm ab}\) & 15.59 \(\pm\) 0.82 \({}^{\rm b}\) & 1.47 \(\pm\) 0.22 \({}^{\rm d}\) & 23.30 \(\pm\) 3.00 \({}^{\rm c}\) & 3.84 \(\pm\) 0.54 \({}^{\rm b}\) \\
4 & 17.23 \(\pm\) 1.88 \({}^{\rm b}\) & 11.07 \(\pm\) 1.24 \({}^{\rm d}\) & 23.56 \(\pm\) 4.33 \({}^{\rm d}\) & 0.488 \(\pm\) 0.552 \({}^{\rm b}\) & 13.23 \(\pm\) 0.82 \({}^{\rm b}\) & 1.78 \(\pm\) 0.17 \({}^{\rm e}\) & 27.29 \(\pm\) 2.32 \({}^{\rm d}\) & 3.91 \(\pm\) 0.33 \({}^{\rm ab}\) \\
5 & 11.93 \(\pm\) 1.33 \({}^{\rm a}\) & 12.52 \(\pm\) 2.34 \({}^{\rm d}\) & 27.43 \(\pm\) 0.30 \({}^{\rm e}\) & 0.470 \(\pm\) 0.852 \({}^{\rm a}\) & 13.02 \(\pm\) 1.67 \({}^{\rm a}\) & 2.21 \(\pm\) 0.27 \({}^{\rm d}\) & 28.78 \(\pm\) 3 The observed differences are significant between the 0 and 1% RSO emulsion and the above 4-5% RSO emulsions, but all of the investigated physico-mechanical parameters are stabile between the 1 to 3% concentration. That phenomenon may be attributed to the oil drop size and distribution in the chitosan matrix [50].