# Rosehip Seed Oil-Incorporated Chitosan Films for Potential Fruit Packaging Applications
## 3 Results and Discussion
### Color Parameters of Chitosan/RSO Edible Films  
The values of the lightness (L*), chroma (C*), the whiteness index, and the total color differences (\(\Delta E_{ab}^{*}\)) between chitosan and rosehip oil-loaded films were measured on the surface of a standard black plate. For the evaluation of the opacity values, the color parameters were detected on the surfaces of both standard black and white plates. The opacity was calculated using the software algorithm of the PCE-CSM 5 portable colorimeter. The opacity of the white and black plates without films is (5.8 \(\pm\) 0.1). The opacity of the pure chitosan film (15.2 \(\pm\) 0.4), the lightness (42.49 \(\pm\) 0.66), and the whiteness index (14.20 \(\pm\) 0.74) are represented in Table 4.  
The addition of rosehip oil causes significant differences in the lightness, the whiteness, and the opacity of the films only at higher concentrations. The opacity values of the films loaded with up to 3% RSO emulsion are not significantly different from those of the pure chitosan film. At a 5% RSO emulsion, the opacity significantly decreased to 11.5 \(\pm\) 1.8.  
Opacity is an important property of edible packaging since it controls the light that enters the food and has a direct effect on its appearance. Its decrease with increasing RSO content in the films is at first glance surprising, since the presence of lipid droplets formed during the coating formulation that are dispersed in the polymer matrix is usually related to the difficult penetration of light [53]. On the other hand, the rise of plasticizer concentration leads to an increase in the mobility of the polymer chains and a decrease in the opacity by permitting a better penetration of light [54]. The plasticizing effect of RSO has already been established in the study of the mechanical properties of the films and is confirmed by the change in the optical characteristics.  
The values of the chrome show a minimum (colorless) for the films with 0.3% oil concentration, which can be explained with the subtraction of the color-opponents and  
\begin{table}
\begin{tabular}{c c c c c c c} \hline
**cc, \%** & **L*** & **C*** & **WI** & **Opacity** & \(\Delta E_{ab}^{*}\) & **Difference** \\ \hline
0 & 42.49 \(\pm\) 0.66 a & 1.26 \(\pm\) 0.16 d & 14.20 \(\pm\) 0.74 b & 15.2 \(\pm\) 0.00 b & & \\
1 & 41.96 \(\pm\) 0.63 a & 1.27 \(\pm\) 0.15 d & 14.00 \(\pm\) 0.50 b & 15.7 \(\pm\) 0.3 b & 0.66 \(\pm\) 0.16 a & slight \\
2 & 41.60 \(\pm\) 0.77 a & 0.76 \(\pm\) 0.12 ab & 13.49\(\pm\) 0.50 b & 15.1 \(\pm\) 0.4 b & 0.97 \(\pm\) 0.14 b & slight \\
3 & 41.37 \(\pm\) 0.22 a & 0.67 \(\pm\) 0.07 a & 13.30 \(\pm\) 0.30 b & 14.8 \(\pm\) 0.1 b & 1.24 \(\pm\)0.17 c & slight \\
4 & 40.65 \(\pm\) 1.07 a & 0.85 \(\pm\) 0.12 b & 13.22 \(\pm\) 0.33 b & 13.8 \(\pm\) 1.4 ab & 1.87 \(\pm\) 0.20 d & noticeable \\
5 & 35.93 \(\pm\) 6.60 b & 1.04 \(\pm\) 0.13 c & 12.04 \(\pm\) 1.59 a & 11.5 \(\pm\) 1.8 a & 6.56 \(\pm\) 0.82 e & very obvious \\ \hline \end{tabular} a  
\end{table}
Table 4: Color parameters of chitosan films with added RSO with different concentrations.  
results in a film with an achromatic color. The decrease in chrome value for films with up to 0.3% RSO loading means discoloration of the film. Above this concentration, the film becomes darker (L*) and the chrome value increases again with significant differences. The values of the total color differences were slightly noticeable under a 0.3% rosehip oil concentration, but for higher concentrations, the differences were increased to a noticeable or very obvious level. These results confirm the results from [PERSON] and [PERSON] [55]. These authors worked with different concentrations of ethanolic extract (from cinnamon, guarana, rosemary, and boldo-do-chile)-loaded gelatin-chitosan films and noticed no significant differences between pure chitosan and gelatin, as well as blended and loaded films in low concentrations.