# Active Biodegradable Packaging Films Based on the
## 3 Results and Discussion
### Film Characterization
#### 3.3.2 Light Transmission and Transparency  
Optical characteristics are critical for determining the effectiveness of packaging as a food preservation agent when exposed to visible and ultraviolet light [38]. The higher the transmittance at a given wavelength, the lower the absorbance of the light, and thus the lower the protection of the film [39]. As can be seen in Table 4, the transmittance increases as the wavelength increases. At the UV wavelengths of 200 and 300 nm, the films incorporated with DF and DFE demonstrated better UV barrier properties, while the control film exhibited a light transmission of 67.3% at the 300 nm wavelength, compared to 0.02% for DF and DFE. At a higher-visibility spectrum (400-800 nm), DF reduced between 1.2 and 27 times the visible light transmission absorbance capacity compared to DFE films. These results agree with those obtained in [9] for CMC films with green coffee sediment, and those obtained by [PERSON] et al. (2018) [37] for chitosan films, in which they add up to 30% olive pomace. The transparency values of the films added with DF and DFE were significantly higher than those of the control film, the films with DF being the ones with higher opacity and consequently more efficient in light barriers [40]. This occurs because DFE solubilizes better in the film matrix, resulting in a more homogeneous matrix as shown in Figure 2. Therefore, a higher protection is expected from DF film [37]. However, these preliminary studies need to be corroborated with others to assess the impact of prolonged exposure under real conditions.  
\begin{table}
\begin{tabular}{l c c c c c c} \hline \hline
**Films** & \multicolumn{5}{c}{**Transmittance (\%)**} & \multicolumn{2}{c}{**Transparency (\%)**} \\ \hline  & **200 nm** & **300 nm** & **400 nm** & **500 nm** & **600 nm** & **800 nm** & **600 nm** \\ \hline CMC & 0.07 \(\pm\) 0.01 a & 67.3 \(\pm\) 0.04 a & 82.8 \(\pm\) 0.00 a & 85.5 \(\pm\) 0.01 a & 86.7 \(\pm\) 0.00 a & 88.2 \(\pm\) 0.01 a & 1.03 \(\pm\) 0.03 c \\ \hline CMC + DF & 0.02 \(\pm\) 0.01 b & 0.02 \(\pm\) 0.00 b & 0.00 \(\pm\) 0.00 c & 0.71 \(\pm\) 0.00 c & 3.72 \(\pm\) 0.00 c & 14.2 \(\pm\) 0.00 c & 11.5 \(\pm\) 1.70 a \\ \hline CMC + DFE & 0.03 \(\pm\) 0.01 b & 0.02 \(\pm\) 0.00 b & 1.23 \(\pm\) 0.01 b & 19.6 \(\pm\) 0.01 b & 38.9 \(\pm\) 0.01 b & 64.7 \(\pm\) 0.00 b & 5.0 \(\pm\) 0.15 b \\ \hline \hline \end{tabular}  
Significant differences (\(p\) \(<\) 0.05) are indicated in the same column with different letters (a, b or c).  
\end{table}
Table 4: Light transmission and transparency of control film (CMC), film with defatted flour (CMC + DF), and film with DF extract (CMC + DFE).  
\begin{table}
\begin{tabular}{l c c c} \hline \hline
**Films** & **Weight (g)** & **Thickness (\(\upmu\)m)** & **Moisture (\%)** & **WS (\%)** \\ \hline CMC & 0.68 \(\pm\) 0.05 b & 62 \(\pm\) 7.49 c & 6.8 \(\pm\) 0.25 c & 100 a \\ \hline CMC + DF & 0.82 \(\pm\) 0.02 a & 108 \(\pm\) 16 a & 12.5 \(\pm\) 1.51 a & 52.6 \(\pm\) 2.62 b \\ \hline CMC + DFE & 0.72 \(\pm\) 0.03 b & 80 \(\pm\) 8.10 b & 9.7 \(\pm\) 0.73 b & 100 a \\ \hline \hline \end{tabular}  
Significant differences (\(p\) \(<\) 0.05) are indicated in the same column with different letters (a, b or c).  
\end{table}
Table 3: Physical properties and water solubility (WS) of control film (CMC), film with defatted flour (CMC + DF), and film with DF extract (CMC + DFE).  
Figure 2: (**A**) Control film (CMC), (**B**) film with defatted flour (CMC + DF), and (**C**) film with DFE extract (CMC + DFE).