# Active Biodegradable Packaging Films Based on the
## 3 Results and Discussion
### Lipid Oxidation Control Using Bioactive Packaging Films  
Figure 4 shows the peroxide (PV) values of the DHA-rich microalgae oil at 40 \({}^{\circ}\)C under agitation. For the uncapped control oil, the PV began to increase significantly from the first day, as expected, reaching 50 meqO\({}_{2}\)/kg in 5 days. These values agree with those obtained in a previous study of oxidative stability of microalgae oil [42]. In the case of the oil covered with CMC film, its PV began to rise drastically after the fourth day, reaching values close to 50 meq O\({}_{2}\)/kg in 6 days. Protective films significantly (\(p<0.05\)) reduce peroxide formation rates, with CMC + DF film standing out as the most effective in minimizing oxidation, followed closely by CMC + DFE (9 and 8 days, respectively).  
The regulation sets the primary oxidation limit (peroxide value) for oils rich in LCP-UFAs at 5 [43]. With the control film, it takes 1-2 days to reach this value, while in the presence of the films with DF and DFE, the oils take 4-5 days to reach this value under the accelerated conditions (40 \({}^{\circ}\)C, 110 rpm). This represents a protection of more than 100% against the control film. This superior performance is due to the high concentration of antioxidant compounds, including phenolics from olive residues, which actively combat oxidative reactions. In addition, the natural opacity of the films provides a protective barrier  
Figure 3: Total phenolic content (TPC) of defatted flour (DF), control film (CMC), film with defatted flour (CMC + DF), and film with DF extract (CMC + DFE). Non-detected (n.d.).  
against photooxidation, making them ideal for preserving product quality and extending shelf life [38]. These results agree with those found in the literature, since there are studies on the incorporation of olive pomace flours in packaging films, olive leaf extracts, grape pomace, or coffee by-product extracts. In the literature, the lipid oxidation of different foods has been studied, and it has been found that the presence of antioxidant compounds in packaging, in addition to its barrier against water, oxygen, and light, positively prevents lipid oxidation [9; 37; 39; 41; 44]. However, these are preliminary data to evaluate whether the film could reduce the oxidation rate of a polyunsaturated oil such as microalgae oil, for a possible use as an encapsulant of these omega-3 oils. Given the potential of the films, further studies at different temperatures are needed to extrapolate the results at room temperature and study the oxidative stability of the oil.  
Finally, both DF and DFE maintain their food-grade quality throughout the manufacturing process, ensuring that they are suitable for direct contact with food products. This makes them useful not just as protective food packaging, but also as potential transporters of bioactive oils, which may improve the nutritional and functional qualities of packed foods. Furthermore, the antioxidant-rich composition of DF and DFE films adds an extra layer of protection against oxidative degradation, improving the shelf life and quality of the encapsulated bioactive components. As a result, potential applications of these films could be the encapsulation of oils rich in polyunsaturated fatty acids, as indicated above. However, digestion studies are needed to determine the bioaccessibility of the oils and bioactive compounds in the capsule. In addition, other possible uses would be internal coatings for boxes, bags for dry products, or wrappings for small foods. Finally, the formula could be adapted for wet products, incorporating hydrophobic compounds.  
Figure 4: Peroxide value (PV) of DHA-rich microalgae oil at 40 \({}^{\circ}\)C under agitation: no film (squares), control film (CMC; circles), film with DF extract (CMC + DFE; triangles), and film with defatted meal (CMC + DF; stars).