Plastic packaging derived from petroleum may have a negative impact on the environment when it is not properly recycled. Some studies present the use of biodegradable packages developed from natural polymers as a sustainable alternative; thus, the present work aimed to develop biodegradable sodium alginate films with antioxidant properties by the incorporation of carotenoid norbixin. Norbixin salts at the concentration of 0.01-0.05% were added to the sodium alginate films complexed with calcium ions. Carotenoid incorporation did not significantly impacted with the moisture content and the swelling capacity of the films. The thickness, water activity, and solubility were higher in the films with 0.05% addition of norbixin salts. The presence of the carotenoid improved the thermal stability of the films, as well as the water vapor barrier properties and lower ultraviolet-visible light transmission. However, the incorporation of 0.03% norbixin salts showed the best result for the analysis of antioxidant activity, with lower formation of oxidation products during sunflower oil storage and potential application for high fat foods. Practical ApplicationsResearchers aim to replace synthetic packaging by eco-friendly packaging. The use of alternative materials such as polysaccharides, proteins, and lipids has been studied for the production of packaging susceptible to degradation under environmental conditions. Thus, the present work developed sodium alginate films complexed with calcium and incorporated with norbixin salts able to decrease sunflower oil oxidation.

Alginate is a biopolymer with film-forming properties that can be used as food packaging material. Norbixin is a carotenoid with antioxidant properties, commonly used as a natural food coloring. The research objective was to create calcium-crosslinked alginate films and incorporated with norbixin concentrations (N%) of 0.05%, 0.10%, and 0.50% (g norbixin/g alginate). The polymer matrix helped to retard the thermal degradation of norbixin during the drying process and decreased leaching losses during the crosslinking process. The addition of norbixin influenced film opacity in ultraviolet light (all N%) and visible light (higher N%), causing an increase in red-yellow coloration. Only the higher N% influenced the water vapor permeability of film. Norbixin thus improved the overall barrier properties of the crosslinked sodium alginate film, with a 0.50 N% showing the most promising results. When used as sunflower oil packaging, films with a N% above 0.10 provided pro-oxidant activity during storage.