Biofilms based on cassava starch containing extract of yerba mate as antioxidant and plasticizer

Cassava starch based films containing different concentrations of yerba mate extract as antioxidant (0, 5, and 20%) were prepared by casting. The effect of the incorporation of the extract on the antioxidant activity, structure, and physicochemical properties of the biofilms was evaluated. Significant antioxidant capacity in the films with yerba mate extract was obtained, especially in the materials containing 5% of the additive. The surface roughness and contact angle of the systems containing the extract increased, indicating hydrofobic behavior of the films surface when the additive was used. This was also confirmed by water vapor permeability and water content results. The incorporation of yerba mate extract led to an important improvement in the elasticity of the biofilms, as well as to a shift of the relaxations associated with the glycerol-rich and starch-rich phases to lower temperature values, revealing a typical behavior of a plasticized film. The relevant antioxidant and plasticizing effects of yerba mate extract on cassava starch films make them promising to be used as coatings or packaging in the food industry.