Biopolymeric matrices made of carrageenan and corn starch for the antioxidant extracts delivery of Cuban red propolis and yerba mate

The design of biopolymeric matrices for the delivery of bioactive compounds constitutes a useful strategy to prevent the spoilage of food products. In the current work, carrageenan-starch films with antioxidant extracts of Cuban red propolis and yerba mate were prepared by casting. The morphological analysis by SEM showed a more homogeneous structure for the yerba mate films in comparison with the propolis ones. The incorporation of the natural extracts affected the dynamic-mechanical behavior of the films, whereas their crystallinity degrees were maintained. FTIR analysis showed stronger interactions of the polymer matrix with the propolis extract than with the yerba mate one. The films exhibited differences in their mechanical properties; higher tensile strength values were obtained for the yerba mate films than for the propolis samples. However, the last films exhibited higher elongation at break. Both matrices showed good stability of the active compounds along 6 months of storage at 75% RH and 23 °C. After this time, the samples showed an increase in their DPPH scavenging activity. The release behavior of the phenolic compounds from the films in an aqueous medium was assayed finding significant differences (p < 0.05) between release rates of both extracts.