Antioxidant starch-based films with encapsulated eugenol. Application to sunflower oil preservation

Starch films containing eugenol, which was added to the film-forming dispersion in free form or encapsulated with different wall materials (whey protein or lecithin), were obtained by casting. The physical and the antioxidant properties of the films, the release kinetics of eugenol in different food simulants and their performance at preventing sunflower oil oxidation during storage were evaluated. Encapsulated eugenol modified the film microstructure, yielding less stretchable films with reduced water affinity, transparency and oxygen permeability as compared to films formulated with non-encapsulated eugenol. The addition of eugenol microcapsules containing oleic acid promoted the eugenol retention in the starch matrix during film formation and thus, these films exhibited the greatest antioxidant activity. Films developed with encapsulated eugenol powder containing lecithin and oleic acid were highly effective at preventing sunflower oil oxidation even throughout 53 days of storage at 30 °C, maintaining low and almost constant values of peroxide index, conjugated dienes and trienes in comparison with the control samples. •Starch films incorporating pre-encapsulated and free eugenol (E) were obtained.•Mechanical, barrier, antioxidant properties and release kinetics were analysed.•The encapsulation process highly enhanced the E retention in the film matrix.•Films containing pre-encapsulated E exhibited a high oxygen barrier capacity.•Sunflower oil oxidation was prevented when using films incorporating encapsulated E.