Gelatin and/or chitosan-based films activated with “Pitanga” (Eugenia uniflora L.) leaf hydroethanolic extract encapsulated in double emulsion

Abstract

The aim of this study was to evaluate the effect of the incorporation of water-in-oil-in water (W/O/W) double emulsion (DE) loaded with “pitanga” leaf hydroethanolic extract on the physicochemical, antimicrobial and antioxidant properties of films based on gelatin, chitosan and gelatin/chitosan blend to target the future application of these films as active food packaging. Scanning electron microscopy and atomic force microscopy images of the films showed that the presence of DE caused heterogeneity on the surface and internal structure. As a consequence, the decrease in the gloss and the water drop contact angle of films was caused mainly by the increase in surface roughness. In addition, the DE significantly improved the UV/Vis light barrier property of the films. The DE increased the strength and stiffness of the films based on gelatin and chitosan, but decreased those properties in the gelatin/chitosan blend, and increased the extensibility of all films, in addition to decreasing water solubility, water vapor permeability and opacity. Films with DE showed high antioxidant activity, but only the films based on gelatin and with DE inhibited Staphylococcus aureus. The other films containing DE inhibited the growth of Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella ssp bacteria just in the region of contact with the films.