Chitosan films containing encapsulated eugenol in alginate microspheres

Alginate microspheres were prepared by extrusion and ionic gelation based on a vibrating technology to encapsulate eugenol as an active ingredient. The effect of their incorporation on the mechanical and barrier properties of chitosan-based films was evaluated, as well as the kinetics of eugenol release and the antimicrobial effect of the films against Listeria innocua and Escherichia coli. Microsphere addition increased the stretchability of chitosan films and improved their oxygen barrier properties, while no significant changes in hue, whiteness index, and transparency were detected compared to pure chitosan films. The release rate and the final released amount of eugenol in food simulants was enhanced in 3 % acetic acid and was markedly reduced in isooctane. Incorporating encapsulated eugenol into chitosan films enhanced their antimicrobial efficacy, especially in polar liquid media where the diffusion of eugenol from the chitosan matrix was promoted.