Vargas, Albors, and Chiralt (2011) applied chitosan-sunflower oil edible films with acetic or lactic acid to cold-stored pork meat hamburgers to extend their shelf life. However, it was noted that the addition of sunflower oil caused a reduction in the antibacterial effect of pure chitosan films against coliform microorganisms. The decrease in the antibacterial activity of edible films can be explained by the dilution effect of chitosan, thus being less available for organisms.