Plasticizers influence the physical properties of edible films by their interaction with the film-forming polymers. Using near-infrared chemical imaging, it is possible to characterize the interaction between compounds through the analysis of their relative presence throughout the film (abundance) and their variability. These parameters and standard mechanical properties were used to characterize the interaction between gelatin, chitosan and several plasticizers, pure or in binary combinations. Triacetin showed the least interaction with the polymers, while polyethylene glycol 400 and glycerol showed high interaction with them. In addition, we observed that the tensile strength of the film was well correlated with the variability of gelatin and chitosan. (C) 2015 Elsevier Ltd. All rights reserved.