Effects of plasticizer on physical properties of pigskin gelatin films

Gelatin-based films are thin, flexible and transparent biodegradable materials based on biopolymers, for use in engineering food, packaging, drug recover and other applications. The addition of plasticizer alters some of the functional and physical properties of these films, such as increasing flexibility, moisture sensitivity, as well as other functional properties. However, details on interactions between the biopolymer and plasticizer are not very well known. The purpose of this work was to present and correlate some results of physical measurements of these biopolymer-based films containing different glycerol content. Results show that the plasticizer causes no apparent tendency to re-crystallization in the film structure, but alter other physical properties, such as flexibility, interactions between the macromolecule chains and susceptibility to humidity. Changes observed in the physical properties of the films can be, in principle, attributed to the fact that the plasticizers reduce the interactions between the adjacent chains in the biopolymer affecting thus, the moisture sensitivity and flexibility of the material. (C) 2006 Elsevier Ltd. All rights reserved.