Edible Films from Starch and Chitosan: Formulation and Gas Permeabilities

Abstract

Starch and chitosan films are both known to be effective barriers to gas permeation. Being naturally abundant, renewable, and biodegradable, starch and chitosan films have the potential to replace petroleum-based materials for food packaging applications. However, the gas permeability of starch-chitosan blend films has not been studied extensively. In order to characterize starch-chitosan blend films for food packaging application, the permeabilities of N2, O2 and CO2 in the blend films were studied at different operating conditions (e.g., relative humidity, chitosan content in the films, cross membrane pressure, and temperature). The gas permeation was measured using the traditional volumetric technique. Gas permeation through films containing different amounts of chitosan was measured at ambient temperature and at a cross membrane pressure of 60psi. In addition, pure chitosan was also tested at a high relative humidity where the gas was saturated with water vapor. The effects of temperature and cross membrane pressure on the gas permeability were studied with starch-chitosan blend films and pure chitosan films as well. It was found that an increase in pressure and/or temperature increased the permeability, and the temperature dependence of permeability followed the Arrhenius relation, from which activation energy of permeation was evaluated. The starch-chitosan blend films with approximately 60wt% chitosan showed the best gas barrier property and the highest activation energy for permeation.