Comparative evaluation of physical properties of edible chitosan films prepared by different drying methods

Edible films are alternative packaging, which have recently received much attention due mainly to environmental reasons. Edible films may be formed from edible biomaterials such as polysaccharides, proteins, or lipids. Among these biopolymers, chitosan is of interest because it has a good film-forming property and is biodegradable, biocompatible, and nontoxic. Several techniques have been used to prepare edible chitosan films with various degrees of success. However, it is always interesting to find an alternative technique to produce films of superior quality at shorter processing (drying) time. In this study, the influences of different drying methods and conditions on the drying kinetics and various properties of chitosan films were investigated. Drying at control conditions (ambient air drying and hot air drying at 40 degrees C) as well as vacuum drying and low-pressure superheated steam drying (LPSSD) at an absolute pressure of 10kPa were carried out at different drying temperatures (70, 80, and 90 degrees C). The properties of chitosan films, in terms of color, tensile strength, percent elongation, water vapor permeability (WVP), glass transition temperature (T-g), and crystallinity, were also determined. Based on the results of both the drying behavior and film properties, LPSSD at 70 degrees C was proposed as the most favorable conditions for drying chitosan films.