Comparative Evaluation of Physical Properties of Edible Chitosan Films Prepared by Different Drying Methods

Abstract

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°C) as well as vacuum drying and low-pressure superheated steam drying (LPSSD) at an absolute pressure of 10 kPa were carried out at different drying temperatures (70, 80, and 90°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°C was proposed as the most favorable conditions for drying chitosan films.

Keywords:

• Biopolymers
• Color
• Crystallinity
• Differential scanning calorimetry
• Mechanical properties
• Water vapor permeability
• X-ray diffraction

ACKNOWLEDGEMENTS

The authors express their sincere appreciation to the Commission on Higher Education, the Thailand Research Fund (TRF), and the International Foundation for Science (IFS) in Sweden for supporting the study financially.

Notes

Different superscripts within the same column mean that the values are significantly different (p < 0.05).

Different superscripts within the same column mean that the values are significantly different (p < 0.05).

Different superscripts within the same column indicate that the values are significantly different (p < 0.05).