16 - Agro-polymers for edible and biodegradable films: Review of agricultural polymeric materials, physical and mechanical characteristics

Abstract

The polymers obtained from products or byproducts of agricultural origin are proposed for the formulation of biodegradable materials or edible films. Different categories of biodegradable plastics obtained from agro-polymers, the starch–polyester blends, and the “microbial” biodegradable plastics satisfy the majority of the requirements proposed by plastic packaging industries (material qualities, processibility, or performance,). Interest has been shown in other bioplastics based on natural polysaccharides or proteins, due to their low costs; however, their nonreproductive quality and their lower performance are still problems. Edible films and coatings provide an added and at times necessary means to control physiological, microbiological, and physicochemical changes in food products. Recently, the concept of “edible active layers” has been introduced. These films or coatings contribute to food preservation, for instance by controlling mass transfer of water vapor, oxygen, carbon dioxide, and ethylene, or by modifying and controlling the food surface conditions. Edible and/or biodegradable packages formed with several compounds (composite or complex materials) have been developed to take advantage of the complementary functional properties of the different constituent materials, and to overcome their respective drawbacks. Most composite films studied to date combine one or several polyester (or lipid) compounds with a hydrocolloid-based one. The future of edible and/or biodegradable materials is therefore probably dependent on the development of applications, where some of their preferential properties are enhanced, or on the development of composite materials.