Active polymers in food packaging: Antimicrobial properties of chitosan and its derivatives

During the last decades, packaging materials were widely used to protect the product from the surroundings, retard food product deterioration, and extend shelf-life, producing a positive effect on the food quality and safety. Nowadays, it is not expected that food packaging acts as a protective food barrier, but it should have a positive effect over food quality, becoming an active packaging upon direct contact with food. Within the different active packaging systems, the most interesting and promising components are antimicrobial species, able to protect the food component from the oxidative damage, by acting in the food surface where the microorganisms growth. Antimicrobial packaging allows industry to potentially combine the preservative functions of antimicrobial agents with the protective functions for foods, and represents an efficient and alternative way for using antimicrobial agents for food safety. Another serious problem in food industry consists in protecting shelf-stable food from oxidation reactions, which affect the food quality, causing loss of nutritional quality and changes in chemical composition. To this regard, chitosan represents an interesting solution for its antimicrobial properties usually related to its polycationic nature. In addition, a suitable chemical modification of this polysaccharide allows the synthesis of multifunctional materials, with specific antimicrobial peculiarity. In this chapter we provide an overview on food packaging material based on chitosan and chitosan derivatives with antimicrobial properties, in order to achieve functional systems able to be used as active packaging devices.