Due to environmental pollution, researchers nowadays have been focused on production of biodegradable films. On the other hand, the conventional heating methods, however, can improve safety and shelf life of food, reduce the food quality. Both reasons leading the production of biodegradable films with antimicrobial properties are considered. Chitosan is identified as an antimicrobial compound and it can be used to decrease the population of microorganisms. The antimicrobial characteristic of chitosan is related to the interaction between positively charged amino groups with negatively charged microbial cell membrane. This interaction leads to the release of proteins and other intracellular components. Since both protein and chitosan are edible therefore the packaging prepared from them is edible and biodegradable. In this study, protein is firstly extracted from the Bean (Phaseolus Lunatus) with alkaline method and then an edible film was prepared using extracted protein. Crab shell chitosan was bought from Sigma Co. and transformed to nano-particles by gelation-inotropic method in presence of sodium polyphosphate. After preparation of three types of protein film, the combination of protein-chitosan film and the protein-chitosan nanoparticles one, their physicochemical and antimicrobial properties were compared. The results indicated that the presence of chitosan in the protein film increases moisture content, vapor permeability, lightness and antimicrobial characteristic; however, film solubility and gas permeability decreased. The nanoparticle of chitosan improves these properties considerably. The percentage and size of chitosan nanoparticles, pH and glycerol content are the other effective parameters on the protein film properties. Kay Words: Chitosan nanoparticle, Bean protein, Edible film, Protein films, Nanocomposite.
