Preparation of chitosan/gelatin/zinc oxide nanocomposite films and their properties
Chitosan and gelatin come from natural sources and have good film-forming properties,but both have poor bacteriostatic performance,which limits their application in food packaging.In order to enhance antimicrobial activity of the film,nano-zinc oxide was incorporated in gelatin/chitosan composite film.In this study,chitosan and gelatin were used as film-forming materials and nano-zinc oxide was added as antibacterial material,and the composite film was prepared by blending method.The effects of nano-zinc oxide content on the structure,mechanical properties and antibacterial properties of chitosan/gelatin/nano-zinc oxide composite films were investigated.The results showed that the introduction of nano-zinc oxide effectively improved the mechanical properties,water vapor permeability,thermal stabili-ty and antibacterial properties of the composite film.When the content of nano-zinc oxide in the compos-ite film is 0.5％,the antibacterial performance of the composite film was the best,with the water solubil-ity of 17.3％,the water absorption rate of 100.0％,the tensile strength of 5.5 MPa,the elongation at break of 8.0％,the water vapor transmittance of 94.72 g·m-2·h-1,the water vapor permeability of 2.44 × 10-12 g·cm-1·s-1·Pa-1,and the diameter of the zone of inhibition of Staphylococcus aureus of(37.8±0.1)mm and Escherichia coli of(25.7±0.1)mm.These findings indicate that chitosan/ge-latin/nano-zinc oxide composite films have great potential to be developed as biodegradable alternative for postharvest packaging of fresh fruits and vegetables.
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