PLA Films Incorporated with Chitosan and ZnO Nanoparticles for Application in Food Packaging

Biopolymers such as PLA, ZnO nanoparticles and chitosan are materials that have some properties in common, such as oxidizing action, antimicrobial activity, biocompatibility and formation of a mechanical barrier, which make them promising for application in food packaging, as they ensure safety in contact with food. In this study, the antibacterial activity of pure PLA films and those incorporating chitosan, ZnO nanoparticles and both was analyzed for four strains (two Gram-positive and two Gram-negative bacteria) by the agar diffusion method, aiming to verify the action of each substance and their combination. The characterization of ZnO NPs was performed by XRD, FTIR, Raman spectroscopy, UV-Vis, SEM and Zeta potential (ZP) methods. The results showed that the ZnO nanoparticles synthesized by the Pechinhi method, with calcination temperatures of 600 and 800ºC, presented a predominant morphology of nanorods and nanospheres, according to SEM images, with high purity and crystallinity. The PLA-based films presented a rough structure, with small pores, and the incorporation of chitosan and ZnO NPs was effective, which was proven by the SEM/EDS technique. The results showed that the films incorporated with ZnO NPs presented inhibition for Gram-positive bacteria in the range of 12.5 to 14 mm.