Antibacterial LDPE/GSE/Mel/ZnONP composite film-coated wrapping paper for convenience food packaging application

Low-density polyethylene (LDPE) based nanocomposite film incorporated with grapefruit seed extract (GSE), melanin nanoparticle (Mel), and zinc oxide nanoparticles (ZnONP) was prepared by the extrusion-blowing method. The UV–vis spectra of LDPE/GSE/Mel/ ZnONP film exhibited the characteristic absorption peak of ZnONP at 370 nm. The UV-barrier, thickness, elongation at break, and thermal stability of LDPE film increased after the incorporation of GSE, Mel, and ZnONP, but transparency, tensile strength, and water contact angle decreased. The LDPE/GSE/Mel/ZnONP films exhibited strong antibacterial activity against Escherichia coli and Listeria monocytogenes. The LDPE/GSE/Mel/ZnONP composite film was coated on a wrapping paper using a thermocomression method. The SEM micrographs of the surface of the coated paper exhibited that the coated films filled the pores and voids of the porous fibers of the paper to make it's surface smooth. The water absorptiveness and oil absorptiveness of the paper decreased profoundly after coating with LDPE and LDPE/GSE/Mel/ZnONP films. The LDPE/GSE/Mel/ZnONP composite film-coated wrapping paper was effective to prevent the growth of coliform bacteria of sandwich and ‘gimbab’ (rolled rice with dried seaweed).