Engineering antibacterial plasma-polymerized polyethylene glycol-ZnO nanocomposite coatings for extending pork...

Recently, interest in eco-friendly techniques for producing antibacterial food packaging films has surged. Within this context, plasma polymerization is emerging as a promising approach for applying degradable antibacterial coatings on various plastic films. This research therefore employs an atmospheric pressure aerosol-assisted plasma deposition technique to create polyethylene glycol (PEG)-like coatings embedding zinc oxide nanoparticles (ZnO NPs) of varying sizes on polyethylene (PE) substrates. The antimicrobial efficacy of these plasma-polymerized PEG-ZnO coatings against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) is assessed, demonstrating a robust antibacterial effect, particularly when using smaller ZnO NPs (35-45 nm). The deposition of uniform, conformal PEG-ZnO nanocomposites with a chemical composition akin to standard PEG polymers has been achieved. In addition, ZnO NPs are homogeneously dispersed within the PEG matrix, up to a concentration of 1 wt%. To assess the antibacterial performance in contact with real food, pasteurized pork sausages inoculated with a mixture of L. monocytogenes or LAB strains are wrapped in plasma-coated PE and vacuum-packed. Bacterial growth is monitored during storage at 7 °C over time, demonstrating that the developed plasma-polymerized PEG-ZnO nanocomposite effectively inhibits bacterial growth during refrigerated storage, with a more pronounced effect on LAB. The release of Zn from the developed PEG-ZnO nanocomposite into various food simulants also remains below the specific migration limit (5 mg kg^-1 or L^-1 food), confirming coating safety. Overall, plasma-polymerized PEG-ZnO nanocomposite coatings thus show great promise as effective degradable antimicrobial films for food packaging applications.