Abstract: The objective of this study was to modify polyethylene (PE) film for better antibacterial capacity via phase transition. Lysozyme solution at 2 mg/mL was mixed with an equal volume of tris(2-carboxyethyl)phosphine (TCEP) solution at 10 mmol/L. The modification efficiency of PE film by amyloid-like aggregates produced from phase transition in the lysozyme solution was evaluated at different reaction times. The results indicated that the average size of phase-transited lysozyme particles increased from 531.2 to 2 305 nm with increasing reaction time up to 60 min. According to the results of Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), the surface of modified PE film was grafted with hydrophilic groups such as carboxyl, hydroxyl and amino groups. In addition, the oxygen content increased, and the elements S and P were found in the surface coating but not in the native film. The coating formed at 120 min was homogenous and compact without excessive fusion, and it stably adhered to the PE film under different temperature conditions. The modified PE film showed better antibacterial effect against Staphylococcus aureus than the uncoated one, thus providing a better packaging environment for foods.

Key words: lysozyme; polyethylene film; phase-transited lysozyme; antibacterial; food packaging