Cold plasma-enhanced polylactic acid/chitosan films incorporating zein nanoparticles: a promising strategy for developing food packaging materials

Abstract

This study developed packaging films using polylactic acid (PLA) and chitosan incorporated with zein nanoparticles (Z-NPs) for active packaging applications. Dielectric barrier discharge (DBD) air plasma treatment was applied to improve adhesion between PLA and the nanocomposite film, resulting in a bilayer film. The plasma treatment reduced the water contact angle from 98.2° to 42.6° and increased surface roughness from 19.75 nm to 31.5 nm, as confirmed by atomic force microscopy. The optimally plasma-treated PLA showed an 80 % increase in tensile strength, while the bilayer film exhibited improved water vapor permeability of 0.64 × 10⁻⁷ g/m.h.Pa. The incorporation of 15 % Z-NPs into the chitosan matrix enhanced the mechanical properties, with a 20 % increase in tensile strength and a 15 % decrease in water vapor permeability. The bilayer film demonstrated a 40 % increase in tensile strength and a 30 % decrease in water vapor permeability compared to the neat PLA film. Additionally, the bilayer film showed enhanced antibacterial activity against S. aureus, with a 6 mm inhibition zone. The results demonstrate that the combination of plasma treatment and Z-NPs incorporation significantly enhances the properties of biodegradable packaging materials, offering a sustainable alternative for the food industry with improved mechanical and barrier properties.