Enhancing functional properties of active chitosan film incorporated with cinnamon oil nanoemulsion by argon dielectric barrier discharge cold plasma treatment

Abstract

The effects of cold plasma treatment (CPT) and cinnamon oil nanoemulsion (CN) on the functional properties of chitosan film were investigated. CN with particle size of 72.20 nm was prepared by ultrasonication method before incorporating into chitosan. Chitosan film (CS) and CS incorporated with CN (CS-CN) were monitored for surface roughness, tensile strength (TS), elongation at break (EAB), optical properties, water vapor permeability (WVP), oxygen transmission rate (OTR), contact angle, and antimicrobial activity against E. coli and S. aureus. CS-CN had lower OTR and contact angle than CS due to the molecular structure reorientation of the CS polymer matrix caused by CN. CS-CN had better antimicrobial activity than CS due to the bioactive compounds from the CN. Depending on the CPT time, CPT could improve roughness, TS, wettability and antimicrobial activity of both CS and CS-CN through the formation of the oxygen-containing groups such as -OH, and -CO and the occurrence of the etching effect of high energy plasma on the film surface, as evident by the analyses of fourier transform infrared spectroscopy, atomic force microscopy, and scanning electron microscopy. Moreover, crosslinking induced by CPT could improve oxygen barriers of films. The increase of antimicrobial activity of CS-CN was potentially because CPT generated reactive species to damage the bacterial cell, facilitated the diffusion of CN through the film matrix, and enhanced the releasing of CN from the film surface. The CPT-treated CS-CN has potential to be used as active film for food.