Gamma radiation-assisted synthesis of tea tree oil-based chitosan films for active packaging applications

Abstract

Sustainable packaging materials with inherent antimicrobial and antioxidant properties are increasingly demanded for food preservation. In this study, chitosan/polyacrylamide/tea tree oil (CS/PAAm/TTO) films were developed via gamma irradiation, varying both the irradiation dose (10–50 kGy) and the TTO concentration (25–100 μL) to attain an optimized formulation with superior performance. In this regard, the optimization was accomplished via atomic force microscopy (AFM) through assessing the surface morphologies of the films prepared at different irradiation doses, which identified 30 kGy as the optimal irradiation dose for TTO incorporation. On the other hand, comprehensive characterizations using Fourier transfer infrared spectroscopy, x-ray diffraction, thermogravimetric analysis, and contact angle measurements revealed that increasing the irradiation dose and TTO content enhanced hydrophobicity and improved mechanical properties. More specifically, the contact angle increased significantly at higher TTO levels, indicating an increased surface hydrophobicity, while tensile tests demonstrated improved flexibility. In addition, antimicrobial assays confirmed the efficacy of the films against a range of pathogens, and the 1,1-diphenyl-2-picryl hydrazyl assay indicated notable antioxidant activity, with an IC50 value of 111.45 μg/mL for the optimized formulation. These findings underscore the potential of the developed biofilms as advanced, multifunctional packaging materials, offering a promising environmentally friendly alternative to conventional packaging for food preservation.