Development of Bioactive Carboxymethyl Cellulose-Based Films via Dual Crosslinking with Citric Acid and X-Ray Irradiation

This study developed biodegradable carboxymethyl cellulose (CMC) films crosslinked with citric acid (CA) and X-ray irradiation as sustainable packaging alternatives to reduce plastic use. CMC/CA films were subjected to three doses of X-ray irradiation at two energy levels. CMC/CA films exposed to 10 kGy at 350 kV exhibited a significant three-fold reduction in water solubility compared to non-irradiated films, while also lowering water vapor and oxygen permeability without affecting mechanical strength (p ≤ 0.05). FTIR analysis confirmed the esterification between CMC and CA, which reduced the film hydrophilicity. Onion peel extract (OPE) was added as a bioactive compound to provide antifungal properties. Release studies showed reduced OPE diffusion in irradiated films, with lower release rate constant (kkp) values. The in situ test on cheese inoculated with Penicillium commune showed that the irradiated bioactive films prolonged shelf life, reducing fungal counts to log 2.3 CFU/g after 18 days compared to log 5.7 CFU/g in control samples. Cheese wrapped with irradiated bioactive films had weight loss from 1.05 to 9.37%, whereas uncovered samples exhibited the highest weight loss (2.07 to 15.07%). Overall, irradiation-assisted crosslinking and OPE incorporation improved film functionality, offering a sustainable and effective packaging solution for cheese preservation within a circular economy framework.