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 (<i>p</i> ≤ 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 (<i>k_kp</i>) values. The <i>in situ</i> test on cheese inoculated with <i>Penicillium commune</i> 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.