Development and application of Opuntia ficus-indica mucilage films incorporated with zinc oxide nanoparticles for active packaging of cherry tomatoes

Abstract

The persistent challenge of food waste, which threatens global food security, has urged exploration of innovative food packaging solutions. Multifunctional nanocomposites have emerged as sustainable packaging alternatives that exhibit antioxidant and antimicrobial effects. This study investigates the development of Opuntia ficus-indica mucilage (OFIM)-based films incorporating cellulose nanofiber (CNF) and zinc oxide nanoparticles (ZnO NPs) at 0.2%, 0.4%, and 0.6% (w/w) for postharvest application. The structural and morphological properties of the films were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FT-IR). Incorporation of ZnO NPs significantly altered film appearance and color, enhanced opacity, and improved ultraviolet barrier properties. Film thickness and tensile strength increased with higher nanoparticle content (55.95–119.28 MPa), while water vapor transmission showed only slight changes (1.03 × 10⁻⁷ to 1.93 × 10⁻⁷ g m m⁻² h⁻¹ Pa). Antioxidant assays revealed that all OFIM/CNF/ZnO films exhibited superior antioxidant activity (51–68%) compared to control films. All formulations displayed comparable or enhanced antimicrobial activity against food-borne pathogens relative to neomycin. OFIM/CNF/ZnO (0.4%) demonstrated the best overall performance and was applied as an edible coating on cherry tomatoes alongside control (uncoated), OFIM, and OFIM/CNF treatments. The composite coating effectively delayed weight loss, respiration rate, pH changes, and ascorbic acid degradation, thereby extending shelf-life and preserving fruit quality. Overall, the findings demonstrate that OFIM-based nanocomposite coatings are sustainable active packaging solutions that enhance food preservation and reduce postharvest losses.