Nano-ZnO-Crosslinked Pectin/CMC Film with Enhanced Hydrophobicity and UV-Blocking for Blueberry Packaging

Developing a biodegradable film with integrated mechanical robustness and multifunctionality remains a significant challenge for sustainable food packaging. Herein, a pectin/carboxymethyl cellulose composite film (PNZxC) incorporated with zinc oxide nanoparticles (ZnO) was fabricated via a solution casting method to achieve the synergistic enhancement of structural and functional properties. ZnO exhibits dual functionality within the polymer matrix, serving both as a reinforcing filler and as a coordination interaction node via interactions with carboxyl groups. At an optimal loading, the PNZ2C film demonstrates a uniform dispersion of nanoparticles, facilitating the development of a dense network structure and enhancing intermolecular interactions. Consequently, the film showed reduced water vapor and oxygen permeability, attributable to the formation of tortuous diffusion pathways, together with increased surface hydrophobicity and a significantly improved tensile strength of 25.4 MPa. Enhanced thermal stability and excellent UV-blocking performance were also achieved. Notably, the optimized film demonstrated superior preservation performance in blueberry storage, effectively reducing moisture loss and delaying quality deterioration compared with the control. These findings provide new insights into the structure–property relationships of ZnO–polysaccharide nanocomposite systems and highlight a viable strategy for designing high-performance, biodegradable packaging materials with integrated multifunctionality.