Ultrasonic engineering of zein-curcumin nanoparticles/sodium alginate composite films for active food packaging applications

Food spoilage poses a significant threat to human health and contributes to substantial global food waste. To address this issue, advancements in biopolymer-based packaging materials have garnered increasing research attention. A novel zein-curcumin nanoparticles/sodium alginate (U-ZcNPs/SA) composite films was fabricated by encapsulating curcumin (Cur) within zein nanoparticles via ultrasonic-assisted self-assembly, followed by integration into an SA matrix. Ultrasonic treatment induced structural reorganization of zein, enhancing electrostatic interactions and hydrogen bonding within the film matrix, which improved nanoparticle dispersion, mechanical properties (tensile strength: 40.51 N/mm 2 ; elongation at break: 72.23 %), and barrier performance (oxygen permeability: 2.44 g/hm 2 ). Characterization techniques (SEM, FTIR, XRD, TGA) confirmed superior interfacial compatibility, thermal stability, and amorphous structure in U-ZcNPs@SA films. Furthermore, the films demonstrated robust antibacterial activity against both Escherichia coli and Staphylococcus aureus , with inhibition zones measuring up to 11.09 cm and 10.78 cm, respectively. In the preservation experiment, the U-ZcNPs@SA film effectively extended the shelf life of grapes and strawberries by maintaining their visual quality. Notably, it significantly reduced weight loss in strawberries while suppressing their respiration rate and ethylene production. These results demonstrated that ultrasonic modification optimized the functional performance of biodegradable films, offering a sustainable strategy for active food packaging.