High UV-shielding multifunctional nanocomposite films based on polyvinyl alcohol/gelatin incorporated with carbon dots and citral-Pickering emulsion for cherry tomato preservation

Photooxidation and microbial contamination are two major factors responsible for postharvest deterioration of fresh fruits, and active packaging offers an effective strategy for shelf-life extension. In this work, multifunctional and eco-friendly nanocomposite films were fabricated from polyvinyl alcohol/gelatin (PVA/GEL) incorporated with branched polyethyleneimine (PEI)-grafted carbon dots (CDs) and citral Pickering emulsions (CIT-PE) stabilized by β-cyclodextrin (β-CD) particles. Fourier-transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) analysis suggested physical interactions between the PVA/GEL matrix and the incorporated active components. The incorporation of CIT-PE and CDs significantly enhanced the UV-shielding, antibacterial, and antioxidant properties of the films. In particular, the PG/E8/C0.8 film exhibited complete UV-blocking ability in the UV region (200–400 nm), strong antibacterial activity against E. coli (18.05 ± 0.20 mm) and S. aureus (55.54 ± 0.87 mm), and high DPPH radical scavenging activity (84.49 ± 3.47%). In cherry tomato preservation experiments, the PG/E8/C0.8 film effectively delayed quality deterioration, maintaining a vivid appearance, lower weight loss (4.24%), and better retention of total soluble solids and titratable acidity after 16 days of storage compared with the control group. Overall, this work provides a feasible strategy for developing multifunctional active packaging materials for postharvest food preservation.