Chitosan/gellan gum nanofiber-reinforced PVA films with photothermal tellurium nanoparticles for strawberry preservation.

In this study, chitosan/gellan gum (CS/GG) polyelectrolyte complex nanofibers prepared by ultrasound-assisted exfoliation and pomelo peel extract-catalyzed tellurium nanoparticles (PPE-TeNPs) were incorporated into a polyvinyl alcohol (PVA) matrix to develop photothermal active packaging films. The optimized PVA film, containing 3 wt% CS/GG nanofibers and 3 wt% PPE-TeNPs, exhibited a tensile strength of 35.21 ± 0.72 MPa, an elongation at break of 80.22 ± 1.81%, a water vapor permeability of 8.95 × 10-11 g·Pa-1·s-1·m-1, and a carbon dioxide permeability of 0.78 × 10-7 g·m-1·s-1. Under 808 nm NIR irradiation, the film surface reached 59.5 °C, achieving antibacterial rates of 99.61% against S. aureus and 98.28% against E. coli, while reducing the colony diameter of Botrytis cinerea by 99.42%. During strawberry storage, the temperature of the fruit surface beneath the film reached only 35.88 °C, while PCG3-Te3-NIR treatment maintained a lower respiration rate and malondialdehyde content and greater catalase activity and vitamin C retention, effectively delaying spoilage during 8 days of storage at 25 °C. Total tellurium migration remained below 0.39 mg/kg in all four food simulants throughout the 10-day test. These results demonstrate the potential of CS/GG nanofiber-reinforced PPE-TeNP-functionalized PVA films for photothermal strawberry preservation.