Development of a resveratrol nanoemulsion/carrageenan functional film for prolonging strawberry shelf life.

Mature strawberries are highly susceptible to mechanical damage and microbial contamination, leading to rapid deterioration during postharvest handling and retail distribution. In this study, a functional resveratrol nanoemulsion (RM)/carrageenan composite preservation film (C-RM) was developed for strawberry preservation. The prepared nanoemulsion exhibited good dispersion stability with an average particle size of 73 nm, a PDI of 0.28, and a zeta potential of -33.16 mV, enabling controlled release within the film matrix. At an RM loading of 6% (C-RM3), the tensile strength of the film increased from 39.97 MPa (control) to 49.19 MPa, accompanied by enhanced UV-blocking performance. FTIR and XRD analyses indicated that the nanoemulsion interacted with carrageenan through hydrogen bonding rather than covalent bonding, resulting in reduced crystallinity of the polymer matrix. The C-RM3 film exhibited strong antibacterial activity, achieving inhibition rates of 97.6% against Escherichia coli (E. coli) and 95.9% against Staphylococcus aureus (S. aureus), while antioxidant capacity was significantly improved, with DPPH and ABTS radical scavenging activities reaching 72.5% and 87.8%, respectively. Toxicity evaluations using mice and zebrafish confirmed good biosafety. After 5 days of storage at room temperature, strawberries packaged with C-RM3 maintained superior color, firmness, titratable acidity, and soluble solid content compared with the control, extending shelf life by 2 days. These results demonstrate that the C-RM film exhibits excellent antibacterial, antioxidant, and preservation performance, highlighting its potential as a sustainable green packaging material for fresh produce.