Synthesis and antibacterial properties of Houttuynia cordata-derived carbon dots regulated by carbonization temperature for prolonging shelf life of chilled beef.

Houttuynia cordata carbon dots (HCO-CDs) were synthesized via the hydrothermal method and incorporated into polyvinyl alcohol/pectin films (PVA/Pec-CD), followed by exploring their applications to extend the shelf life of chilled beef. HCO-CDs transformed from flake-like structures to quasi-spherical nanoparticles at 160 °C, with aggregation occurring at 240 °C. HCO-CDs-160 displayed the strongest antibacterial activity against Pseudomonas aeruginosa and Brochothrix thermosphacta, due to their smaller particle size, higher membrane permeability, AKP leakage induction, ATP depletion, and ROS generation via surface C-O-C groups. HCO-CDs (≤ 3%) incorporation significantly improved film performance, with UV transmittance at 280 nm reduced to 1.96%, tensile strength increasing from 7.4 to 9.1 MPa, and water vapor permeability reaching 4.66 ± 0.13 × 10-8 g Pa-1 s-1 m-1. Zebrafish assays confirmed the biological safety of the films. The PVA/Pec-CD3% film extended the shelf life of chilled beef from 4 d to 8 d.