Active polyvinyl alcohol packaging films incorporated with spermine functionalized carbon dots as antibacterial agents for salmon preservation

Spermine functionalized carbon dots (Spe-CDs) synthesized by microwave were doped in polyvinyl alcohol (PVA) to prepare active composite films with antibacterial activity. The Spe-CDs doping could endow the PVA composite film with fluorescence properties, a smoother and denser surface structure, and brownish yellow color. The addition of Spe-CDs also enhanced the performances of the PVA composite films such as the thermal stability, the ultraviolet shielding properties, and the mechanical properties. The three-phase contact angle increased from 52.6° to 84.7° due to the doping of 0.0050 % Spe-CDs, which might be responsible for the decline in water absorption rate and water vapor permeability. The Spe-CDs/PVA composite films displayed certain antioxidant capacity and could completely suppress the reproduction of E. coli and S. aureus with 0.0025 % and 0.0050 % Spe-CDs, respectively. The packing of Spe-CDs/PVA composite films showed good preservation performance on salmon pieces during the storage, such as the decrease in the drip loss, total plate count, TVB-N value and lipid oxidation, and affected the water mobility and distribution. Therefore, the Spe-CDs/PVA composite films displayed great potential for application in food preservation.