ZnO/C-mediated k-carrageenan based pseudo-pasteurization films for kumquat preservation

To combat the kumquat rot triggered by food-borne microorganisms, this work pioneered the concept of pseudo-pasteurization and integrated it with packaging technology to develop a novel antibacterial packaging film for the storage and preservation of kumquats. In detail, ZnO-doped carbon nanoparticles (ZnO/C) with excellent photothermal properties were first constructed by annealing the ZIF-8 precursor, and then incorporated into the K-carrageenan (KC) matrix as a filler to obtain a series of ZnO/C-KC nanocomposite films. The as-prepared ZnO/C-KC films exhibited the outstanding antibacterial properties (Antibacterial rate ≥99.8%) by virtue of the synergistic effect between NIR-induced autogenous heat and coexisting ZnO components, wherein the equilibrium temperature (60–62 °C) and holding time (5 min) of the film sterilization were significantly lower than that of the traditional pasteurization. The extended shelf-life of kumquats further confirmed the enhanced preservation capacity of ZnO/C-KC films. Furthermore, with the embedding of ZnO/C particles, although the color and transparency of films were slightly lost, the tensile strength, thermal stability, hydrophobicity, and barrier ability have been improved to varying degrees. Finally, the qualified safety of films was also verified through hemolysis and cell cytotoxicity experiments. The successful construction of this antibacterial film may provide new ideas for the innovation of traditional pasteurization and the functionalization of packaging films.