Fabrication, Characterization, and Application of Alginate-Based Biocomposite Films Assisted by Metal-Phenolic Network/Oxidized Starch Nanoparticles

Single-polysaccharide films exhibit drawbacks including insufficient gas permeability, absent antioxidant-antibacterial activities, and inferior mechanical properties. Herein, sodium alginate/konjac glucomannan (SA/KGM) was used as the film-forming matrix to construct a breathable-active dual-network. Oxidized starch nanoparticles (OSNPs) created pores for gas-transport pathways, and tea polyphenol-zinc nanoparticles (TP-Zn-NPs) improved the mechanical strength of the matrix and provided functional enhancement, forming a dual-nano combined reinforcement system. Characterizations of Scanning Electron Microscopy (SEM), Fourier-Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), gas permeability, mechanical, antioxidant, and antibacterial assays were carried out to explore the combined effects of the dual nanofillers. OSNPs enhanced gas permeability, while TP-Zn-NPs filled pores to balance gas transport and conferred high radical scavenging ability; nearly no detectable colonies of E. coli were observed under the test conditions. Soil-burial disintegration assessment, UV-blocking performance, and swelling behavior were further evaluated. The composite films effectively delayed quality deterioration of blueberries within the 10-day storage trial. This dual-nano combined modification optimizes the overall performance of polysaccharide-based composite films and shows promising potential for food-packaging applications.