Metal-phenolic networks immobilized on Zein nanoparticles as an emerging photothermal sterilization for foods.

Bacterial-mediated food spoilage poses global challenges to food safety and waste. While biocompatible metal-phenolic network (MPN)-based photothermal platforms offer a promising alternative to conventional high-temperature sterilization, their pH-responsive disassembly significantly compromises effectiveness in acidic foods. To address this challenge, we developed a photothermal antibacterial nanoplatform composing of all-natural materials by covalently immobilizing epigallocatechin gallate (EGCG)/Fe3+ networks onto zein nanoparticles (ZEF). This design ensures pH-stable photothermal performance across acidic, neutral, and weakly basic matrices. Under near-infrared (NIR) irradiation (808 nm, 10 min), ZEF generated localized hyperthermia (59-65 °C), eradicating 6.5 log10 CFU/mL of E. coli and methicillin-resistant Staphylococcus aureus (MRSA). ZEF achieved complete bacterial elimination (100 % reduction) under NIR treatment in liquid foods, including NFC juice and beer (pH 3-4) and milk (pH 6.5), surpassing the effectiveness of conventional pasteurization. Surface decontamination tests on fresh beef demonstrated nearly complete inhibition of MRSA. With a photothermal conversion efficiency of up to 39.49 % and recyclability over six irradiation cycles, ZEF offers a green, scalable strategy for gentle yet effective food sterilization.