Edible tea polyphenol oxidation self-assembled zein films for fruit preservation

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Tea polyphenols (−)-epigallocatechin-3-gallate (EGCG) oxidation self-assembled nanocomposites (ENP) were synthesized through a one-step self-assembly process without templating or seeding agents and incorporated into zein-based edible films for the purpose of fruit preservation. The ENP nanocomposites maintained the core structural characteristics of EGCG and demonstrated excellent antioxidant activity, and antibacterial properties against E. coli and S. aureus . As a coating, ENP significantly reduced strawberry decay, weight loss, and nutrient degradation during storage. When integrated into zein films, ENP improved structural density, mechanical properties, water vapor permeability, antioxidant capacity, and light transmittance, without affecting the crystallinity of the zein-based films. The zein-based ENP edible films effectively extended the shelf life of strawberries and fresh-cut apples, surpassing the performance of both pure zein and polyethylene films. Mechanistic investigations have demonstrated that ENP compromised bacterial biofilm and structure integrity, leads to the leakage of intracellular contents, and inhibited ATPase activity. Biological safety assessment showed that the ENP nanocomposites exhibited negligible toxicity to zebrafish and seed germination, and the zein-based ENP film has ideal degradation performance. Taken together, zein-based films incorporating ENP offer a sustainable, effective, and safe approach for packaging in fruit preservation.