Non-covalent interaction-driven assembly of antimicrobial potato protein/ε-polylysine hydrochloride/tannic acid bioplastics for blueberries preservation

In this study, ε-polylysine hydrochloride (ε-PL) and tannic acid (TA) were incorporated into a potato protein matrix to develop composite films with non-covalent networks, and their structural characteristics and functional properties were systematically investigated. Compared with the pure protein film, the developed composite films exhibited a more compact cross-linked network structure, resulting in improved mechanical and barrier performances. Specifically, tensile strength and elongation at break increased by 39.98% and 53.38%, respectively, while water vapor permeability decreased by 27.84%. The denser microstructure also enhanced the UV-shielding capability of the films. Moreover, non-covalent interactions among potato protein chains, the amino and imine groups of ε-PL, and the phenolic hydroxyl groups of TA contributed to enhanced surface hydrophilicity. Antimicrobial tests demonstrated that films containing both ε-PL and TA exhibited excellent antimicrobial activity, with inhibition rates exceeding 99% against S. aureus and E. coli. Owing to their low water vapor permeability, the composite films effectively reduced moisture loss and extended the shelf life of packaged blueberries during storage. Therefore, this study provides an efficient and sustainable strategy for developing green, safe, and biodegradable plant protein-based active packaging materials for fresh fruits.