Thioctic acid and thymol-mediated solvent-free processing of soy protein bioplastics: a robust, UV-shielding, and...

Developing plant protein-based active packaging is pivotal for food safety, yet rigid protein structures often necessitate hazardous solvents. Herein, a facile and efficient "solvent-free reactive thermoplasticization" strategy is proposed to fabricate high-performance films using soy protein isolate (SPI) and food-grade thioctic acid (TA)/thymol (Thy). Under hot-pressing, the TA/Thy precursor forms an in-situ eutectic melt that disrupts protein aggregation and triggers ring-opening of TA. This facilitates covalent crosslinking with SPI cysteine residues, constructing a robust supramolecular network stabilized by dynamic hydrogen bonds and disulfide linkages. The resulting bioplastics exhibit superior transparency, synergistic mechanical toughness, and excellent water resistance. Critically, the films integrate intrinsic UV-shielding and sustained antimicrobial activity against foodborne pathogens. In a 7-day blueberry preservation model, STT films achieved 99.99% fungal inhibition (Aspergillus niger) and effectively suppressed microbial spoilage. This study provides a green, scalable paradigm for high-performance active food packaging.