pH triggered on-demand tannic acid release via “open-close” of soybean isolate proteins spatial structure for shrimp preservation

The on-demand release intelligent packaging system ensures the quality and safety of food products by releasing antimicrobial factors in response to environmental changes. However, the complex fabrication process of traditional pH-sensitive packaging restricted their large-scale application. Herein, a novel soy protein isolate (SPI)/carboxymethyl cellulose sodium (CMC)/tannic acid (TA) composite was successfully demonstrated as on-demanded TA release active packaging film, in which TA was in situ wrapped within SPI chains via tailoring the pH. The formed volatile biogenic amines from shrimp raised the headspace pH, inducing the opening of SPI spatial structures to release antimicrobial active factors. When pH was changed from 6.5 to 7.0, the cumulative release amount of TA from SCT-5 composite film increased from 11.61 mg/cm² to 18.69 mg/cm². When the optimized SCT film was utilized as packing material, the shelf life of Pacific white shrimp was extended at least 8 days. Furthermore, SCT-5 composite films exhibited excellent ultraviolet resistance (200–400 nm 99.64%), gas barrier properties (OTR: 11.67 ± 0.87 (cm³·μm/(m²·d·kPa)), WVTR: 638.77 ± 13.97 g/(m²·24h)) and biodegradability. Our findings presented a facile and novel strategy for designing protein-based on-demand release active packaging, facilitating the development of food quality and safety.