Temperature-responsive gelatin-based composite hydrogel pads with smart controlled phage release for intelligent...

Polysaccharide-protein hydrogels offer a biodegradable and structurally tunable platform for next-generation food packaging applications. This study developed an intelligent temperature-responsive hydrogel system by optimizing the combinations of hydroxybutyl chitosan (HBC) and hydroxypropyl methylcellulose (HPMC) to create specific structures within a gelatin matrix, thereby regulating the release of bacteriophages against Listeria monocytogenes. At a 6:4 ratio, the hydrogel exhibited significantly enhanced mechanical strength and a dense, uniform microstructure, providing a stable scaffold for phage encapsulation. Compared with gelatin hydrogel alone, the composite hydrogel demonstrated an increase of up to 38% in hardness, 89% in springiness, and > 73% in storage modulus, while enabling the sustained and efficient release of bacteriophages. Functionally, the hydrogel demonstrated temperature-modulated behavior, maintaining high swelling capacity and sustained release properties after storage at refrigeration temperature (4 °C), while achieving accelerated release of bacteriophages upon temperature increase. Cytotoxicity assays confirmed excellent biocompatibility, with promotion of Caco-2 cell proliferation (147% viability at 100 g/L). When used on stored chicken, the hydrogel effectively inhibited Listeria monocytogenes growth over 7 days. By integrating structural design with stimulus-responsive release, this study presents a novel packaging material that combines long-term preservation with on-demand antimicrobial action, offering a promising solution for intelligent, cold-chain food protection.