A pH-sensitive film with synergistic photothermal antibacterial and antioxidant functions for pork preservation and visual quality alert

The development of smart packaging capable of simultaneously maintaining quality and enabling real-time freshness monitoring remains a major challenge in fresh meat preservation. This work designed a multifunctional gelatin/carboxymethyl cellulose composite film (GCAB) functionalized with hydrothermally optimized Bi₂S₃/BiOBr heterostructure and blueberry anthocyanins. Under NIR irradiation, the film rapidly generated temperatures exceeding 50 °C, and synergized with the inherent antioxidant capacity of anthocyanins to achieve viability reduction rates of 94.42% against Staphylococcus aureus and 96.32% against Escherichia coli. The integration of these components also improved the mechanical strength (18.8 MPa tensile strength), hydrophobicity (116.8° water contact angle), and UV-blocking capability. This film effectively extended pork shelf life to 12 days under refrigerated storage (4 °C) by suppressing microbial proliferation and lipid oxidation. Furthermore, it successfully monitored pork spoilage progression through visible color changes. This work provides a novel strategy for designing next-generation active packaging materials that integrate intelligent sensing and multi-mode antibacterial functions.