Cepharanthine-mediated photodynamic inactivation and active gelatin packaging for pork preservation.
Abstract
Photodynamic inactivation (PDI) offers a green, non-thermal and sustainable strategy for controlling foodborne pathogens and spoilage microorganisms in animal-derived foods, and natural products are increasingly being explored as photosensitizers. Here, we identify the previously underexplored photodynamic antibacterial activity of the natural alkaloid cepharanthine (CEP). SOSG fluorescence increased 6.88-fold after 10 min of irradiation, suggesting that CEP-mediated bacterial inactivation was predominantly associated with 1O2. Viable-count assays showed that CEP completely inactivated Staphylococcus aureus and Pseudomonas aeruginosa within 40 and 60 min, respectively. Its PDI activity was retained in 10% reconstituted milk without significant changes in pH or lipid oxidation. Incorporation of CEP into gelatin (Gel) films improved ultraviolet shielding, water-vapour barrier properties and mechanical strength. When applied to pork at 4 °C, CEP-Gel films markedly suppressed microbial growth, limiting total viable counts to 4.65 log CFU/g on day 12 compared with 7.50 log CFU/g in the control group. The films also delayed increases in pH, TVB-N, TBARS and weight loss. CEP-Gel significantly delayed microbial growth, lipid oxidation and protein degradation during the 12-day refrigerated storage period. Overall, this study expands the functional scope of CEP and establishes a promising strategy for the sustainable preservation of animal-derived foods.
