Abstract:A ternary composite CGB/CDs film was prepared using κ-carrageenan and gelatin (CG) as the film-forming matrix, anthocyanins (BA) extracted from bayberry pomace as natural pH indicators, and carbon dots (CDs) as functional fillers through a solution casting method. The microstructure of the composite film was characterized by SEM, FTIR, and X-ray diffraction. The results revealed that a dense and stable network structure was formed between anthocyanins, CDs, and the polymer matrix through hydrogen bonding interactions, with the CGB/CDs-5% film exhibiting the most uniform and compact structure. Compared to the pure CG film, this composite film demonstrated superior mechanical strength, water vapor and oxygen barrier properties, along with significant antioxidant and photodynamic antibacterial activities. The film exhibited a sensitive colorimetric response to ammonia, enabling visual assessment of food freshness. The practical preservation test indicated that the CGB/CDs-5% film could effectively inhibit microbial growth and delay the increase of total volatile basic nitrogen, pH value and total bacterial count of shrimp under 4 °C refrigeration, it extended the shelf life of shrimp to 5 days.