Curcumin-loaded carboxymethyl cellulose/sodium alginate films with enhanced solubility and bioactivity for freshness monitoring of fish and beef.

Intelligent active food packaging films were developed by enhancing curcumin solubility through 2-hydroxypropyl-β-cyclodextrin inclusion complexes (EC). EC was incorporated at varying concentrations into a carboxymethyl cellulose (CMC)‑sodium alginate (SA) matrix. Sedimentation tests revealed that free curcumin exhibited severe precipitation (80.00%), whereas EC showed negligible sedimentation, confirming markedly improved aqueous dispersion. The optimized CMC-SA-EC3 film exhibited uniform morphology, enhanced thermal stability, strong intermolecular hydrogen bonding, and reduced water vapor permeability. It also demonstrated excellent antioxidant activity and broad-spectrum antibacterial effects against Gram-positive and Gram-negative pathogens. When applied as freshness indicators for refrigerated silver carp and beef, the films displayed distinct color transitions from yellow to red in response to spoilage. This formulation achieved the highest sensitivity and reliability for real-time spoilage detection. These findings provided a feasible strategy for designing dual-functional packaging materials that integrated preservation and intelligent sensing. Further work is needed to validate the long-term stability and scalability under practical storage conditions.