Indicator packaging film based on carboxymethyl cellulose sodium incorporating curcumin-loaded γ-cyclodextrin metal-organic framework for real-time assessment of fish quality.

Curcumin (Cur) is a natural pigment widely used in smart packaging, but its poor thermal and light stability limits practical applications. This study encapsulated curcumin within γ-cyclodextrin metal-organic frameworks (γ-CD-MOFs) via an improved hydrothermal method and incorporated it into a sodium carboxymethyl cellulose (CMC)/polyvinyl alcohol (PVA) matrix to prepare composite indicator films. The γ-CD-MOFs significantly enhanced curcumin stability, while the CMC/PVA composite matrix improved the film's mechanical properties and barrier performance. The film exhibited excellent color difference ΔE >3 at room temperature and demonstrated a distinct visual transition from light yellow to reddish-brown during 36-h storage of crucian carp at 25 °C. This change showed significant correlation with total volatile basic nitrogen (TVB-N) levels. Mechanical strength improved simultaneously: tensile strength and elongation at break increased from 15.71 MPa and 14.64 % to 19.12 MPa and 26.95 %, respectively, at 4 % γ-CD-MOF/Cu content. Findings indicate that CMC/PVA/Cur/γ-CD-MOF films offer an innovative solution for real-time monitoring of fish freshness.