Active Chitosan Films Incorporating a β-Cyclodextrin–Curcumin Inclusion Complex: Enhanced Film Performance and Refrigerated Preservation of Fish Fillets

Achieving stable dispersion and sustained antibacterial activity of natural bioactive compounds in bio-based packaging remains challenging. In this study, chitosan (CS) films incorporating a β-cyclodextrin–curcumin inclusion complex (Cur/β-CD) were developed to improve film properties and the refrigerated preservation of sea bass. The CS/Cur/β-CD films were prepared by one-step solution casting without intermediate isolation or purification. The inclusion conditions were optimized, and the resulting films were evaluated in terms of tensile strength (TS), elongation at break (EAB), and water vapor permeability (WVP). Among the tested formulations, the film prepared at a Cur:β-CD ratio of 1:1, 40 °C, and 1 h (1:1 40 °C 1 h) showed the best overall performance in TS, EAB, and WVP. It was therefore selected for subsequent structural characterization, antibacterial evaluation, and preservation testing. The 1:1 40 °C 1 h film exhibited a 156% increase in tensile strength and a 28.5% decrease in water vapor permeability compared with the neat CS film. The composite film exhibited measurable diffusion-based antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). During the 8 d refrigerated storage period, the film suppressed total viable counts (TVC), slowed the increase in pH, and retarded total volatile basic nitrogen (TVB-N) accumulation, thereby maintaining acceptable microbiological quality throughout the observation period. Compared with the unwrapped, PE, and CS-film control groups, the treated samples showed better preservation performance over the tested storage period. Overall, the incorporation of Cur/β-CD provides a simple strategy for improving the mechanical strength, moisture barrier properties, antibacterial activity, and preservation performance of CS films during refrigerated storage, highlighting their potential for active packaging of chilled aquatic products.