Biodegradable carboxymethyl cellulose/poly vinyl alcohol based films integrated with Cu-MOFs/oregano essential oil for fish preservation

In this work, a copper-based metal-organic framework (Cu-MOFs) combined with oregano essential oil (OEO) was successfully synthesized and incorporated into a CMC/PVA matrix to fabricate a high-performance, multifunctional biocomposite film. The influence of OEO and Cu-MOFs on the film’s morphology, mechanical performance, thermal stability, barrier properties, optical characteristics, antibacterial and antioxidant activities, and UV-shielding capability was systematically investigated. The Cu-MOFs were homogeneously dispersed within the CMC/PVA matrix, resulting in a marked enhancement in tensile strength (from 11.45 to 18.32 MPa) and reduced water vapor permeability, especially at 3 wt% Cu-MOFs content. Furthermore, the films exhibited enhanced UV-blocking performance, with the film containing 3 wt% Cu-MOFs showing the lowest UV transmittance (8.45%), indicating excellent UV-shielding capability. Moreover, these films demonstrated high free radical scavenging activity against DPPH (65.78%) and pronounced antibacterial activity against both Gram-positive and Gram-negative bacteria. Additionally, the films, particularly those containing 3 wt% Cu-MOFs, effectively delayed microbial growth and suppressed pH changes in fish fillets during refrigerated storage. These findings demonstrate the potential of CMC/PVA/Cu-MOF/OEO biocomposite films as multifunctional active packaging materials for shelf-life extension of fish. However, further studies involving standardized industrial-scale validation and comprehensive volatile compound characterization are required to establish the complete performance boundaries of the developed biocomposite films for real-world packaging application.