Preparation and characterization of κ-carrageenan/dextran films blended with nano-ZnO and anthocyanin for intelligent food packaging.

The κ-carrageenan/microbial-originated dextran-based multifunctional intelligent packaging films, integrated with natural anthocyanins as a colorant and ZnO as an antibacterial agent, were successfully developed using a casting method. Their applicability and functionality were systematically assessed through various analytical techniques. The addition of dextran, anthocyanins, and ZnO in the films resulted in an increased tensile strength (from 13.66 ± 0.53 to 29.70 ± 1.29 MPa) and elongation at break (from 16.69 ± 1.05 % to 39.49 ± 0.73 %), and decreased water solubility (from 64.94 ± 0.34 % to 32.84 ± 1.55 %) and water vapor barrier property (from 8.29 ± 0.12 × 10 g/m•s•Pa to 6.92 ± 0.1 × 10 g/m•s•Pa). Spectroscopic analysis revealed that the dextran, ZnO and anthocyanins were uniformly dispersed within the film-forming substrates, achieved through hydrogen bonds and electrostatic interactions. The addition of anthocyanins and ZnO not only enhanced the antibacterial and antioxidant properties of the film but also provided it with good pH sensitivity and color stability, making it highly promising for use in shrimp freshness monitoring. All the films were shown to be biodegradable, decomposing completely in soil within 30 days. Overall, these results suggest that the films could serve as a potential replacement for plastic food packaging and additionally monitor the freshness of food.