Physical properties and bioactivities of chitosan/gelatin-based films loaded with tannic acid and its application on the preservation of fresh-cut apples

The aim of this research is to develop composite (CG-TA) films by using chitosan (CS)/gelatin (GL)/tannic acid (TA), for fresh-cut apples preservation. TA was used as the crossing-linking agent to improve the mechanical and barrier properties, and as the active substance to improve the anti-ultraviolet and antioxidant abilities of the chitosan/gelatin (CG) film. With the incorporation of TA from 0 to 1 wt%, the tensile strength of the CG film was increased while the water vapor and oxygen permeability of the film were decreased. The CG-TA films containing more than 0.5 wt% of TA could effectively block most of UV light. The DPPH radical scavenging assay significant increased to 89.3% when the concentration of TA reached 2 wt%. Finally, CG and CG-TA films, as an active packaging material, were used to preserve the cold-stored fresh-cut apples. Compared with CG film, the CG-TA films obtained better performance on decreasing weight loss, delaying browning degree, inhibiting the lipid oxidase activity and decreasing the malondialdehyde content during 10 d of storage under 4 °C. Therefore, CG-TA films were expected to be a new active packaging material for preserving fresh-cut apples.