Fabrication of chitosan-based smart film by the O/W emulsion containing curcumin for monitoring pork freshness

In this research, curcumin (Cur) was encapsulated in succinylated soy protein isolate (SSPI) emulsion and combined with chitosan (CS) to prepare a smart film. The good adsorption ability of SSPI at the oil-water interface provides good physical stability for preparing Cur-loaded emulsion. These CS smart films containing SSPI emulsions with different curcumin content were evaluated on the structure, mechanical, barrier, antioxidant, antibacterial properties, and controlled release behavior. SEM and FT-IR results showed that the Cur-loaded emulsion was compatible with the CS matrix. By adding the emulsion, the film blocked 97.11% of ultraviolet radiation, reduced the water vapor transmission rate by 42%, and improved the swelling degree (32.26%), water solubility (12%), thermal stability and elongation at break (70.79 %) (p < 0.05). In addition, the film has a high antibacterial effect on Staphylococcus aureus and Escherichia coli (Bacterial inhibition zone diameter: 19.59 mm and 18.66 mm) and the release rate of curcumin in the film reaches 82.60%, mainly following the Fickian diffusion. The film gradually turns red under alkaline conditions, a property that makes the films successful in monitoring the deterioration of pork during storage. Adding SSPI emulsions and curcumin to films has great potential for food freshness monitoring and packaging.