Enhancing the antibacterial and antioxidant activities of chitosan/sodium alginate double-layer film by Pickering emulsion containing tea tree essential oil for food preservation

Considering the environmental challenges posed by petroleum-based plastics, researchers are placing greater emphasis on the development of natural biodegradable packaging materials. This study proposes a design scheme for a double-layer film featuring chitosan (CS) as the outer layer and sodium alginate (SA) as the inner layer. The stable tea tree essential oil (TEO) Pickering emulsion with soy protein isolate and sodium carboxymethyl cellulose was successfully prepared, and then integrated into inner layer. This formulation not only controlled the release rate of TEO within the film but also enhanced the compatibility of the TEO with the film matrix. The incorporation of the Pickering emulsion imparted excellent mechanical properties and barrier functions to the film, effectively blocking ultraviolet rays, water vapor, oxygen and microbes. The use of the developed film to protect strawberries and Pacific white shrimp has yielded encouraging results, underscoring its potential in food packaging applications.