Development of novel EGCG/Fe loaded sodium alginate-based packaging films with antibacterial and slow-release properties

Antibacterial food packaging with slow and sustained release of antibacterial agents exerts a crucial role in ensuring food quality and safety. Herein, metal-phenolic networks based on epigallocatechin gallate (EGCG) and iron (Fe), as well as thyme essential oil nano-emulsion (TEON) were successfully incorporated into sodium alginate (SA) matrix to prepare SA-based films through solution casting method. The effects of EGCG/Fe and different concentrations of TEON on the morphology, structure, physical properties, and functional characteristics of SA-based films were systematically analyzed. Results showed that the addition of EGCG/Fe and TEON significantly enhanced the mechanical intensity, flexibility, thermal stability, UV shielding, water vapor barrier performance, and oxygen barrier ability of the SA-based films. In addition, the introduction of TEON made the SA-based films slow-release of thyme essential oil, which obviously enhanced the antioxidant and dynamic antimicrobial properties of the films. Ultimately, the SA-based film revealed an outstanding preservation effect on pork by significantly reducing the increase rate of pH value and total plate count of pork. This developed SA-based films loaded with EGCG/Fe and TEON were expected to become a potential antibacterial material with slow-release properties for food packaging applications.