Metal–Phenolic Network-Loaded Sodium Alginate-Based Antibacterial and Antioxidant Films Incorporated with Geranium Essential Oil

Owing to its natural degradability and excellent film-forming characteristics, sodium alginate (SA) is gaining growing popularity in the field of food packaging. However, the insufficient antioxidant and antibacterial properties hinder its application. In the current research, protocatechuic acid (PCA) and Fe3+ were utilized to fabricate a metal polyphenol network structure. Subsequently, geranium essential oil emulsion (GEOE) was incorporated into the SA matrix, and SA-based films were prepared through the flat-sheet casting method. The impacts of PCA/Fe and various concentrations of GEOE on the physical, structural, as well as functional characteristics of SA-based films were comprehensively examined. The thickness of the prepared SA-based films was between 30 and 50 μm. The results showed that PCA/Fe, GEOE, and SA exhibited good biocompatibility, and the formed films were uniform. The incorporation of PCA/Fe and GEOE significantly improved the UV blocking ability, thermal stability, and antibacterial activity of SA-based films. In addition, PCA/Fe and GEOE enhanced the total antioxidant capacity of SA-based films from 3.5% to 88%. This research could provide some theoretical basis for the utilization of metal polyphenol networks and natural essential oils within the realm of food active packaging films.