Interfacial Structuring and Functional Enhancement in Pectin-Sodium Caseinate Films Loaded with Deverra tortuosa Essential Oil Nanoemulsions

This study aimed to develop bioactive pectin-based films incorporating Deverra tortuosa (D. tortuosa) essential oil (EO) nanoemulsions stabilized by sodium caseinate for potential active food packaging applications. EO nanoemulsions were incorporated into a pectin–maltodextrin matrix, and the resulting films were characterized for their thermal, morphological, antioxidant, and antimicrobial properties. Thermal analyses revealed an additional low-temperature mass loss in EO-loaded films, attributed to volatile oil constituents, while differential scanning calorimetry showed an endothermic transition at 171.9 °C associated with matrix reorganization and volatile release. Scanning electron microscopy (SEM) demonstrated increased surface heterogeneity and the formation of microcavities compared with EO-free films (F−). The incorporation of EO significantly enhanced antioxidant activity, with half-maximal inhibitory concentration (IC50) values of 9.18 µg mL−1 and 1.95 µg mL−1 in 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays, respectively. In addition, the films exhibited antimicrobial activity against Escherichia coli, Salmonella enterica, and Listeria innocua, with minimum inhibitory concentrations ranging from 1.25 to 2.5 mg mL−1. These results demonstrate that the incorporation of Deverra tortuosa EO nanoemulsions improves the functional properties of pectin-based films and supports their potential use as biodegradable active packaging materials.