Encapsulation of Grapefruit Essential Oil in Emulsion-Based Edible Film Prepared by Plum (Pruni Domesticae Semen) Seed Protein Isolate and Gum Acacia Conjugates

Abstract

A dry-heated Maillard reaction was used to prepare plum seed protein isolate and gum acacia conjugates. Emulsion-based edible films (EBEF) were prepared by the encapsulation of grapefruit essential oil using conjugates solution as the continuous phase. The conjugates formed from 3 days of dry heating showed a significant improvement in emulsifying properties due to the unfolding of protein, as confirmed by structure analysis. The droplet size, electrical charge, and viscosity of emulsions increased with the increasing essential oil concentration, and all emulsions exhibited ‘gel’-like behavior. The water vapor barrier property, surface hydrophobicity, mechanical properties, and thermal stability of the films were improved as the essential oil content increased in the range of 1–4% due to enhancement in intermolecular interaction and compatibility, as well as a denser microstructure. Furthermore, all films exhibited an inhibitory effect against E. coli, while their radical scavenging activity depended on the release rate from films. The results obtained in this work confirmed that EBEF could be used as a novel food active packaging in the near future.