Encapsulation of Essential Oils Using Hemp Protein Isolate-Gallic Acid Conjugates: Characterization and Functional...

Essential oils (EOs) represent natural bioactive agents with broad applications; however, their industrial utilization is often hampered by inherent volatility and instability, which current encapsulation methods struggle to overcome due to limitations such as reliance on synthetic surfactants. Proteins, owing to their amphiphilic nature, serve as materials for EOs microencapsulation, particularly when chemically modified. Building upon our previous work demonstrating improved emulsifying properties of hemp seed protein isolate (HPI) through covalent modification with gallic acid (GA), this study investigated its efficacy for essential oil encapsulation. This study developed a novel microencapsulation system utilizing conjugates of HPI and GA for stabilizing six essential oils (lemon, grapefruit, camellia, fragrans, oregano, and mustard). The microcapsules exhibited encapsulation efficiencies (EE) ranging from 40% to 88%, with oregano oil demonstrating superior performance due to carvacrol's amphiphilic surfactant properties. Advanced characterization techniques revealed that high-EE microcapsules displayed compact morphologies, enhanced thermal stability, and reduced surface oil localization. Release kinetics followed either the Peppas or Weibull model, with oregano microcapsules achieving sustained release via matrix erosion mechanisms. Antioxidant assays and antimicrobial tests demonstrated multifunctional efficacy, where oregano microcapsules exhibited the highest radical scavenging and antimicrobial activity. These findings establish HPI-GA conjugates as unique dual-functional emulsifier-encapsulants, offering a sustainable and effective platform to enhance EO stability and bioactivity, particularly for applications in food preservation and pharmaceutical formulations.