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Encapsulation of Essential Oils Using Hemp Protein Isolate-Gallic Acid Conjugates: Characterization and Functional
Xinyu Zhang1, Haoran Zhu1, Feng Xue1,2
1School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China.
Polymers
|July 12, 2025
Summary
Hemp seed protein isolate (HPI) modified with gallic acid (GA) effectively microencapsulates essential oils (EOs), enhancing their stability and bioactivity. This sustainable approach offers improved solutions for food and pharmaceutical applications.
Area of Science:
- Food Science
- Biomaterials Science
- Chemical Engineering
Background:
- Essential oils (EOs) possess valuable bioactivity but suffer from instability and volatility, limiting industrial use.
- Current encapsulation methods often rely on synthetic surfactants and struggle with EO stability.
- Proteins, like hemp seed protein isolate (HPI), can be modified to improve their amphiphilic properties for microencapsulation.
Purpose of the Study:
- To develop and evaluate a novel microencapsulation system using gallic acid (GA)-modified HPI conjugates for stabilizing six different essential oils.
- To assess the encapsulation efficiency, stability, and release kinetics of the developed microcapsules.
- To investigate the antioxidant and antimicrobial properties of the encapsulated EOs.
Main Methods:
- Covalent modification of hemp seed protein isolate (HPI) with gallic acid (GA).
- Microencapsulation of six essential oils (lemon, grapefruit, camellia, fragrans, oregano, mustard) using HPI-GA conjugates.
- Characterization of microcapsules using techniques to assess morphology, thermal stability, and surface oil.
- Evaluation of encapsulation efficiency, release kinetics (Peppas or Weibull models), antioxidant activity, and antimicrobial efficacy.
Main Results:
- Encapsulation efficiencies ranged from 40% to 88%, with oregano oil showing superior performance.
- High-efficiency microcapsules exhibited compact structures, improved thermal stability, and reduced surface oil.
- Oregano oil microcapsules demonstrated sustained release via matrix erosion and exhibited the highest antioxidant and antimicrobial activity.
- HPI-GA conjugates proved to be effective dual-functional emulsifier-encapsulants.
Conclusions:
- HPI-GA conjugates offer a sustainable and effective platform for enhancing essential oil stability and bioactivity.
- The developed microencapsulation system shows promise for applications in food preservation and pharmaceutical formulations.
- Modified proteins provide a viable alternative to synthetic surfactants in encapsulation technologies.
