Encapsulation of Thymol and Eugenol Essential Oils Using Unmodified Cellulose: Preparation and Characterization

Area of Science:

• Agricultural Science
• Materials Science
• Biotechnology

Background:

• Essential oils (EOs) are natural pesticides but are unstable under heat and light.
• Encapsulation techniques can improve EO stability and expand their applications.
• Low-cost encapsulation methods are desirable for agricultural use.

Purpose of the Study:

• To develop a novel emulsification technique for encapsulating thymol (TY) and eugenol (EU) in unmodified cellulose microcapsules.
• To evaluate the physical characteristics, stability, and anti-mold efficacy of the encapsulated EOs.
• To explore the potential of cellulose-encapsulated EOs for post-harvest crop protection.

Main Methods:

• Unmodified cellulose was dissolved in aqueous NaOH and regenerated into hydrogels.
• Essential oils (thymol and eugenol) were mixed with cellulose hydrogels and processed using mechanical mixing and high-pressure homogenization (HPH).
• Characterization involved light microscopy, cryo-SEM, FTIR, and emulsion stability tests.

Main Results:

• Successful fabrication of EO-loaded cellulose microcapsules (1-8 µm) was confirmed by microscopy and spectroscopy.
• The resulting oil-in-water emulsions exhibited high stability with an instability index near 0.
• Encapsulated EOs demonstrated significant anti-mold activity against post-harvest alfalfa molds, with thymol showing the highest efficacy.

Conclusions:

• The novel emulsification technique effectively encapsulates essential oils within unmodified cellulose microcapsules.
• Cellulose encapsulation significantly enhances the stability and anti-mold properties of thymol and eugenol.
• Cellulose-encapsulated EOs show potential as natural antifungal agents for post-harvest crop preservation.