Microencapsulation and characterization of hemp leaf cannabidiol extracted using supercritical CO2

Abstract

This study evaluated the extraction efficiency of cannabidiol (CBD) from hemp leaves using supercritical CO<inf>2</inf> at pressures of 1600–1800 psi. The optimal CBD yield (277.00 mg/mL) was obtained at 1800 psi, while the highest extraction efficiency (67.10 %) occurred at 1700 psi under 40 °C for 1.5 h. Flash chromatography purification effectively reduced Δ9-tetrahydrocannabinol (Δ9-THC) to legally compliant levels. Antioxidant activity and phenolic content were significantly enhanced in flash chromatography-treated extracts, particularly at 1700 psi. FTIR confirmed polysaccharide structures (∼3280 and 1148–937 cm⁻¹) and successful CBD encapsulation (1749 cm⁻¹), with spectral variations indicating differences in encapsulation efficiency. CBD-loaded microcapsules showed improved properties compared to emulsions, with higher CBD concentrations, stronger antioxidant activity (FRAP, DPPH), and greater total phenolic content, whereas the emulsions displayed higher encapsulation efficiency (98–99 %). Among microcapsules, microcapsule 4 (The emulsifier ratio consisted of MCT oil, Tween 80, and lecithin in the proportion of 6:2:2 (% w/v).) demonstrated the smallest particle size and most negative zeta potential, suggesting enhanced colloidal stability. SEM showed irregular, rough particles with size variations, linked to structural changes that enhanced solubility, release, and encapsulation efficiency. Furthermore, microencapsulated CBD with β-cyclodextrin exhibited moderate antimicrobial activity against Escherichia coli , Staphylococcus aureus , and Saccharomyces cerevisiae , while maintaining antioxidant properties and structural integrity during 75-day storage at 25 °C. These results highlight the effectiveness of combining supercritical CO<inf>2</inf> extraction and β-cyclodextrin-based microencapsulation for producing stable, high-purity CBD, offering promising applications in the pharmaceutical, nutraceutical, and cosmeceutical industries, thereby contributing to the elevation of herbal products to standardized levels that ensure safe utilization.