Volume 49 Number 3

Microencapsulation of Zingiber cassumunar Roxb. essential oil in poly-L-lactic acid: Effect of molecular weight on encapsulation efficiency and controlled release

Methakriat Sirival^a, Sutiam Kruawan^b, Nattika Thanuthong^c, Rujikarn Sirivantharat^c,*

 
ABSTRACT:     This study investigated the encapsulation of Zingiber cassumunar Roxb. essential oil using poly-L-lactic acid (PLLA). Shell capsules containing essential oil were prepared by solvent evaporation using PLLA with number average molecular weight of 77,000, 140,000, and 200,000 g/mol, at PLLA:essential oil mass ratios of 90:10, 70:30, and 60:40. The molecular weight of PLLA plays a crucial role in the encapsulation efficiency and release behavior by influencing microcapsule formation, structural integrity, and the diffusion of the encapsulated oil. Among the formulations investigated, PLLA with a molecular weight of 140,000 g/mol at a 90:10 PLLA:essential oil mass ratio achieved the optimal balance between encapsulation efficiency and controlled-release performance. The microcapsules were characterized by optical microscopy, scanning electron microscopy, ultraviolet-visible spectrophotometry, and Fourier-transform infrared spectroscopy. The highest release rate was 0.54 mg for PLLA at 140,000 g/mol with a 60:40 PLLA:essential oil mass ratio at 120 min. These findings are applicable to preserving essential oil properties over extended durations, including use in cosmetic, spa products, and controlled-release delivery products.

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* Corresponding author, E-mail: rujikarn.s@ku.th

Received 29 Dec 2025, Accepted 16 Aug 2026