Supaporn Noppakundilograt

Encapsulated eucalyptus oil in ionically cross-linked alginate microcapsules and its controlled release

Sodium alginate microcapsules containing eucalyptus oil were prepared by oil-in-water emulsification via Shirasu porous glass (SPG) membrane and cross-linked by calcium chloride (CaCl2). SPG membrane pore size of 5.2μm was used to control the size of eucalyptus oil microdroplets. Effects of sodium alginate, having a mannuronic acid/guluronic acid (M/G) ratio of 1.13, eucalyptus oil and CaCl2 amounts on microdroplet sizes and size distribution were elucidated. Increasing sodium alginate amounts from 0.1 to 0.5% (wv(-1)) sodium alginate, the average droplets size increased from 42.2±2.0 to 48.5±0.6μm, with CVs of 16.5±2.2 and 30.2±4.5%, respectively. CaCl2 successfully gave narrower size distribution of cross-linked eucalyptus oil microcapsules. The optimum conditions for preparing the microcapsules, oil loading efficiency, and controlled release of the encapsulated eucalyptus oil from the microcapsules as a function of time at 40°C were investigated. Release model for the oil from microcapsules fitted Ritger-Peppas model with non-Fickian transport mechanism.

Microencapsulation of menthol by crosslinked chitosan via porous glass membrane emulsification technique and their controlled release properties

Chitosan-encapsulated menthol microcapsules were successfully prepared in an oil-in-water (o/w) emulsion using the Shirasu Porous Glass (SPG) membrane emulsification technique and high-speed dispersion technique for preparing a mixed o/w emulsion. The size of the menthol-loaded chitosan microcapsules was strongly depended on the average pore size of the SPG membrane and the amount of menthol loading in the dispersed phase. The membrane pore size of 5.2 µm was suitable for a viscous dispersed phase containing light mineral oil. The average diameter of emulsion droplets of 28.3 µm was obtained. Increasing the menthol loading in the dispersion phase from 5% to 10% w/w of chitosan decreased the emulsion droplet size with a broad size distribution. The crosslinked microcapsule size and size distribution of mixed emulsion droplets decreased with the increasing crosslinking time. The menthol release was a diffusion control which depended on the proportion of amino group in chitosan-to-tripolyphosphate molar ratio and crosslinking time. This work also demonstrated that hydrophilicity/hydrophobicity of the continuous phase and dispersion phase controlled SPG membrane emulsification efficiency and quality of the resulting emulsion droplets.