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.