Preparation of Monodisperse Water-in-Oil-in-Water Emulsions Using Microfluidization and Straight-Through MicroChannel Emulsification

摘要

Water-in-soybean oil-in-water (W/O/W) emulsions with an internal water phase content of 1 0-30% (vol/vol) were prepared by a two-step emulsification method using microflu-idization and straight-through microchannel (MC) emulsification.A straight-through MC is a silicon array of micrometer-sized through-holes running through the plate.Microfluidization produced water-in-oil (W/O) emulsions with submicron water droplets of 0.15-0.26 mum in average diameter (d_((av)w/o)) and 42-53% in CV (CV_(w/o)) using tetraglycerin monolaurate condensed ricinoleic acid esters (TGCR) and polyglycerin polycon-densed ricinoieic acid esters (PGPR) as surfactants dissolved in the oil phase.The d_(av,w/o) and viscosity of the W/O emulsions increased with an increase in internal water phase content.Straight-through MC emulsification was performed using the W/O emulsions as the to-be-dispersed phase and polyoxyethylene (20) sor-bitan monooleate (Tween~R 80) as a surfactant dissolved in the external water phase.Monodisperse W/O/W emulsions with d_(av,w/o/w) of 39.0-41.0 murn and CV_(w/o/w) below 5% were successfully formed from a straight-through MC with an oblong section (42.8 x 13.3 mum),using the TGCR-containing systems.The d_(av,w/o/w) of the monodisperse W/O/W emulsions decreased as the internal water phase content increased because of the increase in viscosity of the to-be-dispersed phase.Little leakage of the internal water droplets and no droplet coalescence or droplet breakdown were observed during straight-through MC emulsification.