Preparation of monodisperse water‐in‐oil‐in‐water emulsions using microfluidization and straight‐through microchannel emulsification

Abstract

AbstractWater‐in‐soybean oil‐in‐water (W/O/W) emulsions with an internal water phase content of 10–30% (vol/vol) were prepared by a two‐step emulsification method using microfluidization 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 μm in average diameter (dav,w/o) and 42–53% in CV (CVw/o) using tetraglycerin monolaurate condensed ricinoleic acid esters (TGCR) and polyglycerin polycondensed ricinoleic acid esters (PGPR) as surfactants dissolved in the oil phase. The dav,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) sorbitan monooleate (Tween® 80) as a surfactant dissolved in the external water phase. Monodisperse W/O/W emulsions with dav,w/o/w of 39.0–41.0 μm and CVw/o/w below 5% were successfully formed from a straight‐through MC with an oblong section (42.8×13.3 μm), using the TGCR‐containing systems. The dav,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 break‐down were observed during straight‐through MC emulsification.