We investigated the factors affecting preparation of water-in-oil (W/O) emulsions using olive oil as the continuous phase, based on direct observation of microchannel (MC) emulsification. Monodisperse droplets were produced using polyglycerin polycondensed ricinoleic acid ester (PGPR) as an emulsifier. The mean droplet diameter and the time required for droplet formation (droplet detachment time) increased with increased viscosity of the continuous phase. Emulsifier concentration af fects droplet for mation, and stable emulsification was obser ved at PGPR concentrations exceeding 1wt％. Adsorption of PGPR was analyzed based on inter facial tension measurement with different measurement time scales. Monodisperse droplets with mean droplet diameters of 24 µm to 90 µm and coefficients of variation below 7％ could be produced using MC plates having dif ferent MC geometries. Fur thermore, we demonstrated that droplet formation behavior differed with the addition of milk components (skimmed milk powder and whey powder) to the dispersed phase, based on high-speed observation of individual droplet formation.

Microchannel (MC) emulsification for the preparation of monodisperse oil-in-water (O/W) and water-in-oil-in-water (W/O/W) emulsions containing palm oil as the oil phase was investigated for application as basic material solid/semi-solid lipid microspheres for delivery carriers of nutrients and drugs. Emulsification was characterized by direct observation of droplet generation under various operation conditions, as such, the effects of type and concentration of emulsifiers, emulsification temperature, MC structure, and flow rate of to-be-dispersed phase on droplet generation via MC were investigated. Sodium caseinate (SC) was confirmed as the most suitable emulsifier among the examined emulsifiers, and monodisperse O/W and W/O/W emulsions stabilized by it were successfully obtained with 20 to 40 µm mean diameter (dm) using different types of MCs.