Production of sunflower oil-in-water (O/W) emulsions using nickel microsieves

Uniform oil droplets can be used for encapsulation and controlled release of lipophilic active ingredients in various food, cosmetic, and pharmaceutical formulations. In these applications, uniform drops of controlled size are needed to achieve a controlled release at adjustable rates. In this work, O/W emulsions have been prepared by injecting sunflower oil through a flat disc nickel membrane into stirred continuous phase (aqueous solution of Tween® 20 or Pluronic® F-68). Three different membranes were used: 40μm whole membrane, 18 μm whole membrane and 18 μm ring membrane containing open pores only within a ring region. The effect of the paddle stirrer rotational speed, the transmembrane flux, the mean pore size and the membrane type (whole or ring) on the particle size distribution of prepared emulsions have been studied. It was found that stable emulsions could be produced using both Tween® 20 and Pluronic® F-68 but under the same conditions the emulsion droplets stabilized with Pluronic® F-68 are larger than the droplets prepared using Tween® 20. The final concentration of sunflower oil in the emulsions can be as high as 60 vol. % without any detrimental effect on the particle size distribution. The mean particle size was significantly effected by the rotational speed, the transmembrane flux, and the mean pore size and was varied between 76 and 281μm.