Preparation of water-in-oil-in-water emulsions by repeated premix cellulose acetate membrane emulsification

Abstract

The purpose of this study is to determine the potential of cellulose acetate membrane for preparation of formulated water-in-oil-in-water (W/O/W) emulsions by repeated premix membrane emulsification. The effects of selective membrane emulsification process parameters (concentration of the emulsifiers, number of passes of the emulsions through the membrane, and storage temperature) on the properties and stability of W/O/W emulsions were also investigated. The preparation of multiple W/O/W emulsions by repeated premix membrane emulsification (ME) using cellulose acetate membrane (0.8 µm mean pore size) has proposed in this study to reduce low stability problem of the emulsions. A coarse emulsion was passed through the same membrane five times at a constant pressure of 0.3 MPa to minimize the droplets size and to increase the uniformity of droplets size. About 7 wt. % polyglycerol polyricinoleate (PGPR) and 0.5-10 wt. % Tween 80 (Polyoxyethylene (20) sorbitan monooleate) were used as lipophilic and hydrophilic emulsifiers, respectively. In addition, 1,3,6,8-pyrenetetrasulfonic acid tetrasodium salt (PTSA) was used as a hydrophilic model ingredient for the encapsulation of bioactive substances. By using 7 wt. % PGPR concentration and 0.5 wt. % Tween 80 concentrations, the most uniform particles with minimum mean size of oil drops (9.926 µm) were obtained after four passes through the membrane. The encapsulation efficiency greater than 70 % was achieved after emulsions storage at 4°C for seven days with amount of serum about 41.02%. It can be concluded that cellulose acetate membrane does not possess very high potential for preparing a stable W/O/W emulsion by repeated premix membrane emulsification. However, this membrane is still acceptable for preparing W/O/W emulsions with the optimum conditions (0.8 µm mean pore size and applying pressure of 0.3 MPa) obtained throughout this study since cellulose acetate membrane is low cost and relatively easy to handle.