2002 Volume 3 Issue 2 Pages 35-40
The membrane emulsification method combined with preliminary emulsification enables us to prepare O/W or W/O type emulsions with narrow particle size distribution at high production rate without high mechanical stress. The method also prepares stable food emulsions with unique properties such as ultra-high concentration, multi-phase, solid fat particle in water without agglomeration and so on. This paper introduced an interesting feature of the membrane emulsification method combined with preliminary emulsification.
Highly concentrated emulsions were prepared from the low concentration pre-emulsified emulsions by the membrane phase inversion method. The maximum concentration obtained was ca. 90% for O/W emulsion, and ca. 85% for W/O emulsion. The W/O/W emulsions of very small particle (mean diameter, Dp≅2.5μm) with narrow particle size distribution (coefficient of variation, α≅0.1) could be obtained using a PTFE membrane (mean pore size = 1.0 μm) . The permeating flux of pre-emulsified W/O/W emulsion through the membrane was ca. 4-10m3/m2/h at 0.3 MPa. The encapsulation efficiency was not affected by the particle size of W/O emulsions. Increasing passage times through membrane decreased effectively the particle diameter of emulsion. Solid fat (melting point: Tm≅313 K) in water (O/W) emulsions prepared by the method were liquid state, and mean particle diameter (Dp≅2.0 μm) was almost unchanged during standing for several days at room temperature. This indicated that no appreciable aggregation of fat particles in O/W emulsions was observed.
