Preparation of W/O Food Product Emulsions by the Membrane Emulsification Method and Assessment of Stability.

High-water-content (40% (w/w)) W/O emulsions from substances containing fats and oils were prepared at a high emulsification rate by use of a microporous glass membrane, and the stability of emulsions prepared by the membrane emulsification method was assessed. As the indices of stability, variations in dispersed droplet diameter, viscosity, and oil separation rate over time were used. Even under the experimental conditions employed, by changing the pore diameter of the membrane, it was possible to control dispersed droplet diameter for the most part. From the standpoint of stability, when compared to the stirring emulsification method, variations in dispersed droplet diameter and viscosity of W/O emulsions were confirmed to be more stable, which is an advantage of using the membrane emulsification method. As an additional advantage, the stability of W/O emulsions prepared by the membrane emulsification method was not related to the dispersed droplet diameter size. In addition, with regard to the emulsification rate in this experiment,the dispersion phase flow rate through the membrane pores resulted in relatively little O/W interfacial tension, and a theory of flow through the membrane was understood. These results indicate that using the membrane emulsification method, it is possible to prepare at a practical level (high emulsification rate), a more stable, high-water-content W/O emulsion than is possible by means of the existing (stirring emulsification) method.