In emulsions prepared using a membrane emulsification system, dispersion droplet diameter depends basically upon membrane pore diameter. For practical applications, it is necessary to select the appropriate type and concentration of emulsifiers, U and J(e). For practical applications in the food industry, where large volume production is conducted, it is especially important to increase J(e). When preparing an O/W emulsion, this can be carried out by adding emulsifier to the oil phase, and J(e) can be increased up to 10 times. In the preparation of a W/O emulsion, increasing J(e) can be accomplished using a hydrophilic membrane pre-treated by immersion in the oil phase. The dispersion droplet diameter is roughly controlled and J, can be increased about 100 times in comparison to using a hydrophobic membrane. This makes a membrane emulsification system practical for large-scale food application of a W/O emulsion. Without adding preservatives, a low fat spread with a fat content of 25 wt% was created using this system.