A coarse oil-in-water (O/W) emulsion, the oil phase of which was octanoic acid, was prepared at a very low surfactant concentration using a rotor/stator homogenizer. The emulsion was passed in a stainless steel tube immersed in an oil bath at 220 degrees C at a residence time of 60 s, and then mixed with the surfactant solution to produce a finely dispersed emulsion. The diameter of oil droplets in the fine emulsion was ca. 40 nm at the weight ratio of surfactant to oil of ca. 0.35 or higher. (C) 2006 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved.