Suspended particles can have a positive effect on the flux and concentration curve of soy flour extracts during ultrafiltration. This is described by a simple empirical model. The suspended particles in this study were insoluble milled bean material (mean particle size 25 mum). It is shown that it is possible to concentrate soy extracts to a much higher final concentration with an acceptable flux. The suspended particles are able to clean the membrane by a scouring mechanism. They have a positive effect on the reversibility of fouling. (C) 2003 Elsevier Science Ltd. All rights reserved.