This study shows that premix membrane emulsification (ME) with organic microfiltration membranes to produce BSA-stabilized oil-in-water emulsions (10%, v/v oil fraction) is feasible. The effect of two different surface acting agents, a protein (BSA) and a non-ionic emulsifier (Tween-20), used as a single emulsifier or in mixtures, was investigated. The influence of the emulsifier, membrane type (nylon, nitrocellulose mixed esters, and polyethersulfone), transmembrane pressure (500-900 kPa) and number of emulsification cycles (maximum of 5) on the permeate flux and the droplet size distribution of the emulsions were determined. Protein fouling caused by the presence of BSA reduces the transmembrane flux, but does not affect the droplet size diameter of the resulting emulsion. The droplet size of the final emulsion is controlled by the interfacial tension and the pore size of the membrane (pore size close to 1 mu m). Even though the organic microfiltration membranes used in the study undergo some changes in the surface structure and thickness, the results suggest that one or two cycles of premix ME would be enough to reach a final stable value for the oil droplet size when BSA is used as emulsifier. Therefore the life-time of the membranes could be significantly increased. (C) 2010 Elsevier B.V. All rights reserved.