In liquid-liquid extraction processes of bioplants, separation problems due to undesirable emulsifications between aqueous and organic layers are often observed. In this study, surfactants were applied to such a process to avoid separation problems and achieve stable liquid-liquid extraction operations. Homogenized yeast culture broth including a lipophilic physiological active substance was used as the aqueous phase and hexane was used as the extraction solvent. The results of lab-scale extraction tests indicated that adding a small amount of surfactant made of polyoxyethylene-polyoxypropylene block copolymers actualizes extractions with both of high yields and high separation stabilities. Liquid-liquid extraction processes with surfactants required higher power consumptions in order to require high power inputs to diminish droplets to sizes small enough to guarantee high mass transfer. The surfactant was also effective for continuous countercurrent extraction processes, in which it prolonged stable operations. In conclusion, application of a specific surfactant to liquid-liquid extraction processes was confirmed to be effective to achieve high stabilities and high extraction yields of two-layer separations in settlers which would lead to productivity increases and solvent recovery load reductions. (C) 2016 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.