Soybean lipoxygenase-3 reaction in emulsions stabilized by proteins and low molecular weight surfactants was investigated. High lipoxygenase activity was observed in the emulsions stabilized by proteins, whereas the reaction rates were very low in the surfactant-stabilized emulsions. The specificity of hydroperoxide isomers produced by lipoxygenase reaction was independent of the type of emulsifier. The effects of neutral salts and phospholipids addition on lipoxygenase reaction in protein-stabilized emulsions were also studied. Lipoxygenase activity decreased with increasing concentration of neutral salts. The efficiency of inhibition of lipoxygenase activity by salts was related to the activity of salts to decrease zeta-potential at the surfaces of substrate oil droplets. With respect to the effect of addition of phospholipids, it was shown that the lowering of interfacial tension and the fall in zeta-potential at the oil droplet surfaces were responsible for the inhibition of lipoxygenase activity. (C) 2000 Elsevier Science B.V. All rights reserved.