Lipase-catalyzed synthesis Of L-menthyl conjugated linoleate in solvent-free system was studied in this paper. Duel response surface methodology was employed to explore the factors which would influence the reaction conversion by a range of independent experiments. The conditions of reaction temperature, reaction time, enzyme amount, substrate molar ratio and water content were symmetrically investigated. When the substrates were I mmol CLA and 1 mmol L-menthol, the maximum conversion (79.1 +/- 0.8%) was obtained at 30 degrees C, Candida rugosa lipase of 33.7% (w/w by weight Of L-menthol), water content of 32% (w/w by weight Of L-menthol), reaction time of 43 h. The product isomers (9Z, 11 E-/10E, 12Z- = 63/37) were analyzed by GC/MS. The similarity between the oleic acid and 9Z, 11E-CLA conformations which were obtained by molecular modeling could account for the specific catalyzed by C rugosa lipase. (C) 2009 Elsevier Ltd. All rights reserved.