Dual response surface-optimized synthesis of l-menthyl conjugated linoleate in solvent-free system by Candida rugosa lipase

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 1 mmol CLA and 1 mmol l-menthol, the maximum conversion (79.1 ± 0.8%) was obtained at 30 °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,11E-/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.