title: Lipase-catalyzed esterification of conjugated linoleic acid with sorbitol: a kinetic study.
abstract: The kinetics of esterification of conjugated linoleic acid (CLA) with sorbitol in acetone was investigated. An immobilized lipase from Candida antarctica (Chirazyme L-2) was used as the biocatalyst. A 2(2) x 3 factorial design was employed to find an experimental region in which one obtains a high rate of formation of the diester product. Best results were obtained at 10 degrees C using a CLA to sorbitol molar ratio of 5 and a biocatalyst loading of 150 mg/mL of acetone. Under these conditions, in 72 h one obtains a nearly quantitative yield (ca. 98%) of the diester of sorbitol with CLA. To minimize formation of products with degrees of esterification greater than two, the reaction should be carried out at 10 degrees C. A kinetic model developed using the King-Altman method was employed to fit the data. Use of the steady-state approximation for the monoester and an assumption that the concentration of sorbitol was constant and equal to its solubility limit permit one to minimize the number of parameters necessary to model the reaction network. Nonlinear regression analysis based on either two or three parameters provides very good fits of the multiresponse data in the presence or absence of triesters, respectively.
authors.affiliation: Department of Chemical Engineering, University of Wisconsin-Madison, 1415 Engineering Dr., Madison, Wisconsin 53706, USA.
authors.forename: Carlos F
authors.initials: CF
authors.lastname: Torres
authors.forename: Louis P
authors.initials: LP
authors.lastname: Lessard
authors.forename: Charles G
authors.initials: CG
authors.lastname: Hill
mesh_terms: D003198:Computer Simulation; D004789:Enzyme Activation; D004800:Enzymes, Immobilized / Q000737:chemistry; D004951:Esterification; D005656:Fungal Proteins; D007700:Kinetics; D019787:Linoleic Acid / Q000737:chemistry*; D008049:Lipase / Q000737:chemistry*; D008956:Models, Chemical; D017711:Nonlinear Dynamics; D012044:Regression Analysis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013012:Sorbitol / Q000737:chemistry*
chemical_list: D004800:Enzymes, Immobilized; D005656:Fungal Proteins; D013012:Sorbitol; D019787:Linoleic Acid; D008049:Lipase; C431349:lipase B, Candida antarctica