Optimization and kinetic modeling of lipase-catalyzed esterification of saccharide and fatty acid.

摘要

The lipase-catalyzed esterification of D-fructose and oleic acid was studied. The reaction was carried out with 1:1 mole ratio of oleic acid:fructose, using Lipozyme-IM (Novo-Nordisk, Franklington, NC) as immobilized lipase and tert-butanol (tBuOH) as solvent to increase fructose dissolution in oleic acid at the onset of reaction. The presence of esters helped accelerate fructose solubility; therefore, tBuOH was completely removed at the latter stages of the reaction to increase water evaporation without decreasing fructose dissolution [6]. Only solubilized fructose was introduced to the reaction by resaturation of fructose periodically to limit mass transfer problems. The reaction produced an 80% conversion of all substrates. A triangular phase diagram of D-fructose, oleic acid, and monoester was created. Water isotherms of the reaction system were also developed. Initial reaction kinetic study yielded the following parameters: maximal initial forward rate (Vmax = 4.6 +/- 0.2 mmolEster/hr.gcatalyst), fatty acid and saccharide Michaelis constants (KFA = 387 +/- 11mM and KS = 401 +/- 11 mM).