Optimization of sugar fatty acid ester synthesis using lipases in non-aqueous medium

Saccharide-fatty acid esters are potential high-value products used as surfactants and emulsifiers. However, the reaction rate of saccharide-fatty acid esterification is usually low due to the extremely poor co-solubility of saccharides and fatty acids. In this thesis work, fructose and oleic acid were chosen as substrates to design an optimal model reaction which will lead to high conversion rate and extension by using lipases from Rhizomucor miehei and Candida antarctica. The investigated reaction conditions include organic solvent type and concentration, substrate mole ratio and concentration, and water content and fructose solubility. tert-Butyl alcohol (TBA) and a sufficient amount of ester greatly co-solubilized fructose and oleic acid. The highest reaction rate and extent were achieved while applying 46.9 wt.% TBA and small increments of fructose in a stepwise fashion. At the latter stage of the reaction, TBA should be removed because TBA's presence hinders the evaporation of the water, which reduces the reaction rate. A productivity rate of 1.4--1.6 mmol/hr-g was achieved, with 90% conversion of fructose achieved within 30 hours.