Designs of Bioreactor Systems for Solvent-Free Lipase-Catalyzed Synthesis of Fructose-Oleic Acid Esters

Fructose-oleic acid esters, biodegradable, biocompatible and biobased surfactants and value-added products were synthesized under solvent-free conditions at 65 A degrees C in stirred-batch mode and using several different bioreactor systems. For a stirred-tank bioreactor (STBR) using fed-batch fructose addition and 5.0 wt.% immobilized Rhizomucor miehei lipase (Lipozyme(A (R)) IM, Novozymes, Franklinton, NC), the conversion yield was over 80%, and the initial rate of the reaction was comparable to previously obtained results using tert-butanol during the initial phase. The bioreactor systems contained a packed "desorption" column (DC) containing fructose crystals and silica gel for delivery of saccharide, and either a STBR or packed-bed bioreactor (PBBR). The liquid stream, initially containing oleic acid and a mixture of fructose-oleic acid esters at a ratio of 75/25 w/w, was continuously recirculated throughout the system. The PBBR system yielded the highest conversion (84.4%) and rate of reaction subsequent to the addition of 10 wt.% molecular sieves during the latter stage of reaction; however, the reaction rate was several-fold lower than the batch mode reactions due to the lower fructose concentrations provided by the DC.