6-O-β-D(+)-Glucose stearate serving as a model product of glucose fatty acid monoesters was synthesized using lipase B from Candida antarctica (Chirazyme ® L-2) in a mainly solid-phase system in a stirred-tank membrane reactor. Esterification was performed in the presence of a small amount of ethyl methylketone (EMK), maintaining a catalytic liquid phase as well as forming an azeotrope with the reaction water. The azeotrope was evaporated and broken by membrane vapor permeation, then the dried EMK was returned to the reaction medium. The process was optimized by response surface methodology based on five major reaction parameters [time (T r ), substrate ratio (acyl donor to glucose, S r ), temperature (R t ), amount of solvent [solvent to substrates, [w/w], S a ), and enzyme load (E l )] varied at three levels, resulting in higher yields. Thus, under optimized conditions [T r = 58 h; S r = 2.7; E l = 8.9% (w/w); R t = 78°C; S a = 1.9], up to 93% yields of glucose stearate were achieved.Paper no. J9634 in JAOCS 78, 147-152 (February 2001). FIG. 1. Schematic diagram of lipase-catalyzed esterification for the production of sugar fatty acid esters in a stirred-tank membrane reactor. (1) Membrane reactor, (2) permeate condenser, (3) vacuum pump. TIC, temperature measurement; M, mixer; EMK, ethyl methylketone.

Recently we described that the process can be improved if a stirred-tank membrane reactor with a membrane located at the top of the reactor is used and reaction water Regioselective lipase-catalyzed synthesis of glucose ester on a preparative scaleGlucose fatty acid monoesters were produced in a stirred-tank reactor in combination with a membrane-pervaporation separation unit for the regeneration of the solvent ethyl methylketone (EMK) on a preparative scale. Yields up to 79% (169 g product) were achieved in the synthesis of 6-O-stearoyl-D-glucose in a mainly solid phase system in the presence of a small amount of EMK maintaining a catalytic liquid phase as well as forming a suitable azeotropic mixture with the reaction water. High residual activity was found using lipase B from Candida antarctica under reduced pressure at 60°C. EMK could be easily removed from the reaction mixture and is regarded as biocompatible in the preparation of food additives.