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Lipases can catalyze the esterification reaction in a two‐phase system. TheCandida rugosa lipase‐catalyzed esterification of decanoic acid with glycerol is described in this work for an emulsion system and for a hydrophilic membrane bioreactor. The enzymatic activity is studied in relation to the interface area between the two phases, the enzyme load and the reactor volume. The initial rate per unit interface area, the interfacial activity, is roughly equal for both systems indicating that the cellulose membrane does not hinder the esterification. Because the interfacial activities are equal, the volumetric activity of a membrane system is only specific area related, so a hollow fiber membrane device is preferable. The activity is also a function of the enzyme load. The optimum load in a hydrophilic membrane reactor is one to three times the amount of a monolayer, while in an emulsion system several times this amount. This could indicate that in the emulsion system the adsorption is in a dynamic state while at the membrane surface the adsorption reached its equilibrium state.

The equilibrium position in lipase mediated esterification of various fatty acids and butanol was studied. The influence of the chain length and the presence of unsaturations in the fatty acids on the equilibrium position was measured and predicted. To predict equilibrium position the program TREP extended (TREPEX) based on the UNIFAC group contribution method was used. Using an equilibrium constant of 35, calculated on the basis of thermodynamic activities, the equilibrium position between butanol and saturated and/or unsaturated fatty acids with different chain lengths can be predicted. The ester mole fraction at equilibrium increases with the fatty acid chain length, and for fatty acids with the same carbon number, the highest values are found for unsaturated fatty acids. For reaction systems containing two saturated fatty acids, a slightly higher mole fraction is obtained for the fatty acid with the higher chain length, while for mixtures consisting of saturated and unsaturated fatty acids, the mole fractions of the unsaturated esters are lower than those of the saturated ones, regardless the chain length of the fatty acid. These experimental results are in good agreement with the calculations with TREPEX. © 2000 John Wiley & Sons, Inc. Biotechnol Bioeng 67: 364–371, 2000.

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BACKGROUND: Membrane filtration has the potential for purification of oligosaccharide mixtures. However, single stage performance is limited by the relatively low yield and purity that can be achieved. This paper explores the potential of a three-stage pilot-scale spiral wound membrane filtration cascade for the removal of monosaccharides and disaccharides from a galacto-oligosaccharide mixture.