Sucrose bioconversion in membrane reactors

The use of soluble and immobilized biocatalyst membrane reactors has been investigated in connection with the hydrolysis of sucrose. Both β-fructofuranosidase (EC 3.2.1.26) and Saccharomyces cerevisiae cells were tested either as free catalysts or differently immobilized in polyalbumin gels and in hydrogels of poly-2-hydroxyethylmethacrylate (both particles and films). Invertase activity and thermal stability up to 60°C were measured. Activity recovery of immobilized cells is much higher than that of immobilized enzymes and ranges between 36% and 89%, compared to free systems and depends on the immobilization procedures used. Thermal stability of yeast cells is higher than that of enzymes. Experiments carried out with sucrose concentrations between 40 mM and 1 M indicate the possible presence of substrate inhibition for free cells and, for immobilized cells, an invariance of the reaction rate towards sucrose concentration for values greater than 300 mM.