Abstract: Bacterial cells having glucose isomerase activity are properly conditioned prior to use to produce a fructose-containing product by (a) mixing the cells with water or an aqueous dextrose solution under controlled conditions until the cells are properly hydrated and pH equilibrated and then (b) passing water or an aqueous dextrose solution up through a bed of such cells under controlled conditions until the effluent solution is clear and is stabilized at desired characteristics. When water is used in step (b), it is followed by the step of passing an aqueous dextrose solution up through the bed until the effluent solution has the same dextrose content as the entering dextrose solution.