| abstract |
A crystalline mannose which contains substantially no organic solvent, has a melting point of 133 to 135 ° as measured by the DSC measurement and has a purity of 96 % or more. The crystalline mannose can be produced by a method which comprises immobilizing mannose isomerase on a carrier having a basic anion exchange group or an adsorptive resin having basic anion exchange function, contacting this enzyme with fructose to convert it into mannose, increasing the purity of mannose to 85 % or more, concentrating the resultant solution so as for the solution to have a Brix of 80 or more, heating the concentrated solution to a temperature of 60 to 90 °, growing crystals at the temperature with or without a seed crystal added, then lowering the temperature of the concentrated solution to a temperature 5 to 20 ° lower than that in the preceding step, and growing crystals at the lowered temperature. |