Patent ID: 8574873

Claim:
A process for the preparation of aqueous solutions of glucans having a β-1,3-glycosidically linked main chain and side groups having a β-1,6-glycosidic bond thereto, comprising: a) fermenting fungal strains which secrete said glucans in an aqueous culture medium; and b) subsequently separating an aqueous solution of the resulting glucan from the aqueous fermentation broth comprising glucans and biomass by crossflow microfiltration, wherein (i) asymmetrical filter membranes comprising at least one layer of a support material and at least one separating layer are used for the crossflow microfiltration, (ii) the pore size of the separating layer being from 1 μm to 10 μm and the pore size of the support material being from 5 μm to 100 μm, with the proviso that the pore size of the support material is at least 1 μm greater than the pore size of the separating layer, and (iii) the flow velocity of the crossflow is from 0.2 m/s to 20 m/s, and (iv) the transmembrane pressure is from 1 to 10 bar; and c) wherein the concentration of the glucans in the fermentation broth to be filtered is at least 3 g/l.