Processes are disclosed for the purification and recovery of polysaccharide
gums from an aqueous solution, particularly xanthan gum from a fermentation broth.
An aqueous solution of at least one polysaccharide gum is mixed with a non-solvent
stream comprising water and a subprecipitant level of a non-solvent of the polysaccharide
gum. The mixture is concentrated to increase the polysaccharide gum concentration,
and optionally undergoes a heat treatment. Additional non-solvent is added to the
concentrated mixture to precipitate the polysaccharide gum. The precipitated gum
is dried after being separated from the liquid component of the mixture. The removed
liquid component can be recycled to the earlier step in the process in which the
polysaccharide gum solution is mixed with the non-solvent stream.