Ethanol, methanol, acetone, and other water-miscible solvents of similar hydrophobicity are typically used for that purpose. 

Acetone, ethaol and i-propanol are perfect solvents for precipitaion of polysaccharides.

Thanks for the answers. Do you happen to know if it is also possible to do it by salt addition instead of solvent addition?

Hi Niko, you might first use the solvents described for cleaning and try to use Ca2+ ions for precipitation. Works with alginate and Calciumchloride.

Best, Jan

Unlike alginate, guar is nonionic, so salts will have less effect. At high Ca++ concentrations, some precipitation may occur, especially at higher pH values.

you can use solvents to precipitate the gum then dissolve it in water and use amm. sulphate to salte out protein and re precipitate with solvent again then dyalize against tabe water then distalled water.