Method for preparation of dispersible, water-soluble polygalactomannans and polygalactomannan derivatives by crosslinking with borate ions, in which the polygalactomannan-containing endosperm of legumes is allowed to soak in an aqueous alkaline solution of a material containing borate ions in which the concentration of the borate ions, expressed as borax, is between 0.001 and 0.09 wt % and the hydroxyl ion concentration, expressed as NaOH, is between 0.2 and 10 wt % of the polygalactomannan and after taking up the solution, the cell structure of the splits is mechanically destroyed using high shear forces in a flaking, crushing or extruder process and then the product of the process is dried and ground in known fashion.