| 摘要 |
<p>The invention relates to a method for modifying polysaccharides by subjecting the polysaccharides - introduced in an aqueous medium - to the action of a modifying enzyme. At the end of the enzymatic reaction the modified polysaccharide is precipitated by the addition of either an organic solvent selected from the group consisting of C1-4 alcohols, C3-4 ketones, C1-4 alkylacetates and C2-4 ethers, or an inorganic water-soluble salt whereafter the modifying enzyme remained in the obtained liquor is recovered for reuse purposes. For example methanol, ethanol and acetone and most preferably isopropanol may be used as the organic solvent in an amount of 30-60 % w/w. On the other hand MgSO4, NaCl, NaAc, Na2SO4 and Na3BO3 and preferably (NH4)2SO4 may be used as the inorganic water-soluble salt in an amount of 15-30 % w/w. Representatives of polysaccharides are for instance galactomannans like guar having a mannan backbone and alpha -D-galactopyranosyl side chains. In case of guar as the starting material the guar content in the aqueous medium is advantageously about 0.1-3 wt.%, preferably 1%. A further advantage of the invention is based on the fact that in the case of hydrolysed side chains of the polysaccharide (e.g. galactose in the case of guar) the latter may be recovered from the obtained liquor and thereafter can be used for specific applications (e.g. kosher galactose).</p> |
