| 摘要 |
PURPOSE:To obtain a purified xanthan gum of good-quality by depositing a xanthan gum as a calcium gel from an aqueous solution of a crude xanthan gum at an alkaline pH. CONSTITUTION:A neutral or acidic aqueous solution containing a xanthan gum and a calcium salt is rendered alkaline to deposit the xanthan gum. It is desirable to further add a solvent, especially a water-miscible hydrophilic organic solvent, after deposition of the xanthan gum since the separation and dewatering of the xanthan gum in later steps by, e.g. centrifugal separation can be greatly facilitated. As the calcium salt, an inorganic calcium salt, especially a basic inorganic calcium salt is desirable. The concentrations of the xanthan gum and the calcium salt in the aqueous solution are respectively about 0.5-3wt.% and about 0.2-1wt.%. The pH of the solution is adjusted to about 2 to 5 and then to 10 or higher alkaline. |
