超滤-醇析提取黄原胶工艺条件

Process Conditions of Extraction of Xanthan gum via Ultra-filtration and Alcohol-precipitation

考察了3种不同预处理方法对黄原胶提取收率和产品质量的影响,并对采用硅藻土过滤预处理法的稀释倍数与硅藻土的用量进行了优化. 考察了膜、进料流量、温度、操作压力及黄原胶浓度对超滤浓缩黄原胶的透过液透过通量的影响,并对这些参数进行了优化. 考察了溶剂种类、用量及pH对黄原胶醇析的影响,并对其进行优化. 比较了直接醇析、硅藻土过滤然后醇析、硅藻土过滤-超滤-醇析3种不同提取黄原胶方法对黄原胶产品质量与酒精耗量的影响.

Three different pretreatment methods for extracting Xanthan gum from fermentation broth, via diatomite filtration, enzyme degradation and NaClO oxidation were evaluated and the diatomite filtration was found to be the best in terms of the quality of Xanthan gum. The process conditions of extraction of Xanthan gum via ultra-filtration and alcohol-precipitation after the diatomite filtration pretreatment were investigated and optimized. The optimal conditions for diatomite filtration pretreatment were that the fermentation broth was diluted to about 10 g/L and the diatomite loading was 1% of fermentation broth. The optimal conditions for ultra-filtration were membrane UFM-4, operational pressure 0.2 MPa, velocity on membrane surface 2.46 m/s and condensed fermentation broth concentration about 60 g/L. The optimal conditions for alcohol-precipitation were pH 5.5, 95% industrial ethanol as precipitation agent and 95% industrial ethanol loading of 1.2 times of condensed fermentation broth by ultra-filtration. Under the optimal conditions the overall yield of Xanthan gum was 96.4%. Compared with the direct alcohol-precipitation and alcohol-precipitation after the diatomite filtration pretreatment for extraction of Xanthan gum, the ultra-filtration and alcohol-precipitation after the diatomite filtration pretreatment greatly improved the quality of Xanthan gum, especially in total nitrogen content and bacteria number, and decreased the ethanol consumption. Their ethanol consumption was only 22% and 11% of that of the other two methods respectively.