Abstract:

In order to obtain curdlan with high purity , a new technology named Cyclic Ultrafiltration-Solvating-Out Crystallization (CUSOC) was developed to separate and purify crude curdlan. This technology coupled a fractional ultrafiltration separation system as well as two portions (is 30 -100 ku , more than 100 ku) , with the solvating-out crystallization , by which curdlan with the purities of 96. 5 % and 93. 3 % , were obtained. The composition of CUD3
obtained with 100ku membrane was then preliminarily analyzed. The results show that , in the CUSOC process , the rejection rates are all up to 95 % when using 30 ku and 100 ku membrane , and the total recoveηof polysaccharides in the whole process reaches about 93. 10%. It is also indicated by UV spectrum and paper chromatography that most pigment and nucleic acid impurity can be effectively removed in the process of CUSOC , and that the hydrolysis of CUD3 is a mono-ingredient only composed of glucose. Moreover , the IR spectrum reveals that CUD3 possess a β-D- glycoside linkage.

Key words: curdlan, separation, purification, ultrafiltration, solvating-out crystallization, process coupling