Purification Of Tea Polysaccharides Using Reverse Micellar Extraction Technology

Reverse micellear extraction, as one potentially liquid-liquid extraction with high selectivity, simple operation steps, and ease of scaling-up, has good application prospect. From its first appearance at1913, up to now it’s extensively researched, most of study objects focused on small molecules, such as proteins, antibiotics and other biomolecules with low molecular weights. Only a few scholars carried on researches on biomolecules with large molecular weight, such as antigen and DNA. But nobody has done researches on macromolecules polysaccharides with molecular weight up to hundreds of thousands or even millions. Meanwhile, most of researches on the extraction processes concentrated in view of regulating pH values or salt types and concentration etc. In this study, we used the AOT/heptanes systems firstly to research the forward and backward extraction of tea polysaccharides, investigated the effects of pH value, salt types and concentration, AOT concentration, cosurfactant types and concentration and mixing methods, meanwhile we have investigated the effects of two consolvents (GuHCl and urea) on the forward and backward extraction efficiency. Dynamic laser scatting(DLS), Flourier transform infrared spectra(FT-IR) and Karl-Fischer titrator were applied to study the effect of cosolvent on the purification in microscopic mechanism. Optimal condition was obtained for the reverse micellar extraction of TPS after a study of above factors:forward extraction:[AOT]=0.04mol-L"1, pH=4.6,[KCl]=0.03mol·L-1,[NaCl]=0.05mol·L-1,[GuHCl]=0.06mol·L-1; backward extraction:pH=9.18,[AOT]=0.04mol·L-1, ethanol(v/v)=10%,[GuHCl]=1.3mol·L-1, or [Urea]=1.2mol·L-1. Under above conditions, the forward extraction efficiency reached34.15%, and the backward extraction efficiency reacheded110.69%and101.86%respectively. We hope that this study could lay a good foundation for the polysaccharides extraction using micellar extraction techonology.