Optimization of Polysaccharide Extraction from Spirulina platensis by Cell Freeze-Thaw Cooperated with Hot Water Extraction and Deproteinization

Polysaccharide was extracted from Spirulina platensis by cell freeze-thaw cooperated with hot water extraction.Operating parameters for hot water extraction and deproteinization by Sevag method of polysaccharide from cell debris after cell disruption were optimized using an orthogonal array design.The best results were obtained after extraction at 80 ℃ for 1.5 h at a solid-to-solvent ratio of 1:16(g/mL).The extract obtained was pooled with the supernatant after cell disruption and a total total polysaccharide yield of 6.64% was obtained,which was approximately 14% higher than that obtained by hot water extraction alone.The optimal conditions for deprotenizing crude polysaccharide by Sevag’s method were found to be three treatment cycles with a mixture of chloroform and n-butyl alcohol(5:1,V/V) at a solid-to-solvent ratio of 1:3(g/mL).Under these conditions,the deprotentinizaiton rate and the polysaccharide loss were 81.4% and 17.3%,respectively.The crude polysaccharide extract had a total sugar content of 85.3% and contained an 84700 u polysaccharide with a ploydispersity of 1.306,whereas a 54800 u polysaccharide with a ploydispersity of 2.007 was obtained by hot water extraction alone.