Abstract:

Polysaccharides from the roots of Sphallerocarpus gracilis were extracted into water and precipitated with
ethanol, and then determined by the sulfuric acid-phenol method. One-factor-at-a-time and Box-Behnken experimental
designs were used to obtain the optimal extraction parameters for polysaccharides. Analysis of variance showed that solidto-
liquid ratio and extraction time as well as the quadratic terms of all four response factors tested had a significant effect on
the yield of polysaccharides. A regression equation with a correlation coefficient of 94.57% was established, which could fit
the experimental data at a 94.57% confidence interval showing the reliability of the predictive model. Using ridge analysis,
the optimal extraction parameters of polysaccharide were obtained as follows: extraction temperature of 90 ℃, extraction
duration of 67 min, solid-toliquid ratio of 1:26.7 and 2 repeated cycles of extraction. Under these conditions, the yield of
polysaccharides was 3.41%.

Key words: Sphallerocarpus gracilis, polysaccharide, parameter optimization, response surface methodology