Abstract：The polysaccharide has a variety of biological activities, such as anticoagulant activities and antiviral activities. In this paper extraction conditions of Undaria pinnatifida polysaccharides were studied. The polysaccharide was extracted from fresh Undaria pinnatifida which was pretreated with methanol to get rid of most pigment by hot water, then ethanol was used to make polysaccharide precipitated. Anthrone-sulfuric acid was used to determine the content of polysaccharide and the result showed that most polysaccharide was found in the deposition when the consistence of ethanol was 60%. On the base of the single factor experiment and a three-level three-factor Box-Behnken design, the effects of different temperature, extract time and the ratio of solid to solution on the yield of the polysaccharide were investigated. The extraction technique parameters were optimized with Response Surface Methodology and the optimum conditions of extraction were as follow: the temperature 75.8℃, the extraction time 2.2h, extraction twice, ratio of water to solution 6.3∶1, In this condition, extraction rate of Undaria pinnatifida polysaccharide was 7.73%.
Keywords：Undaria pinnatifida; Extraction; Single-factor test; Response surface methodology
