Abstract:In this study，the extraction conditions of water-soluble polysaccharides from purple sweet potato were optimized using single-factor and response tests，and the process parameters giving the best extraction rate were determined.A Sepharose 4B gel was used to separate and purify purple sweet potato polysaccharides，and then ultraviolet（UV）light absorption scanning，IR Spectra and monosaccharide compositionwas performed.The results showed that the optimum extraction conditions for purple sweet potato polysaccharides were as follows:extraction time，2.5 h；extraction temperature，80 ℃；and extraction ratio 15∶1（mL/g）.The extraction rate reached 9.03%under these conditions.Purple sweet potato polysaccharides were purified by Sepharose 4B to obtain a single polysaccharide component，PSPP-A，with a molecular weight of 2.63×103kDa.The UV light absorption spectrum showed that PSPP-A had no absorption peak at 260 nm and 280 nm，indicating that it did not contain nucleic acid or protein.The characteristic absorption peak of PSPP-A was determined by Fourier-transform infrared spectroscopy.Ion-exchange chromatography analysis showed that PSPP-A was composed of rhamnose，arabinose，galactose，glucose，and glucuronic acid，at a molar ratio of 1.89∶8.45∶1.95∶1.13∶1，respectively.