Polysaccharides from Pachyrhizus erosus roots: Extraction optimization and functional properties.

Jicama is a widely cultivated but unexploited crop. This study isolated and characterized polysaccharide from roots of Pachyrhizus erosus (PEP). Optimal extraction conditions were obtained using single-factor experiment and response surface methodology, after which an extraction rate of 41.55% was obtained. Contents of total sugar, uronic acid, moisture, and ash were about 85.24%, 10.82%, 1.55%, and 0.05%, respectively. PEP had relative molecular mass of 18.3 kDa and tangled filaments and loose flaky structure. PEP was thermostable and presented high oil holding capacity but relatively low emulsion properties. Rheological tests indicated that the viscosity of PEP was of concentration and temperature dependence. Salt additions at various concentrations caused only slight increase of viscosity and storage modulus. In a word, PEP from jicama was a type of acidic polysaccharide with high thermostability and oil holding capacity. However, emulsion properties and viscosity are relatively low. Fine chemical structure and bio-function of PEP need further investigations.