Abstract: Cassava starch was subjected to mechanical activation for 60 min on a stirring-type ball mill. Carboxymethyl starch (CMS) was prepared by using activated cassava starch as the raw material, NaOH as the catalyst and ClCH2COOH as the etherification agent. The effects of temperature, CMS concentration, pH, electrolyte, storage time and shear stress on the viscosity of CMS paste were investigated. The results showed that the viscosity of CMS paste was relatively stable between 25 ℃ and 40 ℃, and revealed a gradual decrease at temperatures over 40 ℃. Meanwhile, the viscosity of CMS paste was increased with increasing CMS concentration. CMS paste revealed weak resistance to acid, alkali and salts, the highest viscosity in neutral medium and high sensitivity to NaCl, but was not steady at normal or low temperatures and close to Newtonian liquid.

Key words: cassava starch, mechanical activation, carboxymethyl starch, paste property