Abstract: The crosslinked carboxymethyl double modified starch (CCMS) was made from cassava starch with epichlorohydrin as crosslinking agent and chloroacetic acid as carboxyme thylating agent. The degree of substitution of product was determined by the precipitation method of copper salt. The optimal conditions are as follows: reaction temperature 55 ℃,reaction time 4 h and ratio of starch:ClCH2COOH:NaOH 1.00:0.44:0.44. The DS is about 0.79 under these conditions. Compared with native starch,CCMS shows higher viscosity,paste transparency and thermostability. CCMS possess the stronger environment adaptability with good application performance. The FTIR results showed that the peak at 1008～1164 cm-1 is enhanced,indicating the group of carboxymethyl has been introduced in starch molecule. The DSC results indicated that cross-linked carboxymethyl starch has a higher gelation temperature and can be gelated more easily.

Key words: cassava starch, cross linked carboxymethyl, double modification, property, structure characterization