Synthesis of carboxymethyl potato starch and comparison of optimal reaction conditions from different sources

Carboxymethyl potato starch (CMPS) was synthesized under heterogeneous reaction conditions. The influences of etherification temperature, alkalization and etherification time, sodium hydroxide to monochloroacetic acid (MCA) molar ratio (n(NaOH)/n(MCA)) theoretical degree of substitution (DSt), the ratio of isopropyl alcohol (IPA) volume to starch mass (V-IPA/m(st)) on degree of substitution (DS) and reaction efficiency (RE) of CMPS were investigated. Compared with the previous literature data, the results had significant difference for the optimal carboxymethylation conditions of potato starch from different sources. CMPS prepared under optimal conditions showed the highest DS and RE, which were 1.36 and 0.88, respectively. Furthermore, the RE value in this work is considerably higher than that reported in the literature. The time of alkalization and etherification were also discussed independently. In addition, CMPS was characterized by Fourier transform infrared spectrophotometry and scanning electron microscopy (SEM). Copyright (C) 2008 John Wiley & Sons, Ltd.