Properties of Carboxymethylated-Cassava and Sago Starches Prepared by using Sodium Monochloroacetate

Abstract

In the present study, carboxymethyl starch (CMC) were produced from different sources of starch and their physico-chemical properties were evaluated. Carboxymethylation was performed using different concentrations of sodium monochloroacetate (1.1, 1.3 and 1.5 mol/mol of anhydrous glucose units) in a three-necked round-bottom flask (250 mL) for approximately 3 h (250 rpm and 40°C) in a two-stage reaction comprising alkalization and etherification. The introduction of carboxymethyl groups was confirmed in the results by the appearance of a new peak in the FTIR spectrum in 1650.10-1649.76 cm-1 region. In addition, degree of substitution (DS) of produced CMS was ranged from 0.53-0.60. An increase in the concentration of sodium monochloroacetate (1.1, 1.3 and 1.5 mol/mol of anhydrous glucose unit) resulted in greater paste clarity, higher solubility and greater swelling than native starch. Furthermore, cassava starch (tapioca) produced a CMS exhibited greater swelling than sago starch, however by contrast, CMS-sago was more soluble and clearer than CMS-cassava.