Synthesis and Characterization of Hypochlorite Oxidized Starches

Abstract

Abstract Egyptian rice and maize starches were treated with sodium hypochlorite at different concentrations. The oxidized starches so obtained were monitored for carboxyl content and rheological properties. In addition, the extent and rate of the oxidation reaction was assessed by investigating the chlorine consumption. Results indicated that the extent and rate of oxidation of rice starch, expressed as chlorine consumption, are much higher than those of maize starch. The opposite holds true for the carboxyl content. Pastes of rice and maize starches before and after oxidation exhibit non‐Newtonian thixotropic behaviour but their apparent viscosity decreases by increasing the hypochlorite concentration. At any event, however, the apparent viscosity of rice starch is substantially higher than that of maize starch. Storing the pastes for 24 h adversely affect the apparent viscosity particularly with oxidized starches prepared using higher hypochlorite concentrations.