AbstractRice starch was cyanoethylated by reacting it with acrylonitrile in presence of sodium hydroxide at different concentrations of acrylonitrile and various reaction temperatures. The effect of cyanoethylation on the rheological and solubility properties of starch was examined. It was found that the extent of the cyanoethylation reaction [expressed as %N and degree of substitution (DS)] increased by increasing acrylonitrile concentration provided that the latter was not less than 8 ml acrylonitrile per 10 g starch. A temperature of 50°C constituted the optimal temperature for the cyanoethylation of starch under the conditions studied. Examination of the rheological properties of the modified starch revealed that regardless of the DS, cyanoethylated starches are characterized by pseudoplastic behavior of particular interest were the results of the viscosity. Cyanoethylated starch having smaller amounts of cyanoethyl groups had higher viscosity than those of relatively larger amounts. On the other hand, the cyanoethylated starches were soluble in water regardless of the extent of cyanoethylation
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