بررسي عوامل موثر بر كربوكسي متيلاسيون نشاسته ي گندم

Evaluation of the Optimum Conditions for Synthesis of Carboxymethyl Starch from Wheat

Carboxy methyl starch is a cold water – soluble starch ether. In this research, the optimal reaction conditions for wheat granular starch carboxymethylation were determined. These reactions took place with sodium monocholoro acetate (SMCA) as the carboxymethylation reagent in the presence of alkali ( NaoH) and alcohol. In this research, two types of alcohol, ethanol and isopropanol were used, and the effect of reaction medium, reaction temperature, and NaoH to SMCA molar ratio on the viscosity, yield, and temperature of starch gelatinization was investigated. The results showed that isopropyl alcohol performs better than ethyl alcohol as the reaction medium. Also, 40oC and 50oC temperatures, and NaoH to SMCA molar ratio of 1.25 (mol/mol) produced the highest viscosity and yield, and had lower temperature threshold for gelatinization. Since there was no significant difference between 40oC and 50oC temperatures in their effect on the yield and temperature of gelatinization, the temperature of 40oC was selected as the optimum temperature.