Carboxymethyl konjac glucomannan from konjac flour: The effect of media and temperature on carboxymethylation rate

摘要

To increase the solubility of porang flour or konjac flour in the water, the konjac flour was modified chemically into carboxymethyl konjac-glucomannan (CM-KGM), so that the utilization of the product may be wider. The aims of this research were to study the effect of ethanol concentration as the solvent media (50% ethanol and 90% ethanol) and temperature (45-50 °C dan 65-70 °C) on the rate of degrees of substitution (DS) formation in carboxymethylation step. CM-KGM was prepared by alkalization of konjac flour using sodium hydroxide for 30 minutes at 30°C. Then, the product of alkalization was carboxymethylated using sodium monochloroacetic (Na-MCA) with ratio 1:1 gram flour/NA-MCA. Based on the experimental results, the higher DS was attained by carboxymethylation using media solvent of 90% ethanol and temperature carboxymethylation 65-70°C. The relationship between temperature and reaction constant (k) follows: k = 0.3082 exp ((-15,277)/(8.314 T)).