CHEMICAL MODIFICATION OF GUARAN GUM .3. CARBOXYMETHYLATION IN NONAQUEOUS MEDIUM

Guar gum was isolated from the seeds and subjected to modification via non-aqueous carboxymethylation. Highly substituted carboxymethyl guar an derivatives could be obtained via repeating the reaction four times , where a product of degree of substitution (D.S.) 2.07 was obtained i ndicating that the free hydroxyl groups of both glucose and mannose (w hich form the main constituents of guaran) can react with monochloro a cetic acid. The modification increases the solubility of the gum in co ld water, and increases the stability of its pastes to microorganisms. Pastes of these derivatives are characterized by non-Newtenian pseudo plastic behaviour regardless of their D.S. or the measuring temperatur e, while their apparent viscosity decreases by increasing the D.S. and /or the measuring temperature.