Chemical Modification of Guaran Gum. Part 3: Carboxymethylation in non‐Aqueous Medium

Guar gum was isolated from the seeds and subjected to modification via non‐aqueous carboxymethylation. Highly substituted carboxymethyl guaran derivatives could be obtained via repeating the reaction four times, where a product of degree of substitution (D.S.) 2.07 was obtained indicating that the free hydroxyl groups of both glucose and mannose (which form the main constituents of guaran) can react with monochloro acetic acid. The modification increases the solubility of the gum in cold water, and increases the stability of its pastes to microorganisms. Pastes of these derivatives are characterized by non‐Newtonian pseudoplastic behaviour regardless of their D.S. or the measuring temperature, while their apparent viscosity decreases by increasing the D.S. and/or the measuring temperature.