Functional properties of native and carboxymethyl guar gum

Abstract

Guar gum in its native form exhibits a very good thickening capacity and hence is used as a thickener or agent for 'binding' water in food, cosmetics and toiletries, in pharmaceuticals and in the mining, paper and textile industries (Glicksman 1976). This communication reports the effect of introducing an anionic carboxymethyl group upon the thickening capacity of guar gum and the related secondary functional properties of stabilising foams and suspensions. Compared with native guar gum, carboxymethyl guar gum with a degree of substitution of 0·68 exhibited a higher viscosity and an enhanced ability to stabilise foams and suspensions. Both native and carboxymethyl guar gum induced a non-Newtonian pseudoplastic behaviour to casein (100 g litre^-1) suspension. At the same time only carboxymethyl guar gum containing suspensions above 1 g litre^-1 exhibited measurable yield value.