Guar gum and its derivatives are highly important industrial hydrocolloids as they find applications in various industrial sectors. Guar is a polymer of high molecular weight and its aqueous solutions exhibit unique rheological properties, which has led to its wide acceptance by the industry. In certain industrial applications low molecular weight guar and its derivatives are needed, and conventionally chemical depolymerisation of guar is carried out for this purpose. Radiation processing is a novel and green technology for carrying out depolymerization and can be an ideal substitute for chemical depolymerisation technique. In order to study the effect of radiation on guar derivatives, three types of derivatives have been taken in the present study: carboxymethyl, hydroxyethyl, and methyl guar. The effect of 1–50？KGy radiation dose on the rheological behavior of these derivatives has been studied, and the results have been described in the present paper. The effect on storage and loss modulus with respect to frequency and effect on viscosity with respect to shear rate have been discussed in detail. 1. Introduction Guar gum is a polygalactomannan found in the endosperm of the seeds of the plant Cyamopsis tetragonolobus. It is a hydrophilic heteropolysaccharide of mannose and galactose monomer units where the mannose forms the main linear chain of the polymer and the galactose forms the pendant branches. The mannose units are linked together by β-1,4 glycosidic bonds and the galactose units are linked to mannose through α-1,6 glycosidic bonds [1]. The mannose to galactose ratio of guar gum has been reported to be approximately 2？:？1. Thus, every second mannose unit bears a branch of galactose unit. Guar gum is a high molecular weight polysaccharide (generally more than 2 million g/mol) that can form extensive intermolecular H-bonding resulting in high solvation and thereby increased viscosity [2]. These attributes of guar gum find it varied applications in the industry [3–11]. Guar gum functions as a thickener, emulsion stabilizer, gelling agent, film former, or texture modifier. Despite the unique rheological behavior there are certain limitations of guar gum which need to be overcome to ensure its effective use. The excessive hydrophilicity of guar gum along with the high molecular mass prevents complete or homogeneous solvation or hydration of the polymer. The resulting two-phase aqueous solution has certain regions showing increased viscosity and other regions showing the solid phase of undissolved guar gum. The other drawback of guar gum is the low
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