Salt and Temperature Effects on Xanthan Gum Polysaccharide in Aqueous Solutions

Abstract

Xanthan gum (XG) is a carbohydrate polymer with anionic properties that is widely used as a rheology modifier in various applications, including foods and petroleum extraction. The aim was to investigate the effect of Na+, K+, and Ca2+ on the physicochemical properties of XG in an aqueous solution as a function of temperature. Huggins, Kraemer, and Rao models were applied to determine intrinsic viscosity, [η], by fitting the relative viscosity (ηrel) or specific viscosity (ηsp) of XG/water and XG/salt/water solutions. With increasing temperature in water, Rao 1 gave [η] the closest to the Huggins and Kraemer values. In water, [η] was more sensitive to temperature increase (~30% increase in [η], 20–50 °C) compared to salt solutions (~15–25% increase). At a constant temperature, salt counterions screened the XG side-chain-charged groups and decreased [η] by up to 60% over 0.05–100 mM salt. Overall, Ca2+ was much more effective than the monovalent cations in screening charge. As the salt valency and concentration increased, the XG coil radius decreased, making evident the effect of shielding the intramolecular and intermolecular XG anionic charge. The reduction in repulsive forces caused XG structural contraction. Further, higher temperatures led to chain expansion that facilitated increased intermolecular interactions, which worked against the salt effect.

Investigating the Potential of a Transparent Xanthan Polymer for Enhanced Oil Recovery: A Comprehensive Study on Properties and Application Efficacy

“…The TNCS-ST xanthan consists of the typical xanthan pentasaccharide unit, as shown in Figure 1. Sodium ions are bound to the carboxylic groups of pyruvate and glucuronic acid [30,31]. The unique feature of the xanthan TNCS polymer lies in its transparency and solubility in high salt concentrations; particularly notable is its compatibility with solutions containing up to 18% total dissolved solids.…”

Effect of glycation with three polysaccharides on the structural and emulsifying properties of ovalbumin

“…Typical non-gelling food polysaccharides include anionic XG, nonionic guar gum (GG), and nonionic konjac glucomannan (KGM). Anionic XG has a d -glucose backbone with some trisaccharide side chains in the molecular chain ( Nsengiyumva et al, 2024 ). Nonionic GG has a mannose backbone with some galactose side chains in the molecular chain ( Sharma et al, 2018 ).…”