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Salt and Temperature Effects on Xanthan Gum Polysaccharide in Aqueous Solutions. | LitMetric

Salt and Temperature Effects on Xanthan Gum Polysaccharide in Aqueous Solutions.

Int J Mol Sci

Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York (SUNY), Buffalo, NY 14260, USA.

Published: December 2023

AI Article Synopsis

  • Xanthan gum (XG) is a carbohydrate polymer commonly used to modify the properties of substances like food and petroleum, and the study explored how different salts (Na, K, Ca) affect its characteristics in water at various temperatures.
  • The research found that increasing temperature significantly affected XG's intrinsic viscosity, with clearer changes observed in pure water compared to salt solutions, while calcium ions had a greater impact on reducing viscosity compared to sodium and potassium.
  • As salt concentration increased, the coil shape of XG changed due to the salts screening its charged groups, leading to structural contraction, but higher temperatures also initiated chain expansion, affecting how XG interacts with the salts.

Article 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 Ca 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, [], by fitting the relative viscosity () or specific viscosity () of XG/water and XG/salt/water solutions. With increasing temperature in water, Rao 1 gave [] the closest to the Huggins and Kraemer values. In water, [] was more sensitive to temperature increase (~30% increase in [], 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 [] by up to 60% over 0.05-100 mM salt. Overall, Ca 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.

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Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC10778890PMC
http://dx.doi.org/10.3390/ijms25010490DOI Listing

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