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Tipo: Artigo
Título: Rheological properties of aqueous dispersions of xanthan gum containing different chloride salts are impacted by both sizes and net electric charges of the cations
Autor(es): Galván, Zoila Rosa Nieto
Soares, Lucas de Souza
Medeiros, Eber Antonio Alves
Soares, Nilda de Fátima Ferreira
Ramos, Afonso Mota
Coimbra, Jane Sélia dos Reis
Oliveira, Eduardo Basílio de
Abstract: Xanthan gum (XG) is one of the most effective thickener agents used worldwide. In foods products, one of the factors affecting its physical properties is the ionic strength of the medium. Though it is well known that XG rheological properties in aqueous media depend on both type and concentration of electrolytes, correlations between such dispersion properties and molecular aspects of dispersed XG chains are still to be more deeply studied. Thus, in the present study, aqueous XG dispersions [200 mg⋅(100 mL)^−1] added of Na, K, Mg or Ca chlorides (ionic strength 50 mM or 100 mM) were rheologically characterized, and the corresponding results were explained based on different physicochemical analyses. Comparing to the control (unsalted XG dispersion), KCl and CaCl2 tended to produce a more drastic decrease of apparent viscosities of XG dispersions than NaCl and MgCl2. In dynamic-oscillatory assays, the predominance of elastic character over viscous character was more evident for XG dispersions containing KCl and CaCl2, in particular at frequencies > 0.1 Hz. XG dispersions containing KCl or CaCl2 also presented smaller pH and |ζ-potentials| values, as well as greater densities and average hydrodynamic diameters of dispersed XG chains, when compared to respective counterparts containing NaCl or MgCl2. As the decreasing order of the cations radii is K+ > Ca2+ ≈ Na+ > Mg2+, our results allowed deducing that not only the net electric charges of the cations, but also their sizes, should be considered when analyzing the effect of chloride salts on rheological properties of XG aqueous dispersions, according to the desired for this hydrocolloid (weak thickener, strong thickener or pro-gelling agent).
Palavras-chave: Chloride salts
Food biomolecules
Zeta potential
Ionic radii
Ionic strength
Editor: Food Biophysics
Tipo de Acesso: Springer Science+Business Media, LLC, part of Springer Nature 2018
Data do documento: 27-Mar-2018
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  Until 2100-12-31
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