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Sajid Alavi - One of the best experts on this subject based on the ideXlab platform.
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intrinsic viscosity and viscoelastic properties of Xanthan guar mixtures in dilute solutions effect of salt concentration on the polymer interactions
Food Research International, 2007Co-Authors: Hanna Khouryieh, Thomas J Herald, Fadi M Aramouni, Sajid AlaviAbstract:Abstract An oscillating capillary rheometer was used to investigate the dynamic viscoelastic and intrinsic viscosity properties of deacetylated Xanthan (0.025%), native Xanthan (0.025%), guar gum (0.075%), and Xanthan–guar mixtures in dilute solutions. Influence of ionic strength on Xanthan conformation and interaction with guar gum was elaborated. As the salt concentration increased, a significant ( P η ′) and elasticity ( η ″) values was observed for both native Xanthan–guar mixtures and deacetylated Xanthan–guar mixtures. In water and 2 mM NaCl solution, the relative viscosity and η ″ of both native Xanthan–guar mixtures and deacetylated Xanthan–guar mixtures were much higher than of those calculated for mixtures assuming no interaction, whereas no pronounced increase was found for polysaccharide mixtures in 40 mM NaCl. The intrinsic viscosities of deacetylated Xanthan–guar mixtures in water and 2 mM NaCl were higher, whereas the intrinsic viscosities of native Xanthan–guar mixtures were lower than those calculated from the weight averages of the two individually, assuming no interaction. These results demonstrated that intermolecular interaction has occurred between Xanthan and guar mixtures in water and 2 mM NaCl, but may not occur in 40 mM NaCl, and mutual incompatibility may occur. The results suggest that the degree of disordering of Xanthan played a critical role in Xanthan–guar interaction and may explain the differences in η ′, η ″, and intrinsic viscosity measurements between 2 and 40 mM NaCl.
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rheological study of Xanthan and locust bean gum interaction in dilute solution
Food Research International, 2006Co-Authors: J Higiro, Thomas J Herald, Sajid AlaviAbstract:An oscillatory capillary rheometer was used to investigate visco-elastic properties of Xanthan and locust bean gum (LBG) blends in dilute solution. Gums were evaluated for intrinsic viscosity and the elastic component. Molecular conformation of the complex of Xanthan–LBG was assessed by the power law and the Huggins equations. A 60% Xanthan–40% LBG blend exhibited the strongest attraction between Xanthan and LBG molecules as evidenced by a greater intrinsic viscosity, the polymer miscibility coefficient α, the elastic component, and a positive Huggins coefficient Km. The power-law model was successfully applied to predict the molecular conformation of Xanthan and LBG alone in dilute solution and was exhibited as rod-like and random coil conformation. The power-law coefficient b increased as the LBG fraction increased in the blends, suggesting a more flexible Xanthan–LBG complex dependent on LBG.
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Influence of mixing temperature on Xanthan conformation and interaction of Xanthan¿guar gum in dilute aqueous solutions
Food Research International, 2006Co-Authors: Hanna Khouryieh, Thomas J Herald, Fadi M Aramouni, Sajid AlaviAbstract:Abstract Dynamic viscoelastic and intrinsic viscosity properties of Xanthan, guar, and Xanthan–guar blends in dilute aqueous solutions were investigated by using an oscillating capillary rheometer. Influence of mixing temperature on Xanthan conformation and interaction with guar is discussed. Synergistic interaction occurred at mixing temperatures of 25 and 80 °C, but a stronger synergistic interaction was observed at mixing temperature 80 °C. The viscous component for all gum solutions was greater than that of the elastic component, which indicated a liquid-like behavior in the dilute regime for the polysaccharide solutions. For both mixing temperatures, the relative viscosities and elasticities of Xanthan and guar blends were higher than the relative viscosities and elasticities calculated for blends assuming no interaction. The intrinsic viscosities of Xanthan and Xanthan–guar blends were higher at 80 °C than at 25 °C. The intrinsic viscosities of Xanthan and guar blends were lower than those calculated from the weight averages of the two, and significantly decreased as the Xanthan fraction decreased, indicating that Xanthan was crucial in controlling the blend viscosity, and that the molecular binding occurred between Xanthan and guar.
Hanna Khouryieh - One of the best experts on this subject based on the ideXlab platform.
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intrinsic viscosity and viscoelastic properties of Xanthan guar mixtures in dilute solutions effect of salt concentration on the polymer interactions
Food Research International, 2007Co-Authors: Hanna Khouryieh, Thomas J Herald, Fadi M Aramouni, Sajid AlaviAbstract:Abstract An oscillating capillary rheometer was used to investigate the dynamic viscoelastic and intrinsic viscosity properties of deacetylated Xanthan (0.025%), native Xanthan (0.025%), guar gum (0.075%), and Xanthan–guar mixtures in dilute solutions. Influence of ionic strength on Xanthan conformation and interaction with guar gum was elaborated. As the salt concentration increased, a significant ( P η ′) and elasticity ( η ″) values was observed for both native Xanthan–guar mixtures and deacetylated Xanthan–guar mixtures. In water and 2 mM NaCl solution, the relative viscosity and η ″ of both native Xanthan–guar mixtures and deacetylated Xanthan–guar mixtures were much higher than of those calculated for mixtures assuming no interaction, whereas no pronounced increase was found for polysaccharide mixtures in 40 mM NaCl. The intrinsic viscosities of deacetylated Xanthan–guar mixtures in water and 2 mM NaCl were higher, whereas the intrinsic viscosities of native Xanthan–guar mixtures were lower than those calculated from the weight averages of the two individually, assuming no interaction. These results demonstrated that intermolecular interaction has occurred between Xanthan and guar mixtures in water and 2 mM NaCl, but may not occur in 40 mM NaCl, and mutual incompatibility may occur. The results suggest that the degree of disordering of Xanthan played a critical role in Xanthan–guar interaction and may explain the differences in η ′, η ″, and intrinsic viscosity measurements between 2 and 40 mM NaCl.
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Rheological characterization of Xanthan-guar mixtures in dilute solutions
2006Co-Authors: Hanna KhouryiehAbstract:ABSTRACT Dynamic viscoelastic and intrinsic viscosity properties of native Xanthan, deacetylated Xanthan, guar, and their mixtures in dilute solutions were investigated by using an oscillating capillary rheometer. Influence of mixing temperature, deacetylation, and salt concentration on Xanthan conformation and interaction with guar were studied in order to provide additional evidence that can be used to elucidate the mechanism of the intermolecular interaction between the two biopolymers, and build up a more detailed rheological understanding of molecular interactions between Xanthan and guar gum in dilute solutions. Synergistic interaction was found at mixing temperatures of 25 and 80 °C, but a stronger synergistic interaction was observed at mixing temperature of 80 °C. The differences in viscosity and elasticity measurements between the two mixing temperatures could be attributed to the degree of disordering of Xanthan. For both mixing temperatures, the relative viscosity and elasticity of Xanthan and guar blends were higher than the relative viscosity and elasticity calculated for blends assuming no interaction, indicating that intermolecular binding occurred between galactomannans backbone and disordered segments of Xanthan. Deacetylated Xanthan exhibited a stronger synergistic interaction with guar than native Xanthan. The intrinsic viscosities of deacetylated Xanthan-guar mixtures were higher than those calculated from the weight averages of the two individually, whereas the intrinsic viscosities of native Xanthan-guar mixtures were lower than those calculated from weight averages of the two individually, demonstrating that intermolecular binding occurred between Xanthan and guar gum. Synergistic interaction for both native Xanthan-guar mixtures and deacetylated Xanthan-guar mixtures in the dilute regime was observed in water and 2 mM NaCl but not in 40 mM
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Influence of mixing temperature on Xanthan conformation and interaction of Xanthan¿guar gum in dilute aqueous solutions
Food Research International, 2006Co-Authors: Hanna Khouryieh, Thomas J Herald, Fadi M Aramouni, Sajid AlaviAbstract:Abstract Dynamic viscoelastic and intrinsic viscosity properties of Xanthan, guar, and Xanthan–guar blends in dilute aqueous solutions were investigated by using an oscillating capillary rheometer. Influence of mixing temperature on Xanthan conformation and interaction with guar is discussed. Synergistic interaction occurred at mixing temperatures of 25 and 80 °C, but a stronger synergistic interaction was observed at mixing temperature 80 °C. The viscous component for all gum solutions was greater than that of the elastic component, which indicated a liquid-like behavior in the dilute regime for the polysaccharide solutions. For both mixing temperatures, the relative viscosities and elasticities of Xanthan and guar blends were higher than the relative viscosities and elasticities calculated for blends assuming no interaction. The intrinsic viscosities of Xanthan and Xanthan–guar blends were higher at 80 °C than at 25 °C. The intrinsic viscosities of Xanthan and guar blends were lower than those calculated from the weight averages of the two, and significantly decreased as the Xanthan fraction decreased, indicating that Xanthan was crucial in controlling the blend viscosity, and that the molecular binding occurred between Xanthan and guar.
Peter A Williams - One of the best experts on this subject based on the ideXlab platform.
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control of the properties of Xanthan glucomannan mixed gels by varying Xanthan fine structure
Carbohydrate Polymers, 2013Co-Authors: P Fitzpatrick, John Meadows, Ian Ratcliffe, Peter A WilliamsAbstract:The interaction of native Xanthan gum, deacetylated Xanthan gum and depyruvated Xanthan gum with konjac glucomannan has been studied using DSC and controlled stress rheometry. In the absence of electrolyte the DSC cooling curves for native Xanthan and deacetylated Xanthan showed a single peak and there was a corresponding sharp increase in the storage modulus indicating gel formation. It is apparent that on cooling, association of the konjac glucomannan with the native Xanthan molecules is triggered by the Xanthan coil-helix transition. In the presence of electrolyte, there were two DSC peaks observed. The higher temperature DSC peak was attributed to the Xanthan coil-helix transition while the lower temperature DSC peak was attributed to konjac glucomannan – Xanthan association as noted by an increase in the storage modulus. The gels formed were much weaker than those in the absence of electrolyte. The DSC cooling curves for depyruvated Xanthan in the absence of electrolyte showed two peaks. The higher temperature peak was attributed to the coil-helix transition while the lower temperature peak corresponded to gelation as noted by an increase in the storage modulus. The gels were very much weaker than for native Xanthan gum and deacetylated Xanthan gum.
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Control of the properties of Xanthan/glucomannan mixed gels by varying Xanthan fine structure
Carbohydrate polymers, 2012Co-Authors: P Fitzpatrick, John Meadows, Ian Ratcliffe, Peter A WilliamsAbstract:The interaction of native Xanthan gum, deacetylated Xanthan gum and depyruvated Xanthan gum with konjac glucomannan has been studied using DSC and controlled stress rheometry. In the absence of electrolyte the DSC cooling curves for native Xanthan and deacetylated Xanthan showed a single peak and there was a corresponding sharp increase in the storage modulus indicating gel formation. It is apparent that on cooling, association of the konjac glucomannan with the native Xanthan molecules is triggered by the Xanthan coil-helix transition. In the presence of electrolyte, there were two DSC peaks observed. The higher temperature DSC peak was attributed to the Xanthan coil-helix transition while the lower temperature DSC peak was attributed to konjac glucomannan – Xanthan association as noted by an increase in the storage modulus. The gels formed were much weaker than those in the absence of electrolyte. The DSC cooling curves for depyruvated Xanthan in the absence of electrolyte showed two peaks. The higher temperature peak was attributed to the coil-helix transition while the lower temperature peak corresponded to gelation as noted by an increase in the storage modulus. The gels were very much weaker than for native Xanthan gum and deacetylated Xanthan gum.
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Synergistic interaction of Xanthan gum with glucomannans and galactomannans
Food Hydrocolloids, 1991Co-Authors: Peter A Williams, D.h. Day, M. J. Langdon, Glyn O. Phillips, Katsuyoshi NishinariAbstract:Abstract Xanthan gum forms thermoreversible gels when mixed with konjac mannan or locust bean gum. The stronger gels are formed with konjac mannan and the maximum gel strength for the mixed systems in the absence of electrolyte occurs at a Xanthan-konjac mannan or Xanthan-locust bean gum mixing ratio of about 1:1. In the presence of 0.04 mol/dm 3 NaCl the optimum mixing ratio is unchanged for Xanthan-locust bean gum blends but changes to about 2:1 for Xanthan-konjac mannan blends. These observations support differential scanning calorimetric data which are able to monitor both gelation and the conformational transition of the Xanthan molecules and indicates that (i) in the absence of electrolyte konjac mannan interacts with disordered Xanthan chains whilst in the presence of 0.04 mol/dm 3 NaCl it interacts with ordered Xanthan chains, and (ii) locust bean gum interacts with ordered Xanthan chains both in the presence and absence of electrolyte.
Thomas J Herald - One of the best experts on this subject based on the ideXlab platform.
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intrinsic viscosity and viscoelastic properties of Xanthan guar mixtures in dilute solutions effect of salt concentration on the polymer interactions
Food Research International, 2007Co-Authors: Hanna Khouryieh, Thomas J Herald, Fadi M Aramouni, Sajid AlaviAbstract:Abstract An oscillating capillary rheometer was used to investigate the dynamic viscoelastic and intrinsic viscosity properties of deacetylated Xanthan (0.025%), native Xanthan (0.025%), guar gum (0.075%), and Xanthan–guar mixtures in dilute solutions. Influence of ionic strength on Xanthan conformation and interaction with guar gum was elaborated. As the salt concentration increased, a significant ( P η ′) and elasticity ( η ″) values was observed for both native Xanthan–guar mixtures and deacetylated Xanthan–guar mixtures. In water and 2 mM NaCl solution, the relative viscosity and η ″ of both native Xanthan–guar mixtures and deacetylated Xanthan–guar mixtures were much higher than of those calculated for mixtures assuming no interaction, whereas no pronounced increase was found for polysaccharide mixtures in 40 mM NaCl. The intrinsic viscosities of deacetylated Xanthan–guar mixtures in water and 2 mM NaCl were higher, whereas the intrinsic viscosities of native Xanthan–guar mixtures were lower than those calculated from the weight averages of the two individually, assuming no interaction. These results demonstrated that intermolecular interaction has occurred between Xanthan and guar mixtures in water and 2 mM NaCl, but may not occur in 40 mM NaCl, and mutual incompatibility may occur. The results suggest that the degree of disordering of Xanthan played a critical role in Xanthan–guar interaction and may explain the differences in η ′, η ″, and intrinsic viscosity measurements between 2 and 40 mM NaCl.
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rheological study of Xanthan and locust bean gum interaction in dilute solution
Food Research International, 2006Co-Authors: J Higiro, Thomas J Herald, Sajid AlaviAbstract:An oscillatory capillary rheometer was used to investigate visco-elastic properties of Xanthan and locust bean gum (LBG) blends in dilute solution. Gums were evaluated for intrinsic viscosity and the elastic component. Molecular conformation of the complex of Xanthan–LBG was assessed by the power law and the Huggins equations. A 60% Xanthan–40% LBG blend exhibited the strongest attraction between Xanthan and LBG molecules as evidenced by a greater intrinsic viscosity, the polymer miscibility coefficient α, the elastic component, and a positive Huggins coefficient Km. The power-law model was successfully applied to predict the molecular conformation of Xanthan and LBG alone in dilute solution and was exhibited as rod-like and random coil conformation. The power-law coefficient b increased as the LBG fraction increased in the blends, suggesting a more flexible Xanthan–LBG complex dependent on LBG.
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Influence of mixing temperature on Xanthan conformation and interaction of Xanthan¿guar gum in dilute aqueous solutions
Food Research International, 2006Co-Authors: Hanna Khouryieh, Thomas J Herald, Fadi M Aramouni, Sajid AlaviAbstract:Abstract Dynamic viscoelastic and intrinsic viscosity properties of Xanthan, guar, and Xanthan–guar blends in dilute aqueous solutions were investigated by using an oscillating capillary rheometer. Influence of mixing temperature on Xanthan conformation and interaction with guar is discussed. Synergistic interaction occurred at mixing temperatures of 25 and 80 °C, but a stronger synergistic interaction was observed at mixing temperature 80 °C. The viscous component for all gum solutions was greater than that of the elastic component, which indicated a liquid-like behavior in the dilute regime for the polysaccharide solutions. For both mixing temperatures, the relative viscosities and elasticities of Xanthan and guar blends were higher than the relative viscosities and elasticities calculated for blends assuming no interaction. The intrinsic viscosities of Xanthan and Xanthan–guar blends were higher at 80 °C than at 25 °C. The intrinsic viscosities of Xanthan and guar blends were lower than those calculated from the weight averages of the two, and significantly decreased as the Xanthan fraction decreased, indicating that Xanthan was crucial in controlling the blend viscosity, and that the molecular binding occurred between Xanthan and guar.
Katsuyoshi Nishinari - One of the best experts on this subject based on the ideXlab platform.
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Interaction in Xanthan-Glucomannan Mixtures and the Influence of Electrolyte
Macromolecules, 1994Co-Authors: P. Annable, P. A. Williams, Katsuyoshi NishinariAbstract:The interaction of Xanthan and glucomannan (konjac mannan, KM) has been monitored using DSC, ESR, and mechanical spectroscopy. The DSC and ESR results indicate that interaction occurs in water immediately following Xanthan side chain-backbone association. The process is thermodynamically driven and occurs to reduce Xanthan-water contacts. In the presence of electrolyte, both techniques show that the Xanthan conformational change shifts to higher temperatures and depends on the nature of the cation. Divalent cations give rise to a greater shift than monovalent cations. The results indicate that Xanthan/KM interaction occurs at temperatures much lower than the conformational transition
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Synergistic interaction of Xanthan gum with glucomannans and galactomannans
Food Hydrocolloids, 1991Co-Authors: Peter A Williams, D.h. Day, M. J. Langdon, Glyn O. Phillips, Katsuyoshi NishinariAbstract:Abstract Xanthan gum forms thermoreversible gels when mixed with konjac mannan or locust bean gum. The stronger gels are formed with konjac mannan and the maximum gel strength for the mixed systems in the absence of electrolyte occurs at a Xanthan-konjac mannan or Xanthan-locust bean gum mixing ratio of about 1:1. In the presence of 0.04 mol/dm 3 NaCl the optimum mixing ratio is unchanged for Xanthan-locust bean gum blends but changes to about 2:1 for Xanthan-konjac mannan blends. These observations support differential scanning calorimetric data which are able to monitor both gelation and the conformational transition of the Xanthan molecules and indicates that (i) in the absence of electrolyte konjac mannan interacts with disordered Xanthan chains whilst in the presence of 0.04 mol/dm 3 NaCl it interacts with ordered Xanthan chains, and (ii) locust bean gum interacts with ordered Xanthan chains both in the presence and absence of electrolyte.
