Some properties of xanthan gum in aqueous solutions: effect of temperature and pH

Brunchi, Cristina‐Eliza; Bercea, Maria; Morariu, Simona; Dascălu, Mihaela

doi:10.1007/s10965-016-1015-4

Cited by 78 publications

(55 citation statements)

References 44 publications

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“…Solutions of xanthan prepared using various molecular weights of the polysaccharide, concentrations, temperature, solvents, and pH have been widely studied in terms of their rheological properties . The “weak gel‐like” properties of xanthan solutions arise from lateral association of ordered chain sequences to form extended junction zones comparable to those in true gels but much weaker, since the network structure may be broken down under stress conditions .…”

Section: Introductionmentioning

confidence: 99%

“…The distinct shear thinning behavior of xanthan is associated with its molecular conformation, which at low shear stress association of chains is induced by hydrogen bonding resulting in high viscosity. However, disruption of the intra‐ and intermolecular hydrogen bonding at high shear stress, leads to the decrease of its viscosity …”

Section: Introductionmentioning

confidence: 99%

“…However, disruption of the intra-and intermolecular hydrogen bonding at high shear stress, leads to the decrease of its viscosity. [18,25,26] Previous studies suggested that xanthan could not be electrospun due to the insufficient entanglements during electrospinning. [2] In the present study we report for the first time the formation of electrospun xanthan nanofibers using formic acid as a solvent.…”

Section: Introductionmentioning

confidence: 99%

“…[11] Solutions of xanthan prepared using various molecular weights of the polysaccharide, concentrations, temperature, solvents, and pH have been widely studied in terms of their rheological properties. [12][13][14][15][16][17][18][19][20][21] The "weak gel-like" properties of xanthan solutions arise from lateral association of ordered chain sequences to form extended junction zones comparable to those in true gels but much Electrospun pure xanthan polysaccharide nanofibers are prepared using formic acid as a solvent. Morphological studies by scanning electron microscopy show that uniform fibers with average diameters ranging from 128 ± 36.7 to 240 ± 80.7 nm are formed depending on the polysaccharide concentration (0.5 to 2.5 wt/vol%).…”

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confidence: 99%

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Electrospinning of Xanthan Polysaccharide

Shekarforoush

Faralli

Ndoni

et al. 2017

Macro Materials & Eng

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Electrospun pure xanthan polysaccharide nanofibers are prepared using formic acid as a solvent. Morphological studies by scanning electron microscopy show that uniform fibers with average diameters ranging from 128 ± 36.7 to 240 ± 80.7 nm are formed depending on the polysaccharide concentration (0.5 to 2.5 wt/vol%). The correlation between the concentration and the rheological properties of xanthan solutions, with the morphology of the nanofibers is investigated. At the polysaccharide concentrations where nanofiber formation is observed, an increase of the elastic modulus and first normal stress differences is observed. The typical “weak gel‐like” and thixotropic properties known for aqueous xanthan solutions, are not observed for the xanthan solutions in formic acid. The Fourier transform infrared spectroscopic and circular dichroism studies verify that an esterification reaction takes place, where formic acid reacts with the pyruvic acid groups of xanthan. Hence, formate groups neutralize the pyruvic charges which in turn stabilize the helical conformation of xanthan. The results obtained from size‐exclusion chromatography reveal a small difference in the molecular weight of the polysaccharide when dissolved in distilled water or in formic acid.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Electrospinning of Xanthan Polysaccharide

Shekarforoush

Faralli

Ndoni

et al. 2017

Macro Materials & Eng

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“…Out of all the components, xanthan had the highest intrinsic viscosity which decreased with increase in temperature. This could be due to conformational transition between rigid to a disordered flexible state [31]. There is a high amount of error in 37 • C sample meaning that this trend is not statistically significant (p = 0.41).…”

Section: Intrinsic Viscositymentioning

confidence: 94%

Clinically Relevant Insulin Degludec and Its Interaction with Polysaccharides: A Biophysical Examination

et al. 2020

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Protein polysaccharide complexes have been widely studied for multiple industrial applications and are popular due to their biocompatibility. Insulin degludec, an analogue of human insulin, exists as di-hexamer in pharmaceutical formulations and has the potential to form long multi-hexamers in physiological environment, which dissociate into monomers to bind with receptors on the cell membrane. This study involved complexation of two negatively charged bio-polymers xanthan and alginate with clinically-relevant insulin degludec (PIC). The polymeric complexations and interactions were investigated using biophysical methods. Intrinsic viscosity [η] and particle size distribution (PSD) of PIC increased significantly with an increase in temperature, contrary to the individual components indicating possible interactions. [η] trend was X > XA > PIC > A > IDeg. PSD trend was X > A > IDeg > XA > PIC. Zeta (ζ)-potential (with general trend of IDeg < A < XA < X ≈ PIC) revealed stable interaction at lower temperature which gradually changed with an increase in temperature. Likewise, sedimentation velocity indicated stable complexation at lower temperature. With an increase in time and temperature, changes in the number of peaks and area under curve were observed for PIC. Conclusively, stable complexation occurred among the three polymers at 4 • C and 18 • C and the complex dissociated at 37 • C. Therefore, the complex has the potential to be used as a drug delivery vehicle.Polymers 2020, 12, 390 2 of 15 Alginates (A) are linear polymers of 1,4-linked β-D-mannuronic acid residues and 1,4-linked α-L-guluronic residues, containing homo-polymeric sequences [7]. Xanthan (X) is composed of D-glucosyl, D-mannosyl, and D-glucuronyl acid residues in a 2:2:1 molar ratio and variable proportions of O-acetyl and pyruvyl residues. Its main chain consists of β-D-glucose units linked at the 1 and 4 positions. Side-chains consist of a tri-saccharide composed of mannose (β-1,4) glucuronic acid and (β-1,2) mannose, attached to alternate glucose residues in the backbone by α-1,3 linkages [8,9].Xanthan gum and alginate complexes (XA) have been studied previously [10] and used for functional foods [11], tissue engineering [3,12,13] and drug delivery. As negatively charged polymers, xanthan [14][15][16][17] and alginate [18][19][20] have been used separately, and in combination with positively charged polymers such as chitosan, as potential vehicles for insulin delivery.Interactions among different types of protein-polysaccharide complexes (PPCs) have been previously investigated using a variety of methods [21,22]. The formation and dissociation of PPCs and their solubility depend on many factors such as surface charge, pH, temperature and ionic strength of the solvent [23]. These factors greatly influence non-covalent interactions such as electrostatic, H-bonding, hydrophobic, and steric interactions, as well as covalent interactions [24]. Conjugation of polysaccharides with therapeutic proteins is a well-established phenomenon [25]. In particul...

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Integrating mechanical mixing, headspace, and rheology in a computational model for a fermentation process

et al. 2023

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Although computational fluid dynamics (CFD) modelling has been applied to study bioprocesses where mechanical mixing and aerations are key, the effect of having a free surface has usually been ignored. This work studies a mixing tank for bioprocess applications to analyze the impact that the assumption of a flat liquid level has upon the modelling results, with and without aeration. The methodology takes an experimental and modelling approach. A dual impeller mixer with a speed of 400 rpm is used for batch systems with both non‐Newtonian and Newtonian fluids to characterize the axis torque and surface vortex formation. Several multi‐phase CFD models are applied to study the modelling and numerical effects of the headspace on the results. Regarding modelling accuracy, the CFD models are shown to be able to capture the effect of the free surface on the fluid dynamics of the stirred tank for different fluid rheologies. Therefore, the simplification of the liquid level as a flat and fixed surface should not be applied, especially for a process with aeration or when unaerated conditions can lead to a surface vortex. Regarding the numerical accuracy, it is concluded that the mixture model does not predict the interface shape as well as the Eulerian model. However, only the mixture model shows to be numerically stable. Overall, this work provides validated CFD configurations able to predict the effect of a free surface on the mixing mechanisms in stirred reactors.

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Some properties of xanthan gum in aqueous solutions: effect of temperature and pH

Cited by 78 publications

References 44 publications

Electrospinning of Xanthan Polysaccharide

Electrospinning of Xanthan Polysaccharide

Clinically Relevant Insulin Degludec and Its Interaction with Polysaccharides: A Biophysical Examination

Integrating mechanical mixing, headspace, and rheology in a computational model for a fermentation process

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