Increase In Xanthan Gum Concentration Research Articles

Physicochemical properties and stability of oil-in-water emulsions stabilized by soy protein isolate and xanthan gum

The aim of this work was to determine rheological and disperse characteristics and stability of oil-in-water emulsions stabilized by soy protein isolate (SPI) and xanthan gum (XG), as natural components. The effects of their combination on emulsion stabilization have not been investigated yet. The existence of interactions between the two macromolecules were indicated by the influence of XG on SPI surface hydrophobicity and surface tension values. Increase in SPI concentration from 1 to 3 % shift of distribution curves towards smaller particle size, while the opposite effects of further increase of SPI was obtained. The emulsions stabilized by SPI showed shear-thinning flow behavior, which changed to thixotropic at 5 % of SPI concentration. The presence of XG in emulsions at low concentrations did not affect the size distribution of the droplets, while at 0.1 % of XG Sauter mean diameter value raised and distribution curves were shifted towards a higher particle size. The presence of XG at higher concentration resulted in thixotropic flow behavior of emulsions. Also, increase in XG concentration led to the increase in consistency index and extent of non-Newtonian behavior of emulsions and enhanced the influence of the elastic modulus and creaming stability of the systems.

Synergistic effects of microcrystalline cellulose and xanthan gum on the stability of milk fat-based UHT whipping cream

In this study, microcrystalline cellulose (MCC) and xanthan gum (XG) were used as stabilizers for the preparation of UHT whipped cream. The purpose was to characterize the effect of stabilizers synergies on whipped cream. Analysis of the creaming stability showed that MCC and XG synergistically and effectively increase the absolute value of zeta potential and keep the particle size within a reasonable range. On the other hand, shear thinning followed by thickening was observed when MCC was added to the whipped cream emulsion. In terms of whipping characteristics, with the increase of XG concentration, the whipping time was prolonged and the overrun level was reduced. Furthermore, the thermal behavior of whipped cream is influenced by the MCC, so that the ability of the foam to adapt to temperature changes is enhanced. Based on confocal laser scanning microscope (CLSM), MCC ameliorated XG-induced fluid protein adhesion and excessive aggregation of fat globules were observed. This promotes the uniform distribution of protein and fat globule clusters around the air bubbles, while the high viscosity of XG improves the rigidity of the air bubbles interface membrane. These results highlighted the effectiveness of XG/MCC synergistic effects in stability and whipping properties of the milk-based cream, which assisted in rational design of whipped cream with a distinct texture.

Assessment of Soy Protein Acid Hydrolysate-Xanthan Gum Mixtures on the Stability, Disperse and Rheological Properties of Oil-in-Water Emulsions.

There is a growing need for natural ingredients that could be utilized for the production of food, pharmaceutical, and cosmetic emulsions. Soy protein acid hydrolysate (SPAH) is a plant-based additive used in the food industry mainly as a flavor enhancer. For the purpose of this work, however, it was mixed with a well-known natural polysaccharide, xanthan gum (XG), to produce stable 30% (w/w) sunflower oil-in-water emulsions using a rotor-stator homogenizer. In order to assess the emulsifying properties of the SPAH and its mixtures with XG, the surface tension properties of their water solutions, particle size, creaming stability, and rheological properties of the emulsions were investigated. Since the emulsions prepared using only SPAH, in various concentrations, were not stable, systems containing 5% of SPAH and 0.1, 0.2, 0.3, 0.4, or 0.5% of XG were then studied. The increase in concentration of the macromolecule led to an increase in creaming stability. The emulsions with 5% SPAH and 0.5% XG were stable for at least 14 days. The increase in XG concentration led to a decrease in d4,3, while consistency index and non-Newtonian behavior increased. The systems containing SPAH, in the absence of XG, showed shear-thinning flow behavior, which was changed to thixotropic with the addition of XG. Viscoelastic properties of emulsions containing over 0.2% of XG were confirmed by oscillatory rheological tests, demonstrating the dominance of elastic (G') over viscous (G") modulus.

Stability, microstructural and rheological properties of Pickering emulsion stabilized by xanthan gum/lysozyme nanoparticles coupled with xanthan gum

Effects of xanthan gum (XG) addition and oil contents on the structural and rheological properties of Pickering emulsion stabilized by xanthan gum/Lysozyme nanoparticles (XG/Ly NPs) were analyzed by microstructure, creaming index, and rheological analysis. The results showed that XG addition reduced the droplet size of the emulsion, and a denser three-dimensional network structure was formed between droplets in the continuous phase. Thus, the migration of droplets slowed down, and the stability of Pickering emulsion increased. Rheological studies indicated that the network structure of Pickering emulsion depends on XG addition and oil content. The critical strain (γco) displayed three regimes. For low oil content (20%), γco decreased with the increase of XG concentration. For Pickering emulsion with medium oil content (40%, v/v), γco increased with increasing addition of XG. When high oil content (60–80%) was provided, γco was almost independent of XG addition. The results showed that the microstructure, stability and rheological properties of Pickering emulsion stabilized by XG/Ly NPs could be regulated by XG addition and oil content. This attempt provided theoretical support for regulating Pickering emulsion properties by polysaccharides addition, and established Pickering emulsions with various demands.

Influence of resistant starch, xanthan gum, inulin and defatted rice bran on the physicochemical, functional and sensory properties of low glycemic gluten-free noodles

The study aims to evaluate the effects of xanthan gum (XG), inulin and defatted rice bran on the physicochemical, functional and sensory properties of the gluten-free noodle prepared from Pathumthani 80 rice (RD 31) native autoclaved resistant starch (NARS). The increase in concentration of XG (0.625–5%) in the formulation of gluten free noodles resulted a significant decrease (p ˂ 0.05) in resistant starch content whereas, the tensile strength was increased. RD 31-NARS gluten-free noodles with 2.5% XG received the high sensory scores and further selected for the addition of inulin and defatted rice bran (5%, w/w), separately. RD 31-NARS gluten free noodle with XG (2.5%) and defatted rice bran exhibited the highest protein (4.62%), fiber (0.35%) and ash content (1.45%). Further, addition of inulin and defatted rice bran significantly (p ˂ 0.05) decreased the glycemic index and increased the cooking time and firmness. The surface morphology of gluten free noodles showed relatively porous structure under the scanning electron microscope (SEM) after the addition of rice bran (5%) and inulin (5%). Thus, resistant starch along with gums and fibers can be used to develop gluten free functional foods with better acceptability.

Methane hydrate formation in a water-continuous vertical flow loop with xanthan gum

Hydrate phase transition in drilling fluid is a non-ignorable problem for developing deep-water oil, natural gas and natural gas hydrate resources. Once gas hydrates form during drilling, it will increase the difficulty of wellbore pressure management and flow assurance, which enlarges the risk of hydrate blockage and causes serious property damage and casualties. Methane hydrate formation experiments are conducted in xanthan gum (XG) aqueous solution to mimic the drilling fluid flowing condition in a vertical flow loop. The experiments reveal that the hydrate formation process is a mass transfer process and experiences four different hydrate formation periods, because of the kinetics formation and slough of hydrate shells. The subcooling temperature has a weaker impact on the hydrate formation than the flow velocity and XG. The increase of flow velocity can enhance the hydrate formation rate in drilling fluid but the increase of XG concentration can inhibit the hydrate formation. The influence mechanisms of hydrate shell kinetic slough, flow velocity and XG concentration on hydrate formation are analyzed and discussed in detail. We built a mass-transfer hydrate formation model based on the mechanism of methane molecule diffusing from gas phase to liquid phase. The empirical overall mass transfer coefficient is introduced involving the influence of hydrate shell kinetic slough, flow velocity and XG concentration. In model validation, the maximum discrepancy of the developed model decreases from 146.85% to 11.03% after using the overall mass transfer coefficient.

Rheological Enhancement of Artificial Sputum Medium

Abstract This investigation proposes a synthetic biofluid, artificial sputum medium (ASM) and xanthan gum (XG), that mimics the mucus from a patient with cystic fibrosis, and investigates the rheological properties both macroscopically and microscopically. Macroscopic rheological characterization cannot address the heterogeneity or the behavior of particle transport inside the mucus. Microscopic rheology enables the characterization of the microenvironment by using microparticles as probes. The addition of XG to ASM provides a tunable parameter that enables the mechanical properties to be consistent with real mucus. Particles that were suspended in a media of ASM with XG displayed a subdiffusive behavior at short timescales with a diffusive exponent that decreases with an increase in concentration of XG. At long timescales, particles that were suspended in ASM+XG with a concentration of XG of 0.1% to 0.4% displayed diffusive behavior. While in more concentrated samples (0.5% and 1.0%), the particles were constrained inside local elastic “cages”. The microscopic moduli that were calculated showed consistently lower moduli than rotational rheometry. This discrepancy suggests that the solutions of XG have a hierarchical structure that better represents the weakly associated microstructure of mucus that is found in real sputum.

Formation and stability of colloidal gas aphron based drilling fluid considering dynamic surface properties

The dynamic surface behavior of surfactant in polymer solution is essential information to understand the formation and stability of Colloidal Gas Aphrons (CGAs). Measurements of dynamic surface tension, volume and half-life time of CGAs as well as size distribution of bubbles have been performed in this work. Three different surfactants of anionic sodium dodecyl sulfate (SDS), nonionic Triton X-100 (4-(1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol) and zwitterionic cocamidopropyl betaine (CAPB) were used for producing the CGAs in presence of the polymer Xanthan Gum (XG) as stabilizer. In addition, the influence of stirring time and speed as well as polymer and surfactant concentrations were investigated with respect to CGA volume and half-life time. The results showed an approximately linear relationship between half-life time and volume of CGAs for different stirring times and speeds. This reveals that at fixed polymer and surfactant concentrations, the half-life time mostly depends on the CGA volume. The XG concentration has also a strong influence on CGAs formation and stability. The increase in XG concentration reduces the CGA volume but significantly increases the half-life time. The dynamic surface tension of the applied surfactant has a major influence on CGA formation as only surfactants of a certain type and at a respective concentration provides the conditions for proper CGA formation. However, the stability of CGAs is rather complex and can be affected by the electrostatic nature of the surfactant and possible interactions with other compounds. Ionic SDS and CAPB surfactants allow producing CGAs of significant stabilities in contrast to the poor stability of CGAs made by the nonionic Triton X-100. The increase of the surfactant concentration increases the CGA volume as well as the half-life time, even at concentrations above the CMC. However, for the determination of optimum surfactant concentrations, economic issues should also be considered.

The influence of tongue strength on oral viscosity discrimination acuity.

In this article, the relationship between tongue strength and the ability to discriminate small differences in liquid viscosity during oral processing is explored. Given that tongue strength declines with age in healthy adults and is also reduced in individuals with dysphagia, it is interesting to determine whether reduced tongue strength might contribute to difficulties in evaluating liquid viscosity during the oral stage of swallowing. Using an array of mildly to moderately thick xanthan-gum thickened liquids, this experiment failed to find any evidence that reductions in tongue strength influence oral viscosity discrimination acuity.

Experimental investigations of non‐Newtonian/Newtonian liquid‐liquid flows in microchannels

The plug flow of a non‐Newtonian and a Newtonian liquid was experimentally investigated in a quartz microchannel (200‐µm internal diameter). Two aqueous glycerol solutions containing xanthan gum at 1000 and 2000 ppm were the non‐Newtonian fluids and 0.0046 Pa s silicone oil was the Newtonian phase forming the dispersed plugs. Two‐color particle image velocimetry was used to obtain the hydrodynamic characteristics and the velocity profiles in both phases under different fluid flow rates. The experimental results revealed that the increase in xanthan gum concentration produced longer, bullet‐shaped plugs, and increased the thickness of the film surrounding them. From the shear rate and viscosity profiles, it was found that the polymer solution was in the shear‐thinning region while the viscosity was higher in the middle of the channel compared to the region close to the wall. Circulation times in the aqueous phase increased with the concentration of xanthan gum. © 2017 The Authors AIChE Journal published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers AIChE J, 63: 3599–3609, 2017

Physical and Oxidative Stabilities of O/W Emulsions Formed with Rice Dreg Protein Hydrolysate: Effect of Xanthan Gum Rheology

The shortening of shelf-life of food emulsions is frequently due to poor creaming and lipid oxidation stability. The lipid oxidation of O/W emulsions can be inhibited by rice dreg protein hydrolysate (RDPH); however, emulsions were stabilized by Tween-20. Polysaccharides can control the rheology and network structure of the aqueous continuous phase by increasing viscosity and yield stress, hence retarding phase separation and gravity-induced creaming, especially for xanthan gum. The objective of this research was to evaluate whether emulsions formed with 2 wt% RDPH and stabilized by xanthan gum (0–0.5 wt%) could produce 20 % (v/v) soybean oil-in-water emulsions that had good physical and oxidative stability. The degree of flocculation of droplets as a function of xanthan gum concentration was assessed by the microstructure, rheology, and the creaming index of emulsions. Addition of xanthan gum prior to homogenization had no significant effect on the mean droplet diameter in all emulsions studied. Increase in xanthan gum concentration led to the increase in creaming stability of emulsions, due to an increase in viscosity of the continuous phase and/or the formation of a droplet network with a yield stress, as well as the enhanced steric and electrostatic repulsion between the droplets. Lipid oxidation of the emulsions was significantly inhibited at xanthan gum concentrations of 0.12 wt% or above with RDPH, which could due to the fact that xanthan gum increases the viscosity of the aqueous phase and hindered the diffusion of oxidants to the oil droplet surface area, synergistic effect between RDPH and xanthan gum to suppress oil peroxidation, and metal ion chelation capability of xanthan gum. Thus, stable protein hydrolyzates-type emulsions could be obtained with increasing concentration of xanthan gum.

Experimental Study on Stability and Improving Sweep Efficiency with Microfoam in Heterogeneous Porous Media

In this paper, we attempted to prepare microfoam by using a sandpack filled with glass beads with co-flowing gas and foaming solution, the microfoam stability and effectiveness in improving profile control capacity at micromodel and pore media were evaluated by micromodel tests and double-core experiments. The results of micromodel tests showed that microfoam stability was increased with increasing xanthan gum concentration due to a higher solution viscosity and viscoelasticity of liquid film. The xanthan gum-stabilized microfoam had a longer propagation distance through the low permeable region of heterogeneous micromodel at time of breakthrough than common microfoam, the optimum performance of microfoam for fluid diversion was multiple bubble trapping and mobilization rather than lamella division. According to the results of double-core experiments, the microfoam could plug the high permeability sandpack and improve the sweep efficiency in the low permeability sandpack, which could improve the water injection profile of porous media effectively. The increase in profile control effects had a good correspondence with the increase of xanthan gum concentration. The presented results were useful in understanding and designing microfoam injection in reservoirs for enhanced oil recovery.

Double Emulsions Stabilized by Xanthan in the Absence of Hydrophilic Surfactant

The preparation of double water-in-oil-in-water (W/O/W) emulsions containing xanthan gum (XG) in the absence of hydrophilic surfactant was investigated. The emulsions were prepared by the two-step emulsification process. The stability of these systems was evaluated through the evaluation of physicochemical and rheological properties. Microscopic observations in combination with particle size analysis were also performed. The obtained results show that it is possible to prepare stable double emulsions with a single polysaccharide by using the indirect process. The stability depends on the viscosity of the continuous phase and hence the concentration of XG. The apparent viscosity of the emulsions increased with the increase of XG concentration. Particle size analysis shows that the droplet sizes are directly related to XG concentration.

Influence of xanthan gum on oil-in-water emulsion characteristics stabilized by OSA starch

The aim of this paper is to present results of the influence of different xanthan gum concentrations (from 0.01% to 0.2% w/w) on properties of the oil-in-water emulsions by applying different techniques. The octenyl succinic anhydride (OSA) starch was used as emulsifier at constant concentration 10%. Rheology, microphotography, SEM and creaming studies were used in order to obtain the emulsions' characteristics. The results showed that the increase in xanthan gum concentration led to the decrease in droplets Sauter mean diameter and made droplet size distribution of the emulsions narrower. All determined emulsions showed shear-thinning flow behavior. The increase in xanthan gum concentration led to the decrease in flow behavior index n as well as the increase in consistency index K. Presence of xanthan gum in the emulsions with OSA starch as emulsifier enhances their stability due to formation of oil droplets network as consequence of depletion flocculation as well as due to modification of continuous phase viscosity.

Oral Perceptual Discrimination of Viscosity Differences for Non-Newtonian Liquids in the Nectar- and Honey-Thick Ranges

Thickened liquids are frequently used in the management of oropharyngeal dysphagia. Previous studies suggest that compression of a liquid bolus between the tongue and the palate in the oral phase of swallowing serves a sensory function, enabling the tuning of motor behavior to match the viscosity of the bolus. However, the field lacks information regarding healthy oral sensory discrimination ability for small differences in liquid viscosity. We undertook to measure oral viscosity discrimination ability for five non-Newtonian xanthan gum-thickened liquids in the nectar- and honey-thick range. Xanthan gum concentration ranged from 0.5 to 0.87 % and increased by an average of 0.1 % between stimuli in the array. This translated to an average apparent viscosity increase of 0.2-fold between adjacent stimuli at 50 reciprocal seconds (/s). A triangle test paradigm was used to study stimulus discrimination in 78 healthy adults in two, sex-balanced age cohorts. Participants were provided 5-ml samples of liquids in sets of three; one liquid differed in xanthan gum concentration from the other two. Participants were required to sample the liquid orally and indicate which sample was perceived to have a different viscosity. A protocol of 20 sets (60 samples) allowed calculation of the minimum difference in xanthan gum concentration detected accurately. On average, participants were able to accurately detect a 0.38-fold increase in xanthan-gum concentration, translating to a 0.67-fold increase in apparent viscosity at 50/s. The data did not suggest the existence of a nonlinear point boundary in apparent viscosity within the range tested. No differences in viscosity discrimination were found between age cohorts or as a function of sex. The data suggest that for xanthan gum-thickened liquids, there may be several increments of detectably different viscosity within the ranges currently proposed for nectar- and honey-thick liquids. If physiological or functional differences in swallowing can be demonstrated for these smaller increments of detectably different viscosity, more narrowly defined categories of thickened liquids for dysphagia management will be warranted.

Formulation and Characterization of Double Emulsions Stabilized by Sodium Caseinate–Xanthan Mixtures. Effect of pH and Biopolymer Concentration

Water-in-oil-in-water (w/o/w) double emulsions were stabilized by xanthan gum (XG) in presence of sodium caseinate (SC) using a two-step emulsification process. The evaluation of stability of emulsions was conducted over a period of 20 days. This monitoring was revealed by studying the physicochemical and rheological properties and by optical microscopy observations in combination with granulometry measurements. At natural pH, stability of double emulsions prepared by XG–SC mixture depends on XG concentration. The apparent viscosity of the emulsions increased with the increase of XG concentration. Adjustment of pH of emulsions made with XG–SC near the isoelectric point of the protein improved their stability. At this pH, the viscosity is affected by the XG and SC concentrations. The droplet sizes of double emulsions stabilized by the SC–XG mixture are influenced by the pH and the concentration of two biopolymers. The weight ratio between the two biopolymers in the external aqueous phase has a great influence on the stability of double emulsions formulated at natural pH and pH 5.

Influence of xanthan gum on physical characteristics of sodium caseinate solutions and emulsions

Influence of xanthan gum (XG) on the properties of the solution containing 3.0 wt% sodium caseinate (CN) was estimated firstly by zeta potential, hydrodynamic diameter (DH) and interfacial tension. CN–XG mixture solutions showed larger DH and lower negative zeta potential at higher XG concentration, indicating that molecule interactions may take place in solution. The surface activity of CN was improved with addition of XG at 0.01 wt%, while it weakened to a great extent at 0.04 wt% XG. Then, the influence of XG on the concentrated (36 wt%) emulsion, stabilized with 3.0 wt% CN was assessed by droplet diameter and dispersion characteristics, apparent viscosity, surface protein concentration and microstructure. Results showed that emulsion without XG, characterized by the lowest surface protein concentration and apparent viscosity, showed no sign of flocculation but coarse oil droplets. Increase in XG concentration led to an increase followed by a decrease in d4,3, uniformity values and partial coalescence of fat, while inversely, surface protein concentration decreased firstly and then increased. CLSM images showed extensive enrichment region of XG and depletion flocculation at XG concentration above 0.01 wt%.

Yield stress components of waxy corn starch–xanthan mixtures: Effect of xanthan concentration and different starches

Yield stress of 6% (w/w) waxy maize (WXM), cross-linked waxy maize (CLWM), and cold water swelling (CWS) starches in xanthan gum dispersions: 0%, 0.35%, 0.50%, 0.70%, and 1.0% was measured with the vane method at an apparent shear rate of 0.05 s −1. The intrinsic viscosity of the xanthan gum was determined to be: 112.3 dL/g in distilled water at 25 °C. Values of the static ( σ 0s) and dynamic ( σ 0d) yield stress of each dispersion were measured before and after breaking down its structure under continuous shear, respectively. The WXM and CWS starches exhibited synergistic behavior, whereas the CLWM starch showed antagonistic effect with xanthan gum. The difference ( σ 0s − σ 0d) was the stress required to break the inter-particle bonding ( σ b). The contributions of the viscous ( σ v) and network ( σ n) components were estimated from an energy balance model. In general, values of σ b of the starch–xanthan gum dispersions decreased and those of σ n increased with increase in xanthan gum concentration.

Rheological properties of rice starch–xanthan gum mixtures

Rheological properties of rice starch–xanthan gum mixtures (5% w/w) at different xanthan gum concentrations (0%, 0.2%, 0.4%, 0.6%, and 0.8% w/w) were evaluated in steady and dynamic shear. The rice starch–xanthan gum mixtures at 25 °C showed high shear-thinning flow behavior ( n = 0.13–0.24), and consistency index ( K) and apparent viscosities ( η a,100) increased with the increase in xanthan gum concentration. In the temperature range of 25–70 °C, mixtures followed the Arrhenius temperature relationship. Activation energy (1.83–9.89 kJ/mol) decreased and storage ( G′) and loss ( G″) moduli increased with the increase in xanthan gum concentration. The dynamic ( η ∗) and steady shear ( η a) viscosities at several xanthan gum concentrations followed the Cox–Merz superposition rule with the application of shift factor ( α). Magnitudes of shift factor were in the range of 0.307–0.478. During aging at 4 °C for 10 h, the values of G′ were found to increase rapidly the early stage and attained the plateau region after a few hours. The increase in rate constant ( k) in gelation of rice starch–xanthan gum mixtures was a function of xanthan gum concentration.