Gum Aqueous Solutions Research Articles

Natural Giesekus fluids: Shear and extensional behavior of food gum solutions in the semidilute regime

The shear and extensional behavior of two aqueous gum solutions, namely (1) 1–20 g/L guar gum (Torres et al., Food Hydrocolloids. 2014;40:85–95) and (2) κ/ι‐hybrid carrageenan solutions (5–20 g/L), are shown to exhibit Giesekus‐fluid behavior when in the semidilute regime. In this regime, a common set of Giesekus fluid parameters described both shear and extensional behavior. A new analytical result describing the extension of a Giesekus fluid in the filament stretching geometry is presented. This also gave reasonable predictions of the Trouton ratio. Higher concentration guar solutions, in the entangled regime, yielded different Giesekus fluid parameters for extension to those for simple shear. The extensional data for all concentrations of both gums collapsed to a common functional form, similar to that reported for cake batters (Chesterton et al., J Food Eng. 2011;105(2):332–342); the limits of the new filament thinning expression provide insight into this behavior. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3902–3915, 2014

Experimental Study and Numerical Modeling of Rheological and Flow Behavior of Xanthan Gum Solutions Using Artificial Neural Network

This study investigated effect of temperature, concentration, and shear rate on rheological properties of xanthan gum aqueous solutions using a Couette viscometer at temperatures between 25°C and 55°C and concentrations of 0.25 wt% to 1.0 wt%. The Herschel–Bulkley model described very well the non-Newtonian behavior of xanthan gum solutions. Shear rate, temperature, and concentration affected apparent viscosity and an equation was proposed for the temperature and concentration effect valid for each shear rate. This article also presents an artificial neural network (ANN) model to predict apparent viscosity. Based on statistical analysis, the ANN method estimated viscosity with high accuracy and low error.

Encapsulation of Congo Red in carboxymethyl guar gum–alginate gel microspheres

Congo Red (CR) is a hydrophobic dye commonly used for diagnosis and potentially useful as therapeutic agent of beta amyloid plaques in neurodegenerative diseases. CR, as drug model, was encapsulated on Alginate–Carboxy Methyl Guar Gum (Alg–CMGG) blend microspheres. Guar gum 18% carboxymethylated (CMGG) derivative was synthesized in order to improve aqueous solubility, polymer blending and help reduce surface tension. The derivative was confirmed by FTIR spectroscopy, and elemental analysis. Surface tension of the new CMGG is reduced in about 50% compared with the native polymer. Lowering of Guar Gum (GG) aqueous solutions viscosity from 30,000cps to 350–400cps in case of CMGG is indicating pseudoplastic fluid behavior modifications. Vibrational spectroscopy analysis confirmed interactions among CR molecules in alginate–CMGG matrices ascribed largely to the aromatic motif of the dye and the biopolymer a polar regions. CR was encapsulated on 68/32% alginate/CMGG blend microspheres as the best formulation tested. The release of CR from the microspheres was not detected at pH=1.2 in 25min, but 62% of CR was found in the supernatant when the pH was raised to 7.4 at 37°C after 8h incubation.

Preparation of Low Molecular Weight Guar Gum for Fracturing by Enzymatic Degradation

Guar gum was subjected to degradation in high concentration aqueous solution by enzymatic treating to obtain high concentration low molecular weight guar gum for fracturing. The study indicates that the high concentration guar gum aqueous solution can be degraded effectively by enzymatic treating. The enzymatic treating conditions were investigated and the optical enzymatic treating pH, temperature and enzyme add amount are respectively 6, 50°C and 0.1g/L, and various of low molecular weight guar gum with different molecular weight can be obtained by controlling the enzymatic treating time.

Synthesis, characterization, photocatalytic evaluation, and toxicity studies of TiO2–Fe3+ nanocatalyst

Based on our previous work on the green preparation of Ag–TiO2 photocatalyst with bactericidal activity under visible light, we extended our studies to the synthesis of TiO2–Fe3+ materials with enhanced photocatalytic activity for the degradation of recalcitrant organic pollutants in water. TiO2–Fe3+ nanopowders were synthesized using a robust, environmentally friendly procedure. Established amounts of Fe(NO3)3·9H2O and titanium tetraisopropoxide (TTIP) were mixed using glacial acetic acid as solvent. Hydrolysis of TTIP–Fe3+ was accomplished using a 30 % (W/V) Arabic gum aqueous solution. TiO2–Fe3+ nanopowders were obtained by thermal treatment at 400 °C. In order to elucidate the structure of these photocatalysts, microscopic and spectroscopic characterization techniques were applied. The high resolution transmission electron microscopy (HRTEM) analysis indicated the presence of uniformly distributed particles with average particle size of about 9 nm. According to the HRTEM lattice fringes, ring pattern, and selected area electron diffraction pattern, the crystalline part of the samples consists of anatase (PDF 01-086-1157 with the lattice constant of 3.7852, 9.5139 A and 90°) as dominant phase. X-ray photoelectron spectroscopy (XPS) was applied to determine the oxidation state of iron. The XPS provides evidence for Fe3+ surface species in the TiO2–Fe3+ composite. Complete degradation of aqueous solutions (20 ppm) of methylene blue and/or methyl orange was accomplished after 4 h of treatment using 150 mg of TiO2–Fe3+/150 mL of dye solution. The in vitro toxicity of the materials was tested. The materials showed no toxicity against human red blood cells.

Effect of CuO and ZnO nanofluids in xanthan gum on thermal, electrical and high pressure rheology of water-based drilling fluids

Nanofluids show potential use in applications related to upstream oil and gas industry to improve the performance of several processes such as exploration, drilling and completion, production and enhanced oil recovery operations. However, their applications to water-based drilling mud (WBM) needs attention to address efficient drilling in an High Pressure and High Temperature (HPHT) environment. In the present work, nanofluid-enhanced WBM (NWBM) are prepared using the nanofluids of CuO and ZnO (size ˂50nm) in a xanthan gum aqueous solution as a base fluid, and used as an additive in WBM. The nanofluids are prepared for nanoparticle concentrations of 0.1, 0.3 and 0.5wt% in base. The prepared nanofluids are added as an additive of 1% (by volume) to WBM. The enhancement in thermal and electrical properties of NWBH is studied. It is observed that NWBM show improved thermal and electrical properties by about 35% compared to WBM. An increased concentration of nanoparticles further enhances electrical and thermal properties of drilling fluids. The NWBM based on CuO nanofluid are observed to show improved thermal properties, and are more resistant to HPHT condition than ZnO-based NWBM. High pressure rheological studies are conducted on NWBM to understand the effect of nanofluids on the rheological properties at varying temperatures (25, 70, 90 and 110°C) and pressures (0.1MPa and 10MPa). The effect of pressure on the rheology of NWBM is more significant at higher temperatures, and indicates better rheological stability in case of NWBM. The most significant role that the nanofluids play is in stabilizing the viscosity at higher temperatures. The experimental data on flow curves obtained for various NWBM are fitted to the classical drilling fluid rheological models (Power Law model, Bingham Plastic model and Herschel–Bulkley model). The Herschel Bulkley model is observed to be the best fit-model for rheological behavior of NWBM and can be applied for efficient NWBM design.

Study of interactions between aroma compounds and acacia gum using headspace measurements

This study deals with retention measurements of aroma compounds in acacia gum aqueous solutions. In that purpose, six volatile molecules differing in their physicochemical properties were analysed: ethyl butyrate, ethyl hexanoate, ethyl octanoate, cumene, 1-octanol and linalool. Their gas/liquid partition coefficients were measured by headspace gas chromatography using the phase ratio variation method from acacia gum solutions. Three acacia gum samples exhibiting different emulsifying properties were studied for concentrations ranging from 0 to 20 wt%. These measurements made possible to evaluate the interactions between aroma compounds and acacia gums through the calculation of retention. A correlation between retention and lipophilicity was observed, thus proving that acacia gum interacts with aroma compounds via hydrophobic bonding. Significant interactions occur for volatile molecules that have a pronounced lipophilic character (logP > 3.6). The effect of gum concentration was also studied. No linear relationship was evidenced with retention and a significant effect was observed for concentration higher than 5 wt%. This work also establishes that the emulsifying properties of acacia gum can be evaluated by retention measurements for lipophilic aroma compounds (logP > 3.6).

Associating and rheological behaviors of fluorinated cationic guar gum in aqueous solutions

The fluorinated cationic guar gum (FCGG) was prepared with cationic guar gum (CGG) and fluorinated reactive monomer (FAM). FAM was synthesized from isophorone diisocyanate and 2,2,3,4,4,4-hexafluoro-1-butanol. The molecular structure, associating and rheological behaviors of FCGG were studied by the FT-IR, 19F NMR, X-ray diffraction, dynamic rheometer and fluorescence spectroscopy, respectively. The results show that FAM is successfully incorporated into CGG. With the increased degree of substitution (DS), the crystallinity is reduced from 3.01 to 0.67% and the characteristic relaxation time is changed significantly from 0.10 to 3.3s. At low shear rates (<20s−1), the viscosity of FCGG solution increases with the increase of shear rates. The bigger the DS, the higher the apparent viscosity. The viscosity retention factor of FCGG can reach 126.97% at 30°C and 51.33% at 60°C, respectively. The data indicate that FCGG has much better heat resistance.

Physicochemical properties and rheological behaviour of Ficus glumosa gum in aqueous solution

The physicochemical properties, cationic composition and rheological behaviour of exudates from Ficus glumosa were investigated. The gum was found to be mild acidic, ionic and soluble in water, sparingly soluble in ethanoland insoluble in acetone and chloroform. The trend for the decreasing concentration of elements determined in the gum sample is Mg > Ca > Mn > Zn > Fe > Ni > Zn > Cu > Cd > Pb. Rheological properties of the gums have been adequately modeled using Huggins, Kraemer, Arrhenius, Tanglertpaibul and Rao theories. The results indicated that the viscosity of the gum increases with increasing pH and concentration but decreases with increase in temperature. Values of intrinsic viscosity obtained from Huggins and Kraemer plots were similar (11.197). The value of activation energy (Evis) of the gum studied was found to be 1.915 kJ/mol. The low Evis values obtained suggests the existence of few inter and intra-interactions between the molecules of the gums within the investigated temperature. F. glumosa gum exudate hence, possesses the potentials to be used as an additive in food and other industries. Key words: Ficus glumosa, gum, heavy metal, characterization, rheological modeling.

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Structural change of a polymer solution in a planer channel flow after an abrupt expansion have been investigated. Flow of 0.5wt% xanthan gum aqueous solution through 1:4 expansion channels with height of 1 mm and 0.2 mm has been tested. Distribution of birefringence and orientation angle at a center line of the channel were measured. Flow-induced birefringence and orientation angle after the expansion were depending on the channel height. Influence of elongational effect generated at the center region in height was disappeared in the case of small gap.

Physicochemical and Sensory Characteristics of Arabic Gum-Coated Tomato (Solanum Lycopersicum L.) Fruits during Storage

The effects of gum arabic surface coating (5–20% aqueous gum solution) on physicochemical and sensory properties of mature red tomato fruits during 16 days of storage at 10 ± 1C were investigated. The firmness of uncoated fruits was significantly (P ≤ 0.05) lower, while weight loss was higher than coated ones. Uncoated tomatoes had higher total soluble solids, low acidity and fluctuating pH values. The values of L and b of the fruits decreased, while that of a increased during storage. The hue angle of the fruits significantly decreased, but total color change significantly increased during storage. The chroma and browning index of fruits increased slightly, while the color index increased significantly. Gum coating showed a better retention of all these physical, chemical and optical parameters of stored tomatoes. Panelists' results showed that gum-coated tomato fruits have acceptable sensory quality. Practical Applications Tomato is an important food commodity from nutritional and commercial point of view; however, freshly harvested tomato fruits have shorter shelf life in the market. Strategies to preserve its physicochemical and sensorial characteristics have significance for grower, processor and seller. We observed that gum arabic coating effectively preserved different quality attributes of tomato fruits for 16 days while stored at even more than normal refrigeration temperature. Our findings are valuable for those involved in tomato fruit handling and processing.

Role and properties of guar gum in sodium caseinate solution and sodium caseinate stabilized emulsion

The rheological and interfacial properties of sodium caseinate (Na-CN) and guar gum (GG) aqueous solution have been firstly investigated at a neutral pH value. The Na-CN solution showed slightly shear-thinning behavior and tended to behave in a Newtonian fashion when GG was added. The interfacial tension of Na-CN solution remained unchanged in the presence of 0.01wt.% GG, and then increased at higher GG concentrations. Secondly, the functionality of GG in Na-CN-stabilized emulsions was checked. Although the addition of GG at low concentration promoted micro-phase separation (0.04wt.%) and visual serum separation (0.02wt.%), GG improved the adsorption of Na-CN to the oil–water interface which resulted in a decrease in average droplet diameters and partial coalescence of fat, and an increase in apparent viscosity, consistency index and yield stress. In addition, emulsion with GG was characterized as entanglement networks while without GG it was characterized as weak gel behavior instead. The role of GG on Na-CN-stabilized emulsions was concentration dependent, 0.04wt.% GG was the critical concentration in which flocculation might take place as estimated by the highest interfacial tension and the average droplet diameter, higher partial coalescence of fat and phase separation, as well as by the lower surface protein concentration.

Gelation Mechanism of Polysaccharide Gellan Gum in Aqueous Solutions

Gelation Mechanism of Polysaccharide Gellan Gum in Aqueous Solutions

Effect of Irradiation on the Molecular Weight, Structure and Apparent Viscosity of Xanthan Gum in Aqueous Solution

Xanthan gum samples were irradiated in aqueous solution at different doses (0-120 kGy) of 60Co γ-rays. The changes of molecular weight and structures of irradiated xanthan gum samples were investigated and characterized by using gel permeation chromatography(GPC), X-ray diffraction (XRD), fourier-transform infrared spectra (FTIR), ultraviolet–visible spectral (UV–vis) analysis and rheometer. Results showed the molecular weight decreased gradually with increasing irradiation dose. The radiation chemical yields G(d) of xanthan gum was 26.55. FTIR spectra and XRD indicated that γ-irradiation introduced no significant changes into the structure and crystal texture, but UV spectra showed a distinct absorption peak at about 265 nm, increasing with irradiation dose, which was attributed to the formation of carbonyl groups or double bond. Apparent viscosity of xanthan gum solution decreased with increasing irradiation dose and remain basically constant with the prolonging of shear time after irradiation.

Changes of Dynamic Viscoelastic Properties of Tamarind Gum Aqueous Solutions

Tamarind gum was obtained from the seeds of Tamarindus indica. It was rich in polysaccharide (79.96%) and protein (13.46%) contents. In this work, the dynamic viscoelastic properties of tamarind gum aqueous solutions were investigated with a Haake Rheometer RS75 as a function of gum concentration and temperature. Four types of sample solution systems: a dilute solution, a concentrated solution, a weak gelled system, and a gelled like system were observed. The effect of concentration showed that the typical shape of the mechanical spectra for the dilute solution occurred for 2.30 wt% and the gelled like behaviour arose for the higher concentration (≥7.05 wt%) as measured at 25°C. While the effect of temperature on the dynamic viscoelastic properties of tamarind gum solution (6.91wt%) showed that the gum solution behaved the weak gelled system (25°C) and subsequently gelled like system (≥30°C).

Rheological behaviour of tamarind seed gum in aqueous solutions

Tamarind seed gum as seed polysaccharide from Tamarindus indica L. has been characterized for physicochemical and rheological properties in the present work. The structural analysis determined the presence of glucose:xylose:galactose in a molar ratio of 2.61:1.43:1.The Huggins and Kraemer plots obtained by capillary viscometry gave an intrinsic viscosity of 4.7 dl g −1 and the viscosity average molecular mass was calculated to be 9.18 × 10 5 g mol −1 using the Mark–Houwink relationship. The steady shear and dynamic viscoelasticity properties of tamarind seed gum in aqueous solutions at different concentrations were investigated at 20 °C using a Haake Rheometer RS75. The tamarind seed gum solutions clearly exhibited shear-thinning flow behaviour at high shear rate and Newtonian region occurred at low shear rate range, however, at higher concentrations, pronounced shear thinning was observed. The value of zero shear viscosity ( η 0) was estimated by fitting Cross and Carreau models. The specific viscosity at zero shear rate ( η sp 0) was plotted against the coil overlap parameter ( C[ η]) and the slopes of the lines in the dilute and semi-dilute regions were found to be ∼2.2 and 4.3, respectively. The value of the critical concentration ( C ∗) was about 4.23/[ η]. While, the mechanical spectra in the linear viscoelastic region of tamarind seed gum solutions showed the typical shape for macromolecular solutions. Plots of η versus γ and η ∗ versus ω were superimposable and hence obey the Cox–Merz rule.

Micellar properties of OSA starch and interaction with xanthan gum in aqueous solution

Octenyl succinate (OSA) modified starches are used, as emulsifiers and stabilizers, in many food, cosmetics and pharmaceutical products. The aim of this study was to determine critical micellar concentration (CMC) of two different octenyl succinate modified waxy corn starches at 25 °C, and to examine possibility of their interactions with xanthan gum in aqueous solution. The CMC was determined by viscometry, conductometry, surface tension and dye solubilization. The CMC values for two OSA starches (OS1 and OS2) varied from 0.050 to 0.088 g/100 cm 3 and from 0.041 to 0.081 g/100 cm 3 respectively, depending on applied technique. The same techniques were used for investigation of the interactions between OSA starch and xanthan gum. The addition of xanthan gum decreases the specific viscosity and increases surface tension and the CMC values compared to the single OSA starch solutions.

Critical behavior at sol–gel transition in gellan gum aqueous solutions with KCl and CaCl 2 of different concentrations

The sol–gel transition in aqueous gellan gum solutions with added KCl or CaCl 2 upon cooling was investigated using rheology measurements. The gelation temperature T gel (gel point) and the relaxation critical exponent n were successfully determined according to the Winter's criterion. With increasing salt concentration, T gel increased while n decreased. The scaling for the zero shear viscosity η 0 in the sol phase and the equilibrium modulus G e in the gel phase were established against the relative distance ɛ ( ɛ = | T − T gel|/ T gel) from the gel point, which gave the critical exponents k and z. No universal critical exponent n was found for this sol–gel transition because this gelation belonged to the cross-linking of existing macromolecules and the concept of random connectivity failed. The fractal dimension d f calculated from n without hydrodynamic interaction nor excluded volume suggested a denser filling structure in the critical gel at higher salt concentration.

Relationship between the emulsifying properties of Acacia gums and the retention and diffusion of aroma compounds

Five samples of Acacia senegal gum were selected because of their different emulsifying properties. Acacia gum samples were first characterized by various analytical methods including intrinsic viscosity and arabino-galactan protein amount as determined by gel permeation chromatography. In a second step, stability of emulsions containing orange essential oil and Acacia gums was evaluated by measurement of turbidity. In addition, flavour release of two different hydrophobic aroma compounds from Acacia gum aqueous solutions was studied. Retention was measured using the phase ratio variation method under equilibrium whereas diffusion was assessed by DOSY NMR. This study established the relationship between the emulsifying ability of Acacia gum and the behaviour of aroma compounds in the corresponding solution. Better emulsifying ability of Acacia gum sample appears strongly correlated to an increase in flavour retention and a decrease in molecular mobility as the result of mostly hydrophobic interactions.

Solutions of xanthan gum/guar gum mixtures: shear rheology, porous media flow, and solids transport in annular flow

Mixtures of xanthan and guar gum in aqueous solution were studied in two flow situations: simple shear and porous media. In addition, solids transport in vertical annular flow of sand suspensions was explored. The zero shear rate viscosity of the solutions displayed a pronounced synergy: the viscosity of the mixture is higher than that of the polymer solutions in a wide range of relative concentrations of the two polymers, in agreement with previous literature. However, at relatively high shear rates, the viscosity approaches the value of the more viscous xanthan gum solutions at mass fractions of xanthan gum between 0.1 and 0.15, and the degree of synergy substantially decreases. Stress relaxation experiments in simple shear indicate that the polymer mixtures exhibit a well-defined yield stress after relaxation that is absent in solutions of pure polymers. In porous media flow experiments, a synergistic behavior mimicking the shear flow results was obtained for the polymer mixtures at low shear rates. However, at a critical shear rate, the apparent viscosity in porous media flows exceeds the shear viscosity due to the elongational nature of flow in the pores. The solids transport capacity in annular flows is well-represented by trends in shear viscosity and stress relaxation behavior. However, the lack of viscosity synergy at high shear rates limits the applicability of the mixtures as a way to improve solids suspension capacity in annular flows.