Xanthan Gum Research Papers - Academia.edu (original) (raw)

Protein concentrates prepared by expanded bed adsorption (EBA) chromatography from industrial potato juice (PJ) were analysed for chemical composition, color, enzyme activities, thermal properties and selected functional properties (solubility and emulsifying stability). Two EBA multi-modal resins, MIMO I-45 and MIMO 1300 (UpFront Chromatography), were employed under various pH conditions resulting in four potato protein concentrates, AD. Concentrate B contained an electrophoretically pure protease inhibitor fraction (20-21 kDa), whereas concentrate A, C and D contained both patatin (41 kDa) and protease inhibitors. The potato protein concentrates were explored for the presence of transitions from native to denatured states using differential scanning calorimetry (DSC). Concentrate C had lower heat of transition (DH) and T-onset than the other concentrates. The concentrate containing protease inhibitors exhibited the highest denaturation temperature and enthalpy. All concentrates differed significantly (P < 0.05) in color brightness, with concentrate B and D emerging as the brightest. The solubility of the concentrates was evaluated at pH 6 and pH 4.5. All concentrates had lower solubility at pH 4.5 than at pH 6 (70-80%). The stability of emulsions (1% protein, 20% oil, 0.08% xanthan gum) against creaming was analysed with a new method based on the Single electrode Capacitance Probe (SeCaP) technology. Small differences among concentrates were observed by the new SeCaP method.

- by
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- Chemistry, Animal Production, Potato, Differential scanning calorimetry

In this study, rheological properties of several food hydrocolloids (carrageenan, pectin, gelatin, starch and xanthan) were evaluated using a rotational viscometer at three concentrations (1-6%, depending on the type of hydrocolloid) and four temperatures (20, 40, 60 and 80 C). Samples were subjected to a programmed shear rate increasing linearly from 0 to 300 s À1 in 3 min, followed by a steady shear at 300 s À1 for 10 min and finally a linearly decreasing shear rate from 300 s À1 to 0 in 3 min. Experiments were performed in duplicate. In general, the power law model fitted most of the experimental results. Xanthan gum and carrageenan (at 20 o C) were exceptions, characterized by a yield stress and hence the rheograms were fitted with the Herschel-Bulkley model. Furthermore, gelatin showed a Newtonian behavior. Three models (power, exponential and polynomial) were used to evaluate the concentration effect on apparent viscosity. Arrhenius model was used to describe the temperature effect. Among the samples, carrageenan showed the most temperature dependency and xanthan gum, the least.

- by Hosahalli Ramaswamy
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- Chemical Engineering, Rheology, Food, Concentration

TSURUTA, M., T. KAWADA, T. FUKUWATARI AND T. FUSHIKI. The orosensory recognition of long-chain fatty acids in rats. PHYSIOL BEHAV 66 (2) 285-288, 1999.-To determine the selectivity of long-chain fatty acid (LCFA) in the oral cavity, short-term (5 min) two-bottle tests were conducted in rats. Fifteen male Wistar rats were given oleic acid, linoleic acid, linolenic acid, and their derivatives. All compounds used were 99% pure. The concentration of test fluids was made 1% in 0.3% xanthan gum to minimize postingestive and textural effects. The rats preferred LCFA fluids to the control of 0. 3% xanthan gum solution. The preference order of LCFA was linolenic acid Ͼ linoleic acid Ͼ oleic acid. Four LCFA derivatives (methyl oleate, oleyl alcohol, methyl linoleate, and linolyl alcohol), triolein, and capric acid were not preferred to LCFA, but LCFA derivatives were preferred to the control of xanthan gum solution. These studies suggest that rats select LCFA from olfactory or gustatory cues that are related to both the carbon chain and carboxylate group.

- by Tohru Fushiki
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- Biological Sciences, Xanthan Gum, Long Chain Fatty Acid, Oral Cavity

Objective: Domperidone is a synthetic benzimidazole compound that acts as a dopamine D 2 receptor antagonist. The main aim of this study was to optimize and evaluate the floating tablets of domperidone that prolongs the gastric residence time using Hibiscus rosa-sinensis mucilage. Methods: The directly compressible floating tablets of domperidone were formulated using varying amount of hydroxypropyl methylcellulose K100 M, carbopol 934P and H. rosa-sinensis mucilage. The effervescent components sodium bicarbonate is used for the generation of CO 2 gas. The prepared tablets were evaluated for physicochemical parameters and found to be within range, viz., hardness, swelling index, floating capacity, thickness, and weight variation. Further, tablets were evaluated for in vitro release characteristics. The concentration of H. rosa-sinensis mucilage with a gas-generating agent was optimized to get the sustained release of domperidone. Result: The % cumulative drug release of all formulation from F1 to F6 was within the range of 81.37% to 98.62% for 18 hrs. The release kinetics of all the dosage forms was calculated using zero order, first order, Higuchi, and Korsmeyer-Peppas. It concludes that the release followed zero order release, whereas the correlation coefficient (r 2 value) was higher for zero order release. The release mechanism follows Higuchi model, Korsmeyer-Peppas model, and non-Fickian diffusion. Conclusion: As a result of this study, it may be concluded that the floating tablets using H. rosa-sinensis mucilage in optimized concentrations can be used to increase the gastric retention time of the dissolution fluid in the stomach to deliver the drug in a sustained manner. Furthermore, from 1 month stability data shows no significant change compared to initial result.

- by Pranav Kumar
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- Algorithms, Water, Drug delivery, Drug Delivery System

It has been observed previously that xanthan gum (XG) and hydroxypropylmethyl cellulose (HPMC) show different drug release behavior. In order to clarify these findings, the rheological properties of both polymers have been determined by oscillatory as well as by steady shear measurements. Aqueous solutions of 4 and 7% (w/w) polymer have been used to simulate the outer surface of a hydrated tablet. The dynamic moduli, i.e., storage modulus (G′) and loss modulus (G″) of the two polymers have been determined in pure water and USP phosphate buffer pH 7.4 at different dilutions. In this concentration range XG solution exhibits “gel-like” behavior, while HPMC behaves as a typical polymer solution. These findings are quite consistent with the reported higher ability of XG matrices to retard drug release than HPMC matrices for controlled-release formulation. The effects of differences in drug solubility and acidity, as well as the addition of lactose, and of the ionic strength of the medium on the rheological properties of XG and HPMC solutions have been studied in detail. Among these parameters, only the salt concentration exerts an enhancing effect on both moduli of XG, while no detectable influence on HPMC solution could be observed.

- by renaat kinget
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- Rheology, Drug delivery, Pharmaceutical Chemistry, Controlled release

Partitioning and release of limonene and transK2-hexenal from polysaccharide solutions was studied by applying static headspace gas chromatography. Experiments were carried out on xanthan/propylene glycol alginate and xanthan/gum arabic solutions at various concentrations. Changes in the polysaccharide matrix exhibited a considerable effect on the thermodynamic component as expressed by the air/liquid partition coefficient (K a/l ) values at equilibrium (37 8C). Viscosity increase was shown to affect the initial release rate, as this is defined by the amount of limonene and trans-2-hexenal released over the first few minutes of the experiments. The physicochemical properties of both aroma compounds, especially their hydrophobicity, were also of importance in air/liquid partition, with limonene to be mostly affected by polysaccharide addition. q

- by Adamantini Paraskevopoulou
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- Thermodynamics, Kinetics, Xanthan Gum, Gas Chromatography

Experimental data are reported for fully developed laminar flow of a shear-thinning liquid through both a concentric and an 80% eccentric annulus with and without centrebody rotation. The working fluid was an aqueous solution of 0.1% xanthan gum and 0.1% carboxymethylcellulose for which the flow curve is well represented by the Cross model. Comparisons are reported between numerical calculations and the flow data, as well as with other laminar annular-flow data for a variety of shear-thinning liquids previously reported in the litera- ture. In general, the calculations are in good quantitative agreement with the experimental data, even in situations where viscoelastic effects, neglected in the calculations, would be expected to play a role.

- by Paulo Oliveira
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- Mechanical Engineering, Aerospace Engineering, Xanthan Gum, Laminar Flow

The microstructure of acid skim milk gels (14% w/w milk protein low heat powder) with or without addition of locust bean gum (LBG), xanthan gum (XG) and LBG/XG blends was determined by transmission electron microscopy (TEM), phase-contrast light microscopy (PCLM) and scanning electron microscopy (SEM). Three polysaccharide concentrations (0.001%, 0.02% and 0.1%, w/w) were used for binary mixtures. In the case of ternary mixtures, three LBG/XG weight ratios were used (4/16, 11/9 and 16/4) at 0.02% total polysaccharide concentration. Control acid skim milk gels were structured by a homogeneous network of casein particles (0.1–0.7 μm in diameter) and clusters immobilizing whey in small pores (1–5 μm in diameter). Filamentous structures and small aggregates were observed at the surface of casein particles. Low concentration of LBG or XG (0.001% w/w) did not affect markedly the microstructure of acid skim milk gels. Conversely, LBG or XG at 0.02 or 0.1% concentration and LBG/XG blends at the three ratios selected had a great influence on the gel microstructure. Although the size and surface structure of the casein particles were not modified by the presence of polysaccharides, the primary casein network appeared very compact with a decrease of pore size and a large increase in the porosity of the network at the supramolecular level (sponge-like morphology). The effect is stronger for gels containing LBG and XG used at higher concentration and less apparent for gels containing LBG/XG blends. Skim milk/XG gels were highly organized into fibrous structures whereas skim milk/LBG gels were more heterogeneous. These structures were discussed in the light of volume-exclusion effects (demixing) and specific interactions between casein micelles and polysaccharides. At the three weight ratios, skim milk/LBG/XG gels displayed both jagged “coral-like”, “veil-like” and filamentous structures. These structures could originate from a secondary network constituted by the known LBG/XG synergistic interactions.

The cheese whey is an abundant residue obtained during the cheese processing and its disposal in the environment causes several drawbacks. The bioconversion of this by-product in added-value products is an important alternative to overcome this environmental problem. In this work, the feasibility of using cheese whey as carbon source for xanthan gum production was investigated using two strains of Xanthomonas campestris. The cheese whey:sucrose ratio and the supplementation of the medium were investigated by a Central Composite Design (CCD) in order to improve the xanthan gum production. Maximum xanthan gum productions were observed after 72 h using cheese whey as sole carbon source, 0.1% (w/v) MgSO 4 Â 7H 2 O and 2.0% (w/v) of K 2 HPO 4 , yielding approximately 25 g L À1 . This value is quite higher than some results presented in the literature using glucose as substrate. Although the production was similar for the two strains, chemical composition and ionic strength presented several differences in chemical characteristics between the polysaccharides produced.

- by Francine Padilha
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- Food Engineering, Food, Xanthan Gum, Food Sciences

In this study, it was aimed to compare rheological properties of rice cake batter and quality characteristics of rice cakes prepared using different gums with or without an emulsifier blend. Rice cake batter was formulated with different gums (xanthan gum, guar gum, locust bean gum, k-carrageenan, hydroxy propyl methyl cellulose (HPMC), xanthan-guar gum blend and xanthan-k-carrageenan gum blend) and an emulsifier blend (Purawave TM ). As a control cake, batters containing no gum and emulsifier blend were used.

- by Gulum Sumnu and +1
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- Rheology, Rice, Power Law, Xanthan Gum

Response surface methodology (RSM) was used to analyse the e+ect of corn-our, green gram-our, xanthan, guar gum, arabic gum and carboxymethyl cellulose (CMC) on the sensory and objective (expansion ratio) attributes of an extruded snack food. A rotatable central-composite design was used to develop models for the sensory and objective responses. ¹he experiments were run at 160 3C with a feed rate of 70 g/min. Responses were most a+ected by changes in corn-our, green gram-our and guar gum levels and to a lesser extent by xanthan, gum arabic and CMC levels. Individual contour plots of the di+erent responses were superimposed, and regions meeting the maximum sensory score of 21.4 and an expansion ratio of 13.2 were identi,ed at 692 g/kg corn-our, 307 g/kg green gram-our, 0.302 g/kg xanthan, 0.216 g/kg guar gum, 0.196 g/kg gum Arabic and 0.262 g/kg CMC levels.

- by Sushma Thakur
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- Response Surface Methodology, Animal Production, Optimization, Xanthan Gum

Hydrocolloid stabilizers (carrageenan, carboxymethyl cellulose, xanthan gum, sodium alginate, locust bean gum (LBG) and gelatin) were labeled with rhodamine isothiocyanate and incorporated into solutions of sucrose with or without milk solids-not-fat (MSNF). Resultant solutions were quench frozen to 2 50 8C and cycled between 2 3.5 and 2 6 8C, five times. The location of the stabilizer was observed using fluorescence microscopy. Significant retardation of recrystallization was observed in alginate and xanthan sucrose solutions without MSNF.

- by A. Regand
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- Fluorescence Microscopy, Ice Cream, Xanthan Gum, Solute transport

Strawberry sauces thickened with oat, potato, and corn starches blended with xanthan gum were prepared and their sensory, textural, and rheological properties evaluated. The sensory analysis was performed with the five-point scale of quality. The products were also characterized rheologically at 25 °C in the controlled rate of shear (CR) mode. Resulting flow curves were fitted to the Herschel–Bulkley and Ostwald–de Waele rheological models. The second model provided worse fitting. The K and n parameters of the Herschel–Bulkley model revealed that, although to a different extent, all thickener combinations were suitable for thickening of sauces. The textural analysis of the sauces involving so-called back extrusion tests, providing maximum positive and negative extrusion force, revealed that thickening with potato sauce requires less xanthan gum for reaching desired effect, than corn and oat starches did. Sensory analysis distinguished the potato starch containing 0.12% xanthan gum as superior thickener. The sensory properties of the sauces insignificantly changed on the 3-month storage.All sauces were pseudoplastic, shear thinning liquids with the properties varying in time. The structure of the sauces thickened with potato and corn starches was statistically significantly more stable on storage than these thickened with oat starch.

- by Marek Sikora and +1
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- Food Engineering, Potato, Xanthan Gum, Rheological properties

The effect of CaCl 2 , Ca(NO 3 ) 2 , CaSO 4 , CaCO 3 and Ca 3 (PO 4 ) 2 on the flow behavior of xanthan gum solutions was investigated. Regardless the concentration and type of calcium salt used, xanthan solutions presented pseudoplastic behavior. The soluble salts (CaCl 2 and Ca(NO 3 ) 2 ) induced the disordered state in the xanthan chains at concentration of 1.0 g/L or 10 g/L, decreasing the flow consistency index (K) values. At 100 g/L soluble salts K values were similar to those found for pure xanthan solutions, whereas at the same concentration of insoluble particles the K values increased 20%. The adsorption of xanthan gum onto Si/SiO 2 surfaces in the presence of calcium salts was investigated by ellipsometry and atomic force microscopy (AFM). The adsorbed layer of xanthan onto Si/SiO 2 consisted of two regions: (i) a thin acid resistant sublayer, where xanthan chains were like highly entangled fibers and (ii) a thick upperlayer, whose morphology was calcium salt dependent.

- by Denise Petri
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- Organic Chemistry, Atomic Force Microscopy, Xanthan Gum, Food Sciences

The time-dependent evolution of the phase-separated microstructure of a caseinate-stabilised emulsion containing xanthan gum added before emulsification has been investigated by confocal laser scanning microscopy, image analysis and rheology. Moderately low levels of xanthan addition lead to depletion flocculation and gravity-induced phase separation. Increasing the polysaccharide concentration causes immobilisation of the microstructure due to an increase in the local viscoelasticity: that is, the emulsion structure cannot easily rearrange to expel xanthan-enriched aqueous serum phase because a weak gel-like network is generated. The effect of xanthan on the evolving microstructure of phase-separated regions, which reflects indirectly the local emulsion micro-rheology, has been estimated from image analysis of time sequences of confocal micrographs. A comparison has been made between object shape analysis using four different shape descriptors. The roundness parameter has been found to be a convenient descriptor for reliably quantifying the structural change in terms of the relaxation rate of xanthan-rich aqueous drops. The Taylor parameter has been used to link the kinetics of drop relaxation to the timedependent small-deformation rheological behaviour. The analysis of the combined experimental data reveals the difficulty of relating the evolving microstructure to bulk rheological measurements.  2004 Elsevier Inc. All rights reserved.

- by Thomas Moschakis
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- Engineering, Kinetics, Rheology, Image Analysis

We used the LUMiFuge w 114 particle separation analyser to investigate the sedimentation kinetics of bentonite/xanthan gum mixtures through pH 2 -7 during centrifugation. This new technique monitors timed near infrared transmission profiles of different samples in the centrifugal field. Statistical analysis of the data then identifies the formulations with minimal clarification tendency.

- by Martin Kuentz
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- Kinetics, Statistical Analysis, Rheology, Experimental Design

This work describes a practical way to optimize the high level of the chef creativity to produce rational approaches to food design. It is particularly focused on the preparation of two dishes: bubbly juice and false skin. For the first dish, three samples were prepared with egg white protein (EWP) and xanthan gum at pH 4.6 and pH 7.0. At pH 4.6 (isoelectric point), there were substantial differences of the interfacial dilational modulus of EWP when xanthan gum was added. At 1 mg/ml xanthan, the system showed a very strong interface (high viscoelasticity) compared to the other samples. Measuring half drainage time revealed which samples were the most stable. The properties discussed were related to stability. For the false skin dish, edible films were made by gelatin extracted from cod skins (A solution) and a mixture of cod skin gelatin and commercial gelatin (AG solution). The results showed that tensile strength (TS) of gelatin films increases almost by 25%, elongation at break (EAB) by 14%, and the Young modulus (E) by almost 100% when increasing protein concentration. To confirm water plasticizer effect, the results were compared to a gelatin film made with 30% glycerol (plasticizer). Water content affects to a great extent the mechanical properties of the films. Finally, images of the dishes are presented in order to have a full view of the purpose and the results obtained.

- by Daniel Lasa and +1
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- Xanthan Gum, Rheological properties, Water Content, Tensile Strength

In this study, the rheological properties of rice bread dough containing different gums with or without emulsifiers were determined. In addition, the quality of rice breads (volume, firmness and sensory analysis) was evaluated. Different gums (xanthan gum, guar gum, locust bean gum (LBG), hydroxyl propyl methyl cellulose (HPMC), pectin, xanthan-guar, and xanthan-LBG blend) and emulsifiers (Purawave TM and DATEM) were used to find the best formulation for gluten-free breads. Rice dough and wheat dough containing no gum and emulsifier were used as control formulations. The rice dough containing different gums with or without emulsifiers at 25°C showed shear-thinning behavior with a flow behavior index (n) ranging from 0.33-0.68 (except pectin containing samples) and consistency index (K) ranging from 2.75-61.7 Pa s n . The highest elastic (G 0 ) and loss (G 00 ) module were obtained for rice dough samples containing xanthan gum, xanthan-guar and xanthan-LBG blend with DATEM. When Purawave TM was used as an emulsifier, dough samples had relatively smaller consistency index and viscoelastic moduli values compared to DATEM. The viscoelastic parameters of rice dough were found to be related to bread firmness. Addition of DATEM improved bread quality in terms of specific volume and sensory values.

- by Gulum Sumnu
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- Food Science, Nutrition, Food Engineering, Food and Nutrition
- by MD. RAMIM TANVER RAHMAN
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- Xanthan Gum, Gum Arabic, Gum Base, Textural Properties of Gum

The goal of this project was to utilize pea pod powder in development of nutrient rich gluten free rusk. Dried pea pod was grinded to powder form. The experiment was designed to optimize the broken rice flour, defatted soy flour and pea pod powder proportion for the development of gluten free rusk with high protein, fibre and to maximize the acceptability by the application of central composite rotatable design (CCRD) of Response Surface Methodology (RSM). The independent variables for rusk were in the proportions of broken rice flour (40-100g/100g), defatted soy flour (5-20g/100g and pea pod powder (5-20g/100g). The predicted responses were protein, crude fiber and hardness of rusk. The optimum level of broken rice flour, defatted soy flour and pea pod powder was found 84.66g, 16.95g and 16.95g respectively. Optimized gluten free rusk had 15.99%protein and 4.88% crude fibre which is significantly (p < 0.01) higher than control rusk.

- by Riya Sakpal
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- Bakery Products, Xanthan Gum, HPMC, Response Surface Methodology (RSM)

Mixtures of starch, xanthan gum and either polyvinyl alcohol, epichlorohydrin, valeric acid or adipoyl chloride were extruded. Properties of extrudates including apparent viscosity, water solubility, water absorption indices and exrudate expansion were measured for different proportions of xanthan gum, 70% amylose starch (with or without irradiation) and chemical agents. Extrusion with chemical agents and irradiation changed physical properties of both starch and xanthan gum. Expansions of extrudates were higher than that of starch. Viscosity of extrudates increased with xanthan gum concentration. The addition of 1% (w/w) polyvinyl alcohol had the greatest effect of the chemical agents. Irradiation increased the apparent viscosity of starch-xanthan gum mixtures.

- by Milford Hanna
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- Chemical Engineering, Food Science, Viscosity, Xanthan Gum

Suitability of xanthan gum (XG)-locust bean gum (LBG), carrageenan (CAR)-LBG, and XG-CAR in 1:1 proportion at 0.42% in the formulation was assessed in the manufacture of Mozzarella cheese analogue. The stabilizer blends did not signifi cantly infl uence the composition, texture profi le, organoleptic, baking qualities and pizza-related characteristics of cheese analogues. Considering the infl uence of stabilizer blend on the sensory quality of analogue and sensory rating of pizza pie, XG-LBG blend (1:1) was preferred over XG-CAR and CAR-LBG.

- by Atanu Jana
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- Food Science and Technology, Xanthan Gum, Food Sciences, Mozzarella cheese

Cereal Chem. 81(5):567-575

- by Peter Dockery
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- Analytical Chemistry, Potato, Xanthan Gum, Cereal Chemistry

The rheological effects of propylene glycol alginate (PGA) added to solutions and model emulsions containing xanthan gum (XG) were studied using controlled stress rheometry with concentrations appropriate for salad dressings. For samples with XG and XG + PGA blends, solutions and emulsions showed a Newtonian plateau at low shear stresses. The Newtonian plateau of a solution accurately predicted (Tz = 1.00) the Newtonian plateau for an emulsion of equivalent gum concentration. Addition of PGA to constant levels of XG showed a more than additive increase in the Newtonian plateau viscosity for solutions and emulsions. For XG aqueous solutions, pseudoplasticity decreased upon addition of PGA. Storage and loss moduli increased with addition of PGA to XG for solutions and emulsions, although G' for solutions of PGA alone were negligible.

- by Jo Wayne
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- Chemical Engineering, Food Science, Food, Xanthan Gum

In the present paper, the functionality of hydrocolloids related to the rheological, physical and sensory characteristics of ice cream mixes and frozen ice cream was studied. Carboxylmethylcellulose, guar gum, sodium alginate and xanthan gum were used as primary stabilizing agents, whereas k-carrageenan as secondary. The hydrocolloid concentrations were 0.1 and 0.2% and the primary to secondary ratio was 9:1. The ice cream samples were stored under quiescent frozen conditions. Samples were taken after 4, 8 and 16 weeks of storage and examined for the functionality of the stabilizing systems.

- by Christos Soukoulis
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- Principal Component Analysis, Rheology, Animal Production, SHELF LIFE

Xanthan gum (XG, 15 g kg −1 ), citrus fiber (CF, 100 g kg −1 ) and variable concentration of guar gum (GG) were used to formulate the optimum ratios of polysaccharide gums as fat replacers. The fat content in LF mayonnaise was reduced to... more

- by Марина Студзинская
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- Food Science, Nutrition, Food and Nutrition, Xanthan Gum

Xanthan Gum, a product used widely in the food industry, possesses high commercial value. The problem with Industrial Xanthan fermentation is its prohibitive cost of using pure sucrose as substrate. Food waste such as Carrot and Pumpkin peels contains glucose, sucrose, vitamins and minerals that are utilized by Xanthomonas campestris at a favourable pH. Effect of pH, whey and multivitamins have been studied on the yield. Xanthan was purified using chilled Isopropyl alcohol following a standard protocol. The yields of xanthan gum with Carrot, Pumpkin and MGYP at pH 6.0 were 40.88g/L, 31.4g/L and 14.06, respectively. Altering the pH in the experiment from 6.0 to 6.8 immensely influenced the biopolymer's yield. Supplementing media with whey and multivitamins rendered positive results. Tackling the problem of food waste in India is difficult and we have recycled food waste to make an economical medium for a high-value food additive i.e., Xanthan gum.

- by GRD JOURNALS and +1
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- Biotechnology, Food Biotechnology, Xanthan Gum, Exopolysaccharides
- by Peter Dockery
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- Analytical Chemistry, Potato, Network Formation, Digital Image Analysis

An olive oil -lemon juice Greek salad dressing was developed employing xanthan gum as stabilizer and gum arabic or propylene glycol alginate as emulsifier in various combinations. In general, samples containing xanthan gum arabic were more stable against oil droplet coalescence and less stable against creaming. The use of propylene glycol alginate in the place of gum arabic, on the other hand, resulted in emulsions of higher creaming stability. Application of steady shear rheology and determination of rheological parameter values from the shearing stress-rate of shear curves, indicated that the rheological properties of the dressings were decreased with storage. Dressing texture assessment preference tests indicated that potential consumers of the product may opt for a medium viscosity product and this has to be taken into consideration when designing polysaccharide -stabilized dressings exhibiting a decrease in their textural characteristics with storage time.

- by Adamantini Paraskevopoulou
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- Food Chemistry, Olive Oil, Multidisciplinary, Xanthan Gum

The 3D flow field generated by a Scaba 6SRGT impeller in the agitation of xanthan gum, a pseudoplastic fluid with yield stress, was simulated using the commercial CFD package. The flow was modeled as laminar and a multiple reference frame (MRF) approach was used to solve the discretized equations of motion. The velocity profiles predicted by the simulation agreed well with those measured using ultrasonic Doppler velocimetry, a non-invasive fluid flow measurement technique for opaque systems. Using computed velocity profiles across the impeller, the effect of fluid rheology on the impeller flow number was investigated. The validated CFD model provided useful information regarding the formation of cavern around the impeller in the mixing of yield stress fluids and the size of cavern predicted by the CFD model was in good agreement with that calculated using Elson's model.

Pectinase from Aspergillus niger associated with polygalacturonase activity, caused considerable debranching-depolymerization of guar galactomannan. Zymogram analysis further confirmed the action of pectinase on the latter. Optimum activity occurred at pH 5.0 and 50 8C and the reaction obeyed Michaelis-Menten kinetics with K m and V max values of 3.72 mg mL K1 and 1.852 mmoles min K1 mg K1 . Viscometry, GPC and HPLC analyses of the native guar galactomannan showed a molecular weight (M w ) of w240 kDa with a galactose:mannose (G:M) ratio of 1:1.6, as revealed by GLC analysis, whereas, after enzymatic catalysis for 60 min, the major resultant product had a M w of w70 kDa with a G:M ratio of 1:2.8, respectively. The latter had a solubility of w98% in water at ambient temperature (within 30 min) compared to w60% for native galactomannan. IR spectral analysis revealed differences in the conformation of enzyme catalyzed guar galactomannan. The latter showed better gelling property with xanthan gum compared to native galactomannan. Use of non-specific pectinase for debranching-depolymerization of guar galactomannan is of commercial interest as modified galactomannans find multiple applications as functional food ingredients. q

- by R. Koka
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- Organic Chemistry, Kinetics, Functional Food, Spectral analysis

The proposal of the present study was to select and carry out the molecular characterization of strains of Xanthomonas sp. in order to correlate with gum production and determine possible genetic alterations during the study. The gums produced were also evaluated rheologically. Ten strains of Xanthomonas were used in the screening and the best ones in terms of productivity were Xanthomonas campestris pv. mangiferaeindicae 1230 (8.93 g/L), X. campestris pv. campestris 254 (9.49 g/L) and X. campestris pv. campestris 1078 (9.67 g/L). The gum produced by X. campestris pv. mangiferaeindicae presented the best apparent viscosity. The results for the profiles of the bands produced by RAPD showed considerable genetic variability amongst the evaluated strains, making not possible to neither group the strains according to pathovar or species, nor correlate the band profile with the productivity obtained. According to the RAPD analysis, no detectable mutations occurred in these bacteria during the study.

- by Helen Treichel and +3
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- Genetics, Organic Chemistry, Xanthan Gum, Molecular Characterization
- by Nazimah Hamid
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- Response Surface Methodology, Regression Analysis, Xanthan Gum, Particle Size

Xanthan gum were produced from the following Xanthomonas strains; standard strain Xanthomonas campestris NRRL B-1459 and isolated strains Xanthomonas arbicola pv. juglandis, Xanthomonas axonopodis pv. vesicatoria, Xanthomonas axonopodis pv. begonia, Xanthomonas axonopodis pv. dieffenbachia. The viscosity features of the xanthan gums obtained were determined at 25–80°C with different pH values and were compared to commercial xanthan gum. Our results indicate that X. arbicola pv. juglandis showed the highest productivity (8.22±1.52 g/L gum). This was followed by X. axonopodis pv. begonia (7.74±1.30 g/L gum), and the control bacterial strain X. campestris NRRL B-1459 (7.46±0.28 g/L gum). X. axonopodis pv. vesicatoria showed the lowest productivity (6.40±0.55 g/L gum). No xanthan gum could be obtained from X. axonopodis pv. dieffenbachia. Xanthan gum produced by X. axonopodis pv. vesicatoria showed the highest viscosity value (428 mPa·sec at 1% solution) in all Xanthomonas strains isolated from plants.

- by ahmet demirci
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- Food Science, Agricultural Biotechnology, Xanthan Gum, Food Sciences

We investigate the use of two distinct and complementary approaches in measuring the viscometric properties of low viscosity complex fluids at high shear rates up to 80,000 s −1 . Firstly, we adapt commercial controlled-stress and controlled-rate rheometers to access elevated shear rates by using parallelplate fixtures with very small gap settings (down to 30 μm). The resulting apparent viscosities are gap dependent and systematically in error, but the data can be corrected-at least for Newtonian fluids-via a simple linear gap correction originally presented by Connelly and Greener, J. Rheol, 29(2): [209][210][211][212][213][214][215][216][217][218][219][220][221][222][223][224][225][226] 1985). Secondly, we use a microfabricated rheometer-ona-chip to measure the steady flow curve in rectangular microchannels. The Weissenberg-Rabinowitsch-Mooney analysis is used to convert measurements of the pressure-drop/flow-rate relationship into the true wall-shear rate and the corresponding rate-dependent viscosity. Microchannel measurements are presented for a range of Newtonian calibration oils, a weakly shear-thinning dilute solution of poly(ethylene oxide), a strongly shear-thinning concentrated solution of xanthan gum, and a wormlike micelle solution that exhibits shear banding at a critical stress. Excellent agreement between the two approaches is obtained for the Newtonian calibration oils, and the relative benefits of each technique are compared and contrasted by considering the physical processes and instrumental limitations that bound the operating spaces for each device.

- by Gareth McKinley
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- Mechanical Engineering, Chemical Engineering, Shear bands, Xanthan Gum

The capability of seed extracts in stabilizing emulsions has particularly received interest in recent years. Upon soaking quince seeds into water, biopolymers inside the seeds are extracted to water, forming mucilage. This study investigates the physical stability, rheology and microstructure of oil (sunflower oil) in water emulsions, stabilized by 2% (w/v) whey protein isolate with varying concentrations of xanthan and quince seed gum. Quince seed gum resulted in emulsions with smaller low-shear viscosities and shear thinning capabilities compared to the same concentrations of xanthan. Quince seed gum emulsions with concentrations ≤ 0.1 (w/v), displayed rapid creaming due to bridging flocculation. Despite the difference in apparent viscosities, for gum concentrations b 0.2 (w/v), both gums demonstrated comparable stability with xanthan gum in general yielding marginally more stable emulsions. Gum concentrations N 0.3 (w/v) resulted in physically stable emulsions even after 5 months. Overall, quince seed gum displayed significant emulsification and stabilization properties.

- by Emrah Kırtıl
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- Food Science, Nutrition, Food and Nutrition, Xanthan Gum

, the influences of the operational conditions have been studied. Temperature (between 22 and 34°C). aeration (changing stirrer speed between 150 and 1,000 rpm, maintained at constant or varied through fermentation time), and the pH control (with two alkalis) were analyzed. Then. unstructured kinetic models proposed in the literature for this system were reviewed and applied. These models have been checked to describe the experimental results, calculating the parameters by nonlinear regression. The results show that these models do not take into account all the necessary nutrients, which are carbon source, nitrogen source. and dissolved oxygen.

- by EMILIA OCHOA
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- Environmental Biotechnology, Parameter estimation, Nonlinear Regression, Xanthan Gum

The knowledge of the head loss in the flow of non-Newtonian fluids is very important for the execution of pipelines and pumping systems designs, common in plants of almost all kinds of industries. The determination of the total head loss involves the establishment of the friction factor corresponding to pressure drop in the straight section and the loss coefficients caused by each fittings and valves existent in piping systems. In this context, the head loss in globe valve, sudden contraction, 90 degree standard elbow and straight smooth circular pipe was studied. The fluids used in the tests were aqueous solutions of carboxymethylcellulose (CMC) and xanthan gum, in different concentrations, flowing in fully-developed turbulent flow. The rheology was determined by a capillary rheometer, in the same temperature condition of the head loss experiments. All solutions employed in this work showed non-Newtonian and pseudoplastic behavior. The rheological data were adjusted for the Ostwald-de Waele model and the correlation coefficients were above 0.99. The experimental data of friction factors were compared with predictive correlations proved in literature. On the other hand, the experimental data of loss coefficients were compared to that obtained to water flow and non-Newtonian flow those data available in literature.

- by Claudia Scheid
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- System Design, Xanthan Gum, Non-newtonian Fluid Mechanics, Pressure Drop

The effect of different hydrocolloids (sodium alginate, k-carrageenan, xanthan gum and hydroxypropylmethylcellulose) on the rheological properties of the wheat¯our dough and the ®nal quality of breads was investigated. A complete study of the rheological behaviour of the dough containing hydrocolloids was performed by using the following instruments: farinograph, extensograph, alveograph and rheofermentometer. The baking response was also determined by using an oven rise recorder. Xanthan and alginate had the most pronounced effect on dough properties yielding strengthened doughs. A great improvement in dough stability during fermentation was achieved by adding hydrocolloids. Regarding their effect on bread properties, the hydrocolloids increased the speci®c volume, with the exception of alginate, as well as both moisture retention and water activity. In addition, textural studies revealed that addition of k-carrageenan or hydroxypropylmethylcellulose reduced the ®rmness of bread crumb. In conclusion, k-carrageenan and hydroxypropylmethylcellulose could be used as improvers in the bread-making performance. q

- by José Rojas Galván
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- Xanthan Gum, Water Activity, Rheological properties, Food Sciences

The main objective of the present work was to develop sustained release bilayer tablets ofwater soluble drug tramadol using Guargum, HPMC, NaCMC and Xanthan gum, either alone or in combinations. Tablets were prepared by immediate release direct compression and sustained release wet granulation method and evaluated for various physical parameters. The drug release studies were performed using USP apparatus type І using 0.1N Hcl and pH 6.8 phosphate buffer as dissolution medium. The drug release was dependent on the type and concentration of the polymer. Drug release was faster from tablets prepared with Guargum, NaCMC and HPMC alone. However, in combination with HPMC, NaCMC, Guargum with Xanthan gum it sustained drug release effectively. The rate and mechanism of release of Tramadol Hcl analysed by fitting the dissolution data into the zero order, First order, Higuchi, Korsmeyer-Peppas and hexon crowel equations. All the Formulations (F1-F10) followed Zero order release Mechanism. Higuchi plots for all the formulations were linear indicating the drug release by diffusion controlled. Hixon-Crowell cube root model showed high r 2 value proportionality due to erosion of hydrophilic gel layer. To explore the release pattern, results of the in-vitro dissolution data were fitted to the Korsmeyer-Peppas equation, which characterizes the transport mechanism indicates the non fickian transport it refer to combination of both diffusion and erosion rate release. It can be concluded that the optimized batch F7 by adopting biphasic drug release pattern in a single dosage could improve patient compliance and give better disease management.

- by Nguyen Binh
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- Chemistry, Medicine, Xanthan Gum, Tramadol

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.

- by Nestor Ramirez
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- Mechanical Engineering, Chemical Engineering, Stress relaxation, Porous Media

Purpose: The aim of this study was to design and evaluate matrix controlled release delivery system of a highly water-soluble analgesic, Tramadol Hydrochloride, using Hydroxy Propyl Methyl Cellulose K 100 M and Xanthan Gum alone and in combination as retarding polymers.
Methods: Tablets were prepared by direct compression and wet granulation using PVP K 30 as granulating agent. HPMC and XG were used alone. Combinations were designed by using 32- full factorial design. Polymer concentrations were taken as variables. Dosage forms were characterized for powder properties like angle of repose, bulk density, tapped density, Carr’s Index, % porosity, Void volume and tablet properties like content uniformity, weight variation, hardness, friability, thickness, % swelling, and in vitro dissolution. The effects by both polymers were analyzed by using factorial contour plots.
Results: The wet granulation and directly compressed tablets showed good flow property and compressibility. There was no variation in content uniformity, thickness and weight. Swelling was ranging from 11 to 30 %. Dissolution profile showed the polymer concentration dependent release up to 12 hrs. Combination of xanthan gum and HPMC was retarded the drug release for more than 12 hours.
Conclusion: For a water soluble drug single polymer like HPMC K 100 M or xanthan gum could not retard the release for longer time. But the combination of these polymers significantly retarded the release rate.

- by Yogesh Thorat
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- Controlled release, Factorial Design, Xanthan Gum, Swelling

The present study was designed to formulate and evaluate balanced Floating Drug Delivery Systems as controlled release modules, which prolongs the release rate of the drugs. Amoxycillin is an anti-bacterial acts by inhibiting the synthesis of bacterial cell walls. It inhibits cross-linkage between the linear peptidoglycan polymer chains that make up a major component of the cell walls of both Gram-positive and Gram-negative bacteria. Helicobacter pylori exists in the gastric mucous layer or epithelial cell surfaces. Thus, the concentration and resident time of Amoxycillin trihydrate in stomach would be effective for complete eradication of Helicobacter pylori. Formulation of Amoxycillin trihydrate as gastro retentive drug delivery systems (GRDDS) is especially advantageous over other prolonged type drug delivery systems and conventional tablets because the drug is having absorption window in upper part of gastro intestinal tract and having relatively short half life. Amoxycillin trihydrate was taken as the model drug to optimized formulations was prepared. The single unit floating matrix tablets of Amoxycillin trihydrate with different natural and synthetic polymers such has HPMC K4M, HPMC K15M, HPMC K100M by taking single polymer in the formulation.The evaluation of physicochemical characteristics of all formulations and to carryout in vitro drug release studies using USP XXIV apparatus and data were analyzed at 272nm.The drug release of Amoxycillin trihydrate from formulations containing HPMC K4M,HPMC K15M followed zero order kinetics where has formulation containing combination of xanthan gum(natural polymer) and HPMC K100M(synthetic polymer) followed Higuchi and First-order pattern respectively. Of all the formulations in which combination of polymers has retarded the drug successfully upto 12 hours.

- by Nitin Ingle
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- Helicobacter pylori, Xanthan Gum

Probiotic ice cream is a functional frozen dairy dessert with peculiar sensory characteristics combining the flavor and taste of fermented milks with the texture of ice cream. In this study, the effects of compositional parameters (hydrocolloids type and percentage, yogurt and milk fat content) on its texture and flavor were evaluated. The use of xanthan gum or hydroxypropylmethylcellulose at a level of 0.3 g/ 100 g in full fat (4 g/100 g milk fat) and low acidified (25 g/100 g yogurt addition) formulations is recommended to achieve improved creamy sensation, high textural quality and enhanced flavor. Based on hedonic and descriptive judgements, consumers' acceptability is mainly affected by ten sensory drivers including "sweet", "sour", "astringent", "vanilla flavor", "gummy", "coarse", "watery", "creamy", and "foamy". Partial least squares (PLS) regression was applied to model samples overall acceptability using the descriptive analysis data. One generic and six related to each compositional parameter (hydrocolloids type, yogurt and milk fat content) PLS models were successfully constructed. The generic PLS model can be used for the quantification of the consumers' acceptability of probiotic ice creams and related fermented products whereas the compositionally restricted PLS models could be a useful tool for the purposes of R&D in the food industry to design and develop novel products.

- by Christos Soukoulis
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- Animal Production, Ice Cream, Xanthan Gum, Milk Fat

Studies have been made of the changes in droplet sizes, surface coverage and creaming stability of emulsions formed with 30% (w/w) soya oil, and aqueous solution containing 1 or 3% (w/w) sodium caseinate and varying concentrations of xanthan gum. Addition of xanthan prior to homogenization had no significant effect on average emulsion droplet size and surface protein concentration in all

- by Yacine Hemar and +2
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- Xanthan Gum, Particle Size, Phase Separation, Food Sciences

Electrical resistance tomography (ERT) provides a non-intrusive technique to examine, in three dimensions, the homogeneity and flow pattern inside the mixing tank. In this study, a 4-plane 16-sensor ring ERT system was employed to study the shape and the size of cavern generated around a radial-flow Scaba 6SRGT impeller in the mixing of xanthan gum solution, which is a pseudoplastic fluid possessing yield stress. The size of cavern measured using ERT was in good agreement with that calculated using Elson's model (cylindrical model). The 3D flow field generated by the impeller in the agitation of xanthan gum was also simulated using the commercial computational fluid dynamics (CFD) package (Fluent). The CFD model provided useful information regarding the impeller pumping capacity, flow pattern, and the formation of cavern around the impeller. CFD results showed good agreement with the experimental data and theory. ᭧

The past decade has seen considerable progress in the development of models simulating pesticide transport in structured soils subject to preferential flow (PF). Most PF pesticide transport models are based on the two-region concept and usually assume one (vertical) dimensional flow and transport. Stochastic parameter sets are sometimes used to account for the effects of spatial variability at the field scale. In the past decade, PF pesticide models were also coupled with Geographical Information Systems (GIS) and groundwater flow models for application at the catchment and larger regional scales. A review of PF pesticide model applications reveals that the principal difficulty of their application is still the appropriate parameterization of PF and pesticide processes. Experimental solution strategies involve improving measurement techniques and experimental designs. Model strategies aim at enhancing process descriptions, studying parameter sensitivity, uncertainty, inverse parameter identification, model calibration, and effects of spatial variability, as well as generating model emulators and databases. Model comparison studies demonstrated that, after calibration, PF pesticide models clearly outperform chromatographic models for structured soils. Considering nonlinear and kinetic sorption reactions further enhanced the pesticide transport description. However, inverse techniques combined with typically available experimental data are often limited in their ability to simultaneously identify parameters for describing PF, sorption, degradation and other processes. On the other hand, the predictive capacity of uncalibrated PF pesticide models currently allows at best an approximate (order-of-magnitude) estimation of concentrations. Moreover, models should target the entire soil-plant-atmosphere system, including often neglected above-ground processes such as pesticide volatilization, interception, sorption to plant residues, root uptake, and losses by runoff. The conclusions compile progress, problems, and future research choices for modelling pesticide displacement in structured soils.

- by Robin Gerlach
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- Information Systems, Spatial Analysis, Biofilms, Kinetics

In this study, response surface methodology was used to design gluten-free cakes made from rice flour to be baked in infrared-microwave combination oven. Two types of cake formulations containing different types of gums were used in the experiments, which were xanthan gum and xanthan-guar gum blend. The independent variables were emulsifier content (0, 3, and 6% of flour weight), upper halogen lamp power (50, 60, and 70%), and baking time (7, 7.5, and 8 min). Specific volume, surface color change, firmness and weight loss of the cakes were determined for optimization. Cakes formulated with xanthan gum had better quality characteristics than cakes containing xanthan-guar gum blend. Cakes formulated with xanthan gum and 5.28% emulsifier and baked using 60% halogen lamp power for 7 min had the most acceptable quality.

- by Gulum Sumnu and +1
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- Response Surface Methodology, Weight Loss, Xanthan Gum, Infrared