Viscosity Of Xanthan Gum Solutions Research Articles

Formulation, Evaluation, and Clinical Assessment of Novel Solid Lipid Microparticles of Tetracycline Hydrochloride for the Treatment of Periodontitis.

The novel solvent-free process to formulate long-acting microparticles of tetracycline hydrochloride (TH) using hot melt extrusion granulation process coupled with size reduction using comil for the treatment of periodontitis was investigated using hydrogenated castor oil (HCO) as hydrophobic matrix former. The microparticles were characterized for micromeritics, drug diffusion, SEM studies, and stability analysis by DSC, FTIR, and proton NMR. Xanthan gum gel was used as delivery vehicles to administer microparticles inside periodontal pockets. The microparticles were sterilized using gamma radiation; delivery vehicle was sterilized using gamma radiation and autoclave process. Microparticles were evaluated for microbial load as per compendial guidelines. Optimized composition was evaluated for clinical parameters such as plaque index, gingival index, probing pocket depth, and clinical attachment level. Based on the statistical analysis of the data, the micromeritic properties and drug diffusion profiles vary based on the concentration of HCO in the formulation. SEM images reflect the surface properties prior and post drug diffusion studies, which indicates that release takes place predominantly by diffusion of TH through HCO matrix. DSC studies indicate no change in the respective spectra of initial and stability samples. FTIR studies indicate possibility of hydrogen bonding. Proton NMR data suggests characteristic peaks of TH being retained in the stability samples, indicating stable composition. Gamma radiation has led to significant reduction in viscosity of xanthan gum solution over autoclave. Clinical studies indicated statistical improvements in the formulation compared to baseline results, indicating the efficacy of the formulation in the treatment of periodontitis.

Determination method of the cavern boundary viscosity in a stirred tank with pseudoplastic fluid

AbstractIt is essential to predict the cavern boundary accurately for investigating the cavern characteristics and achieving efficient mixing of the pseudoplastic fluids. The distribution characteristics of apparent viscosity of xanthan gum solutions at different mass concentrations stirred by the impeller of perturbed six‐bent‐bladed turbine (6PBT impeller) were numerically investigated through the computational fluid dynamics (CFD) simulation based on laminar flow model. The determination method of the cavern boundary viscosity was presented, and the predicted results were compared with those of traditional velocity method. Results showed that the data of the power consumption predicted using CFD simulation agreed well with those measured by torque experiment, which validated the laminar flow model. The ηa − γ curve changes from nearly horizontal straight line to the power function curve along the direction of center axis toward tank wall. As a result, the location of the transitional point can be determined as the cavern boundary, and the corresponding viscosity is the cavern boundary viscosity. The ratio of the cavern boundary viscosity and the fluid yield viscosity ( ηa/ηy) always remains approximately constant, that is, at different speeds. Compared with the traditional velocity method, the boundary viscosity method can maintain its high accuracy for exhibiting the cavern boundary, and the predicted cavern size and development are always in good agreement with the CFD results free from the speed and the impeller type. So this work can provide a new way for accurately characterizing the cavern boundary.

Investigation of the compatibility of xanthan gum (XG) and calcium polysulfide and the rheological properties of XG solutions

ABSTRACTShear thinning xanthan gum (XG) solutions as the delivery media can solve the bypassing problem induced by heterogeneity, especially with low permeable zones in aquifers. Experiments were conducted to investigate the compatibility of XG and calcium polysulfide (CPS) aiming at chromium contamination in groundwater. Rheological properties of XG solutions DURING delivery were studied. Results indicated that (1) XG slowed down the reduction of hexavalent chromium by CPS, and the reaction fitted well with the second-order kinetics. (2) CPS dosage had a significant effect on the removal of chromium (VI), but it was less pronounced as the CPS concentration over 160 mg/L. (3) Cationic ions (e.g. Na+ and Ca2+) decreased the solution viscosity, while anionic ions maintained the viscosity and shear thinning properties of XG solutions. CPS decreased the viscosity of XG solutions. (4) The solution viscosity increased linearly with the XG concentration (less than 1500 mg/L) at a low shear rate. The presence of aquifer media resulted in a drastic decrease in solution viscosity due to physical molecular breakdown and biodegradation. (5) The rheological properties of XG solutions were described by a power law model. The presented empirical relations may also provide a theoretical basis for field applications.

INFLUENCE OF SURFACE COATING WITH XANTHAN GUM ON HEAT TRANSFER DURING DEEP‐FAT FRYING OF POTATO STRIPS

ABSTRACTPotato strips were coated with xanthan gum solutions (0.3, 0.6, 0.9%, w/v) which exhibited shear‐thinning and weak gel‐like characteristics. Then, the effects of the surface coating on heat transfer during deep‐fat frying of the potato strips were investigated as a function of concentration of xanthan gum solutions. Deep‐fat frying of surface‐coated potato strips exhibited sigmoidal temperature profiles which were shown to be dependent on the concentration of xanthan gum solutions. Heat transfer coefficients were also determined to be between 215 and 254 W/m2 K. The use of higher concentration of xanthan gum led to a distinct decrease in heat transfer coefficients during frying of potato strips, which were shown to be highly correlated to the viscosity of xanthan gum solution (R2 = 0.99). It thus suggested that the surface coating of potato strips with xanthan gum might create an insulating layer, consequently reducing the rate of heat transfer during frying.PRACTICAL APPLICATIONSCoating and batters in the frying industry are the common methods to reduce the oil uptake of fried foods. However, few experiments have been carried out to investigate the changes in the heat transfer during frying when a food matrix is coated or battered. In this study, a food matrix coated with hydrocolloid solutions was subjected to deep‐fat frying during which heat transfer coefficients were investigated. Our results obtained in this study can provide a fundamental understanding for the mechanisms of heat transport in coated (or battered) fried food systems, consequently helping optimization and control of a frying process.

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.

Viscosity of Xanthan Gum Solutions at Low Shear Rates

The viscosity of xanthan gum solutions in the low shear region was investigated with the aid of a Couette instrument. All solutions were highly pseudoplastic. Solutions containing 0.3–0.5% of the gum exhibited a highly ordered phase at very low shear. Viscosity, the degree of pseudoplasticity, and the value of the transition from soft gel to pseudoplastic behavior were directly related to gum concentration. The effect of the addition of a salt on viscosity depended on the xanthan gum concentration. The viscosity of a 0.3% xanthan gum solution was practically unaffected by the salts. Higher gum concentrations exhibited a viscosity increase when salt was present. Concentrations >0.3% exhibited a viscosity decrease in the presence of a salt. All viscosity effects seemed to reach limiting values at ~10−3 to 3.3 × 10−3N salt. No major differences were observed between sodium chloride, calcium chloride, and sodium citrate in their influence on xanthan gum viscosity.