Modelling the microbial dynamics and antimicrobial resistance development of Listeria in viscoelastic food model systems of various structural complexities

Minimal processing for microbial decontamination, such as the use of natural antimicrobials, is gaining interest in the food industry as these methods are generally milder than conventional processing, therefore better maintaining the nutritional content and sensory characteristics of food products. The aim of this study was to quantify the impact of (i) structural composition and complexity, (ii) growth location and morphology, and (iii) the natural antimicrobial nisin, on the microbial dynamics of Listeria innocua. More specifically, viscoelastic food model systems of various compositions and internal structure were developed and characterised, i.e. monophasic Xanthan gum-based and biphasic Xanthan gum/Whey protein-based viscoelastic systems. The microbial dynamics of L. innocua at 10 °C, 30 °C and 37 °C were monitored and compared for planktonic growth in liquid, or in/on (immersed or surface colony growth) the developed viscoelastic systems, with or without a sublethal concentration of nisin. Microscopy imaging was used to determine the bacterial colony size and spatial organisation in/on the viscoelastic systems. Selective growth of L. innocua on the protein phase of the developed biphasic system was observed for the first time. Additionally, significant differences were observed in the colony size and distribution in the monophasic Xanthan gum-based systems depending on (i) the type of growth (surface/immersed) and (ii) the Xanthan gum concentration. Furthermore, the system viscosity in monophasic Xanthan gum-based systems had a protective role against the effects of nisin for immersed growth, and a further inhibitory effect for surface growth at a suboptimal temperature (10 °C). These findings give a systematic quantitative insight on the impact of nisin as an environmental challenge on the growth and spatial organisation of L. innocua, in viscoelastic food model systems of various structural compositions/complexities. This study highlights the importance of accounting for system structural composition/complexity when designing minimal food processing methods with natural antimicrobials.

Xanthan gum production from acid hydrolyzed broomcorn stem as a sole carbon source by Xanthomonas campestris

Xanthan gum is an exo-polysaccharide industrially produced by fermentation using simple sugars. In this study, broomcorn stem was introduced as a low-cost- and widely available carbon source for xanthan gum fermentation. Broomcorn stem was hydrolyzed using sulphuric acid to liberate reducing sugar which was then used as a carbon source for biosynthesis of xanthan gum by Xanthomonas campesteris. Effects of hydrolysis time (15, 30, 45 and 60 min), sulphuric acid concentration (2, 4, 6 and 8% v/v) and solid loading (3, 4, 5 and 6% w/v) on the yield of reducing sugar and consequent xanthan production were investigated. Maximum reducing sugar yield (55.2%) and xanthan concentration (8.9 g/L) were obtained from hydrolysis of 4% (w/v) broomcorn stem with 6% (v/v) sulphuric acid for 45 min. The fermentation product was identified and confirmed as xanthan gum using Fourier transform infrared spectroscopy analysis. Thermogrvimetric analysis showed that thermal stability of synthesized xanthan gum was similar to those reported in previous studies. The molecular weight of the produced xanthan (2.23 × 10⁶ g/mol) was determined from the intrinsic viscosity. The pyruvate and acetyl contents in xanthan gum were 4.21 and 5.04%, respectively. The chemical composition results indicated that this biopolymer contained glucose, mannose and glucoronic acid with molecular ratio of 1.8:1.5:1.0. The kinetics of batch fermentation was also investigated. The kinetic parameters of the model were determined by fermentation results and evaluated. The results of this study are noteworthy for the sustainable xanthan gum production from low-value agricultural waste.

Influence of gas injection on viscous and viscoelastic properties of Xanthan gum

Xanthan gum is widely used as a model fluid for sludge to mimic the rheological behaviour under various conditions including impact of gas injection in sludge. However, there is no study to show the influence of gas injection on rheological properties of xanthan gum specifically at the concentrations at which it is used as a model fluid for sludge with solids concentration above 2%. In this paper, the rheological properties of aqueous xanthan gum solutions at different concentrations were measured over a range of gas injection flow rates. The effect of gas injection on both the flow and viscoelastic behaviour of Xanthan gum (using two different methods - a creep test and a time sweep test) was evaluated. The viscosity curve of different solid concentrations of digested sludge and waste activated sludge were compared with different solid concentrations of Xanthan gum and the results showed that Xanthan gum can mimic the flow behaviour of sludge in flow regime. The results in linear viscoelastic regime showed that increasing gas flow rate increases storage modulus (G'), indicating an increase in the intermolecular associations within the material structure leading to an increase in material strength and solid behaviour. Similarly, in creep test an increase in the gas flow rate decreased strain%, signifying that the material has become more resistant to flow. Both observed behaviour is opposite to what occurs in sludge under similar conditions. The results of both the creep test and the time sweep test indicated that choosing Xanthan gum aqueous solution as a transparent model fluid for sludge in viscoelastic regime under similar conditions involving gas injection in a concentration range studied is not feasible. However Xanthan gum can be used as a model material for sludge in flow regime; because it shows a similar behaviour to sludge.

Magnetically triggered release of amoxicillin from xanthan/Fe3O4/albumin patches

This work was motivated by the need of stimuli responsive drug carriers, which can be activated by low cost non-invasive stimuli such as external magnetic field (EMF). Thus, novel antimicrobial materials based on xanthan gum (XG), magnetic nanoparticles (MNP), bovine serum albumin (BSA) and amoxicillin (Amox) were designed in order to promote the release of Amox under magnetic stimuli. Firstly, surfaces with different functionalities were prepared by sequential deposition of thin layers on Si wafers and characterized by means of ellipsometry and atomic force microscopy. Amox adsorbed preferentially onto XG or BSA films. In solution, favorable interactions between Amox and BSA were evidenced by substantial changes in the BSA secondary structure, as revealed by circular dichroism. Patches of XG and XG/MNP/BSA were immersed in 2 g L^-1 Amox, yielding 10 ± 3 and 17 ± 4 μg/cm³ Amox loading, respectively. The inclusion of 0.2 wt% Fe₃O₄ in the patches and their exposure to EMF enabled in vitro release of Amox, at pH 5.5 and 0.02 mol L^-1 NaCl, following the quasi-Fickian behavior. Amox diffused from XG/MNP/BSA patches in agar medium containing Staphylococcus aureus and Escherichia coli, inhibiting their growth. The inhibition of E. coli growth was particularly efficient under EMF.

Magnetic hydrogels for levodopa release and cell stimulation triggered by external magnetic field

Magnetic responsive hydrogels composed of alginate (Alg) and xanthan gum (XG), crosslinked with Ca²⁺ ions, were modified by in situ magnetic nanoparticles (MNP) formation. In comparison to magnetic Alg hydrogels, magnetic Alg-XG hydrogels presented superior mechanical and swelling properties, due to the high charge density and molecular weight of XG. The loading efficiency of levodopa (LD), an important antiparkinson drug, in the Alg-XG/MNP hydrogels was the highest (64%), followed by Alg/MNP (56%), Alg-XG (53%) and Alg (28%). A static external magnetic field (EMF) of 0.4 T stimulated the release of LD from Alg-XG/MNP hydrogels achieving 64 ± 6% of the initial loading after 30 h. The viability, proliferation and expression of dopaminergic markers of human neuroblastoma SH-SY5Y cell on the LD loaded magnetic hydrogels were successful, particularly under EMF, which stimulated the release of LD. Overall, the results of this study provided the rational design of magnetic hydrogels for the delivery of drugs, which combined with external magnetic stimulus, might improve cell proliferation and specific differentiation.

Effects of Nonionic Surfactants on Xanthan Gum Production: a Survey on Cellular Interactions

Background

Xanthomonas campestris is a biopolymer producing gram negative bacterium. Production of xanthan biopolymer can be affected by different extrinsic factors as well as surfactants. Hitherto, effects of nonionic surfactants on xanthan production have been studied in a limited number of articles.

Objective

In the present study, nonionic surfactants were used to pursue their effects on improvement of xanthan production. Moreover, a number of cellular consequences upon the treatment were investigated with impacts on gum production.

Materials and Methods

Effects of different nonionic surfactants (Tween 20, Tween 80 and Triton X100) on xanthan production and Xanthomonas campestris cells were assessed by ultramicroscopy (SEM), changes in culture turbidity, leakage of sugars and ATP, and quality of xanthan (i.e. pyruvate content and determination of polymer molecular weight).

Results

The nonionic surfactant Tween 20 increased ATP (3.2 folds) and sugar leakage (3.1 folds). Furthermore, they caused cell shape alteration. Tween 80 improved both xanthan production (11 g.L^-1) and viscosity of the product (1368 cP), while the total biomass remained unchanged (2.2 g.L^-1). Molecular weight of xanthan was enhanced (from 23 to 59 million Da). Toxic effect of 5% (v/v) Triton X 100 decreased the turbidity of culture to 120 NTU and total biomass was diminished to 1 g.L^-1. Tween 20 caused the loss of ATP and sugar leakage and led to lower xanthan production. It had no effect on biomass content.

Conclusions

In general, amounts of surfactants that bacterial cells can tolerate seem to be helpful in substrate and metabolite transportation, and enzyme activities involved in xanthan biosynthesis and release. Surfactants induce harsh damages to cell barriers, preventing the growth and adversely affecting quantity and quality of xanthan gum.

Construction and application of a Xanthomonas campestris CGMCC15155 strain that produces white xanthan gum

In the industrial production of xanthan gum using Xanthomonas campestris CGMCC15155, large amounts of ethanol are required to extract xanthan gum from the fermentation broth and remove xanthomonadin impurities. To reduce the amount of ethanol and the overall production cost of xanthan gum, a xanthomonadin‐deficient strain of CGMCC15155 was constructed by inserting the Vitreoscilla globin (vgb) gene, under the control of the LacZ promoter, into the region of the pigA gene, which is involved in xanthomonadin synthesis. The insertion of vgb inactivated pigA, resulting in the production of white xanthan gum. The lack of xanthomonadins resulted in a decreased yield of xanthan gum. However, the expression product of vgb gene, VHb, could increase the metabolism of X. campestris, which allowed the production of xanthan gum to reach wild‐type levels in the engineered strain. The yield, molecular weight, and rheological properties of the xanthan gum synthesized by the engineered and wild‐type bacteria were essentially the same. When the same volume of ethanol was used, the whiteness values of the xanthan gum extracted from engineered and wild‐type bacteria were 65.20 and 38.17, respectively. To extract xanthan gum with the same whiteness, three and seven times the fermentation volume of ethanol was required for the engineered and wild‐type strains, respectively. Thus, the engineered train reduced the requirement for ethanol in xanthan gum production by 133.3%. The results demonstrated that the engineered bacteria used less ethanol, thus reducing the downstream processing cost in xanthan gum production.

High fibre tiger nut pasta and xanthan gum: cooking quality, microstructure, physico-chemical properties and consumer acceptance

The feasibility of replacing wheat semolina by tiger nut flour (20 and 40%) and xanthan gum (1%) in order to obtain high fibre dry pappardelle with fair techno-functional, structural and sensory attributes, was assessed. The cooking properties, texture, colour and sensory acceptance of uncooked and cooked pasta were evaluated. The proximate chemical composition of the raw materials, and the microstructure of the dry pasta were also assessed. The results in this manuscript address the improved nutritional value in terms of its dietary fibre, mineral content, oleic and linoleic acids, and the positive effects on the textural characteristics and cooking behaviour achieved on dry tiger nut based pappardelle using 1% of xanthan gum as a structural agent. Micrographs revealed in fact that the gluten network was better formed when xanthan gum was used. Furthermore, the obtained results seem to support that consumers would prefer pappardelle with 40% tiger nut flour.

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

Shear 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.

Natural gum-type biopolymers as potential modified nonpolar drug release systems

In this work, the relationship between surface properties and drug release mechanism from binary composition tablets formed by quetiapine fumarate and biopolymer materials was studied. The biopolymers correspond to xanthan and tragacanth gums, which are projected as modified drug release systems. The surface studies were carried out by the sessile drop method, while the surface free energy (SFE) was determinate through Young-Dupree and OWRK semi-empirical models. On the other hand, the drug release studies were performed by in vitro dissolution tests, where the data were analyzed through kinetic models of zero order, first order, Higuchi, and Korsmeyer-Peppas. The results showed that depending on the type and the proportion of biopolymer, surface properties, and the drug release processes are significantly affected, wherein tragacanth gum present a usual erosion mechanism, while xanthan gum describes a swelling mechanism that controls the release of the drug.

Thermodynamic compatibility and interactions between Speckled Sugar bean protein and xanthan gum for production of multilayer O/W emulsion

Thermodynamic compatibility and probable interactions between Speckled Sugar been protein (SSBP) and xanthan gum for production of multilayer O/W emulsion (30% oil) were investigated. Different interactions were observed between SSBP and xanthan at different pH (3-7) including electrostatic interactions and hydrogen bonding. These interactions were predominant at pH 3. When low xanthan gum concentration (0.1%) was used, phase separation and complex coacervation observed at this pH (negative effect of interactions). However, at pH 5, only 0.1% xanthan was enough to drastically reduce non-dissolved protein and its precipitation which normally occurs at this pH. In addition, incompatibility or segregative phase behavior which normally occurs when protein and polysaccharide have same charges was not observed (positive effects of interactions). Protein-gum interactions influenced emulsion properties (zeta potential, particle size, PDI, rheology, emulsion capacity, heat stability and creaming rate). Interactions had considerable influence on emulsion shelf life and produced completely stable emulsions at all pH values. Results confirmed that SSBP-xanthan gum mixture has a high potential for production of multilayer emulsions.

Novel in situ forming hydrogel based on xanthan and chitosan re-gelifying in liquids for local drug delivery

Injectable hydrogels have been an attractive topic in biomaterials. However, during gelation in vivo, they are easy to disperse due to tissue exudates, thus leading to failure of controlled drug release. To solve this problem, we present a novel polysaccharide-based injectable hydrogel via self-crosslinking of aldehyde-modified xanthan (Xan-CHO) and carboxymethyl-modified chitosan (NOCC). The physical properties were optimized by adjusting the mass ratio of Xan-CHO and NOCC. Experiments revealed that this material exhibited the characteristics of self-healing, anti-enzymatic hydrolysis, biocompatibility and biodegradability. The releasing curve demonstrated stable release of BSA-FITC within 10 h after injection in liquids. After incorporation with a vascular endothelial growth factor, there was an interaction between this biomaterial and the host, which accelerated the reconstruction of the abdominal wall in rats. Therefore, this injectable hydrogel, as a drug delivery system, can prevent drug outburst in a variety of settings and function as a tissue scaffold.

Ultrasound degradation of xanthan polymer in aqueous solution: Its scission mechanism and the effect of NaCl incorporation

Degradation of xanthan polymer in aqueous solution by ultrasonic irradiation was investigated. The effects of selected variables i.e. sonication intensity, irradiation time, concentration of xanthan gum and molar concentration of NaCl in solution were studied. Combined approach of full factorial design and conventional one-factor-at-a-time was applied to obtain optimum degradation at sonication power intensity of 11.5Wcm^-2, irradiation time 120min and 0.1gL^-1 xanthan in a salt-free solution. Molecular weight reduction of xanthan gum under sonication was described by an exponential decay function with higher rate constant for polymer degradation in the salt free solution. The limiting molecular weight where fragments no longer undergo scission was determined from the function. The incorporation of NaCl in xanthan solution resulted in a lower limiting molecular weight. The ultrasound-mediated degradation of aqueous xanthan polymer chain agreed with a random scission model. Side chain of xanthan polymer is proposed to be the primary site of scission action.

Application of xanthan gum as polysaccharide in tissue engineering: A review

Xanthan gum is a microbial high molecular weight exo-polysaccharide produced by Xanthomonas bacteria (a Gram-negative bacteria genus that exhibits several different species) and it has widely been used as an additive in various industrial and biomedical applications such as food and food packaging, cosmetics, water-based paints, toiletries, petroleum, oil-recovery, construction and building materials, and drug delivery. Recently, it has shown great potential in issue engineering applications and a variety of modification methods have been employed to modify xanthan gum as polysaccharide for this purpose. However, xanthan gum-based biomaterials need further modification for several targeted applications due to some disadvantages (e.g., processing and mechanical performance of xanthan gum), where modified xanthan gum will be well suited for tissue engineering products. In this review, the current scenario of the use of xanthan gum for various tissue engineering applications, including its origin, structure, properties, modification, and processing for the preparation of the hydrogels and/or the scaffolds is precisely reviewed.

Effects of xanthan gum and HPMC on physicochemical and microstructure properties of sponge cakes during storage

The effects of xanthan gum (XG) and hydroxypropyl methylcellulose (HPMC) in sponge cakes were studied. Hydrocolloids enhanced the thickening effect in batter that affected the textural attributes of sponge cakes. During storage, the structural changes in XG-cake resulted in higher hardness compared to HPMC-cake. Similar to XG, HPMC also contributed moistness to cake. The moisture loss of cake containing XG was slower than HPMC-cake. FTIR study showed absorption of OH at region of 3600-2900 cm^-1 that explained the strong interaction of water in cake containing XG compared to other cake formulations.

mangiferaeindicae IBSBF 2103

The conditions of storage, cultivation and maintenance of microbial cultures should preserve the microbiological homogeneity, phenotypic and genotypic characteristics to ensure better reproducibility of metabolic production. To evaluate the influence of the storage condition on the composition of cell fatty acids, genetic profile and biochemical characteristics of Xanthomonas campestris pv. mangiferaeindicae IBSBF 2103, as well as, to identify its relationship with the yielding and viscosity of the xanthan gum produced, this study monitored the strain preserved in two simple and widely used conditions, ultra-freezer (-80 °C) and refrigeration (3-8 °C) during 5 months. Were identified and quantified 13 fatty acids. The cells preserved at -80 °C showed more stable concentration of all fatty acids, producing more xanthan gum and with higher viscosity. The chromosomal analysis obtained with the enzyme XbaI revealed 17 distinct fragments with maximum size of 485 kilobases, without variations among the subcultures maintained in both storage conditions. The X. campestris pv. mangiferaeindicae subcultures preserved at -80 °C showed less pronounced phenotypic variations, which had positive influence in the qualitative and quantitative characteristics of the xanthan gum produced.

Xanthan gum production using jackfruit-seed-powder-based medium: optimization and characterization

Xanthan gum (XG) production by Xanthomonas campestris NCIM 2961 using jackfruit seed powder (JSP) as a novel substrate was reported. Central composite design (CCD) of response surface method (RSM) was used to evaluate the linear and interaction effects of five medium variables (JSP, peptone, citric acid, K₂HPO₄ and KH₂PO₄) for XG production. Maximum XG production (51.62 g/L) was observed at the optimum level of JSP (4 g/L), peptone (0.93 g/L), citric acid (0.26 g/L), K₂HPO₄ (1.29 g/L) and KH₂PO₄ (0.5 g/L). K₂HPO₄ and KH₂PO₄ were found as significant medium components, which served as buffering agents as well as nutrients for X. campestris growth. The obtained biopolymer was characterized as XG by XRD and FTIR analysis. Results of this study revealed that JSP was found to be a suitable low cost substrate for XG production.

Differentiation of dental pulp stem cells into chondrocytes upon culture on porous chitosan-xanthan scaffolds in the presence of kartogenin

Adhesion, proliferation and differentiation of dental pulp stem cells (DPSCs) into chondrocytes were investigated in this work with the purpose of broadening the array of cell alternatives to the therapy of cartilage lesions related to tissue engineering approaches. A porous chitosan-xanthan (C-X) matrix was used as scaffold and kartogenin was used as a selective chondrogenic differentiation promoter. The scaffold was characterized regarding aspect and surface morphology, absorption and stability in culture medium, thickness, porosity, thermogravimetric behavior, X-ray diffraction, mechanical properties and indirect cytocompatibility. The behavior of DPSCs cultured on the scaffold was evaluated by scanning electron microscopy and cell differentiation, by histological analysis. A sufficiently stable amorphous scaffold with mean thickness of 0.89±0.01mm and high culture medium absorption capacity (13.20±1.88g/g) was obtained, and kartogenin concentrations as low as 100nmol/L were sufficient to efficiently induce DPSCs differentiation into chondrocytes, showing that the strategy proposed may be a straightforward and effective approach for tissue engineering aiming at the therapy of cartilage lesions.

Green synthesis of oriented xanthan gum-graphene oxide hybrid aerogels for water purification

Three-dimensional xanthan gum (XG)/graphene oxide (GO) hybrid aerogels were fabricated by ice crystal templating without using chemical modifiers. The hybrid aerogels were prepared by the stirring of xanthan gum-graphene oxide hybrid solution, followed by freezing at low temperature and finally by freeze-drying. The whole preparation could be completed within 12h without producing any contamination and thus considered a fast, simple, economical, and green method for aerogel fabrication. XG/GO hybrid aerogels possessed different hierarchical pore structures because of various freezing temperatures. A network composed of co-aligned pore channels was obtained at a freezing temperature of -40°C. The as-prepared hybrid aerogels exhibited stability and excellent adsorption capacity for organic dyes and heavy metal ions. Therefore, these aerogels could be used as efficient adsorbents in water purification. This study provided a basis for the cost-effective and large-scale commercial production of high-performance graphene oxide-based aerogels for water purification.

Synthesis of xanthan gum graft copolymer and its application for controlled release of highly water soluble Levofloxacin drug in aqueous medium

Graft copolymers (XG-g-PNVP-1 to XG-g-PNVP-5) of xanthan gum (XG) and poly(N-vinyl-2-pyrrolidone) (PNVP) was synthesized by free radical polymerization using peroxymonosulphate/thiourea redox pair. The synthesized graft copolymers were well characterized by ¹H NMR, FTIR, XRD, SEM, TGA/DTA and AFM analyses. The optimum conditions for maximum grafting were determined by varying the concentrations of N-vinyl-2-pyrrolidone (NVP) from 10×10^-2 to 18×10^-2moldm^-3; the grafting ratios increases up to 14×10^-2moldm^-3, while thereafter decreased. Graft copolymer (XG-g-PNVP-D) hybrid was prepared to load levofloxacin drug, about 15mg drug was loaded; and its release was studied in phosphate buffer solution (PBS) at pH 7.4 on 37±0.1°C; About 80% drug was released in 36h.

Enhanced transportability of zero valent iron nanoparticles in aquifer sediments: surface modifications, reactivity, and particle traveling distances

In this study, we assessed the transportability of zero valent iron nanoparticles (nano-Fe⁰) coated with different organics (carboxy methyl cellulose (CMC), poly acrylic acid (PAA), and xanthan gum) in standard porous sand and in real aquifer sediments. Our results suggest that the organic surface coatings optimized for nano-Fe⁰ in porous sand media do not necessarily reflect the same transportability in real field aquifer sediment. Xanthan gum-coated nano-Fe⁰ showed highest transportability in standard porous sand, but the performance was much lower in real aquifer sediment, whereas the PAA-coated nano-Fe⁰ particle showed better transportability both in aquifer sediment and in porous sand media. Nano-Fe⁰ without organic surface coating exhibited very low transportability and was largely retained by the porous medium. Our results suggest that the molecular weight and surface charge density of the organic may play a role in transportability of these nanoparticles. To assess the impact of organic coating on the nanoparticle reactivity with contaminants, we also conducted batch tests to follow TCE degradation using different surface coatings and found no significant difference albeit a minor delay in kinetics. Using theoretical calculations, we also estimated the potential distance traveled by nanoparticles in porous sand as well as in aquifer sediment. Our results suggest that using xanthan gum and PAA as surface coating, nano-Fe⁰ could travel up to 9.8 and 4.1 m, respectively, in the porous sand media as compared to 0.2 and 0.9 m in real aquifer sediment, respectively. Graphical abstract Nanoparticle mobility in porous sand vs and aquifer sediment.

Gelation and thermal characteristics of microwave extracted fish gelatin-natural gum composite gels

In this study, the gelation and thermal characteristics of microwave extracted fish scale gelatin blended with natural gums such as gum arabic (AG), xanthan gum (XG), guar gum (GG), and tragacanth gum (TG) was evaluated. The nature of interaction and behavior of gelatin in presence of various gums was confirmed by particle size analysis, viscosity profile, FT-IR analysis and turbidity measurements. DSC data revealed that addition of AG, TG and GG remarkably improved the thermal stability of fish gelatin gel. The composite gels of TG, AG, and XG exhibited higher hardness and bloom strength values as compared to pure fish gelatin implying its textural synergy. Based on qualitative descriptive analysis, TG was found to be superior in improving the stability of fish gelatin gel, closely followed by AG. The results suggest that addition of these gums can reduce syneresis and retard melting of gelatin gels at ambient temperature, which are otherwise soft and thermally unstable.

Randomized, double-blind, placebo-controlled clinical trial to assess the safety and effectiveness of a novel dual-action oral topical formulation against upper respiratory infections

Background

Current prevention options for upper respiratory infections (URIs) are not optimal. We conducted a randomized, double-blinded, placebo-controlled pilot clinical trial to evaluate the safety and efficacy of ARMS-I™ (currently marketed as Halo™) in the prevention of URIs.

Methods

ARMS-I is patented novel formulation for the prevention and treatment of influenza, comprising a broad-spectrum antimicrobial agent (cetylpyridinium chloride, CPC) and components (glycerin and xanthan gum) that form a barrier on the host mucosa, thus preventing viral contact and invasion. Healthy adults (18–45 years of age) were randomized into ARMS-I or placebo group (50 subjects each). The drug was sprayed intra-orally (3× daily) for 75 days. The primary objectives were to establish whether ARMS-I decreased the frequency, severity or duration of URIs. Secondary objectives were to evaluate safety, tolerability, rate of virus detection, acceptability and adherence; effect on URI-associated absenteeism and medical visits; and effect of prior influenza vaccination on study outcomes.

Results

Of the 94 individuals who completed the study (placebo: n = 44, ARMS-I: n = 50), six presented with confirmed URI (placebo: 4, ARMS-I: 2), representing a 55% relative reduction, albeit this was statistically not significant). Influenza, coronavirus or rhinovirus were detected in three participants; all in the placebo group. Moreover, frequency of post-treatment exit visits was reduced by 55% in ARMS-I compared to the placebo group (N = 4 and 2, respectively). Fever was reported only in the placebo group. ARMS-I significantly reduced the frequency and severity of cough and sore throat, and duration of cough (P ≤ .019 for all comparisons). ARMS-I was safe, well tolerated, had high acceptability and high adherence to medication use. Medical visits occurred only in the placebo group while absenteeism did not differ between the two arms. Prior influenza vaccination had no effect on study outcome.

Conclusions

This randomized proof-of-concept clinical trial demonstrated that ARMS-I tended to provide protection against URIs in the enrolled study participants, while reducing severity and duration of cough and sore throat. A clinical trial with a larger number of study participants is warranted.

Trial registration

ClinicalTrials.gov NCT02644135 (retrospectively registered).

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-2177-8) contains supplementary material, which is available to authorized users.

Effect of pretreatment on the enzymatic hydrolysis of kitchen waste for xanthan production

The study was carried out to gain insight into the effect of pretreatment on enzymatic hydrolysis of kitchen waste (KW) for xanthan fermentation. Herein, various pretreatments were applied and it was found that chemical pretreatment had positive effect on the following enzymatic or overall hydrolysis process. The highest reducing sugar concentration was obtained as 51.87g/L from 2% HCl (90°C) pretreated sample, while the Kjeldahl nitrogen (KDN) concentration was 7.79g/L. Kinetic study showed that first order kinetic model was suitable to describe the enzymatic hydrolysis process. The obtained kitchen waste hydrolysate (KWH) was successfully applied for xanthan fermentation. Xanthan concentration reached 4.09-6.46g/L when KWH with 2% HCl (90°C) pretreatment was applied as medium. In comparison, a xanthan concentration of 3.25-5.57g/L was obtained from KWH without pretreatment. Therefore, pretreatment of KW using diluted acid is favorable for the overall hydrolysis process and effective for xanthan fermentation.

Some Qualitative and Rheological Properties of Virgin Olive Oil- Apple Vinegar Salad Dressing Stabilized With Xanthan Gum

Purpose: Lipid oxidation and rheological properties are the main qualitative parameters determined in food emulsions. Salad dressings are food emulsions important in our daily diet, but conventional salad dressings have high amounts of cholesterol and saturated fatty acids because of egg yolk in their formulations. There are many studies on the modification of salad dressing formulations to replace egg yolk and saturated fats. The present study describes new formulation of salad dressing with olive oil and apple vinegar to produce a functional food product. Methods: This study investigated the qualitative properties, oxidative stability, rheological behavior and microstructure of the salad dressing without egg yolk. Oil-in-water emulsions were prepared with virgin olive oil and apple vinegar stabilized with various percentages of xanthan (T1: 0.25%, T2: 0.5%. T3: 0.75%). Samples were stored at refrigerator for 90 days and experiments were performed at production day and during storage. Results: The obtained results showed that peroxide value was increased for all samples during storage, but it was at an acceptable level. Fatty acid changes were not significant during storage. Droplet size was reduced by increasing xanthan gum. T2 had the best rheological properties during storage. Generally, T2 and T3 had higher scores and were more acceptable in organoleptic assay. Conclusion: Obtained results showed that T₂ had suitable qualitative and rheological properties and can be a proper egg yolk free salad dressing to introduce to the market.

Efficacy of a fixed combination of 0.09 % xanthan gum/0.1 % chondroitin sulfate preservative free vs polyethylene glycol/propylene glycol in subjects with dry eye disease: a multicenter randomized controlled trial

Background

Dry eye disease (DED) is multifactorial, affecting 5–34 % of the global adult population and reducing quality of life. The artificial tears or lubricants are the therapy most used for the treatment of DED, due to their low side effect profile, which attempt to modify the properties of the tear film. The aim of the present study was to evaluate the clinical efficacy of a fixed combination of xanthan gum and chondroitin sulfate preservative free on the ocular surface of patients with dry eye disease during 60 days of intervention.

Methods

A phase III, double-blind, masked, controlled, multicenter, clinical trial of 148 subjects, randomized to either a fixed combination of xanthan gum 0.09 % and chondroitin sulfate 0.1 % (XG/CS) ophthalmic solution (n = 76) or a fixed combination of polyethylene glycol 400 0.4 % and propylene glycol 0.3 % (PEG/PG) (n = 72). Subjects self-dosed four times daily during 60 days. Follow-up was set on days 2, 7, 15, 30 and 60. Assessments of anterior/posterior segment ocular signs were performed. The outcome measures included Schirmer test, tear film break-up time and OSDI score. Security variables included intraocular pressure, lisamine green and fluorescein ocular surface stains.

Results

The primary efficacy endpoints were similar between groups at baseline. After intervention time Schirmer test increased in both groups compared to baseline, XG/CS (6.4 ± 2.2 vs 11.0 ± 6.6; p = 0.002) and PEG/PG (6.5 ± 2.5 vs 10.5 ± 5.6; p = 0.019) respectively. Similar results were reported in the tear film break-up time in XG/CS (5.5 ± 2.1 vs 7.4 ± 2.9; p = 0.027) and PEG/PG (5.2 ± 2.0 vs 7.4 ± 2.7; p = 0.046) respectively. The OSDI score decreased to normal values in both groups, XG/CS (19.3 ± 7.4 vs 7.3 ± 5.9; p = 0.001) and PEG/PG (19.3 ± 7.5 vs 7.9 ± 8.2; p = 0.001) respectively. There was no significant difference between treatments for any parameter. Moreover, both groups decreased the presence of burning sensation, tearing, foreign body sensation, conjunctival hyperemia and photophobia. The adverse events were not related to the interventions.

Conclusions

Xanthan gum/chondroitin sulfate preservative free showed similar clinical efficacy, evaluated with OSDI score, TBUT and Schirmer test compared to polyethylene glycol/propylene glycol in the treatment of dry eye disease.

Trial registration

ClinicalTrials.gov: NCT01657253. Date of registration May 19, 2014.

Dynamic light scattering of xanthan gum biopolymer in colloidal dispersion

The dynamical properties of nanogels of xanthan gum (XG) with hydrodynamic radius controlled in a size range from 5 nm to 35 nm, were studied at the different XG concentrations in water/sodium bis-2-ethylhexyl-sulfosuccinate (AOT)/decane reverse micelles (RMs) vs. mass fraction of nano-droplet (MFD) at W = 40, using dynamic light scattering (DLS). The diffusion study of nanometer-sized droplets by DLS technique indicated that enhancing concentration of the XG polysaccharide resulted in exchanging the attractive interaction between nano-gels to repulsive interaction, as the mass fraction of nano-droplets increased. The reorientation time (τr ) of water nanodroplets decreased with MFD for water-in-oil AOT micro-emulsion comprising high concentration (0.0000625) of XG. On the other hand, decreasing concentration of biopolymer led to increasing the rotational correlation time of water nanodroplets with MFD. In conclusion, a single relaxation curve was observed for AOT inverse microemulsions containing different XG concentrations. Furthermore, the interaction between nanogels was changed from attractive to repulsive versus concentration of XG in the AOT RMs.

Activation of glycerol metabolism in Xanthomonas campestris by adaptive evolution to produce a high-transparency and low-viscosity xanthan gum from glycerol

Many studies have focused on using crude glycerol from biodiesel to obtain valuable products, but few of these studies have focused on obtaining polysaccharides. A mutant strain of Xanthomonas campestris CCTCC M2015714 that could use glycerol to produce high-transparency and low-viscosity xanthan gum was obtained by adaptive evolution, and the yield of xanthan gum reached 11.0g/L. We found that transcriptional levels of genes related to glycerol metabolism (glpF, glpK, glpD, and fbp) in the mutant strain were all higher than those from the parent strain. Using 5g/L sucrose or glucose as starter substrate, cell growth time decreased from 36h to 24h and xanthan gum yield increased. Moreover, the mutant strain can tolerate high titer glycerol, and its activity was not affected by the impurities in crude glycerol. All these results proved that crude glycerol from biodiesel industries can be used for xanthan gum production.

A Randomized Controlled Comparison of Esophageal Clearance Times of Oral Budesonide Preparations

BACKGROUND

Topical steroids prepared as oral viscous slurries have become common in the treatment of eosinophilic esophagitis. Esophageal mucosal contact time correlates with clinical and histologic improvement.

AIM

To compare the mucosal contact time of alternative oral viscous budesonide (OVB) slurries with the conventional sucralose OVB.

METHODS

A blinded randomized crossover trial investigating esophageal clearance of three OVB slurry preparations was done on healthy adults. Honey and xanthan gum OVB slurries were compared with standard sucralose OVB in 24 randomly assigned subjects. Each subject ingested the sucralose OVB and either the honey or xanthan gum OVB slurries. The esophageal clearance of each slurry was evaluated as an area under the curve (AUC) using 1 millicurie of technetium-99m-sulfur colloid (Tc99) co-administered in each OVB preparation using nuclear scintigraphy. A standardized taste survey was also administered.

RESULTS

Xanthan gum had greater mucosal contact time compared to sucralose as measured by a higher AUC at 3 min (P = 0.002), while honey showed no significant difference in esophageal clearance relative to sucralose. Taste scores were significantly higher in the honey group, while scores for xanthan gum were no different from standard sucralose.

CONCLUSION

OVB slurries utilizing xanthan gum may be a superior alternative to a sucralose-based slurry due to its increased mucosal contact time and similar taste tolerance. Honey may be a suitable alternative as well, due to its similar contact time and favorable taste.

Effect of stabilizers, oil level and structure on the growth of Zygosaccharomyces bailii and on physical stability of model systems simulating acid sauces

The effect of xanthan gum, guar gum, oil and the structure promoted by these compounds on the growth of Zygosaccharomyces bailii and on physical stability of emulsified systems simulating acid sauces was studied. Furthermore, the effect of yeast growth on physical stability of emulsions was also evaluated. Yeast growth was evaluated by plate count and modeled by the modified Gompertz equation. Emulsions characteristics and their stability were determined by droplet size, zeta potential and rheological measurements. The latter was also used to evaluate structure's effect on yeast growth. Physical characteristics of emulsions depended on system composition. Yeasts slightly affected droplet size. Z. bailii growth was satisfactorily modeled by the modified Gompertz equation. The specific growth rate (μ_m) and the asymptotic value (A) obtained depended on xanthan gum, guar gum and oil content. Furthermore, the structure promoted by these compounds exerted a significant effect on growth. In general, an increase in the solid character and yield stress through the addition of xanthan gum promoted a decrease in A parameter. On the contrary, a decrease in the solid character through the addition of guar gum promoted an increase in the A parameter. The results obtained stressed that stabilizers, oil and their structuring ability play an important role on Z. bailii growth.

Determination of relationship between sensory viscosity rating and instrumental flow behaviour of soluble dietary fibers

The shear-thinning low, medium and high-viscosity fiber preparations (0.15-1.05 % psyllium husk, 0.07-0.6 % guar gum, 0.15-1.20 % gum tragacanth, 0.1-0.8 % gum karaya, 0.15-1.05 % high-viscosity Carboxy Methyl Cellulose and 0.1-0.7 % xanthan gum) showed that the consistency coefficient (k) was a function of concentration, the relationship being exponential (R(2), 0.87-0.96; P < 0.01). The flow behaviour index (n) (except for gum karaya and CMC) was exponentially related to concentration (R(2), 0.61-0.98). The relationship between k and sensory viscosity rating (SVR) was essentially linear in nearly all cases. The SVR could be predicted from the consistency coefficient using the regression equations developed. Also, the relationship of k with fiber concentration would make it possible to identify the concentration of a particular gum required to have desired consistency in terms of SVR.

Development and evaluation of natural gum-based extended release matrix tablets of two model drugs of different water solubilities by direct compression

The study was aimed at developing extended release matrix tablets of poorly water-soluble diclofenac sodium and highly water-soluble metformin hydrochloride by direct compression using cashew gum, xanthan gum and hydroxypropylmethylcellulose (HPMC) as release retardants. The suitability of light grade cashew gum as a direct compression excipient was studied using the SeDeM Diagram Expert System. Thirteen tablet formulations of diclofenac sodium (∼100 mg) and metformin hydrochloride (∼200 mg) were prepared with varying amounts of cashew gum, xanthan gum and HPMC by direct compression. The flow properties of blended powders and the uniformity of weight, crushing strength, friability, swelling index and drug content of compressed tablets were determined. In vitro drug release studies of the matrix tablets were conducted in phosphate buffer (diclofenac: pH 7.4; metformin: pH 6.8) and the kinetics of drug release was determined by fitting the release data to five kinetic models. Cashew gum was found to be suitable for direct compression, having a good compressibility index (ICG) value of 5.173. The diclofenac and metformin matrix tablets produced generally possessed fairly good physical properties. Tablet swelling and drug release in aqueous medium were dependent on the type and amount of release retarding polymer and the solubility of drug used. Extended release of diclofenac (∼24 h) and metformin (∼8-12 h) from the matrix tablets in aqueous medium was achieved using various blends of the polymers. Drug release from diclofenac tablets fitted zero order, first order or Higuchi model while release from metformin tablets followed Higuchi or Hixson-Crowell model. The mechanism of release of the two drugs was mostly through Fickian diffusion and anomalous non-Fickian diffusion. The study has demonstrated the potential of blended hydrophilic polymers in the design and optimization of extended release matrix tablets for soluble and poorly soluble drugs by direct compression.

Xanthan gum as a fat replacer in goshtaba-a traditional meat product of India: effects on quality and oxidative stability

Goshtaba is a restructured meat product of Kashmiri wazwan prepared from meat emulsion with added fat (20 %), salt, spices and condiments and cooked in the curd. The present study was undertaken for the development of low fat goshtaba with the addition of xanthan gum as a fat replacer and was evaluated for proximate composition, pH, colour, lipid and protein oxidation, texture, microstructure and sensory properties. Low fat goshtaba formulations containing xanthan gum were higher in protein and moisture contents but, lower in fat content and pH value than the high fat control (p < 0.05). Colour evaluation revealed that high fat goshtaba had significantly higher L* value, but lower a* value than its low fat counterparts (p < 0.05). The significant decrease of TBARS values, protein carbonyls and loss of protein sulphydryl groups in low fat goshtaba formulations reflects the potential antioxidant activity of xanthan gum (p < 0.05). Hardness was significantly higher in high fat control but, cohesiveness, gumminess, and chewiness did not show any significant difference. Springiness increased with the increasing concentration of xanthan gum (0.5-1.5 %) and was higher in low fat product containing 1.5 % xanthan gum. SEM results indicate that xanthan gum lead to formation of an additional gel network which holds more water. Sensory evaluation revealed that goshtaba product with 0.5 % xanthan gum had quality characteristics that were similar to the control product containing 20 % fat.

Development of eggless gluten-free rice muffins utilizing black carrot dietary fibre concentrate and xanthan gum

Gluten-free muffins are generally made from purified flours and starches (from non-gluten sources) which are deficient in dietary fibre and have poor quality attributes. In this regard, the present work was undertaken to explore application of black carrot pomace dietary fibre concentrate (BCF) and xanthan gum (XG) in gluten-free rice muffins. Physicochemical properties of BCF and rice flour were studied. BCF was incorporated at three levels (3, 6 and 9 %) in rice flour, while XG was added at 0.5 % level to study their effect on muffin batters and physicochemical properties of muffins. BCF showed higher water absorption and oil absorption capacities than rice flour. Incorporation of BCF and XG increased flour paste viscosities and batter viscoelasticity. Incorporation of BCF increased total dietary fibre content (TDF) and decreased the L* and b* values, water activity (aw), specific volume and firmness. On the other hand, XG improved appearance and specific volume of the rice muffins prepared with and without BCF. Muffins prepared with 6 % BCF incorporation and XG were the most acceptable. This study demonstrated that BCF and XG can be used as viable functional ingredients in the preparation of gluten-free muffins.

Effective removal of humic acid using xanthan gum incorporated polyethersulfone membranes

In this study, xanthan gum (XA) was used as a hydrophilic biopolymer additive for the modification of polyethersulfone (PES) membrane to removal of humic acid (HA). The membranes are prepared using phase inversion technique and the concentration of XA was varied from 0.5 to 1.5wt%. The prepared membranes are characterized as a function of hydrophilicity, equilibrium water content (EWC), porosity studies and functional group analysis. Membrane surface and cross-sectional morphology was studied using scanning electron microscope. The lower contact angle value 64.2° was exhibited, when 1.5wt% of XA incorporated in PES membrane and this ensures that increase of hydrophilicity in pristine PES membrane. Further, higher water permeability (PWP) of 68.9(-9)m/skPa was observed for 1.5wt% of XA/PES membrane. The effect of pH on HA removal was studied for neat PES and XA/PES membranes. The rejection performance of XA incorporated in PES membranes were compared with commercial available PES membrane.

Stepwise bioprocess for exopolysaccharide production using potato starch as carbon source

Xanthan gum is a biopolymer produced by Xanthomonas sp. XC6. In this study, xanthan gum is produced from potato starch using a stepwise bioprocess design. Potato starch is hydrolyzed using Bacillus sp. having amylase activity and 30.2 g/L reducing sugar was released, while Xanthomonas sp. XC6 can release only 14.5 g/L. Bacillus sp. hydrolyzed potato starch extract was further used as a carbon source for xanthan gum biosynthesis using Xanthomonas sp. XC6. Yeast extract acts as the best nitrogen source, and 10.0 g/L xanthan gum was recovered. Downstreaming process after stepwise bioprocess resulted in 17.4 g/L xanthan gum production, which is 2.8 times higher as compared to single step process.

Poloxamer bioadhesive hydrogel for buccal drug delivery: Cytotoxicity and trans-epithelial permeability evaluations using TR146 human buccal epithelial cell line

A salbutamol sulfate (SS)-Poloxamer bioadhesive hydrogel specially developed for buccal administration was investigated by studying interactions with TR146 human buccal epithelium cells (i.e. cellular toxicity (i) and trans-epithelial SS diffusion (ii)). The assessment of cell viability (MTT, Alamar Blue), membrane integrity (Neutral Red), and apoptosis assay (Hoechst 33342), were performed and associated to Digital Holographic Microscopy analysis. After the treatment of 2h, SS solution induced drastic cellular alterations that were prevented by hydrogels in relation with the concentrations of poloxamer and xanthan gum. The formulation containing P407 19%/P188 1%/Satiaxane 0.1% showed the best tolerance after single and multiple administrations and significantly reduced the trans-epithelial permeability from 5.00±0.29 (×10(3)) (SS solution) to 1.83±0.22 cm/h. Digital Holographic Microscopy images in good agreement with the viability data confirmed the great interest of this direct technique. In conclusion, the proposed hydrogels represent a safe and efficient buccal drug delivery platform.

Viscosupplementation of synovial fluid with xanthan gum for treatment of osteoarthritis and its clearance kinetics in the rabbit knee joint

BACKGROUND

Injection of xanthan gum (XG) has been demonstrated to reduce the symptoms and progression of osteoarthritis (OA) in experimental models. Due to its high viscosity and stability, it may restore the rheological homeostasis of osteoarthritic synovial fluid (SF), and avoid numerous intra-articular injections.

OBJECTIVE

The present study investigated the effect of XG on the rheological properties of SF, and determined its residence time in the rabbit joint cavity.

METHODS

Rabbit knees were subject to intra-articular injection with XG or XG labeled with green fluorescence, and the SF was collected at different time. Rheological properties of SF with XG injected were compared with those with sodium hyaluronate injected. Resistance to oxidant damage was tested by adding H2O2 to the viscosupplement. Fluorescence intensity was measured for the SF with XG labeled with green fluorescence.

RESULTS

Results showed that XG could significantly improve the SF viscosity at 24, 96, 168 h, and increase the storage moduli (G') and loss moduli (G″) tested at frequency of 0.5 and 2.5 Hz. SF with XG injection exhibited a gel-like behavior at 24 h, in that G' exceed G″ over the entire oscillation frequency range. XG preparation had a high resistance to oxidant damage. Half-life of XG in the joint cavity was 35.9 h, with clearance obeying first-order kinetics.

CONCLUSIONS

Intra-articular injection of XG could improve the rheological properties of SF, and this effect could last for several days.

Injectable thermo-responsive hydrogel composed of xanthan gum and methylcellulose double networks with shear-thinning property

Injectable hydrogel precursor solution was prepared by physical blend of xanthan gum (XG) and methylcellulose (MC) in aqueous solution. Due to the formation of XG network composed of XG double helical strand structure, XG/MC blend was a high viscous solution with good shear-thinning property at room temperature. When the temperature was changed from 23 to 37 °C, thermo-responsive MC network formed, which caused XG/MC blend solution to gelate. The gelation time and storage modulus of the blend can be tuned by XG and/or MC concentrations. Both in vitro and in vivo investigations revealed that the blend solution immediately recovered its high viscosity and rapidly formed hydrogel at body temperature after injection using a syringe. In vivo biocompatibility and biodegradability of the hydrogel were validated by implantation of the hydrogel in rats. In vitro investigation demonstrated that XG/MC blend is a promising injectable hydrogel material for long-term drug delivery.

Xanthan gum protects rabbit articular chondrocytes against sodium nitroprusside-induced apoptosis in vitro

We have previously reported that intra-articular injection of xanthan gum (XG) could significantly ameliorate the degree of joint cartilage degradation and pain in experimental osteoarthritis (OA) model in vivo. In this present study, we evaluated the protective effect of XG against Sodium nitroprusside (SNP)-induced rabbit articular chondrocytes apoptosis in vitro. Rabbit articular chondrocytes were incubated with various concentrations of XG for 24h prior to 0.5mmol/L SNP co-treatment for 24h. The proliferation of chondrocytes was analyzed using MTT assay. The chondrocytes early apoptosis rates were evaluated using Annexin V-FITC/PI flow cytometry. The morphology of apoptosis chondrocytes were observed by scanning electron microscopy (SEM). The loss/disruption of mitochondrial membrane potential was detected using rhodamin 123 by confocal microscope. The concentration of prostaglandin E2 (PGE2) in cell culture supernatants was evaluated using ELISA assay. The results showed that XG could significantly reverse SNP-reduced cell proliferation and inhibited cell early apoptosis rate in a dose-dependent manner. XG alleviated loss/disruption of mitochondrial membrane potential and decreased the PGE2 level of chondrocytes cell culture supernatants in SNP-induced chondrocytes. These results of the present research strongly suggest that XG can protect rabbit articular chondrocytes against SNP-induced apoptosis in vitro.

Synthesis of macroporous silica biomass nanocomposite based on XG/MgSiO₃ for the removal of toxic ions

Biomass is known as a low-cost adsorbents and there is a need for the development of synthesis method further increase its efficient applications. In this work, a macroporous nanocomposite biomass was synthesized by natural polymer (Xanthan gum) and silicate. The resulting nanocomposite was characterized with XRD, SEM, TEM, BET and FTIR. The analysis confirmed that the functions silicate groups were successfully introduced and the nanocomposite not only showed a special macroporous structure but also showed a better cation exchange capacity which helps to retain cation ions. What's more, in order to investigate the adsorption capacity of the biomass, adsorption experiments were considered. The experiment results revealed that nanocomposite showed a high-efficiency adsorption capacity to remove toxic ions such as arsenic, chromium, mercury and cadmium.

Thiol derivatization of Xanthan gum and its evaluation as a mucoadhesive polymer

Thiol-derivatization of xanthan gum polysaccharide was carried out by esterification with mercaptopropionic acid and thioglycolic acid. Thiol-derivatization was confirmed by Fourier-transformed infra-red spectroscopy. Xanthan-mercaptopropionic acid conjugate and xanthan-thioglycolic acid conjugate were found to possess 432.68mM and 465.02mM of thiol groups as determined by Ellman's method respectively. Comparative evaluation of mucoadhesive property of metronidazole loaded buccal pellets of xanthan and thiolated xanthan gum using chicken buccal pouch membrane revealed higher ex vivo bioadhesion time of thiolated xanthan gum as compared to xanthan gum. Improved mucoadhesive property of thiolated xanthan gum over the xanthan gum can be attributed to the formation of disulfide bond between mucus and thiolated xanthan gum. In vitro release study conducted using phosphate buffer (pH 6.8) revealed a sustained release profile of metronidazole from thiolated xanthan pellets as compared to xanthan pellets. In conclusion, thiolation of xanthan improves its mucoadhesive property and sustained the release of metronidazole over a prolonged period.

Improved functional properties of glycosylated soy protein isolate using D-glucose and xanthan gum

Functional properties of the soy protein need to improve to have better applications in food industry. Alkali extracted and acid precipitated soy protein isolate (SPI) was glycosylated using D-glucose (G) and Xanthan gum (X) via Maillard reaction to improve solubility. The effects of SPI to G and SPI to X ratios (SPI:G = 2:1, 1:1, and 1:2; SPI:X = 100:1 and 10:1) and incubation time (0, 6, 12, and 24 h) on the solubility and functional properties of glycosylated SPI were evaluated. The SPI:G ratio of 1:2 yielded a maximum degree of glycosylation of 71.1 %. The solubility of SPI after glycosylation significantly increased (P < 0.05) at pH 4.0-8.0 compared to SPI alone. Although the emulsion stability of glycosylated SPIs has not significantly increased (P > 0.05), the emulsifying activity improved significantly (P < 0.05). Glycosylation with SPI-X at a ratio of 10: 1 showed maximum emulsifying activity of 191.6 m(2)/g (SPI alone: 66.3 m(2)/g). Moreover, the SPI:X (ratio of 100:1) showed the maximum foaming activity (205 mL) compared to SPI alone (155 mL). The foaming stability of SPI (2.6 %) increased to 5.5 and 8.2 % when using xanthan gum at the ratio of 100:1 and 10:1, respectively. Glycosylated SPI with enhanced emulsifying and foaming properties has potential to improve the functional quality of the food products.

Gel-embedded niosomes: preparation, characterization and release studies of a new system for topical drug delivery

In the present paper physical gels, prepared with two polysaccharides, Xanthan and Locust Bean Gum, and loaded with non-ionic surfactant vesicles, are described. The vesicles, composed by Tween20 and cholesterol or by Tween85 and Span20, were loaded with Monoammonium glycyrrhizinate for release experiments. Size and zeta (ζ)-potential of the vesicles were evaluated and the new systems were characterized by rheological and dynamo-mechanical measurements. For an appropriate comparison, a Carbopol gel and a commercial gel for topical applications were also tested. The new formulations showed mechanical properties comparable with those of the commercial product indicating their suitability for topical applications. In vitro release experiments showed that the polysaccharide network protects the integrity of the vesicles and leads to their slow release without disruption of the aggregated structures. Furthermore, being the vesicles composed of molecules possessing enhancing properties, the permeation of the loaded drugs topically delivered can be improved. Thus, the new systems combine the advantages of matrices for a modified release (polymeric component) and those of an easier permeability across the skin (vesicle components). Finally, shelf live experiments indicated that the tested gel/vesicle formulations were stable over 1 year with no need of preservatives.

A comparison of physicochemical methods for the remediation of porous medium systems contaminated with tar

The remediation of former manufactured gas plant (FMGP) sites contaminated with tar DNAPLs (dense non-aqueous phase liquids) presents a significant challenge. The tars are viscous mixtures of thousands of individual compounds, including known and suspected carcinogens. This work investigates the use of combinations of mobilization, solubilization, and chemical oxidation approaches to remove and degrade tars and tar components in porous medium systems. Column experiments were conducted using several flushing solutions, including an alkaline-polymer (AP) solution containing NaOH and xanthan gum (XG), a surfactant-polymer (SP) solution containing Triton X-100 surfactant (TX100) and XG, an alkaline-surfactant-polymer (ASP) solution containing NaOH, TX100, and XG, and base-activated sodium persulfate both with and without added TX100. The effectiveness of the flushing solutions was assessed based on both removal of polycyclic aromatic hydrocarbon (PAH) mass and on the reduction of dissolved-phase PAH concentrations. SP flushes of 6.6 to 20.9 PV removed over 99% of residual PAH mass and reduced dissolved-phase concentrations by up to two orders of magnitude. ASP flushing efficiently removed 95-96% of residual PAH mass within about 2 PV, and significantly reduced dissolved-phase concentrations of several low molar mass compounds, including naphthalene, acenaphthene, fluorene, and phenanthrene. AP flushing removed a large portion of the residual tar (77%), but was considerably less effective than SP and ASP in terms of the effect on dissolved PAH concentrations. Persulfate was shown to oxidize tar components, primarily those with low molar mass, however, the overall degradation was relatively low (30-50% in columns with low initial tar saturations), and the impact on dissolved-phase concentrations was minimal.

Rapid adsorptive removal of toxic Pb(2+) ion from aqueous solution using recyclable, biodegradable nanocomposite derived from templated partially hydrolyzed xanthan gum and nanosilica

This work studied the application of a novel biodegradable nanocomposite based on partially hydrolyzed polyacrylamide grafted xanthan gum and nanosilica (h-XG/SiO2) towards efficient and rapid removal of toxic Pb(2+) ions from aqueous environment. The uptake ability of Pb(2+) using h-XG/SiO2 has been studied in batch adsorption experiments with variation of adsorption parameters. The excellent removal rate (99.54% adsorption within 25min) and superior adsorption capacity (Qmax=1012.15mgg(-1)) of the composite material have been explained on the basis of synergistic and chelating effects of h-XG/SiO2 with Pb(2+) ion through electrostatic interactions. The kinetics, isotherm and thermodynamics studies reveal that Pb(2+) adsorb rapidly on nanocomposite surface, which is in agreement with pseudo-second-order kinetics and Langmuir adsorption isotherm models. In consequence of excellent adsorption as well as regeneration characteristics of nanocomposite, it has been found to be a promising adsorbent towards removal of Pb(2+) ions from battery industry wastewater.

High shear mixer granulation using food grade binders with different thickening power

Mixer agglomeration, in particular high shear wet granulation, is a unit operation typically used in the pharmaceutical industry to improve the flowability, the compressibility, the dosing accuracy during tableting or the content uniformity of a blend. Thanks to its advantages (production of spherical and dense granules, reduction of production time), this technique can be potentially successful also in the food industry as for example in the production of dietary supplements. In this work four thickening agents (povidone, maltodextrin, k-carrageenan and xanthan gum) have been tested to study their effects on the granule growth behavior and on some technologically relevant granule properties (size, shape, strength and flowability). Experiments highlighted the full feasibility of the process and the possibility of using these agents to get products with satisfactory technological properties. The dependence of product properties on the formulation variables (water and binder amount) has been analyzed according to a multivariate approach and a robust predictive tool for the granule size has been developed. Furthermore it was observed that a reduced amount of binding liquid (water) can be used in the presence of strongly thickening binders with a reduction up to 25%. This would decrease drying time and energy requirement and be beneficial especially in the food and food supply industry where products have generally lower added value than in the pharmaceutical one and reducing production costs is critical.

Phase separation behavior of egg yolk suspensions after anionic polysaccharides addition

The objectives of this study were to understand the interactions between three anionic polysaccharides (gum arabic, xanthan gum and ι-carrageenan) and egg yolk at pH 3, 5, 6, 8, 10 and possible phase separation behavior. Zeta potential of egg yolk was not affected by gum arabic addition while it became more negative at pH 5 after xanthan gum and ι-carrageenan addition. The particle size of ι-carrageenan yolk suspension was considerably higher than the other polysaccharide yolk suspensions at pH below 6 but was dramatically decreased at alkaline pH. Most polysaccharide yolk suspensions formed either a biphasic or a monophasic system, whereas three distinct phases were observed for xanthan gum yolk suspension at pH 6. Protein profile analysis of the lipid-rich cream phase obtained from xanthan gum added yolk showed similarities to apoproteins from low density lipoproteins (LDL) of egg yolk. Microscopy analysis indicated the co-presence of xanthan gum and LDL in the creamy phase, within a network formed by xanthan gum. It was suggested that electrostatic and hydrophobic interactions between the egg yolk and xanthan gum as well as xanthan gum's rheological properties could be responsible for the unique phase separation observed in the study. The findings of this study can form the basis for future studies to develop a new method to separate LDL from egg yolk.

Development, validation and influence factor analysis of a near-infrared method for the molecular weight determination of xanthan gum

A practical molecular weight determination model of xanthan gum (XG), based on near-infrared (NIR) spectroscopy, was built in this study. Two sample measurement modules, integrating sphere module and fiber-optic probe module, were compared, and the best partial least square (PLS) regression model was based on fiber-optic probe module. The values of coefficient of determination in calibration (R(2)c), coefficient of determination in prediction (R(2)p), residual predictive deviation (RPD) and root mean square error of prediction (RMSEP) were 0.967, 0.975, 6.028 and 0.250×10(6)Da, respectively. The molecular weight range, linearity, accuracy and precision of the established method were also validated. Furthermore, influence factors on this method were discussed in order to establish an appropriate measurement protocol. Results showed that the proposed NIR method may be suitable for practical applications in manufacturing plants and probably be accepted as a good alternative approach for fast determination of molecular weight of XG in production process.

Role of growth morphology in the formulation of NaCl-based selective media for injury detection of Escherichia coli, Salmonella Typhimurium and Listeria innocua

Sublethal injury (SI) poses major public health concerns since injured cells are responsible for serious limitations in food diagnostics and are susceptible to recovery, often developing adaptive stress responses. Detection of SI is based on the difference in plate counts between non-selective media, which represent the total cell population, and selective media, to which injured cells become sensitive. Selective media for detection of sublethal membrane damage are often based on NaCl supplement, although there is a lack of consensus in the literature about appropriate levels. Planktonic cells are generally used to investigate SI mechanisms, although they often exhibit different stress tolerance than cell colonies in/on solid food (model) systems. In this work, the effect of growth morphology, colony size and concentration of the gelling agent in the growth media, on the maximum non-inhibitory NaCl concentration in the plating medium was assessed for Escherichia coli, Salmonella Typhimurium and Listeria innocua. Stationary phase cultures of planktonic cells and large and small colonies grown in either 1.5% (w/v) xanthan gum-based system or 2.5% (w/v) xanthan gum-based system exhibited significantly different viable counts and osmotolerance. The effect of cell arrangement and xanthan gum percentage in the growth media depended on the microorganism under investigation. Additionally, differences in the maximum non-inhibitory concentration were evident, with 5.0% (w/v) NaCl for the Gram-negative bacteria and 6.5% (w/v), for L. innocua. Different extent of colony shrinkage and morphological damage was observed as NaCl concentration in the plating medium increased. This information will contribute to define NaCl-based selective media for accurate SI detection under realistic scenarios.