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DYNAMIC AND STEADY-SHEAR RHEOLOGICAL PROPERTIES OF XANTHAN AND GUAR GUMS DISPERSED IN YELLOW PASSION FRUIT PULP (Passiflora edulis f. flavicarpa)

MORAES, I. C. F.; FASOLIN, L. H.; CUNHA, R. L.; MENEGALLI, F. C.
Fonte: BRAZILIAN SOC CHEMICAL ENG Publicador: BRAZILIAN SOC CHEMICAL ENG
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37.73%
Yellow passion fruit pulp is unstable, presenting phase separation that can be avoided by the addition of hydrocolloids. For this purpose, xanthan and guar gum [0.3, 0.7 and 1.0% (w/w)] were added to yellow passion fruit pulp and the changes in the dynamic and steady-shear rheological behavior evaluated. Xanthan dispersions showed a more pronounced pseudoplasticity and the presence of yield stress, which was not observed in the guar gum dispersions. Cross model fitting to flow curves showed that the xanthan suspensions also had higher zero shear viscosity than the guar suspensions, and, for both gums, an increase in temperature led to lower values for this parameter. The gums showed different behavior as a function of temperature in the range of 5-35 degrees C. The activation energy of the apparent viscosity was dependent on the shear rate and gum concentration for guar, whereas for xanthan these values only varied with the concentration. The mechanical spectra were well described by the generalized Maxwell model and the xanthan dispersions showed a more elastic character than the guar dispersions, with higher values for the relaxation time. Xanthan was characterized as a weak gel, while guar presented a concentrated solution behavior. The simultaneous evaluation of temperature and concentration showed a stronger influence of the polysaccharide concentration on the apparent viscosity and the G` and G `` moduli than the variation in temperature.

The effect of calcium salts on the viscosity and adsorption behavior of xanthan

DARIO, Aline F.; HORTENCIO, Lucas M. A.; SIERAKOWSKI, Maria Rita; QUEIROZ NETO, Joao C.; PETRI, Denise F. S.
Fonte: ELSEVIER SCI LTD Publicador: ELSEVIER SCI LTD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37.77%
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. (C) 2010 Elsevier Ltd. All rights reserved.; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); CNPq; FAPESP; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); CAPES-REDE Nanobiotec; PETROBRAS; PETROBRAS

Produção de goma xantana utilizando casca de soja como substrato em cultivo submerso e cultivo semi-sólido; Xanthan gum production using soybean hull substrate by submerged and solid-state cultnations

Varela, Willian José
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
37.61%
A goma xantana continua sendo o polissacarídeo microbiano mais produzido no mundo. Características como aumento da viscosidade em soluções, agente de geleificação, estabilidade frente aos diversos tratamentos despertam um interesse especial para a indústria de alimentos, porém, a aplicação para fins não alimentícios vem crescendo significativamente, como é o caso da indústria petrolífera e têxtil. A utilização de substratos alternativos e baratos para a produção de biomoléculas de interesse comercial, como resíduos agroindústrias, vem sendo alvo de virias pesquisas na atualidade. Sendo assim, neste trabalho, produzimos goma xantana utilizando a casca de soja como substrato para a Xanthomonas campestris. Utilizou-se um planejamento experimental e da metodologia de superfície de resposta a fim de identificar as melhores condições de produção de goma xantana em cultivo semi-sólido em biorreatores estáticos (CSSE). As melhores condições para este cultivo foram: temperatura de 31.2ºC, aeração de 467.5 L.min-1 e densidade óptica do inóculo de 0,929 em 600 nm. Em paralelo, conduziu-se um estudo da produção de goma xantana em cultivo submerso (CSm) e em cultivo semi-sólido agitado (CSSA), fazendo-se um comparativo entre os três sistemas quanto à produção e a viscosidade do exopolissacarídeo. Quanto à conversão de casca de soja em goma...

Optical and Structural Properties of Zein-Xanthan Gum Biofilms

de Almeida, Crislene Barbosa; Lopes Filho, Jose Francisco; Pinto, JC
Fonte: Wiley-v C H Verlag Gmbh Publicador: Wiley-v C H Verlag Gmbh
Tipo: Conferência ou Objeto de Conferência Formato: 20-25
ENG
Relevância na Pesquisa
37.61%
Structural and optical characteristics of zein-based films produced with different xanthan gum concentrations have been studied in this work. Scanning electronic microscopy (SEM) and optical microscopy (OM) were performed to identify if the incorporation of the material into the matrix film, formed a homogeneous structure, as well as to characterize its constituents as the colour and shape. SEM showed a homogeneous matrix for the control (0% xanthan) with good lipid distribution. However, when the samples were investigated by OM, lipids globules in the control biofilm appeared larger and more dispersed in the matrix than the others samples. Transparency/opacity test measurements by UV-VIS analysis indicated that the addition of xanthan to the film matrix lowered significantly its transparency properties Overall, the addition of xanthan gum favoured lipid dispersion in the matrix, making biomaterials more homogeneous, although with less transparency.

Morphological and Structural Characteristics of Zein Biofilms with Added Xanthan Gum

de Almeida, Crislene Barbosa; Catelam, Kelly Tafari; Cornelio, Marinonio Lopes; Lopes Filho, Jose Francisco
Fonte: Faculty Food Technology Biotechnology Publicador: Faculty Food Technology Biotechnology
Tipo: Artigo de Revista Científica Formato: 19-27
ENG
Relevância na Pesquisa
37.68%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Processo FAPESP: 05/02407-4; Processo FAPESP: 06/01775-2; Morphological and structural characteristics of zein-based biofilms have been studied in this work. The sorbitan component in the control formulation of the film was substituted with xanthan gum at concentrations between 0.01 and 0.04% to analyze its effect on lipid dispersion. Scanning electron microscopy (SEM) showed a surface for the control (0 % xanthan) with good lipid distribution. However, when the samples were investigated by optical microscopy (OM), lipid globules in the control biofilm appeared larger and more dispersed in the matrix than in the other samples. Fourier transform infrared (FTIR) spectroscopy indicated that xanthan concentrations deeply affected C=O linkages from amide I group, as well as the functional N-H group of amide H of the zein structure. Other weak interactions of amide I and 11 with carboxylic acids and aliphatic compounds were also observed. UV/VIS analysis as well as transparency measurements indicated that the addition of xanthan to the film matrix lowered significantly its transparency properties. Overall...

Influencia da desnaturação termica e do pH sobre as propriedades reologicas de proteinas do soro e sua compatibilidade termodinamica com a xantana; Influence of heat denaturation and the pH on rheological properties of whey protein and its thermodynamic compatibility with xanthan

Angelo Luiz Fazani Cavallieri
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 18/03/2003 PT
Relevância na Pesquisa
37.61%
Proteínas e polissacarídeos correspondem a biopolímeros muito utilizados pela indústria de alimentos devido às suas características funcionais, porém apresentam uma incompatibilidade natural quando em soluções. Sistemas compostos por proteínas do soro e xantana foram avaliados neste trabalho em diferentes condições de pH, com as proteínas nativas e desnaturadas termicamente. Análises de eletroforese em gel de poliacrilamida foram realizadas para verificar o efeito do tratamento térmico nas proteínas do soro, mostrando que o aquecimento de soluções de proteínas do soro a 80oe por trinta minutos causou a formação de grandes agregados protéicos estabilizados principalmente por interações dissulfídicas. Estes agregados tiveram influência marcante no comportamento de fases destas proteínas com a xantana. Soluções nativas de isolado protéico de soro 5% (p/p) e xantana entre 0,01 % a 1 % se revelaram compatíveis, porém quando as proteínas foram termicamente desnaturadas, estes sistemas se mostraram termodinamicamente incompatíveis, separando em duas fases. Um diagrama de fases capaz de descrever a região de incompatibilidade termodinâmica desses sistemas foi determinado, porém limitações experimentais atribuídas principalmente à ineficiência da ultracentrifugação na separação das fases incompatíveis quando as soluções possuem elevada viscosidade impediu a determinação da binodal de equilíbrio. O principal mecanismo termodinâmico envolvido na incompatibilidade termodinâmica seria a baixa entropia quando as proteínas do soro estão agregadas...

Estudo do efeito do "stress" alcalino na produção de goma xantana.; Study of the effect of alkaline "stress" in production xanthan gum

Marcia de Mello Luvielmo
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 26/02/2007 PT
Relevância na Pesquisa
37.8%
O presente estudo teve como objetivo fazer uma seleção de linhagens de X. campestris para a produção de goma xantana e verificar o efeito do processo de "stress" alcalino em diferentes condições de produção deste biopolímero, através da avaliação da produção de goma e da viscosidade aparente, que é um fator de elevada relevância para designar em quais processos e setores da indústria a goma xantana será aplicada. A pesquisa também teve como objetivo investigar as mudanças na estrutura da goma xantana causadas pelo "stress" alcalino, e as mudanças na ultraestrutura das células, assim como a disposição da goma em diferentes etapas da sua produção e em diferentes tempos de "stress" alcalino, a fim de contribuir com uma maior compreensão desse complexo processo. Foi selecionada a linhagem X. campestris pv. manihotis 280-95, como a de melhor desempenho em produção e qualidade, com uma produção de goma xantana de 10,8 g/L. A partir destes estudos, X. campestris pv. manihotis 280-95 passou a ser a bactéria utilizada para os estudos posteriores. O maior valor de produção de goma xantana foi atingido em ?stress? alcalino com pH 12 (EA12), seguido do "stress" alcalino em pH 11 (EA11) e "stress" alcalino em pH 8 (EA08). Porém a qualidade da goma obtida após o processo de EA12 é menor se comparada à obtida sem o processo de "stress" alcalino. O hidróxido de sódio (NaOH) foi o álcali que apresentou melhor desempenho para o processo de "stress" alcalino. A produção de goma xantana (g.L-1) e as viscosidades aparentes das gomas não foram afetadas nos diferentes tempos de "stress" alcalino (EA12) testados nesse estudo (1h...

Produção de goma xantana em reator de coluna de bolha utilizando processo de batelada repetida; Xanthan gum production in a buble column reactor using a repeated bath process

Erika Durão Vieira
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 22/08/2008 PT
Relevância na Pesquisa
37.61%
O objetivo deste trabalho foi avaliar a viabilidade de produção de goma xantana em reator de coluna de bolha utilizando processo de batelada repetida bem como otimizar as condições de produção e avaliar algumas etapas típicas da recuperação da goma. Foram utilizadas neste estudo duas linhagens da bactéria Xanthomonas campestris: ATCC 13951 (ou NRRL B-1459) e ATCC 55298. Os ciclos variaram de 3 a 8 bateladas consecutivas de 48 horas. Ao final de cada batelada, parte do caldo fermentado era retirado do reator e aproximadamente 20% do volume era deixado no reator para servir de inóculo para a próxima batelada que se iniciava com a adição de meio para produção de goma. O primeiro ensaio preliminar que consistiu de um ciclo com 6 bateladas demonstrou ser viável o processo em bateladas repetidas de modo que ensaios subseqüentes foram realizados com a finalidade de se otimizar as condições de operação para cada linhagem por planejamento fatorial de dois níveis em configuração estrela com repetição do ponto central. Os fatores estudados foram concentração inicial de sacarose, vazão de ar e temperatura e as respostas analisadas foram rendimento, concentração final de xantana bruta e o índice de consistência k (mPa.sn)...

Uso de xantana em substituição ao alginato em membranas coacervadas de quitosana projetadas para a cicatrização de lesões de pele; Use of xanthan to replace the alginate in chitosan membranes designed for the healing of skin lesions

Itiara Gonçalves Veiga
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 28/04/2009 PT
Relevância na Pesquisa
37.77%
O corpo humano é recoberto por aproximadamente 2 m2 de pele e, lesões cutâneas, além de causarem danos físicos, mecânicos e térmicos, podem também afetar as funções fisiológicas de outros tecidos. As membranas desenvolvidas para o tratamento de lesões podem ser constituídas por vários tipos de polímeros, sendo a quitosana um dos mais estudados. Polissacarídeos negativamente carregados como alginato, pectina, carragena e xantana são capazes de formar complexos polieletrólitos (PEC) com a quitosana. Uma das técnicas de preparação de membranas contendo simultaneamente quitosana e poliânion envolve a produção de coacervados das matérias-primas. Membranas de quitosana e alginato foram já detalhadamente estudadas para uso em lesões de pele. Neste contexto, o presente trabalho teve por objetivo o desenvolvimento de metodologia escalonável de preparação de membranas de quitosana-xantana (em substituição ao alginato), estudando-se o efeito do uso de diferentes vazões e relações mássicas durante a preparação do PEC e da reticulação térmica nas propriedades das membranas obtidas. Outros poliânions foram também testados, mas a xantana apresentou as características mais adequadas. As membranas de quitosana-xantana foram caracterizadas quanto à morfologia...

DYNAMIC AND STEADY-SHEAR RHEOLOGICAL PROPERTIES OF XANTHAN AND GUAR GUMS DISPERSED IN YELLOW PASSION FRUIT PULP (Passiflora edulis f. flavicarpa)

MORAES, I. C. F.; FASOLIN, L. H.; CUNHA, R. L.; MENEGALLI, F. C.
Fonte: BRAZILIAN SOC CHEMICAL ENG Publicador: BRAZILIAN SOC CHEMICAL ENG
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37.73%
Yellow passion fruit pulp is unstable, presenting phase separation that can be avoided by the addition of hydrocolloids. For this purpose, xanthan and guar gum [0.3, 0.7 and 1.0% (w/w)] were added to yellow passion fruit pulp and the changes in the dynamic and steady-shear rheological behavior evaluated. Xanthan dispersions showed a more pronounced pseudoplasticity and the presence of yield stress, which was not observed in the guar gum dispersions. Cross model fitting to flow curves showed that the xanthan suspensions also had higher zero shear viscosity than the guar suspensions, and, for both gums, an increase in temperature led to lower values for this parameter. The gums showed different behavior as a function of temperature in the range of 5-35 degrees C. The activation energy of the apparent viscosity was dependent on the shear rate and gum concentration for guar, whereas for xanthan these values only varied with the concentration. The mechanical spectra were well described by the generalized Maxwell model and the xanthan dispersions showed a more elastic character than the guar dispersions, with higher values for the relaxation time. Xanthan was characterized as a weak gel, while guar presented a concentrated solution behavior. The simultaneous evaluation of temperature and concentration showed a stronger influence of the polysaccharide concentration on the apparent viscosity and the G` and G `` moduli than the variation in temperature.

Chemical deacetylation natural xanthan (Jungbunzlauer®)

Pinto,Ellen P.; Furlan,Lígia; Vendruscolo,Claire T.
Fonte: Associação Brasileira de Polímeros Publicador: Associação Brasileira de Polímeros
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2011 EN
Relevância na Pesquisa
37.61%
With the aim of adapting a method for removal of acetyl groups from xanthan, reactions of chemical deacetylation were carried out with natural xanthan (Jungbunzlauer®) with variations on the following parameters: biopolymer and alkali concentration (sodium and potassium hydroxide). The deacetylation reaction was performed at 25 ºC for three hours. The proposed methodology was efficient to promote the deacetylation reaction. The viscosity of xanthan increased when the alkali concentration was higher in the deacetylation reaction. Xanthan concentration in the solution used in the deacetylation reaction did not influence the solutions viscosity, as similar results in both tested biopolymer concentrations (0.5 and 1%) were obtained for all experiments in different shear rates. Deacetylation reactions at 25 ºC for three hours with sodium and potassium hydroxide in 0.01 mol.L-1 showed a viscosity of 410 and 420 mPa.s at 10 s-1 and acetylation degree 1.3 e 1.4%, respectively.

Use of green coconut shells as an alternative substrate for the production of xanthan gum on different scales of fermentation

Nery,Tatiana Barreto Rocha; Cruz,Antonio José Gonçalves da; Druzian,Janice Izabel
Fonte: Associação Brasileira de Polímeros Publicador: Associação Brasileira de Polímeros
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2013 EN
Relevância na Pesquisa
37.68%
Xanthan, a biopolymer with extensive industrial applications, is commercially produced by fermenting glucose or sucrose using the bacteria Xanthomonas. Green coconut shells, rich in nutrients, could be an alternative substrate to obtain xanthan. This study aimed to evaluate the production and rheological properties of xanthan obtained on different fermentation scales using green coconut shells as the substrate, using its production from sucrose for comparison. Media containing minimal nutritional requirements (carbon, urea, phosphate) were prepared. Upon changing from the conventional medium to the alternative medium there was a 30% increase in production using the shaker and 81% increase using the bioreactor. Increasing the fermentation scale resulted in an increased yield of xanthan and a 30% increase in apparent viscosity. Coconut shells deserve special attention, constituting a possibility for the large scale production of xanthan with cost reduction and application of a residue.

Effect of virulence and serial transfers of Xanthomonas campestris on xanthan gum production

Nitschke,Marcia; Rodrigues,Vanessa
Fonte: Sociedade Brasileira de Microbiologia Publicador: Sociedade Brasileira de Microbiologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2000 EN
Relevância na Pesquisa
37.68%
The virulence of six Xanthomonas campestris isolates was evaluated using the percentage of lesion area of leaves in Brassica oleraceae host plant, compared to diameter of colonies, xanthan production and gum viscosity. In terms of virulence, the isolates belonged to two statistically different groups: isolates B, UPF and C7 showed values between 52 and 69%, while isolates CF, C and strain B-1459 gave 0-30% of lesion area. Final xanthan concentration, gum viscosity and colony diameter did not correlate with virulence calculated by percentage of lesion area, showing that this parameter is not a good criterium for selection of potential xanthan producer isolates. Serial transfers of X. campestris isolates in host plant did not show a significant effect on "in vitro" production of xanthan or on viscosity levels, suggesting that the increasing interaction between plant and bacteria did not stimulate the increase in xanthan production and viscosity.

Estudo das condi????es operacionais na produ????o de xan-tana por X. arboricola pv pruni para aplica????o em fluido de perfura????o de po??os de petr??leo; Study of operational conditions in xanthan production by Xanthomonas arboricola pv pruni for oilwell drilling fluid

BORGES, Caroline Dellinghausen
Fonte: Universidade Federal de Pelotas; Biotecnologia; Programa de P??s-Gradua????o em Biotecnologia; UFPel; BR Publicador: Universidade Federal de Pelotas; Biotecnologia; Programa de P??s-Gradua????o em Biotecnologia; UFPel; BR
Tipo: Tese de Doutorado Formato: application/pdf
POR
Relevância na Pesquisa
37.85%
Xanthan yield and physical and chemical characteristics can be improved by modification in culture conditions, as well as, by post-fermentation treatments in order to obtain a xanthan with the required characteristics. The aim of this work was to study the operational conditions in xanthan production by Xanthomonas arbor??cola pv pruni strains 106 and 115 to be used in oilwell drilling fluids. The influence of thermal treatment applied to the fermentation broth was evaluated in the xanthan produced by strain 106 in a range of pH and stirrer speed. The thermal treatment decreased the yield between 5.8 and 14%, nevertheless, was observed increase of aqueous solution and fermentation broth viscosities. The aggregation of xanthan molecules caused by thermal treatment and determined by increase of molar mass was dependent on the sodium content. As a result, a correlation between molar mass and xanthan solution viscosity can be observed. The fermentation broth sterilization was adopted for experiment in which a pre-selection of production medium in orbital shaker was performed for subsequent pH, production medium and stirrer speed study in fermentor by strains 106 and 115. Xanthan production and viscosity was dependent on the strain of X. arbor??cola pv pruni and on the operational condition used. The production medium B showed the best balance of yield and viscosity results...

Avalia????o comparativa das propriedades hidrodin??micas de xantanas produzidas pelo pv Pruni e Clairana; Comparative evaluation of hydrodynamic properties of the xanthan produced by pv Pruni and Clairana

DIAZ, Patr??cia Silva
Fonte: Universidade Federal de Pelotas; Biotecnologia; Programa de P??s-Gradua????o em Biotecnologia; UFPel; BR Publicador: Universidade Federal de Pelotas; Biotecnologia; Programa de P??s-Gradua????o em Biotecnologia; UFPel; BR
Tipo: Tese de Doutorado Formato: application/pdf
POR
Relevância na Pesquisa
37.8%
The knowledge on the biopolymers properties are important to predict his future industrial applications because reflects his chemical primary structure. Besides, the physical and chemical characteristics of the biopolymers are a consequence of the process used in his synthesis. The aim of this work was the study of the hydrodynamic properties of solution of biopolymers xanthan synthesized by Xanthomonas arboricola pv pruni, strains 06 and 82, and clairana FL, synthesized by Beijerinckia sp. strain 7070, in 7L fermentation volume. The results from rheological analysis, acetyl and piruvate content, ion content and thermal stability were compared with the ones obtained for commercial xanthan. The commercial xanthan is more efficient in the rheological properties due to divalent ion in their composition. The results for acetyl and piruvate content were in accordance with the literature. Thermal analysis showed presence of protein in the pv pruni xanthan??s and in clairana, but not in commercial xanthan. Hydrodynamic properties behavior of xanthan (Xc06), clairana and tara gum, in various concentrations, was examined using dynamic light scattering. Concentration regimes were determined by critical concentrations c* and c**, applying two methods. The first method was based on diffusional coefficient behavior of a range of biopolymers concentrations. A theoretical curve was proposed for results evaluation. With this method...

Xantana como aditivo crioprotetor externo para congelamento de s??men ovino; Xanthan as an additive external cryoprotectant for frozen ram semen

GASTAL, Gustavo Desire Antunes
Fonte: Universidade Federal de Pelotas; Veterin??ria; Programa de P??s-Gradua????o em Veterin??ria; UFPel; BR Publicador: Universidade Federal de Pelotas; Veterin??ria; Programa de P??s-Gradua????o em Veterin??ria; UFPel; BR
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
37.83%
The xanthan gum can contribute to reduce the formation of ice crystals in the sperm freezing solution, facilitating the preservation of sperm viability after thawing. However, there is no information about the use of xanthan gum as an additive for cryoprotection of ram sperm. This study aimed to determine the effect of three different concentrations of xanthan (0.15%, 0.20% and 0.25%) on post-thawing ram sperm quality. In vitro tests, evaluating sperm motility and vigor, membrane and acrossome integrity and mitochondrial functionality were conducted before freezing and after thawing. Biochemical tests were performed to evaluate reactive oxygen species (ROS) and total antioxidant capacity (TOSC) by using a fluorometer and the fluorescent probe H2DCF-DA. The addition of xanthan did not benefit sperm membrane and acrossome integrity and mitochondrial functionality (p>0.05), but the post-thawing sperm motility was lower (p<0.05) in treatments with 0.20 and 0.25% xanthan (22.2% ?? 4.1 and 20.8% ?? 4.1, respectively) than in the control without xanthan (32.2% ?? 4.1). On the other hand, xanthan showed antioxidant characteristics, since the concentration of ROS decreased with increasing xanthan production (p<0.05). Thus, xanthan showed extracellular antioxidant capacity...

Xanthan production by a native strain of X. campestris and evaluation of application in EOR

Shaghayegh, N.; Soudi, M.; Haghighi, M.
Fonte: Asian Network for Scientific Information (A N S I N E T) Publicador: Asian Network for Scientific Information (A N S I N E T)
Tipo: Artigo de Revista Científica
Publicado em //2007 EN
Relevância na Pesquisa
37.68%
In this study, we used a native strain of X. campestris for xanthan production in lab-scale fermentor and the product was recovered with organic solvents and dried. Then we studied the potential usage of our products in different harsh conditions, including heat, pH and salinity treatments. Furthermore, we used 2D-micromodel for microbial oil recovery investigations. According to present experiments, temperature and salt contents did not have a significant influence on rheological behavior of xanthan solutions and these aqueous solutions maintained at least 80% of their primary viscosity. In addition, these solutions were resistant to a broad range of pH variations. Viscosity of the xanthan solution was increased as it was heated over 120°C. Micro-model experiments showed that the most efficient concentration of xanthan for Enhanced Oil Recovery (EOR) is 1000 mg L-1 and 53% of original oil in place was recovered, which showed remarkable increase comparing to original oil in place that was recovered (31%) from sole water flooding. The same or even better results were obtained from native xanthan, when its properties were compared to those of a commercial sample which was gifted by NIOC.; Shaghayegh Nasr, Mohammad Reza Soudi and Manouchehr Haghighi

Dynamic and steady: shear rheological properties of xanthan and guar gums dispersed in yellow passion fruit pulp (Passiflora edulis f. flavicarpa)

MORAES, I. C. F; FASOLIN, L. H; CUNHA, R. L; MENEGALLI, F. C
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica
ENG
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Yellow passion fruit pulp is unstable, presenting phase separation that can be avoided by the addition of hydrocolloids. For this purpose, xanthan and guar gum [0.3, 0.7 and 1.0% (w/w)] were added to yellow passion fruit pulp and the changes in the dynamic and steady - shear rheological behavior evaluated. Xanthan dispersions showed a more pronounced pseudoplasticity and the presence of yield stress, which was not observed in the guar gum dispersions. Cross model fitting to flow curves showed that the xanthan suspensions also had higher zero shear viscosity than the guar suspensions, and, for both gums, an increase in temperature led to lower values for this parameter. The gums showed different behavior as a function of temperature in the range of 5 - 35ºC. The activation energy of the apparent viscosity was dependent on the shear rate and gum concentration for guar, whereas for xanthan these values only varied with the concentration. The mechanical spectra were well described by the generalized Maxwell model and the xanthan dispersions showed a more elastic character than the guar dispersions, with higher values for the relaxation time. Xanthan was characterized as a weak gel, while guar presented a concentrated solution behavior. The simultaneous evaluation of temperature and concentration showed a stronger influence of the polysaccharide concentration on the apparent viscosity and the G' and G" moduli than the variation in temperature.

Dynamic and steady: shear rheological properties of xanthan and guar gums dispersed in yellow passion fruit pulp (Passiflora edulis f. flavicarpa)

Moraes,I. C. F; Fasolin,L. H; Cunha,R. L; Menegalli,F. C
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2011 EN
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Yellow passion fruit pulp is unstable, presenting phase separation that can be avoided by the addition of hydrocolloids. For this purpose, xanthan and guar gum [0.3, 0.7 and 1.0% (w/w)] were added to yellow passion fruit pulp and the changes in the dynamic and steady - shear rheological behavior evaluated. Xanthan dispersions showed a more pronounced pseudoplasticity and the presence of yield stress, which was not observed in the guar gum dispersions. Cross model fitting to flow curves showed that the xanthan suspensions also had higher zero shear viscosity than the guar suspensions, and, for both gums, an increase in temperature led to lower values for this parameter. The gums showed different behavior as a function of temperature in the range of 5 - 35ºC. The activation energy of the apparent viscosity was dependent on the shear rate and gum concentration for guar, whereas for xanthan these values only varied with the concentration. The mechanical spectra were well described by the generalized Maxwell model and the xanthan dispersions showed a more elastic character than the guar dispersions, with higher values for the relaxation time. Xanthan was characterized as a weak gel, while guar presented a concentrated solution behavior. The simultaneous evaluation of temperature and concentration showed a stronger influence of the polysaccharide concentration on the apparent viscosity and the G' and G" moduli than the variation in temperature.

INFLUENCE OF POLYPHOSPHATE AND FAT ADDITION IN MEAT-WATER-XANTHAN GUM SYSTEMS; INFLUÊNCIA DA ADIÇÃO DE POLIFOSFATO E DE GORDURA EM SISTEMAS CARNE-ÁGUA-GOMA XANTANA

GARCIA-CRUZ, CRISPIN HUMBERTO; Universidade Estadual Paulista, São José do Rio Preto -SP; SCAMPARINI, ADILAM R. P.; UNICAMP
Fonte: UFPR Publicador: UFPR
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Formato: application/pdf
Publicado em 28/05/2009 POR
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The,effect to addition of polyphosphates to the system meat-water-xanthan gum was stidied. it. It was observed that this system is more stable on cooking that the' system meat-water-polyphosphate. The xanthan-polyphosphate mixture (0.5% each) was better than only xanthan gum (0.5%) or only polyphosphate (0.5%) in the meaat-water-system because the quantity of juice exudated were 0.20 ml; 0.34 ml and 0.30 ml, respectivelly. The offect fat adition was studied as well. The fat was added at concentrations of 6.0, 12,.5, 25.0 and 30.0%, to the mixtures made of meat-water, meat-water-xanthan gum (1,0%), meat-water xanthan gum (0.5%) and meat-water-polyphosphate (0.5%). It was observed that fat addition lowered the sineresis in all mixture studied, with the one formed by meat-water-xanthan gum (0.5%- polyphosphate (0.5%) showing the lowest sineresis.; Foi estudado o efeito da adição de polifosfatos no sistema formado por carne-água-goma xantana e foi observado que esse sistema é tão estável ao cozimento quanto o sistema formado por carne-água-polifosfato. Entretanto o sistema formado pela mistura xantana-PQ lifosfato (0,5% de cada) foi superior ao sistema formado só com a goma xantana ou só com polifosfato (0...