Concentration and Temperature Dependence of Flow Behavior of Xanthan Gum Dispersions

Goma xantana é um biopolímero comercial produzido por fermentação de glicose e Xanthomonas com larga aplicação industrial. O objetivo deste trabalho foi estudar a síntese e a viscosidade da goma obtida por cepas nativas de Xanthomonas campestris utilizando soro de mandioca como substrato fermentativo alternativo. Três tipos de Xanthomonas foram utilizados. A maior produção foi de 13,83 g.L-1 obtida do meio fermentativo com X. campestris mangiferaeindicae a 25 ºC, 250 rpm por 120 horas apresentando uma viscosidade aparente de 96,14 cP na concentração de 2,0% de solução de xantana a 25 s-1, 25 ºC. O uso do resíduo industrial de soro de mandioca para biossíntese da xantana é uma alternativa de baixo custo para o processo fermentativo e um destino para esse soro.

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“…Segundo Speers [30] , a magnitude de n e a dependência dos valores com a concentração em solução aquosa são dependentes do tamanho das moléculas.…”

Section: Resultado E Discussãounclassified

Utilização do soro de mandioca como substrato fermentativo para a biosíntese de goma xantana: viscosidade aparente e produção

Brandão¹,

Esperidião²,

Druzian³

2010

Polímeros

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“…(2), then it may also be possible to organize the rate constant and the equilibrium gel strength with respect to temperature using an Arrheniustype relationship. Models of this type have been used in this laboratory to predict the change in viscosity of some drilling fluid constituents such as xanthan gum [6]. The Arrhenius equation can be expressed as:…”

Section: Background and Literature Reviewmentioning

confidence: 99%

Drilling fluid shear stress overshoot behavior

et al. 1987

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Shear stress overshoot behavior was studied in four drilling fluid systems and ten bentonite dispersions. These overshoot properties, also described by the American Petroleum Institute as gel strengths, were measured after gelation times of 10 s to 24 h at temperatures of 20-80 °C. Two different rheometers were used to measure overshoot behavior. Gel strength development with time followed a first-order model. Gel development rates at 20°C varied from 0.005 to 0.01 rain -1 for drilling fluid systems and from 0.0004 to 0.02 min -1 for bentonite dispersions. Increasing the gelation temperature for each drilling fluid system caused an increase in the gelling rate constant. Comparison of gel strengths in bentonite dispersions were made using a Fann 35 A viscometer and a Weissenberg Rheogoniometer. Higher gel strength values observed using the Rheogoniometer were believed to be due to differences in instrument spring stiffness and fixture inertia.

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“…According to Cepeda and Villaran [22], temperature influence on viscosity has been found to be related to soluble solids content, and experimental data for fixed concentrations can be related to the temperature using the Arrhenius-Guzman equation. Many researchers reported that flow behavior index (n) of juices varies only slightly with temperature and moisture content and used a combined model (Equation (1)) to describe their effect on flow consistency index (K) values [20,23,24]:…”

Section: Introductionmentioning

confidence: 99%

Rheological Models of Kiwifruit Juice for Processing Applications

Goula¹,

Adamopoulos²

2011

J Food Process Technol

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Rheological behavior of kiwifruit juice at different solids concentrations (13.5-30 o Brix) and different temperatures (25-65°C) was studied with the objective of defining suitable mathematical models for use in evaporation and other processing procedures. Kiwifruit juice samples exhibited pseudoplastic behavior and were characterized by the power law model. The flow consistency index decreased with an increase in temperature and a decrease in concentration, whereas there was no significant effect of temperature and concentration on flow behavior index. The apparent viscosity at a reference shear rate of 1.0 s -1 (μ α1 ) was used instead of the flow consistency index. The temperature and concentration effects on μ α1 were expressed with a single equation. At low shear rates, kiwifruit juice samples exhibited a thixotropic behavior, which turned to rheopectic at high shear rates. In addition, the Bostwick consistency levels were related to the apparent viscosity measurements and the flow consistency index values.

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Concentration and Temperature Dependence of Flow Behavior of Xanthan Gum Dispersions

Cited by 103 publications

References 10 publications

Utilização do soro de mandioca como substrato fermentativo para a biosíntese de goma xantana: viscosidade aparente e produção

Utilização do soro de mandioca como substrato fermentativo para a biosíntese de goma xantana: viscosidade aparente e produção

Drilling fluid shear stress overshoot behavior

Rheological Models of Kiwifruit Juice for Processing Applications

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