Mechanistic analysis of xanthan gum production in a stirred tank

Funahashi, Hitoshi; Hirai, Koh-ichi; Yoshida, Takemi; Taguchi, Hiroyasu

doi:10.1016/0385-6380(88)90115-x

Cited by 24 publications

(13 citation statements)

References 8 publications

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“…The average OUR S remained approximately constant as 5.85 ± 0.1 mmol O 2 /g biomass/h for dissolved oxygen levels in the range of 6% to 20%. These values are in good agreement with those reported in the literature (Pinches and Pallent [1986]: 6.3 mmol O 2 /g biomass/h; Funahashi et al [1988b]: 6.4 mmol O 2 /g biomass/h). However, a significant decrease in OUR S to 4.43 mmol O 2 /g biomass/h was measured when the dissolved oxygen was lowered to 3%.…”

Section: Exponential Growth Phasesupporting

confidence: 93%

“…Ever since Xanthan gum was first reported by Rogovin et al (1961), considerable research has been devoted to address the problems of poor bulk mixing and low oxygen transfer rates in Xanthan gum fermentations (Flores et al, 1994;Funahashi et al, 1987bFunahashi et al, , 1988aFunahashi et al, , 1988bNienow, 1992, 1993;Herbst et al, 1992;Nienow, 1984;Nienow and Elson, 1988;Moraine and Rogovin, 1973;Peters et al, 1989aPeters et al, , 1989bPeters et al, , 1992Zhao et al, 1994). It is generally agreed upon in the literature that the process bottleneck in highly productive Xanthan fermentations is related to these two parameters.…”

Section: Introductionmentioning

confidence: 96%

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Agitator speed and dissolved oxygen effects in Xanthan fermentations

Amanullah

Tuttiett²,

Nienow³

1998

Biotechnol. Bioeng.

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Section: Exponential Growth Phasesupporting

confidence: 93%

Section: Introductionmentioning

confidence: 96%

Agitator speed and dissolved oxygen effects in Xanthan fermentations

Amanullah

Tuttiett²,

Nienow³

1998

Biotechnol. Bioeng.

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“…Xanthan gum is an extracellular polysaccharide produced by the fermentation of the bacteria, Xanthomonas campestris [29][30][31]. As a yield-stress fluid exhibiting pseudoplastic behavior, its rheology can be described by the Hershel-Bulkley rheological model [19,30]:…”

Section: Experimental Setup and Proceduresmentioning

confidence: 99%

Using CFD and Ultrasonic velocimetry to Study the Mixing of Pseudoplastic Fluids with a Helical Ribbon Impeller

Ihejirika

Ein‐Mozaffari

2007

Chem Eng & Technol

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A commercial CFD package was used to simulate the 3D flow field generated in a cylindrical tank by a helical ribbon impeller. The study was carried out using a pseudoplastic fluid with yield stress in the laminar mixing region. Ultrasonic Doppler velocimetry (UDV), a noninvasive fluid flow measurement technique for opaque systems, was used to measure xanthan gum velocity. From flow field calculations and tracer homogenization simulations, power consumption and mixing time results were obtained. The torque and power characteristics remain the same for upward and downward pumping of the impeller, but the mixing times are considerably longer for the downward pumping mode. Overall, the numerical results showed good agreement with experimental results and correlations developed by other researchers. From the power and mixing time results, two efficiency criteria were utilized to determine the best pumping mode of the impeller.

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“…According to that work, liquid viscosity attenuates the concentration gradients surrounding the bubbles by means of absorbing bubble oscillations reducing "k L ". Bubbles are 1385 [17,19,20] and different types of surfactants/alcohols are also often produced [18,23]. Salts together with surfactants affect bubble surface properties.…”

Section: Introductionmentioning

confidence: 99%

“…. [17][18][19][20][21], etc., providing a wide range of physical properties to the liquid phase which affect not only the mechanisms of the physical processes involving bubbles, namely bubble formation, coalescence and break-up, but also the mass transfer rates.…”

Section: Introductionmentioning

confidence: 99%