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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 21 (1979), S. 745-774 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Laboratory and pilot-plant high-speed bead mills of 0.6 and 5 liter capacity and consisting of four and five impellers in series, respectively, were used to follow the batch and continuous disruption of bakers' yeast (Saccharomyces cerevisiae). The mills are not scaled equivalents. Throughputs ranging from 1 × 10-6m3/sec to 12 × 10-6m3/sec for the 0.6 liter mill and from 16 × 10-6m3/sec to 100 × 10-6m3/sec for the 5 liter mill were used for continuous disruption studies. Variables studied included the effect of impeller tip speed, temperature, and packed yeast concentration (ranging from 15 to75% by weight packed yeast). Disruption kinetics, as measured by the release of soluble protein, followed a first-order rate equation, the rate constant being a function of impeller tip speed and yeast concentration. For continuous disruption studies the bead mills behaved as a series of continuous stirred-tank reactors, each impeller forming a reactor. In the smaller mill a considerable degree of backflow between the reactors was evident. For certain mixing conditions the maximum amount of releasable protein was dependent on the impeller geometry, construction material, and also the concentration of packed yeast. The relative power efficiencies of the two mills are discussed along with possible criteria for scaling of bead mills.
    Additional Material: 18 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 425-429 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 1169-1169 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982), S. 127-141 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Isoelectric soya-protein precipitate densities were measured for mean particle sizes ranging from 3.4-65 μm by gradient centrifugation, centrifugation in water-immiscible solvents, tracerdilution, gravity sedimentation of isolated particles. Coulter counter volume determination, and a comparison of Coulter counter and centrifugal sedimentation size distributions. The immiscible system and tracer dilution methods were both found to be unreliable due to experimental uncertainties. The Coulter counter volume measurement indicated the existence of a density-size relationship with the aggregate density decreasing as the size increased. Comparison with sedimentation measurements showed that the Coulter counter measures 80% of the total aggregate volume for 6-μm particles. The relation between aggregate density (ρa, kg m -3) and size (d, μm) was measured for isoelectric soya protein and casein precipitated by ammonium sulfate, using a comparison of the Coulter counter size distribution and centrifugal sedimentation. The functions were described for soya by \documentclass{article}\pagestyle{empty}\begin{document}$$ \rho _a - 1004 = 246d^{ - 0.408} $$\end{document} and for casein by \documentclass{article}\pagestyle{empty}\begin{document}$$ \rho _a - 1136 = 31d^{ - 0.441} $$\end{document} The gradient centrifugation method measured the buoyant density of hydrated protein precipitate which was independent of size, and is consistent with an aggregate structure consisting of primary particles. However, the aggregate structure was not described for all sizes by the theoretical cubic packing of hard-sphere primary particles, nor by the successive random addition of primary particles. The density-size functions indicated up to a fivefold difference in Stokes settling velocities compared to those calculated assuming a constant density difference.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982), S. 871-887 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The acid precipitation of soya protein was studied in a continuous-flow tubular reactor under conditions of turbulent flow. Preliminary batchwise experiments of a semiquantitative nature were also carried out on a bench-scale reactor to better define the parameters affecting precipitate growth. The experiments indicated the dominant growth mechanism to be the aggregation of primary precipitate particles produced by the contacting of the protein and acid streams. The rate of particle growth was observed to rise with an increase in the protein concentration as well as with greater intensity of turbulence. The final mean particle size decreased with increased intensity of turbulence. A theoretical model was set up to simulate the growth of the precipitate particles.
    Additional Material: 14 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 57 (1998), S. 666-675 
    ISSN: 0006-3592
    Keywords: protein ; recovery ; purification ; crystallization ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Bulk crystallization is emerging as a new industrial operation for protein recovery. Characterization of bulk protein crystallization is more complex than protein crystallization for structural study where single crystals are grown in flow cells. This is because both nucleation and crystal growth processes are taking place while the supersaturation falls. An algorithm is presented to characterize crystallization using the rates of the two kinetic processes, nucleation and growth. The values of these rates allow ready comparison of the crystallization process under different operating conditions. The crystallization, via adjustment to the isoelectric pH of a fungal lipase from clarified fermentation broth, is described for a batch stirred reactor. A maximum nucleation rate of five to six crystals formed per microliter of suspension per second and a high power dependency (≈11) on the degree of supersaturation were found. The suspended protein crystals were found to grow at a rate of up to 15-20 nm/s and also to exhibit a high power dependency (≈6) of growth rate on the degree of supersaturation. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 666-675, 1998
    Additional Material: 11 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 59 (1998), S. 517-519 
    ISSN: 0006-3592
    Keywords: antibody fragments ; stability ; shear ; interface ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of shear on the antigen binding activity of a recombinant scFv antibody fragment was investigated in the presence of air-liquid interfaces using a stirred vessel that was incompletely filled. Changes in binding activity of the scFv to its antigen were monitored using an optical biosensor which had been sensitized with hen egg lysozyme (the antigen). The biosensor response was used as a measure of scFv binding activity. In buffer solution (mean velocity gradient ∼20,000 s-1), loss of binding activity followed a first-order model with a mean rate constant of 0.83 h-1. In unstirred buffer solution, no such loss was observed. Similarly, in sheared fermentation broth there was no loss of binding activity and protective effects were attributed to the antifoam PPG. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59: 517-519, 1998.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 31 (1988), S. 984-994 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The use of microporous membranes has been examined for the recovery of precipitated protein suspensions and related soluble protein. Membrane flux rates and soluble protein transmissions are reported for unstirred batch-cell studies and cross-flow experiments. The unstirred batch-cell gave soluble protein transmissions in the range 80-100% for feeds containing either soluble protein or a mix of soluble and isoelectrically precipitated protein. In all cases a sharp decline in flux was observed which was, for example, considerably greater for soluble protein at its isoelectric point, pH 4.6, than at pH 8.8. The presence of precipitated protein led to a further decrease in flux rate. In cross-flow studies, flux decline was eventually accompanied by a significant decline in soluble protein transmission. The flux protein-transmission characteristics of microporous membranes are discussed in terms of the interaction of the soluble and precipitated protein with the membrane.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 29 (1987), S. 24-32 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of acoustic conditioning on the particle size distribution of isoelectric and calcium-ion-precipitated soya protein has been examined in low-residence-time chambers. In a previous study a beat frequency of 5 Hz obtained using a dual-source system of opposing vibrators was determined as giving optimal improvement in particle-settling characteristics for isoelectric soya protein precipitate. In this study the effect of amplitude of vibration, a measure of acoustic power input, and residence time of acoustic conditioning has been examined.Acoustic power input changed the flow pattern in the conditioning chamber from laminar streamline flow to a well-mixed, turbulent pattern. Such a mixing effect promoted the rapid aggregation of fine particles, a process that was modeled on the basis of orthokinetically controlled collisions. The rate of removal of fine particles due to acoustic conditioning was shown to be proportional to a mixing effect that was releated to the acoustic power dissipated per unit volume.The consequences of fine-particle aggregation on the centrifugal recovery of the precipitate are discussed.
    Additional Material: 9 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 354-366 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A biochemical engineering framework for optimizing the design and operation of fractional protein precipitation has been developed. The method utilizes a fractionation diagram to represent the purification of a product protein relative to total contaminating protein. The purification factor for a single or double-cut fractional precipitation is obtained as the gradient of an appropriate operating tie-line. A computer algorithm has been devised to maximize the tie-line gradient for a given yield enabling a plot of optimum purification factor versus yield to be constructed. The recovery of the enzyme alcohol dehydrogenase from clarified bakers homogenate using saturated ammonium sulphate has been examined. Fractionation and purification versus yield diagrams were used to investigate the effects of such process parameters as pH, temperature, and initial total protein concentration on fractionation efficiency. The results are discussed in terms of the underlying solubility and mixing phenomena and the industrial application of fractional precipitation.
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