Bioprocess Engineering

, Volume 14, Issue 1, pp 1–8 | Cite as

The effects of fermentation conditions on yeast cell debris particle size distribution during high pressure homogenisation

  • S. F. Siddiqi
  • M. Bulmer
  • P. Ayazi Shamlou
  • N. J. Titchener-Hooker


Experiments were performed to characterize the particle size distribution of bakers' yeast cells during high pressure homogenisation. Results were obtained for mechanically agitated batch and continuously grown cultures under a range of operating conditions. It was found that the dependency of cell debris size distribution on the number of passes through the homogeniser and the homogeniser pressure was independent of the cell properties and culture conditions, but for a fixed pressure and number of passes the extent of disruption was strongly affected by the operating conditions in the fermenter. The entire cell debris size distributions were successfully simulated using the mean and variance of the distributions and a previously published model equation which related these parameters to the operating pressure and number of passes through the homogeniser.

List of Symbols


breakage coefficient in Eq. 1


cell diameter


median diameter of homogenate size distribution


dimensionless d50 defined as \(\frac{{d_{50_{N = 0} } - d_{50} }}{{d_{50_{N = 0} } }}\)


dilution rate


cumulative undersize distribution (volume basis)


number of passes


total pressure


threshold pressure




Boltzmann parameter, Eq. 4


dimensionless standard deviation defined as \(w^ \star = \frac{{w_{N = 0} - w}}{{w_{N = 0} }}\)

Greek Letters


exponent in Eq. 1


exponent in Eq. 1


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Copyright information

© Springer-Verlag 1995

Authors and Affiliations

  • S. F. Siddiqi
    • 1
  • M. Bulmer
    • 1
  • P. Ayazi Shamlou
    • 1
  • N. J. Titchener-Hooker
    • 1
  1. 1.The Advanced Centre for Biochemical Engineering, Department of Chemical and Biochemical EngineeringUniversity College LondonLondonUK

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