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Studies supporting the use of mechanical mixing in large scale beer fermentations

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Abstract

Brewing fermentations have traditionally been undertaken without the use of mechanical agitation, with mixing being provided only by the fluid motion induced by the CO2 evolved during the batch process. This approach has largely been maintained because of the belief in industry that rotating agitators would damage the yeast. Recent studies have questioned this view. At the bench scale, brewer’s yeast is very robust and withstands intense mechanical agitation under aerobic conditions without observable damage as measured by flow cytometry and other parameters. Much less intense mechanical agitation also decreases batch fermentation time for anaerobic beer production by about 25% compared to mixing by CO2 evolution alone with a small change in the concentration of the different flavour compounds. These changes probably arise for two reasons. Firstly, the agitation increases the relative velocity and the area of contact between the cells and the wort, thereby enhancing the rate of mass transfer to and from the cells. Secondly, the agitation eliminates spatial variations in both yeast concentration and temperature, thus ensuring that the cells are maintained close to the optimum temperature profile during the whole of the fermentation time. These bench scale studies have recently been supported by results at the commercial scale from mixing by an impeller or by a rotary jet head, giving more consistent production without changes in final flavour. It is suggested that this reluctance of the brewing industry to use (adequate) mechanical agitation is another example where the myth of shear damage has had a detrimental effect on the optimal operation of commercial bioprocessing.

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Abbreviations

A :

Cross-sectional area of the cylindroconical vessel (m2)

D :

Impeller diameter (m)

g :

Gravitational constant (9.81 m2/s)

H :

Static head due to the height of liquid in the cylindroconical vessel (m)

H A :

Static head due to atmospheric pressure (m)

N :

Impeller speed (rev/s)

n :

Number of impellers (–)

P :

Power (W)

Po:

Power number of impeller (–)

\( Q_{{{\text{CO}}_{2} }} \) :

Volumetric CO2 production rate (m3 CO2/m3 liquid/s)

Re :

Reynolds number (= ND 2/ν) (–)

t m :

Mixing time (s)

V :

Volume of liquid (m3)

v S :

Superficial gas velocity in the cylindroconical vessel (m/s)

εT :

Local specific energy dissipation rate (W/kg)

\( \bar{\varepsilon }_{\text{T}} \) :

Mean specific energy dissipation rate (W/kg)

λK :

Kolmogoroff microscale of turbulence (m)

ν:

Kinematic viscosity (m2/s)

ρ:

Liquid density (kg/m3)

g:

Under gassed conditions

References

  • Amanullah A, Nienow AW, Buckland BC (2003) Mixing in the fermentation and cell culture industries. In: Paul EL, Atiemo-Obeng VA, Kresta SM (eds) Handbook of industrial mixing; science and practice. Wiley-Interscience, New York, pp 1071–1157

    Chapter  Google Scholar 

  • Boswell CD, Nienow AW, Hewitt CJ (2002) Studies on the effect of mechanical agitation on the performance of brewing fermentations: fermentation rate, yeast physiology, and development of flavour. J Am Soc Brew Chem 60:101–106

    CAS  Google Scholar 

  • Boswell CD, Nienow AW, Gill N, Kocharunchitt S, Hewitt CJ (2003a) The impact of fluid mechanical stress on Saccharomyces cerevisiae cells during continuous cultivation in an agitated, aerated bioreactor; its implications for mixing in the brewing process and aerobic fermentations. Food Bioproduct Proc 81:23–32

    Article  Google Scholar 

  • Boswell CD, Varley J, Boon L, Hewitt CJ, Nienow AW (2003b) Studies on the impact of mixing in brewing fermentation: comparison of methods of effecting enhanced liquid circulation. Food Bioproduct Proc 81:33–39

    Article  CAS  Google Scholar 

  • Boulton CA, Price SG, Peters A (2007) Yeast distribution in cylindro-conical vessels, new insights into fermentation performance and management. In: Proceedings of the 31st European brewing convention congress, Venice. Hans Carl Fachverlag, Nurnberg, pp 267–279. ISBN 798-90-70143-24-4

  • Boulton-Stone JM, Blake JR (1993) Gas bubbles bursting at a free surface. J Fluid Mech 254:437–466

    Article  CAS  Google Scholar 

  • Chamsartra S, Nienow AW, Hewitt CJ (2005) The impact of fluid mechanical stress on Corynebacterium glutamicum during continuous cultivation in an agitated bioreactor. Biotechnol Lett 27:693–700

    Article  CAS  PubMed  Google Scholar 

  • Cherry RS, Papoutsakis ET (1986) Hydrodynamic effects on cells in agitated tissue culture reactors. Bioprocess Eng 1:29–41

    Article  Google Scholar 

  • Garcia AI, Pandiella SS, Garcia LA, Diaz M (1994) Mechanism for mixing and homogenization in beer fermentation. Bioprocess Eng 10:179–184

    Article  CAS  Google Scholar 

  • Garcia AI, Garcia LA, Diaz M (1995) Analysis of internal concentration profiles in industrial beer fermentation columns. Master Brew Assoc Am Tech Q 32:201–207

    CAS  Google Scholar 

  • Hewitt CJ (2003) Brewing: an ancient process benefiting from modern scientific and engineering techniques. Food Bioproduct Proc 81:1

    Article  Google Scholar 

  • Hewitt CJ, Nebe-von-Caron G (2001) An industrial application of multi-parameter flow cytometry: assessment of cell physiological state and its application to the study of microbial fermentations. Cytometry 44:179–187

    Article  CAS  PubMed  Google Scholar 

  • Hewitt CJ, Nebe-von-Caron G (2004) The application of multiparameter flow cytometry to monitor individual microbial cell physiological state. Adv Biochem Eng Biotechnol 89:197–223

    CAS  PubMed  Google Scholar 

  • Hewitt CJ, Nienow AW (2007) The scale-up of microbial batch and fed-batch fermentation processes. Adv Appl Microbiol 62:105–135

    Article  CAS  PubMed  Google Scholar 

  • Hewitt CJ, Boon LA, McFarlane CM, Nienow AW (1998) The use of flow cytometry to study the impact of fluid mechanical stress on Escherichia coli W3110 during continuous cultivation in an agitated bioreactor. Biotechnol Bioeng 59:612–620

    Article  CAS  PubMed  Google Scholar 

  • Hewitt CJ, Onyeaka H, Lewis G, Taylor IW, Nienow AW (2007) A comparison of high cell density fed-batch fermentations involving both induced and non-induced recombinant Escherichia coli under well-mixed small-scale and simulated poorly-mixed large-scale conditions. Biotechnol Bioeng 96:495–505

    Article  CAS  PubMed  Google Scholar 

  • Hind A (2000) The application of modelling to the brewing process. In: Proceedings of the 26th convention of the institute of brewing. Asia-Pacific Section, Singapore, pp 104–109

  • Lewis MJ, Young TW (2001) Brewing, 2nd edn. Klewer Academic, New York

    Google Scholar 

  • Luyben KChAM (1997) Fermentation dynamics and fermenter design. Proceedings of the 6th convention of the institute of brewing (SA Section), Durban, pp 37–46

  • Masschelein CA (1981) Flavour development in large-capacity vessels. Brew Distill Int (May): 37–42

  • McLeod G (2007) Studies on the impact of mechanical agitation during brewing fermentation using mid and near infrared spectroscopy. PhD Thesis, University of Birmingham, UK

  • Nienow AW (1997) The mixer as a reactor—liquid/solid systems. In: Harnby N, Edwards MF, Nienow AW (eds) Mixing in the process industries, 2nd edn (paperback revision), Chapter 17. Butterworth Heinemann, London, pp 394–411

    Google Scholar 

  • Nienow AW (1998) Hydrodynamics of stirred bioreactors. In Pohorecki R (ed) Fluid mechanics problems in biotechnology. Appl Mech Rev 51:3–32

    Google Scholar 

  • Nienow AW (2006) Reactor engineering in large scale animal cell culture. Cytotechnology 50:9–33

    Article  CAS  PubMed  Google Scholar 

  • Nordkvist M, Lazar JA, Boulton CA, Nienow AW, Villadsen J (2007) Mixing in sanitary systems by rotary jet heads: fundamentals and applications. In: NAMF XXI, Park City, Utah, USA

  • Nordkvist M, Vognsen M, Nienow AW, Villadsen J, Gernaey KV (2008) Mixing by rotary jet heads: indications of the benefits of head rotation under turbulent and transitional flow conditions. Chem Eng Res Des 86:1454–1461

    Article  CAS  Google Scholar 

  • Okabe M, Katoh M, Furugoori F, Yoshida M, Mitsui S (1992) Growth and fermentation characteristics of bottom brewer’s yeast under mechanical stirring. J Ferment Bioeng 73:148–152

    Article  CAS  Google Scholar 

  • Onyeaka H, Nienow AW, Hewitt CJ (2003) Further studies related to the scale-up of high cell density Escherichia coli fed-batch fermentations: the additional effect of a changing micro-environment when using aqueous ammonia to control pH. Biotechnol Bioeng 84:474–484

    Article  CAS  PubMed  Google Scholar 

  • Vrieling AM (1978) Agitated fermentation in high fermenters. EBC monograph V. European Brewery Convention, Amsterdam, pp 135–144

    Google Scholar 

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Author notes

  1. Georgina McLeod

    Present address: Abbott Laboratories, Queenborough, Kent, ME11 5EL, UK

Authors and Affiliations

  1. Department of Chemical Engineering, Centre for Bioprocess Engineering, University of Birmingham, Birmingham, B15 2TT, UK

    Alvin W. Nienow & Georgina McLeod

  2. Department of Chemical Engineering, Centre for Biological Engineering, Loughborough University, Leicestershire, LE11 3TU, UK

    Christopher J. Hewitt

Authors
  1. Alvin W. Nienow
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  2. Georgina McLeod
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  3. Christopher J. Hewitt
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Correspondence to Alvin W. Nienow.

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Nienow, A.W., McLeod, G. & Hewitt, C.J. Studies supporting the use of mechanical mixing in large scale beer fermentations. Biotechnol Lett 32, 623–633 (2010). https://doi.org/10.1007/s10529-010-0213-0

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