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Malt-induced premature yeast flocculation: current perspectives

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Journal of Industrial Microbiology & Biotechnology

Abstract

Premature yeast flocculation (PYF) is a sporadic problem for the malting and brewing industries which can have significant financial and logistical implications. The condition is characterised by abnormally heavy (and sometimes early) flocculation of yeast during brewery fermentations. The resulting low suspended yeast cell counts towards the end of the fermentation can result in flavour defects and incomplete attenuation (fermentation of sugars to alcohol). Despite several decades of research into the phenomenon, its precise nature and mechanisms have not been fully elucidated. In part this is because the term PYF has become a ‘catch-all’ syndrome which can have multiple origins. Furthermore, there are complex interactions in the malting and brewing processes which together mean that the PYF status of a malt sample is hard to predict at a generic level. Whether or not PYF is observed depends not only on barley quality, but on process factors in the maltings and to a substantial extent on the brewing yeast strain concerned. This article highlights the significance of PYF, and reviews current knowledge relating to the origins of this complex phenomenon.

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Abbreviations

PYF:

Premature yeast flocculation

PYF+:

A premature yeast flocculation positive sample (barley, malt or wort giving rise to PYF)

PYF−:

A premature yeast flocculation negative sample (control barley, malt or wort sample yielding normal flocculation characteristics)

ns-LTP:

Non-specific lipid transfer protein

T-RFLP:

Terminal restriction fragment length polymorphism

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Acknowledgments

The authors would like to thank the UK Home Grown Cereal Authority for financial support. Professor Katherine Smart is the SABMiller Professor of Brewing Science and gratefully acknowledges SABMiller for their continued support.

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Authors and Affiliations

  1. Brewing Science Section, Division of Food Sciences, The University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire, LE12 5RD, UK

    Apostolos G. Panteloglou, Katherine A. Smart & David J. Cook

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  1. Apostolos G. Panteloglou
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  2. Katherine A. Smart
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  3. David J. Cook
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Correspondence to David J. Cook.

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Panteloglou, A.G., Smart, K.A. & Cook, D.J. Malt-induced premature yeast flocculation: current perspectives. J Ind Microbiol Biotechnol 39, 813–822 (2012). https://doi.org/10.1007/s10295-012-1086-0

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