Factors that promote Premature Yeast Flocculation (PYF) condition in malt


Cereals & Oilseeds
Project code:
01 April 2008 - 31 March 2009
AHDB Cereals & Oilseeds.
AHDB sector cost:
£24,829 from HGCA (Project RD-2007-3417).
Project leader:
G. Fisher Campden BRI, Centenary Hall, Coopers Hill Road, Nutfield, Surrey RH1 4HY



About this project



The overall aims of this project were to investigate potential links between malting procedures and the phenomenon of premature flocculation of yeast (PYF) during subsequent brewing.

In this preliminary study, commercial malts were tested for the presence or absence of PYF factor and results correlated with production parameters such as barley batch, malting plant or specific malting processes. The intention was to establish what part of the malting procedure has greatest effect on PYF in order to prevent or at least minimise occurrence of PYF in commercial malts.


Tests on more than forty commercial malts have shown that formation of PYF+ve malts in the malting process is reassuringly uncommon. Presence of PYF factor does not appear to correlate with the variety or bulk batch of the barley used, or the malting plant in which it was made, but seems to be restricted to certain operating conditions that are not standard. There are no simple solutions to this complex problem, it cannot yet be statistically linked with any particular process and some established dogma has been invalidated.


Clearly further work needs to be done to establish the nature of the microbial community through the malting process, and how this community changes with modifications to the malting process.