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The study of premature yeast flocculation and its relationship with gushing of beer
Blechov, P., Havlov, P., Havel, J.

The production of good quality beer requires a consistent performance of fermentation. Many brewers around the world have problems associated with certain batches of malt that experience so-called premature flocculation of yeast. Premature yeast flocculation (PYF) is the phenomenon whereby fermenting yeast coagulates and settles prematurely. Premature yeast flocculation results in a sudden ending of the fermentation process, even if fermentable sugars are still present in the solution. This phenomenon causes an undesirable beer flavour and a low attenuation which results in a reduction of the sugar-alcohol conversion.This work looks at the prediction of premature yeast flocculation right of barley grain using so-called PYF method and compares the results with the conventional method for the determination of fermentability. Also the results of the PYF method were compared with the results for gushing determination in malt.It was found that premature yeast flocculation closely correlates with the gushing of beer. Further it was ascertained that the results of the PYF prediction obtained directly from barley grain correlated very well with the results of the conventional method for the determination of fermentability. In practice is possible to substitute for the conventional method.

Descriptors: Spring barley, malt, premature yeast flocculation (PYF), fermentability, barley antifungal activity, gushing

BrewingScience Monatsschrift fr Brauwissenschaft, 58 (September/October 2005), pp. 64-78