A Discussion of Malt-Induced Premature Yeast Flocculation
Peer-Reviewed Paper
MBAA TQ vol. 45, no. 3, 2008, pp.
253-262 |
VIEW ARTICLE
Joseph C. Lake and R. Alex Speers. Food Science and Technology, Dalhousie
University, 1360 Barrington Street, D401, Halifax, NS B3J 2X4, Canada.
Abstract
Premature yeast flocculation (PYF) is qualitatively described as the early
flocculation of yeast during fermentation. The effects of PYF can be devastating
to brewers. Moreover, the frequency of PYF occurrence is unknown but has been
suggested to occur more often than traditionally believed. Since the 1950s it
has been suggested that certain compounds found in wort induce early
flocculation in yeast. However, there is still much debate as to the nature and
mechanisms of PYF-inducing factors found in wort, malt, and barley. This review
examines PYF factors reported in the literature since the late 1950s.
Furthermore, it discusses the origins and effects of PYF-positive malt, as well
as proposed mechanisms of interaction between yeast and PYF-inducing factors. It
is also well known that PYF is difficult to predict and detect. Current methods
of detection are presented, and finally, the reported brewing industry research
concerning PYF is discussed.
Keywords: fermentation, premature yeast flocculation
S�ntesis
La floculaci�n prematura de levadura (FPL) es descrita de manera cualitativa
como la floculaci�n demasiada temprana de levadura durante la fermentaci�n. Los
efectos de FPL pueden ser devastadores para un cervecero. No se sabe con certeza
cu�n frecuente es la ocurrencia de FPL pero se cree que ocurre m�s a menudo de
lo que uno puede pensar. Ya en la d�cada de 1950 se sugiri� que ciertos
compuestos en el mosto induc�an la pronta floculaci�n de la levadura. Aun
existen muchos debates en cuanto a la naturaleza y mecanismos de factores en
cebada, malta y mosto que inducen a la FPL. Aqu� se examinan los factores
reportados en la literatura desde 1950. Se discute los or�genes y efectos de
malta FPL-positivo, as� como de los mecanismos propuestos para la interacci�n
entre la levadura y los factores que inducen a la FPL. Es bien conocido que la
FPL es dif�cil de predecir y detectar. Se presentan algunos m�todos de detecci�n
y se informa sobre las investigaciones de la industria cervecera con respecto al
FPL.
Palabras claves: fermentaci�n, floculaci�n prematura de levadura
