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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

 

Síntesis
La floculación prematura de levadura (FPL) es descrita de manera cualitativa como la floculación demasiada temprana de levadura durante la fermentación. Los efectos de FPL pueden ser devastadores para un cervecero. No se sabe con certeza cuán frecuente es la ocurrencia de FPL pero se cree que ocurre más a menudo de lo que uno puede pensar. Ya en la década de 1950 se sugirió que ciertos compuestos en el mosto inducían la pronta floculación 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. Aquí se examinan los factores reportados en la literatura desde 1950. Se discute los orígenes y efectos de malta FPL-positivo, así como de los mecanismos propuestos para la interacción entre la levadura y los factores que inducen a la FPL. Es bien conocido que la FPL es difícil de predecir y detectar. Se presentan algunos métodos de detección y se informa sobre las investigaciones de la industria cervecera con respecto al FPL.

Palabras claves: fermentación, floculación prematura de levadura

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