BIOCHEMICAL ASPECTS OF YEAST FLOCCULATION AND ITS MEASUREMENT: A REVIEW

Abstract

Factors affecting flocculation of brewing yeast, our current understanding of the process and traditional methods of assessing flocculence are discussed in this review. In spite of extensive study during the last two decades, a number of uncertainties and controversies regarding yeast flocculation still remain. This confusion is due in part to the polyploid or aneuploid nature of most brewing strains studied. At present, uncertainty exists as to the number of genes involved in flocculation as well as the nature and mode of action of the resulting gene products. Another restriction to our investigation of flocculation is the lack of a fundamental and standard test method. Along with a general discussion of yeast flocculation, this report will note conflicting reports concerning the influence of temperature, the effect of metal ions such as magnesium and barium, and the importance of the carboxyl and phosphate groups in yeast cell—cell interactions. As well, past and current methods employed for the assay of brewing yeast flocculation will be discussed. 1992 The Institute of Brewing & Distilling