Flocculation
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At the end of fermentation, when all fermentable sugars are converted into alcohol and carbon dioxide, yeast cells in suspension clump together and sediment at the bottom of the fermenter, a process called flocculation.
Some strains of yeast are known to generally flocculate very well, and other strains flocculate poorly. Often the yeast lab providing a beer yeast culture will describe the flocculation tendency. Low flocculation strains will stay in suspension and add a haze, such as Weizen yeast for example, whereas high flocculation strains will settle quickly and leave little to no haze.
Compared to other brewing technical properties of yeasts, flocculation is one of the most variable,[1] meaning even the same exact strain of yeast may flocculate to a different degree or at a different time, depending on the conditions. Unfortunately the mechanisms are not currently well understood, and so manipulating this characteristic is difficult.
References
- ↑ Van Mulders, S.E., et al. "Flocculation gene variability in industrial brewer’s yeast strains." Appl Microbiol Biotechnol, vol. 88, 2010, pp. 1321–1331.