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Difference between revisions of "Flocculation"
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(cells into aggregates by the addition of multivalent cations, metal salts or polymers (for example, polyaluminum chloride).) |
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==== Yeast flocculation ==== | ==== Yeast flocculation ==== | ||
In the brewing industry flocculation is a very important process | In the brewing industry flocculation is a very important process during the production of beer by fermentation where cells form macroscopic flocs. These flocs cause the yeast to sediment or rise to the top of a fermentation at the end of the fermentation. Subsequently, the yeast can be collected (cropped) from the top (ale fermentation) or the bottom (lager fermentation) of the fermenter in order to be reused for the next fermentation. | ||
Yeast flocculation is primarily determined by the calcium concentration, often in the 50–100 ppm range. Calcium salts can be added to cause flocculation, or the process can be reversed by removing calcium by adding phosphate to form insolubable calcium phosphate, adding excess sulfate to form insoluble calcium sulfate, or adding EDTA to chelate the calcium ions. While it appears similar to sedimentation in colloidal dispersions, the mechanisms are different. | Yeast flocculation is primarily determined by the calcium concentration, often in the 50–100 ppm range. Calcium salts can be added to cause flocculation, or the process can be reversed by removing calcium by adding phosphate to form insolubable calcium phosphate, adding excess sulfate to form insoluble calcium sulfate, or adding EDTA to chelate the calcium ions. While it appears similar to sedimentation in colloidal dispersions, the mechanisms are different. | ||