Yeast harvesting methods vary depending on the vessel used for fermentation, with different techniques applied to conical tanks versus open vessels.
Harvesting from Conical Tanks
In conical tanks, the most desirable yeast cells settle into a specific layer at the bottom. This layer is located between:
- The bottom layer, consisting of trub and cells that flocculate early.
- The top layer.
The middle layer is the one brewers want to harvest because it contains the healthiest yeast.
Harvesting from Open Vessels
When using an open vessel, the harvesting process involves skimming the top:
- Discard the first skim: This "dirt" skim contains unwanted materials.
- Harvest the second skim: This skim contains the desired yeast.
- Discard subsequent skims: Any further skims are considered undesirable.
In summary, yeast harvesting is a selective process that targets specific layers or skims to obtain the healthiest and most viable yeast for subsequent brewing batches.
