Key Considerations for Yeast Recovery

Generally for a fermentation vessel, the yeast gather at the top and bottom of the fermentation broth, but if you give the yeast enough time, they will all run to the bottom of the fermenter and wait for you to collect as much as possible.

1. Advantages of recycling yeast.

• Reduced cost of yeast.

• You can get some yeast from unfiltered beer that is not openly available for sale.

• A lot of yeast is not always available, especially liquid yeast, and the shorter shelf life means that the yeast you want may not always be available, recycling your own yeast allows you to always have yeast available.

2. Disadvantages of recycled yeast.

• The process of recovering yeast increases the chance of infection, and any mix of other varieties of yeast or even bacteria in any one session may ruin the beer brewed later.

• The yeast itself can mutate genetically, and if the brewing environment is high gravity or high altitude, the possibility of yeast mutation will be even higher, resulting in a brew with absolutely no quality control.

• Preservation will take up space and also needs to be treated correctly.

3. When to collect yeast

The vast majority of winemakers choose to start collecting yeast after fermentation is complete. Generally for collecting yeast from the bottom, most winemakers choose to drain the yeast directly from the bottom of the fermenter when the yeast is not completely finished fermenting, as well as impurities such as cold condensate. This will ensure that the wine is clean and will also help to get pure, vigorous yeast faster when collecting yeast from the bottom of the cone later. However, for winemakers who collect yeast from the top (mostly for home brewing), they choose to do so at the peak of fermentation.

4. Storage methods for recovered yeast

• Ensure that the temperature of the storage environment is sufficiently low, but at the same time not freezing, 1˚C – 2˚C is optimal.

• You can preserve it in cold boiling water or in the wort left over from the expansion, but do not leave air in the test tubes if you preserve it in wort.

• Preserve in sterile containers, plastic ones that can withstand the pressure of the carbon dioxide produced by the yeast.

• The less oxygen in the container, the better.

• Because the refrigerator does not allow the yeast to reach the preserving temperature immediately, the yeast will also produce carbon dioxide, and you will need to unscrew the container from time to time for the first few days torelease the pressure.