Yeast Washing Ė (Quick and Dirty)

By: Mike Dixon mpdixon@ipass.net

In homebrewing, yeast are everything. They also contribute to a significant portion of the cost of the brew. An easy way to defray some of that cost is to save the slurry from a previous batch and pitch that in future brews.

Sometimes in the transfer process from the original brew pot some of the trub carries over into the fermenter. To "clean" and separate the yeast from this trub there is an easy process called "yeast washing". Iíll go over the basic equipment needed and the process.

The equipment required would be at least two sanitized mason jars, a couple of rubber bands, and some plastic cling wrap (Reynolds wrap). Also, you might need some sterile water, either boiled and cooled or distilled. If you need water it is best if it is already chilled.

The procedure is a piece of cake. Just be sure to do this in a draft free room, and with as much cleanliness and care as you utilize when brewing and pitching yeast.

Step 1: Harvest the Yeast

After racking the beer off the yeast in either the primary or secondary fermenter, swirl the container (carboy/bucket) until all the yeast is in suspension. If there is not enough liquid to achieve this add about half a cup of the sterile water to the fermenter to loosen it up. Dump this into one of your sanitized mason jars, cover with cling wrap, and secure the wrap with a rubber band. Put this into the refrigerator for 20 min to 1 hour (depending upon how cold the initial slurry was).

Step 2: Separation of the Trub from the Yeast

After being in the fridge you will see a separation of the components of the slurry, something like below.

 

The hardest part to see is the thin line of yeast between the trub and the liquid above. When your solution looks similar to the diagram, carefully pour off the suspended yeast into a sanitized mason jag and leave the trub layer behind. The thin layer between the two contains yeast, but donít worry about collecting it, there will be plenty in the suspension provided the solution has not been sitting in the fridge so long as to allow the top to become clear.

Step 3: Wash again?

If some of the trub carried over, place the mixture back into the fridge and wait for separation to occur so you can repeat the process. I rarely find this necessary if I did a good job of decanting the suspended yeast off the trub.

Step 4: Pitch or Save?

Now you are either ready to pitch to a brew, or want to save the yeast for later. If you are ready to pitch, you can do so immediately without making a starter. If you want to save the yeast, place a sanitized number 13 stopper and a sanitized airlock on the mason jar and keep in the fridge until time for use. (Placing a mason jar lid and ring on the jar is not a good idea unless you are positive the fermentation you got the yeast from is complete.) If the solution sits long enough, you will see clear liquid above the yeast, this clear liquid can be discarded prior to use since it has no yeast.

If you do not reuse your yeast within 2 weeks of the washing it is a good idea to make a starter using the washed yeast. The yeast can also be divided and pitched over several brews. Finally, yeast slurry from the primary fermenter will have greater yield than the yeast slurry from the secondary fermenter.

Note:

The original website where I learned to make starters is no longer available. The writer of that article was Robert Arguello, I took much of the information for this article from his old website.

Wyeast Labs also has a yeast washing web page at:

http://www.wyeastlab.com/hbrew/hbyewash.htm