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Harvesting (washing) Yeast - KC - 03-27-2017 02:33 PM
Posting this for information to help maintain the wild yeast culture for the barrel brews. It can't be bought in vial form or in a smack pack so we need to make sure this yeast stays available long term.
There is a lot of information available on how to collect and preserve yeast after primary fermentation is over. This is a link I've been pointing to:
https://www.brewersfriend.com/2010/01/30/yeast-washing-101/
I've taken a couple personal notes that may also help if you don't have a FastFerment, Catalyst, or other conical fermenter.
- Tip #1: Minimize the amount of unwanted sediment
The pictures in the link above show a lot of trub, and that makes it harder to collect as much usable yeast. Remove as much of the protein hot/cold break, hop material, and residual flour from the boil as possible.
Whirlpooling is a common way to do this with a pump. Otherwise filtering is usually necessary. For a carboy, I use a colander lined with a paint strainer or cheesecloth. The colander keeps the strainer bag from plugging up the funnel when its full of saturated hops. For a bucket or other wide lidded fermenter, the paint strainer could go in first with the wort poured over it. Then the sediment can be lifted out like a grain bag.
As always, sanitize. I sanitize new paint strainers by steaming them on the stove for 10-20 minutes. - Tip #2: Start large, then go smaller
The jar to initially collect the slurry with should be fairly large (the link shows a 2L flask). Fill that no more than half way with slurry and dilute it by topping off the jar with sterilized water. When the unwanted trub settles, decant into a smaller jar only the liquid part containing yeast in suspension.
After the yeast have totally dropped out of suspension in the second jar, decant most of the water from that jar and transfer the concentrated pure yeast slurry into something as small as a vial. - Tip #3: Utilize timing and temperature
Holding the first jar with the yeast and trub at room temperature keeps the yeast in suspension longer, so you get more when decanting. Be sure to do this after the clear layer of trub forms but before the lighter yeast layer builds up.
Similarly, putting the second jar with the decanted liquid in the fridge drops yeast out of suspension more quickly.
I've been able to turn a yeast cake into pitchable slurry in as little as 4 hours. That's relevant only if you want to repitch quickly into a new beer without carrying over color or flavor from the first batch. Normally, the point of harvesting yeast is to save it for later.
For longer term storage, here's an article on freezing yeast:
http://www.homebrewtalk.com/freezing-yeast.html