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Yeast harvesting first timer

So I’ve gotten to the point where I want to re-use the yeast from batches to re-pitch for the same beer at a later date. Problem is: I have a very vague idea (at best) on how to do this.

Here’s what I do know:

1)Take the top layer of yeast off the cake, attempting to leave the trub behind.
2) wash the yeast
3) refrigerate.

What I don’t know ( but imagine I should):

  1. best/easiest/ most effective way to separate the trub from the yeast??
  2. how to identify what’s good and what’s not?
  3. how to wash the yeast? Or why I need to?
  4. how long it will store for before it loses it’s viability?
  5. and making an appropriate starter?

Thanks in advance. I know that’s a laundry list if questions.


Some will say to wash the yeast, but the more handling you do, the more chance of infection. IMO it’s just not necessary.

What I do is sanitize a mason jar and spoon. Try to get the top layer of yeast off the cake as this is probably the most healthy, although least flocculent. Put it in the fridge and don’t touch it until you pitch it again. Consult to see how much you should pitch in your next batch.

  1. After packaging the beer, I add about 1/2 gallon of water to carboy and mix it all up. Then I let that sit for 15 minutes. Then I pour off all but the bottom layer from the carboy into a gallon jug. Only one rinse and what’s left is a good amount of viable yeast with little trub.
  1. Once you let your container sit for a day or two in the fridge you will see distinct layers. Trub is at the bottom and beer is at the top. Everything in between is good yeast.
  2. Unless you use acid to separate out only living yeast, it’s rinsing. See #1 for procedure. You could separate #1 into smaller jars, thus eliminating more trub. The purpose is to separate yeast from trub.
  3. I will pitch directly from jug after 4 weeks. Longer than that and I’m better off making a starter. I’ve pitched up to 6 months old but it’s possible to go even longer.
  4. Mr. Malty has a “Repitching from slurry” tab. I use this as a guide. The viability rate drop is too high IMO so I usually calculate a 15% drop for each month.

This video was a huge help for me.

Awesome! Thanks. It seems like a fairly simple process, might just take a little trial and error.

3 tips I can give.

  1. When you first pour your sanitized water (I just used purified bottled water) into your fermentor, let it sit for 30min or so. Then when you pour your yeast/trub/water mixture into your jug (I use a 1gallon glass jug) don’t be overly concerned about how much trub your transferring. You’ll rinse it again so it’s not a big concern.

  2. When you get your single rinsed gallon of yeast/trub/water mixture into the jug, let the jug sit in your fridge for about an hour or so before you then pour that into smaller mason jars. If you don’t let it sit long enough, the trub won’t have time to separate out. If it sits too long, you’ll have a layer of trub on the bottom and the yeast will start to form a layer above it. You don’t want that. You want the trub layer at the bottom, but you don’t want the yeast to start dropping out. When you see a thick layer of trub, that is a good time to pour off the rest into your mason jars.

  3. Let the mason jars (I usually have 5 or 6) sit in the fridge for 5-7 days. After a week most or all of the yeast will have floculated out. Then you can pour off most of the water/beer solution and combine your 5 -6 jars down into 2 or 3.

With some yeast you’ll get 1-2 good jars of yeast. With others you’ll get 3-4.

I just sterilize the jar in the pressure cooker and scoop up the yeast with a sterile ladle or spoon into it. Don’t really bother cleaning off the throb if I’ll use it shortly afterwards because there is gonna be throb in the new beer anyways. If it’s long storage or I think the yeast is contaminated, I just streak out the sample, pick colony and grow from that. I agree that the more manipulations you do with the yeast, the higher the chance for infection is, so I try to keep it at minimum.

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