Reusing yeast

[MrHalfStash]

So I recently brewed a Belgian wit and used wyeast Belgian wit yeast. Tonight I racked into secondary and put some of the yeast in a Tupperware and threw it in the fridge. I've never repitched yeast before and I'm kinda winging it. Is the yeast gonna be reusable? What do I do when I'm ready to use it again or is it worthless now?

 

[pumpkinman2012]

Check out this thread:

https://www.homebrewtalk.com/f163/yeast-washing-illustrated-41768/

 

[boydster]

The sooner you use it, the healthier it will be. Use a pitch rate calculator to determine how much to pitch; you don't want to pitch the entire slurry in most cases as that would be an extreme overpitch.

 

[JimRausch]

I repitch yeast frequently, so yes your yeast will still be alive and repitchable. You did sanitize the Tupperware, right? Otherwise you could have added some contaminants. Sometimes the yeast will continue to produce some CO2, so burp the Tupperware after 24 hours or so.
Check out the 'Mr.Malty' website to figure out how much to pitch. It varies depending on the OG of your next brew, as well as how long ago you harvested the yeast.

 

[Calder]

General rule of thumb is pitch a quarter of a cake for a similar sized beer. If the OG is 2X, then pitch half the cake. The slurry should be used within a week, but a month doesn't seem to be an issue.

Mr Malty can be a guide, but I have issues with it:

- How do you know what your yeast concentration is?
- How do you know your non-yeast percentage?
- The yeast viability is way too conservative.

So you have to make a couple of guesses, coupled with an unrealistic viability number = nothing useful.

 

[theck]

Just started myself this year, saved myself $6+ a pop on some apple cider (on 3rd batch now) using a 3rd gen yeast from a couple ales I did. Got a hefe in the fermentor now. I'll be saving that yeast as well. Knock on wood it's been going really well so far.

I think you'll get more out of the primary than the secondary as well? Also, I think putting it in the fridge after a bit cold crashes it so it doesn't keep fermenting.

Also, @boydster what happens when you overpitch? I've been chunking mine into 4ths and pitching that.

 

[boydster]

Just started myself this year, saved myself $6+ a pop on some apple cider (on 3rd batch now) using a 3rd gen yeast from a couple ales I did. Got a hefe in the fermentor now. I'll be saving that yeast as well. Knock on wood it's been going really well so far.

I think you'll get more out of the primary than the secondary as well? Also, I think putting it in the fridge after a bit cold crashes it so it doesn't keep fermenting.

Also, @boydster what happens when you overpitch? I've been chunking mine into 4ths and pitching that.

Pitching in 4ths isn't terrible, I think others on HBT can confirm they use that as a rough rule of thumb. A big overpitch (like pitching on a full cake) can be detrimental if you reuse yeast because there is less cell division, meaning the cells you harvest at the end will be older, scarred cells instead of younger, healthier daughter cells.