Reusing yeast cake

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azazel1024

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So...I've been thinking about next brews and next steps.

I think my next two brews I am going to do back to back in the same brew session. I am thinking I am either going to do a 5 Gallon American Rye Ale partial mash and a 5 Gallon honey IPA or a 2.5G honey IPA (partial mash or AG depending on volume).

After that I want to try to do a session dry stout and I am either going to do a Coffee oatmeal milk stout or an Imperial coffee stout.

My question is about reusing the yeast cakes. I am thinking I am going to use either S-05 or BRY97 for them. I am thinking S-05 in the IPA and BRY97 for the Rye ale.

What possibilities do I have for reuse? I was thinking I could reuse the IPA yeast in the Imperial stout if I go that direction on the brew (probably, I LOVE imperials and I want to try to push my limits by doing a 1.1 or 1.11OG beer). I figure if I've breed up the yeast on something like a 1.09 IPA, that it'll have selected for pretty alcohol tolerant yeast, and supposedly S-05 is tolerant to 12% as it is.

If I do this, should I pitch the entire yeast cake? Or only part of it? I want it to do a good ferment, but I'd also prefer to to volcano wort all over my basement (I assume I MUST use a blow off valve between the OG and reusing the yeast cake). Would an IPA be a bad brew to reuse the yeast cake for an imperial stout?

The little I have read on it is not to use the yeast cake from a darker beer on a light beer. I've read little other than that (well, that a "rule of thumb" is not to use the yeast for more than 3 brews. True?)

The IPA is probably going to sit for a month and I'd brew probably the same day I rack to secondary (for another few days before bottling). Anything I should do to preserve the yeast for the few hours between racking to secondary and the new brew being ready? Should I just dump the new wort right on top of the yeast cake? Or should I clean the yeast cake out in to something else, clean the sanatize the container, pour the wort in and then the yeast?

Also for the Rye Ale, would it be a bad idea to reuse the yeast from that in something like a dry light stout (I am thinking like 1.035OG to get a real session stout)? Are the rye flavors going to carry over (I assume yes, to some extent)? The Rye ale I am thinking only 2 weeks in primary before bottling and probably brew up the session stout the same time I am bottling.
 

william_shakes_beer

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You do what you prefer. Many brewers reuse yeast cake from one batch to another with great success. You have to remember, however, that there is more in the trub than just yeast cells. Unless you wash, you are also getting a bit of wort and a great deal of hops from the previous batch. It'd be a real shame to tweak down to the perfect recipe, only to discover that you cannot repeat it because of the incalculable contributions from the trub.

I do the opposite: after I pitch my starter, I reserve a bit of yeast in the flask and refeed with fresh starter wort (made from DME) After the starter ferments out, I decant and store the slurrey for future starters. That means my yeast library never sees anything but pilsen starter wort.
 

fosaisu

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Here's a lengthy thread on reusing yeast cakes, worth a look if you're thinking about it: https://www.homebrewtalk.com/f163/why-not-pitch-your-yeast-cake-166221/ Majority opinion appears to be you're best off using a cup or two of the yeast slurry from the bottom of the fermenter (rather than pitching directly onto the entire yeast cake) to avoid over-pitching.

I hadn't heard that you shouldn't use yeast slurry from a dark beer in a subsequent lighter-colored beer -- especially if you're only using a cup or two of slurry, you shouldn't be adding too much dark material to the lighter beer so I wouldn't think you'd have a problem.

There are a variety of opinions about how many times you can "safely" re-use yeast. I've only ever done two in a row b/c I get bored and want to try other yeast strains. I've read many times on this site that there's very low likelihood of significant mutations up to 10 "generations" (I think mutation, plus selection for either overly floculent or non-floculent yeast depending on how you collect them, are the primary concerns with repeated re-use -- if your technique is sound contamination shouldn't be an issue, and if it's not you'll have contamination whether you're on your first or 50th batch). But I have no idea if there's any science backing that 10 generation number up.
 

PDX_T

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commercial brewing uses this practice routinely. Always a good idea to remove the yeast, wash it, and sanitize your fermenter. if you want to get technical about pitch rates there's a lot more to it, but for most 5 gallon batches, a cup of washed and settled yeast is good.
 
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