How long is a yeast cake good?

Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum

Help Support Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

TRainH2o

Well-Known Member
Joined
Aug 13, 2009
Messages
430
Reaction score
7
Location
North Georgia
Long story, but I brewed Yooper's Dead Guy Clone on November 7th. I used the recommended Pac Man yeast and it turned out fantastic.

I had every intention of washing that yeast cake and reusing it in future brews. Well I racked the beer to a keg right after Christmas. I left a little bit of beer covering the yeast cake, and was going to wash it the next day. Well, my whole family came down with the flu and needless to say, I forgot about the yeast.

It was been sitting in the carboy since then. I remembered it a few days ago. It's still covered with about 1/2 inch on beer. The temp has gone up a bit where it is stored but I would say it has been 60-65˚F the whole time. There doesn't seem to be anything growing in it and it smells normal. I know I should dump it but part of me wonders if it is still good.

Anyone with a similar experience? I know it's just $7 or so to buy more, but man that was some good, hard-working yeast.
 
Make a starter with your yeast that you harvest and you'll see whether or not it's viable. I think that you have a good chance of still being able to use it, but I wouldn't pitch it without making a starter.
 
No, I wasn't going to pitch onto the yeast cake. I figured that my biggest risk of contamination would be from the stuff stuck to the sides of the carboy. I would add some cheap BMC beer, swirl, and then rack the suspended yeast with the auto siphon.

That Dead Guy clone was so good, I am going to make it again for sure. Thanks for your thoughts.
 
I've left yeast cakes for a week or two and they were still ok. If it smells fine in there and no sign of mold or anything it should be good. I always have intentions of doing it the next day and I too get busy and forget. I actually have one sitting now for just about a week now...going to wash tomorrow....if I remember.:cross:
 
That's a long time to be around room temp. If it had been cold, I'd feel differently. When you racked out, you probably introduced a lot of air/oxygen to replace the space where the beer used to be.
 
That's a long time to be around room temp. If it had been cold, I'd feel differently. When you racked out, you probably introduced a lot of air/oxygen to replace the space where the beer used to be.

Those are good reasons to make starter, but I would be very surprised if there weren't enough viable cells to get a starter going.

My main concern is you probably want to get a pretty good bit of slurry in your starter to increase the chance of viability, but you will likely want to avoid letting that old slurry get into your next beer (since it may be fairly oxidized/autolyzed). So you should probably do a starter with a healthy helping of old slurry, let that finish, decant, and then do another starter using the layer of healthy cells on top of the starter's yeast cake. That second starter (assuming you get the cell counts right) should be fine to pitch into your next beer. That's my 2 cents anyhow.
 
I was making a dubbel several months ago, and my LHBS couldn't get me a fresh pack of 1762 quickly enough. So I went to a friend's house, who had a 1 year old slurry of 1762 that had been immaculately packaged, and sitting in a fridge all that time.

I decided to go for it with the same reasoning: "They can't ALL be dead - there's got to be something viable in there." So I made a 250mL starter, let it go a few days, stepped it up to 2L, decanted, and made another 2L starter. I definitely pitched the proper amount of yeast cells, but were my results good?

Well, the beer was awesome, but for a dubbel with 10% sugar, I only achieved 71% attenuation. Pretty shameful. It was a little sweeter than it should have been.

So for me it's not a question of viability, it's optimization. Of course you'll make beer if you reuse the yeast - but will it be the best beer?
 
Point taken -- I should have added YMMV. I revived some Wyeast 1272 slurry that had been in a jar in my fridge for like a year, and I've since used it to brew 3 batches. High attenuation, no off flavors, seems like the same neutral, simple yeast it was originally. But, obviously my success does not guarantee anyone else's.
 
Thinking about this logically, I have the following thoughts:

1. The yeast were healthy and made from a 2 liter starter when I pitched.
2. My sanitation was good with the first batch.
3. I left 1/2 of beer on the yeast cake. Maybe should have been more.
4. Yeast cake has been at slightly lower than room temp, 60-65˚F for 4 months counting active fermentation.
5. People sometimes leave beer on the yeast for that long with good results.

I guess it all comes down to:

1. Will the air that I introduced will have any ill effects?
2. Will I have something that shows up, due to the time the yeast has sat dormant?
3. Am I willing to risk a batch?

I guess I'll be buying new yeast and starting over. I continue to use my American Ale yeast. It started off in a light OG Blond Ale, Pale Ale, Apple Cider and now it is working its way through an IPA. Yeast washing and repitching is a good thing if you do it right.
 
Back
Top