storing yeast cake warm ?

[odie]

How long can yeast cake stay at room temps before going bad?

Yeast cake in a standard fermentor bucket or carboy?

How about yeast cake in a sealed corny keg?

I ask because I ferment and serve from the same keg. When a keg goes empty, I currently have to brew another beer immediately or find a place to cold store the keg with yeast cake if I want to re-pitch it. Sometimes it might be a couple weeks.

If yeast cake is OK at room temperature, then it opens up more options.

 

[VikeMan]

At room temperature, yeast cells are going to die off faster than if refrigerated. Exactly how much faster, I dunno. But in the absence of specific data, it might make sense to SWAG it using the rule of thumb that results from the Arrhenius equation, i.e. that chemical and biological reactions tend to happen about twice as fast for every increase in temperature of 10C.

 

[odie]

Interesting. Yeast cells live and propagate and room temperature just fine. I guess when they run outta food they die unless they get cold and hibernate?

I guess, even in the fridge the yeast are dying off...but at a much slower rate?

I've pitched year old jars of yeast from the fridge without any starter and it's taken off just fine and made good beer.

I guess what I was asking, does the stagnate "warm" yeast go bad, get infected, spoil, whatever if left at room temperature without any more wort to ferment?

Then again, I've heard of people leaving beer in the bucket for a month or longer before bottling and it was just fine. In the bucket sitting on the yeast cake. I suppose a lot has to do with it being a closed environment.

 

[day_trippr]

I imagine extant bacterial infection allowed to run rampant at warm temperatures is a factor wrt spoilage...

Cheers!

 

[rallenhall]

I've cloned yeast from commercial bottles that I'm sure have survived warm temperatures and extended shelf time. Assume that the yeast is pretty pure though without the trub, etc., that would be found in a homebrew.

 

[Dland]

From what I've experienced, yeast cake will loose most of its viability in a couple weeks if not kept cool.

However I'm not a yeast expert, just based on these observations;

I've been running strings of batches pitched on yeast cake left in sealed conicals for a while now. Due to the nature of my cooling temp control, it does not really work when fermentor is mostly empty. Right now I'm on 9th batch in a row on S-189, and I can leave it for a couple of weeks between brews and it is up and running in a couple of hours after adding new wort, but cellar fermentor is in is 43F right now, and has been that cold all winter.

However, when temps warm up, cellar gets up into 60s & 70sF. I often switch to ale yeast like US-05 or S-04 so as not to overwork my home made chilling system. In the warmer weather, I can only go about a week between brews, or I've found the yeast may not take off at all, at least it does not take quickly enough for me to risk a 10 gallon batch. I'm only willing to wait 24 hrs before pitching in some new yeast. To put into perspective, one pack of dry pitched ale yeast in 10 gallons of wort is always working within 12 hours of pitch.