Saved yeast cake gushing. Question.

[jekeane]

I just took a 5 week old jar of saved yeast cake out of the fridge after about 15 minutes i noticed the jar lid was buldging and when I opened it it quickly began fizzing and gushing. It was 300ml of slurry i kept under the original beer. There are no off colors or smells. Did I get some extra fermentation in there or is this not worth pitching?

 

[Denny]

The yeast is waking up. That's why I take the yeast out of the fridge and pitch immediately. There is nothing to be gained by letting the yeast warm before pitching. In fact, it can be detrimental, because as you've just seen it will start consuming its nutrient reserves before it gets into the beer.

 

[jekeane]

cool was surprised how fast that happened.

 

[TheRussMeister]

Yup, no problem here. Its partially the yeast waking up, which was said, but it is also the release of gases as the slurry warms (gas solubility decreases with increasing temperatures).

I will say, that this is the first time I have heard it is not good to let your slurry warm up. I generally let mine warm up to within 10 degrees or so before feeding some fresh wort, and then pitch when its the same temperature as my wort. I have read in a few places, and heard on the BN, that if you pitch with too high of a temperature differential, you can shock your yeast, decreasing the health of the yeast in general, producing some off flavors due to stress, and increasing lag time. Just my 2 cents.

 

[Denny]

Yup, no problem here. Its partially the yeast waking up, which was said, but it is also the release of gases as the slurry warms (gas solubility decreases with increasing temperatures).

I will say, that this is the first time I have heard it is not good to let your slurry warm up. I generally let mine warm up to within 10 degrees or so before feeding some fresh wort, and then pitch when its the same temperature as my wort. I have read in a few places, and heard on the BN, that if you pitch with too high of a temperature differential, you can shock your yeast, decreasing the health of the yeast in general, producing some off flavors due to stress, and increasing lag time. Just my 2 cents.

"Yeast shock" is an outdated, disproven myth. I've cold pitched the yeast for at least 350 batches with great results. Try it for yourself and decide.

 

[youreanimpulse]

Or you could just open the jar when you take it out of the fridge. Just leave the cap loose, allowing it to release CO2. I think the yeast shock thing is more about lag time than anything else, just a thought.

 

[brewboy04]

If you pitch at different temp it will cause and increased lag phase , pitching at a lower temp than the wort will not have as much of a detrimental effect as pitching yeast at a hight temp


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[evillalon]

I think the shock happens in the reverse direction. When you pitch warm yeast in cool wort.

 

[Denny]

I think the shock happens in the reverse direction. When you pitch warm yeast in cool wort.

This is correct. Pitching cooler yeast into warmer wort has never been a problem for me. If anything it starts a bit faster becasue the yeast nutrients are still intact.

 

[eadavis80]

So if I use harvested yeast and add it to a starter, should I let the jar of harvested yeast sit at room temp before adding to the starter? Should I crack the jar of the lid and let it sit out before adding to the starter? I plan on using starters and harvested yeast in future batches, but never considered the temp of the harvested yeast or the jar's lid as being factors, but I guess they are huh?

 

[stpug]

Here's my take on the bulging lid:

As the slurry warms, the co2 gas build-up begins to release causing expansion. This co2 can be felt if you put a small spoontipful of yeast on your tongue - you'll feel the acidic bite of the carbonation. If you look closely at your slurry as it warms up you can see the bubbles trapped in it which causes expansion of the entire slurry - eventually reaching the lid if your jar is too full. I always decant my slurries when pulling out of the fridge to give room for expansion (some times you need almost 30% room for expansion). Additionally, I never crank down on the lids to the canning jars when initially collecting and storing my slurries; I turn the ring until it barely contacts the lid and that's where I leave it. It allows for a slow escape of co2 during storage if needed. The buildup of pressure (generally by co2 in the fridge) can lead to a significant increase in cell death if left unchecked for long durations. While I don't doubt that the yeast might be "waking up" within 15 minutes, even if they were they (themselves) don't expand in size.

As far as "yeast shock", I generally feel it more an issue of wort temps that are out of whack (<50F or >80F) or pitching warm yeast into cold wort. I feel less inclined to believe there's an issue with cold yeast into proper pitching-temp wort. However, Yeast (p. 95) mentions the occurrence of what he calls "heat shock protein" expression when yeast deviate too much from their optimal temperature range (up OR down). Because of this potential, I've always pulled my slurries out of the fridge as I'm bringing my wort to a boil and allowed it to slowly raise in temp during the boil/chilling/aeration stages of brewday. I'm generally within about 5-10F below the wort when I'm pitching, and it's been working good so far.

 

[Denny]

So if I use harvested yeast and add it to a starter, should I let the jar of harvested yeast sit at room temp before adding to the starter? Should I crack the jar of the lid and let it sit out before adding to the starter? I plan on using starters and harvested yeast in future batches, but never considered the temp of the harvested yeast or the jar's lid as being factors, but I guess they are huh?

All I can tell you is that I never let yeast warm before pitching, whether into a starter or a batch. I get great results and will continue to do it that way.

 

[thaymond]

I had a party yesterday, and the beer fridge was a revolving door to say the least. My jars of yeast were hidden towards the back of the fridge. My brother-in-law said he heard a pop in the back. Sure enough, my 1qt jar of 1056 had a huge bulge in the lid. I brought it out and degassed it. I tried again a couple of times throughout the night, then finally gave up for fear of contamination. I ended up dumping the whole lot of it. It was not a huge loss, as it also had been sitting in the fridge for about 6 months. I checked my other jars, and everything seemed fine. My Belgian, lager, and hefe strains were all fine. It will give me an excuse to try some new yeasts in my brews!

 

[Denny]

Keep in mind that yeast will keep slowly fermenting even if refrigerated. That's why I don't use jars. I use plastic tubs with snap on lids. That way, there's no danger of explosion if the lid is too tight.

 

[TheRussMeister]

"Yeast shock" is an outdated, disproven myth. I've cold pitched the yeast for at least 350 batches with great results. Try it for yourself and decide.

I forgot about this thread! But, I did try it myself, both ways. As I mentioned, I usually allow the slurry to warm a bit and then pitch. I made my usual house pale ale and direct pitched the cold, decanted slurry. Results from my own tasting, and others...... no detectable difference. That being said, my house pale is of mid gravity and pretty heavily hopped, so the possibility that off flavors were produced is lower than if it was a higher gravity beer, and more likely to be covered up via heavy hopping. So all in all, yes, not much difference.

I am curious, Denny, you mentioned it was disproven. In a purely academic manner, do you happen to remember where you read that? I am surprised that it was disproven; thermal shock is the norm for pretty much any organism, fungus or otherwise. Many organisms have their own set of proteins that are produced in times of thermal shock (of memory serves, I think yeast also have heat shock protein coding genes). There is much literature out there about bacterial thermal shock, but I can't seem to locate much on yeast. Any one have anything for me to read?

 

[Denny]

I forgot about this thread! But, I did try it myself, both ways. As I mentioned, I usually allow the slurry to warm a bit and then pitch. I made my usual house pale ale and direct pitched the cold, decanted slurry. Results from my own tasting, and others...... no detectable difference. That being said, my house pale is of mid gravity and pretty heavily hopped, so the possibility that off flavors were produced is lower than if it was a higher gravity beer, and more likely to be covered up via heavy hopping. So all in all, yes, not much difference.

I am curious, Denny, you mentioned it was disproven. In a purely academic manner, do you happen to remember where you read that? I am surprised that it was disproven; thermal shock is the norm for pretty much any organism, fungus or otherwise. Many organisms have their own set of proteins that are produced in times of thermal shock (of memory serves, I think yeast also have heat shock protein coding genes). There is much literature out there about bacterial thermal shock, but I can't seem to locate much on yeast. Any one have anything for me to read?

Sorry, it's been so long that I can't recall where I read it. But it inspired me to try it. I've done it with beers from 1.040 to 1.100...same results, no problems. Also, there can supposedly be thermal shock going the other way...warmer yeast into cooler wort. My point of view is that despite what any literature might say, all that matters to me is that it works.

 

[TheRussMeister]

Sorry, it's been so long that I can't recall where I read it. But it inspired me to try it. I've done it with beers from 1.040 to 1.100...same results, no problems. Also, there can supposedly be thermal shock going the other way...warmer yeast into cooler wort. My point of view is that despite what any literature might say, all that matters to me is that it works.

No worries, just wanted to educate myself.

Huh, I guess it isn't a big deal in homebrew. Yes, I am not surprised issues can occur pitching warm yeast to cold wort, my guess would be most notably a slow start.

Agreed, I didn't see a difference, but it still makes me nervous.

 

[Denny]

Agreed, I didn't see a difference, but it still makes me nervous.

Trust your own experience, not something you read that contradicts what you've experienced.