Stored yeast is building pressure

[Barley_Bob]

Hey folks, I've got a question for you. I have a sealed container of yeast slurry in my fridge, and it's pretty consistently building pressure in the container. Whenever I see it, I crack the container and vent the gas.

Do you think I should be worried? It still smells fine and it doesn't have a pelicle. The beer on top is hazy, but the slurry came from a wheat ipa, so that's to be expected.

It's either still slowly fermenting, it's infected, or it's somehow still off-gassing. I've used the slurry once so far, and that batch did not become infected. Thoughts? My inclination is to RDWAHAHB.

 

[CA_Mouse]

How long have you been storing it? It could be off gassing or minor fermentation continuing, but if it is refrigerated, the yeast should be dormant. I've had jars of slurry build u pressure for up to a week, but rarely have I seen any after that.

 

[RM-MN]

It's probably just off gassing. Leave the lid loose so it can vent.

 

[Legume]

It isnt 3711 or belle saison is it?
I have had these do this, it seems like maybe they are capable of some slight fermentation at fridge temps.
There may be other strains that are prone to this.

 

[wmcc75]

I've had this happen pretty often with several strains. Likely off gassing or maybe fermenting some still. Nothing to worry about though.

 

[Barley_Bob]

It's just us-05, and the slurry is only a couple of months old. I find it really hard to believe it's fermenting, but I wanted to see what the community thought. I'm guessing it's off-gassing. Certainly, an infection seems possible, so I really wanted to hear if it's common. It sounds like this isn't anything to worry about.

 

[CA_Mouse]

It's just us-05, and the slurry is only a couple of months old. I find it really hard to believe it's fermenting, but I wanted to see what the community thought. I'm guessing it's off-gassing. Certainly, an infection seems possible, so I really wanted to hear if it's common. It sounds like this isn't anything to worry about.

A couple of months? I would suspect it has an infection then. Off gassing would not be still happening after more than a week.

 

[Barley_Bob]

A couple of months? I would suspect it has an infection then. Off gassing would not be still happening after more than a week.

Booo

 

[jfolks]

Supposedly, homebrewers should only store yeast for up to 2 weeks at refrigerator temperatures, otherwise they should just buy new yeast (due to viability loss and so on). For easily available (and cheap) strains like US-05, I would agree with that mantra.

If you want to keep a rare strain going for longer than 2-3 weeks, put it in a gallon jug with an air lock, decant and add a few cups of 1.040 wort every 4 weeks or so.

 

[RM-MN]

Supposedly, homebrewers should only store yeast for up to 2 weeks at refrigerator temperatures, otherwise they should just buy new yeast (due to viability loss and so on). For easily available (and cheap) strains like US-05, I would agree with that mantra.

If you want to keep a rare strain going for longer than 2-3 weeks, put it in a gallon jug with an air lock, decant and add a few cups of 1.040 wort every 4 weeks or so.

I think that advice is from the makers of malt extract to sell you more. http://www.woodlandbrew.com/2012/12/refrigeration-effects-on-yeast-viability.html

 

[Barley_Bob]

I've had yeast survive several months in the fridge. I keep them in sealed 1.5L juice containers. This slurry is alongside a half-dozen containers that are fine.

I guess it probably is an infection... I just don't have a chance to get to the LHBS before this weekend (when I hope to brew an amber). I have some really old WLP006 I can trot out? It has been stored for several months. I think I have enough DME for a starter...

 

[CA_Mouse]

I've stored yeast in ball jars for up to 8 months and used them. I have made a vitality starter 3 or 4 days before brew day, just to make sure that the yeast is active and ready to go back to work.

I would just be concerned by yeast that is still building positive pressure in a jar after that long of a period.

 

[Barley_Bob]

I've stored yeast in ball jars for up to 8 months and used them. I have made a vitality starter 3 or 4 days before brew day, just to make sure that the yeast is active and ready to go back to work.

I would just be concerned by yeast that is still building positive pressure in a jar after that long of a period.

Right. And that's very sensible. The CO2 is coming from somewhere. It's disappointing, but okay. I guess it gives me an excuse to revive the 'ol Charles Wells! I'll get a starter going this evening, which will give me plenty of time to finish it before pitching Sunday.

Side note: This slurry can really only have picked up the infection out of the air. Everything was scrupulously sanitized, and the slurry was stored under beer. It's frustrating. But it's such a low probability event, one can hope it won't happen twice.

 

[CA_Mouse]

Side note: This slurry can really only have picked up the infection out of the air. Everything was scrupulously sanitized, and the slurry was stored under beer. It's frustrating. But it's such a low probability event, one can hope it won't happen twice.

Just a note about sanitized container. They may be clean and have had a sanitizing rinse, but that doesn't mean they can't harbor something. The only way to know that the container is not the issue is to autoclave it at 15psi for 15 minutes. That sterilizes the container where nothing can survive.

There could have been a contamination in beer that the slurry came from that you didn't pick out because the beer was finished and drank quickly enough that it didn't exhibit the infection. I only bring this up as a warning not to radically change your post fermentation process for saving slurry.

 

[Barley_Bob]

Just a note about sanitized container. They may be clean and have had a sanitizing rinse, but that doesn't mean they can't harbor something. The only way to know that the container is not the issue is to autoclave it at 15psi for 15 minutes. That sterilizes the container where nothing can survive.

There could have been a contamination in beer that the slurry came from that you didn't pick out because the beer was finished and drank quickly enough that it didn't exhibit the infection. I only bring this up as a warning not to radically change your post fermentation process for saving slurry.

It's certainly possible. I more or less rules that out because the slurry was used once without causing an infection in that beer. I might have picked a speck of dust up off a table or something, or maybe a bit clung to the inside of my funnel. Who knows?

I do truest my storage process - I've successfully kept colonies alive for months at a time. I had a hell of a time with Mason jars. The damn things wanted to spill all the time and they never fit snugly anywhere.

 

[petrolSpice]

I store yeast in mason jars all the time and most of the time they continue to off-gas for several months. Even at fridge temps it will continue to ferment the sugars that may still be in the slurry, albeit very very slowly.

 

[Barley_Bob]

I store yeast in mason jars all the time and most of the time they continue to off-gas for several months. Even at fridge temps it will continue to ferment the sugars that may still be in the slurry, albeit very very slowly.

That's plausible, but at what rate? In this case, I was venting it maybe twice a week.

If that level of fermentation continued naturally in a finished and bottled beer, gushers would be a constant problem.

I can buy that some very mild fermentation might continue briefly, but that off gassing has got to just be the last of the CO2 coming out of suspension.

 

[petrolSpice]

That's plausible, but at what rate? In this case, I was venting it maybe twice a week.

If that level of fermentation continued naturally in a finished and bottled beer, gushers would be a constant problem.

I can buy that some very mild fermentation might continue briefly, but that off gassing has got to just be the last of the CO2 coming out of suspension.

I harvest yeast from the blowoff, in which there is still unfermented sugar. As soon as I get enough it goes in the fridge, so it's definitely not done fermenting at that point.

 

[HausBrauerei_Harvey]

Supposedly, homebrewers should only store yeast for up to 2 weeks at refrigerator temperatures, otherwise they should just buy new yeast (due to viability loss and so on). For easily available (and cheap) strains like US-05, I would agree with that mantra.

If you want to keep a rare strain going for longer than 2-3 weeks, put it in a gallon jug with an air lock, decant and add a few cups of 1.040 wort every 4 weeks or so.

yes I would agree. I keep a stock of about 10 strains in my fridge, and I've 'roused' 6+ month old slurry quite a few times with no issues. In fact I just did it again last week for my first lager of the season.

 

[Barley_Bob]

I harvest yeast from the blowoff, in which there is still unfermented sugar. As soon as I get enough it goes in the fridge, so it's definitely not done fermenting at that point.

Ah, that makes sense. And it's also not at all what I've been doing.

 

[Barley_Bob]

Last night, after I had already boiled DME for a starter, I remembered there's another homebrewer in town. I'm willing to get he had some slurry or a yeast packet. Woops!

 

[passedpawn]

Hey folks, I've got a question for you. I have a sealed container of yeast slurry in my fridge, and it's pretty consistently building pressure in the container. Whenever I see it, I crack the container and vent the gas.

Do you think I should be worried? It still smells fine and it doesn't have a pelicle. The beer on top is hazy, but the slurry came from a wheat ipa, so that's to be expected.

It's either still slowly fermenting, it's infected, or it's somehow still off-gassing. I've used the slurry once so far, and that batch did not become infected. Thoughts? My inclination is to RDWAHAHB.

I don't think it's worth worrying about, but it can make a mess when you open them later.

I use Pickle Pipes. They're silicone valves for wide-mouth mason jars. They are made specifically for fermenting foods in the jars. They only let air out, not in (I've tested with mouth). Second picture there is fermenting hot sauce.

 

[timdillon36]

Did you smell and/or taste the beer that was ontop of your yeast?

 

[Barley_Bob]

@Passedpawn I'm reasonably sure those are just rubber nipples for drinking beer when you're too drunk to hold a glass (tested with mouth for sure!). They're a little pricey, but they do look really useful, especially for the small batch fermentation you're doing for hot sauce. I'll keep them in mind!

@timdillon36 I did smell the beer and slurry, and I thought it smelled fine. But I've had at least one infected batch that smelled and tasted almost totally fine. So, I don't know. After the feedback above, I thought this fell into the category "better safe than sorry."

 

[MockY]

I just started out saving yeast and grew quickly tired of manually offgassing. And if you use the 2-piece lid that comes standard with mason jars, they tend to corrode a bit and get harder and harder to open/close. So I got those Pickle Pipes as well, though I have yet to use them.
Just like passedpawn, I too ferment various things besides beer, and my worry about using these nipples interchangeably is contamination. Even after a proper wash and sanitizing, lids tend to continue to smell of what you previously fermented and I'm terrified of wild yeast entering any of my beer fermentors. Kimchi is especially pungent, so I will probably keep them separate. One set for fermenting vegetables and one for yeast storage.