Yeast slurry expansion?

[ballsy]

Hey all, not new to brewing but I am to storing yeast slurry. I'll make this as short as possible. I collected 3 mason jars full of yeast slurry (BRY 97) from bottom of a batch of IPA OG 1.060 (didn't wash the yeast). Filled it almost to the top of each (I did sterilize via boil prior, except flat disc portion of lid with the gummy seal for fear heat would damage it, so dipped in Star san). They were stored in fridge at about 32F.
- 2 wks after collecting, I pitched one jar into Yoopers pale ale and it did great. Beer was awesome (as usual).
- 4 wks after collecting, second jar went into a bells two hearted clone. I had shaken the jar up to get yeast unstuck from the sides and when opened, it started expanding over the rim quickly, dumped it in quickly and chalked it up to the agitation causing the expansion. I just kegged the IPA and it looks and tastes great on sample.
- So now I am ~6wks post collecting and and brewing this weekend, I looked at my final jar and noticed the small amt of clear beer that was at the top for weeks was now at the bottom, and the slurry above it was bubblier looking and part of the lid was bulging
I took it outside and opened it, the slurry came slithering out quite a bit. I tossed it. It didn't smell or infected at all. I did some research and Wyeast says to leave adequate head space to allow for yeast expansion when storing it? But elsewhere I hear people say fill up all air space in the container.
For those of you experienced in storing slurry (not washed yeast), does this sound infection related or is it common for expansion like this (to the point of bulging the metal lid a bit)?? I'm going to use US-05 this weekend and try it again with more head space just to see.

 

[Rdom]

You can have some CO2 coming out of solution for a few days after transferring into the mason jars. Some suggest leaving the lid a little lose for a couple of days after transferring to allow some of that gas to escape before tightening. I usually do this just in case. I have had the lid on my jars bulge a bit when I did not do this. The yeast seemed to ferment fine when pitched though.

 

[ballsy]

You can have some CO2 coming out of solution for a few days after transferring into the mason jars. Some suggest leaving the lid a little lose for a couple of days after transferring to allow some of that gas to escape before tightening. I usually do this just in case. I have had the lid on my jars bulge a bit when I did not do this. The yeast seemed to ferment fine when pitched though.

Yeah, I'm not sure how long the bulge was there for. It's been in there 6 wks so maybe it was there early on? It definitely didn't take on this "bubbly" look until very recently though...weird.

 

[IslandLizard]

I've had lids bulge too to the point it created a 3 point star-shaped crease where it vented. I've also seen what you experienced with the 2nd jar. Some yeast starts to kick right back into action as soon as it warms up a bit. I'm willing to bet that 3rd jar was fine too. I've seen yeast floating up like that, again when it warms up a bit. I now leave 1/2" of headspace and don't screw the band tight until it's been in the fridge for a day (or 2). Then when I take them out, I sanitize and loosen the band somewhat.

 

[ballsy]

I've had lids bulge too to the point it created a 3 point star-shaped crease where it vented. I've also seen what you experienced with the 2nd jar. Some yeast starts to kick right back into action as soon as it warms up a bit. I'm willing to bet that 3rd jar was fine too. I've seen yeast floating up like that, again when it warms up a bit. I now leave 1/2" of headspace and don't screw the band tight until it's been in the fridge for a day (or 2). Then when I take them out, I sanitize and loosen the band somewhat.

The odd thing is the jar was never removed from the fridge thus it never experienced temp above 32...I've seen research of people that toss slurry in cold right from the fridge vs allowed to warm to room temp and the slurry tossed in cold from the fridge actually takes off quicker (might have been one the exbeerimenter did?) than the one that warmed up...therefore I never removed it until the wort was at pitching temp....probably 1 min b/w fridge to dip in star san to shaking to wort. But either way I will do the increased air space and also probably boil the piece of lid that has the seal material...I'd imagine it can withstand the temp of boiling water.....