Chilling caused keg fermenter to suck up Star San?

[Brewmetheus]

I recently started fermenting in kegs, and did my first lager the other day.

At the end of fermentation after the diacetyl rest, I set the temp to lager to hopeful get more yeast out of suspension before transferring to a lagering/serving keg. I did this with a blow off hose attached into a bucket of Star San.

With the lowering of temp it appears to have sucked up all the Star San out of the bucket and ruined the beer? Is this possible? Like the cooler temp created a void pressure which the star San filled?

If this is the case, I will be detaching the whose and replacing the Keg gas in connector before chilling in the future.

 

[day_trippr]

Yes, "suck back happens" with any closed vessel having significant head space.
If there wasn't a lot of Star San involved that beer may be salvageable...

 

[SleepyCreekBrews]

How big of a bucket we talking about?

I feel the need to point out a couple things about blow-off tubes.
1) You should use a container capable of holding all the FOAM that may come out of the fermenter (generally 1/2 -1 gal)
2) That container should only contain about 1" of sanitizer.
3) the TUBE does not need to be submerged under 4" of sanitizer, in fact that only makes it harder to push the CO2 out and creates the potential for sucking significant quantities of sanitizer back up into the fermenter during chilling of draining.

 

[FunkedOut]

If you 86 the hose and seal the keg before chilling, add about 5psi.
If you don’t, the vacuum created may collapse the walls a bit.

Better yet, close it up with a few points left to attenuate.
That’ll let the yeast create the 5 psi for you.

Best yet, attach a spunding valve and set to 15psi after a couple of days.
Your beer will be almost (if not fully) carbed when it’s done fermenting.

 

[Brewmetheus]

I think almost a galon of starsan got sucked up, as the bucket was 2 gal and about half full. It filled all the head space in the keg and I'd left about Gallons worth and the bucket was empty.

I dumped just to free the keg up, as I only have so many, and didn't want to take the chance on lagering an unsalvageable beer. I kind of regret it though. The StarSan seemed to be just sitting on top and the beer and it smelled really good as I dumped it. =(

Thanks for the info, and I do have have spunding valve, that I just assembled for preasure checks and dry hoping under pressure.

Next time I will replace the gas in and do the diacetyl rest at room temp with spunding on and set to 15psi. Would that work for a lager? I did that with an Ale and it dropped to 5psi on cold crashing.

 

[FunkedOut]

You need pressure in the vessel before lowering temp to avoid collapsing the walls.

15psi at d-rest temps will not give you carbed beer.
use a force carbing table to get the temp and pressure right for the volumes you want.
I wouldn’t go much higher than 15psi.

I personally seal the keg (no spunding valve) for d-rest and cold crash. I set the valve to 15psi for all of the attenuation and skip the blow off tube.
The pressure keeps blow off at a minimum, but I do have 10 gallon kegs for fermenting.
I used to use a blow off for the first couple days when I had 5 gallon kegs.

 

[SleepyCreekBrews]

Ya, a gallon of Starsan in the batch is a little too much to justify keeping in my book. Sorry for your loss.

FWIW, I was kegging a batch once many years ago and heard this gurgle-gurgle sound, and realized I'd just sucked all the Starsan out of the blow-off Jug, thankfully it was only a pint, and couldn't detect it in the IPA .

 

[Brewmetheus]

Just started with 5 gal cornies. No room in my freezer/fermenter for spunding valves, but my LHBS just started carrying the shorter one's with the red rubber. Those might fit with spunding valves. What kind of head room do leave for primary fermentation under pressure? @FunkedOut

Thanks for the commiseration. @SleepyCreekBrews

It's more the fact that I had to dump my first lager, cost wise it was nothing, and at least I got a sharp and object lessons about vacuums created by temp. Honestly never occurred to me I might collapse the walls of a keg. Thermodynamics is a *****.

I'll brew up another one shortly. Thanks for the advice guys.

 

[FunkedOut]

Just started with 5 gal cornies. No room in my freezer/fermenter for spunding valves, but my LHBS just started carrying the shorter one's with the red rubber. Those might fit with spunding valves. What kind of head room do leave for primary fermentation under pressure? @FunkedOut

I was putting 5 gallons in for W-34/70 at 55*F and 15psi.
4.5 gallons in for US-05 at 65*F and 15psi.

Never had any krausen come up the tubing between the gas post and spunding valve.
The tubing helps you need less space above the keg and it gives a small blowoff some place to go.
Even if the tube is too skinny and short to hold much, at least you can see if it happened even a little.

 

[brewbama]

I recommend building a better air lock: Epic Fail
https://r.tapatalk.com/shareLink?sh...ex.php?threads/Epic-Fail.642854/&share_type=t

 

[Brewmetheus]

To be honest airlocks, based on my research, are pointless if you don't have to worry about pest contaminants. Like something literally crawling in. Prior to this I brewed in buckets with a lid and no air lock. Positive pressure created inside is sufficient to keep O2 out, and if the lid isn't a perfect seal the gas escapes. Inside a freezer/fermenter no pests or physical contaminants need be eliminated.

With an airlock I'd still get StarSan sucked up, although probably less, because of the vacuum created on chilling the beer. Brewing as I do now I requires a blow off into a bucket in the event of an abundant krausen and too little headspace, or spunding valve to keep the pressure up and the krausen down.

But there's a problem with pressurized fermentation.

@FunkedOut I am sampling a beer a dry hopped with a spunding at room temp and I taste an ambundance of DMS and diacetyl. From some cursory reading both are eliminated during primary and secondary fermentation with off gassed CO2.... trapping those in the beer during these phases has introduced significant amounts of off flavor. This similar to 'green beer' flavor which then necessitates extended aging so any gains in carbonation from this is negated by the extended aging?

In any case I will keep my current setup, and in the future I will ensure to seal and pressurize with CO2 before chilling.

 

[FunkedOut]

...But there's a problem with pressurized fermentation.

@FunkedOut I am sampling a beer a dry hopped with a spunding at room temp and I taste an ambundance of DMS and diacetyl. From some cursory reading both are eliminated during primary and secondary fermentation with off gassed CO2.... trapping those in the beer during these phases has introduced significant amounts of off flavor. This similar to 'green beer' flavor which then necessitates extended aging so any gains in carbonation from this is negated by the extended aging?

Room temp. What’s your room’s temp?
I’ve read that one of the advantages of pressurized fermentation is suppressing off flavors enabling higher temperatures, shortening fermentation times.
But I’ve not yet altered my fermentation temps since introducing the pressure variable.
I just carried over my fermentation schedule and temp from the buckets.
Maybe room temp is the culprit of your off flavors?
What yeast? What temp? What pressure? How long? How’d you accomplish the dry hop?

I worried a lot about sulfur being produced getting ‘trapped’ in with the beer by carbonating during fermentation. I read a lot on the subject and found good anecdotal information on pro brewer.
The distilled information I took away is that if you want natural carbonation, there’s no difference, taste wise and aroma wise, between the primary fermentation and priming a bottle, keg or fermenter.
I decided to try it and have not noticed any difference in the beers. I did however, keep all other variables constant.

Even in a bucket, my 34/70 schedule was 14 days @ 55*F, 4 days free rise (inside a freezer) to 68*F, then drop 5*F per day down to 32*F, fine with gelatin, then rack 3 days later.

I will say this about my pressures. My spunding valve uses a variable PRV. I sneak up on 15psi over the course of a few days.
I’ll hook it up on pitch day set wide open, where it builds somewhere less than 3psi.
Day 2, I open the freezer and smell the expelled CO2. If it’s not there, I keep it at that setting until the next day. Being a stainless keg, that’s an easy way for me to tell that the yeast took off.
Day 3, bump the pressure up a bit.
Day 4, check and see what pressure I hit, and bump up a bit more.
Day 5+, repeat day procedure until I get 15psi, without going over.

This method isn’t perfect, but the gear is cheap and I feel like 2 advantages are:
1) the yeast are not stressed by pressure as much on the first few days, making it easier for them to multiply.
2) the headspace is purged pretty quickly, getting rid of O2 and maybe some other lag phase gasses.