An ambitious pressure cooker experiment

[MitchK]

So I decided with this snow day off work that I would try and brew a one gallon kit I had laying around.

My 8 litre pressure cooker is the right size for a one gallon stovetop biab so that's the pot I have used in the past.

I realized my airlocks for my 6l buckets are at my old apartment still (moving over the month).

G-rock ferments in a kettle, so I thought I would try that.

My pressure cooker should self seal once the yeast builds up enough co2 (may have to kinda lock the vent closed to get the initial seal as it expects a vigorous boil).

Pressure cooker vents at 18psi. 18psi at 60f (within acceptable range for the yeast involved) = carbonated beer. I might have my beer already carbonated when it's done. Worth a shot, no?

It's not too late for me to chicken out and go buy an airlock and stopper from maritime wine and beer

[GuingesRock]

Sounds like a fantastic idea. Carbing with the pressure cooker = Real Ale. Leave the weight off for the first 4 days of fermentation and then put the weight on after 4 days exactly. after 10-14 days you can chill and serve.

Awesome!

[RubberToe]

Do it!

However be careful krausen doesn't gum up the relief valve.

[GuingesRock]

Oh yes. That could be dangerous. Don't seal the lid until active fermentation is over (usually 3-4 days). Let CO2 burp the lid and krausen lift the lid and overflow under it if it wants to. Then maybe remove the lid and check the relief valve before sealing lid and putting on the weight.

If the lid isn't clamped on, maybe you could have the weight in place to stop krausen getting in the pressure relief port.

[RubberToe]

Hmm, read about pressurized fermentation. If those pressures are ok it may keep the karausen down anyway and be beneficial. 18psi may be too high though.

[MitchK]

my kuhn rikon didn't even seal. They're not exactly meant to build pressure slowly over days... A weight based one would probably work better.

[GuingesRock]

can you put keg lube in the pressure valve to get a seal?

Edit: re-read that, it doesn't have a weight. I don't understand how it works.

[MitchK]

its a spring loaded pressure release instead, which is open both at zero pressure and at 16 psi or so, and closed at anything in between. I did prop that up (closed) though so I'm pretty sure the part that isn't 100% air tight is the weird gasket vent safety system. Basically I think this experiment would've worked a lot better on a simpler american model instead of a higher end european pressure cooker that goes overboard with safety features.

Basically the whole thing is set up, like a keg, to actually seal when positive pressure forces compression on the gasket, and fermenting a one gallon batch of beer in it doesn't seem to actually cause enough pressure quickly enough for it to seal instead of vent. If I had an all american canner with its gasket-less metal to metal seal and a weighted valve that is closed at anything below 5/10/15 psi (depending on weights) I think it would work, but they're also made of aluminum so you'd want to line them with something (and unless you wanted a high end american giant pressure canner I wouldn't buy one just for beer - they're expensive enough that there are better ways to spend your beer money).

[jason.loxton]

Doing the whole fermentation under pressure doesn't sound like a good idea for a few reasons:
1. As other people have noted, if the relief valve got jammed you're sitting on a bomb. (I know that those things probably have pretty high real world failure pressures, but I wouldn't want to mess around regardless.)
2. I don't know how you would release the pressure to open the lid post fermentation.
3. Even if you chilled it before opening, you'd likely get a huge foam up, since it would be carbed to over two volumes with the fermentation temp and release valve setting, and there would be a crazy amount of material for nucleation.
4. You'd have a hard/impossible time transferring it to keg/bottle since you cannot transfer under pressure, a must for a carbonated product.

[MitchK]

that is fair, if it had pressurized I'd probably have a hell of a time trying to move it afterwards.

in the future I can experiment all I like with pressurized fermentation in a keg (maybe build a spunding valve) and then just jump keg to keg at the end.

[GuingesRock]

The Blichmann fancy conical fermenters have a pressure cooker like pressure relief valve with a weight.

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Don't throw in the towel yet

[GuingesRock]

Would something like this actually explode, or would the rubber gasket under the lid leak pressure first? http://www.bedbathandbeyond.ca/store/pr ... AuwF8P8HAQ" onclick="window.open(this.href);return false;

[GuingesRock]

Uh-oh, I guess they do explode!

[MitchK]

modern ones should never "explode". Mine the gasket will buckle and it will leak down the side first.

I am basically 100% confident in the safety features of my kuhn rikons.

[GuingesRock]

Heat is a good energy source for a bomb but at what pressure does yeast pack it in and stop generating CO2?

[MitchK]

The pressure cooker vents over X psi anyway (I think with mine its 17-18 psi for the primary valve, 20 for the safety overpressure plug, and some number higher than that but lower than 30 for the gasket no longer containing pressure and venting through a hole in the lid rim). Honestly since the last of those can't really even get clogged (but does wear out the gasket) there are no safety concerns with this.

Also a can of pepsi is under 15 psi. Even if it "explodes" it isn't dangerous because it isn't hot. The dangerous part of a pressure cooker is that if there is an uncontrolled vent or pressure release due to a crack or clog or just plain using a cooker that is out of date and lacking in safety features (some old ones would let you open them while they were at pressure. Mine locks) that uncontrolled venting consists of superheated steam (higher than normal boiling point water vapour rapidly expanding as it immediately burns enough energy to get back down to the atmospheric boiling point of water)

At any rate the transfer out of the cooker is what will kill you here I think. Which is why I'll just scale these experiments up a bit and build myself a spunding valve for a keg and use that in the new year (hey, if I invested in some 6.5 gallon kegs as fermenters, I could still fill a 5 gallon with the result and have headspace for fermentation)