Pressure fermenting a stout at room temperature?

[luckybeagle]

I've got a Fermzilla that I was thinking of pressure fermenting a nice 7.4% ABV stout in. The recipe I like calls for either Irish Ale yeast or a lager yeast, and gives temperature recommendations for each. I have WY1084 Irish Ale slurry in my fridge and was thinking about doing a 5-7 PSI pressure ferment of this stout with it at room temperature, since it sounds like not a lot of yeast character is desired in this beer (there are roast, chocolate, and other brown malts etc).

Would fermenting under pressure produce a bland beer despite these character malts and moderate IBUs (50)? I've only ever fermented lagers at room temp. Thoughts?

 

[McKnuckle]

At room temp, which is basically where 1084 thrives, what are you accomplishing by imposing pressure on the equation? It sounds like a solution in search of a problem, to be honest. I would want the subtle ale yeast esters in that type of beer.

if you are explicitly trying to dial out the yeast character, then okay... but it wouldn’t be my choice (to each his/her own of course!).

 

[day_trippr]

If this is a sweet stout, an english ale yeast allowed to run at its fruity wheelhouse temperature for the first week actually contributes a background character I find desirable in my stouts. I don't think I'd want to suppress that...

Cheers!

 

[luckybeagle]

If this is a sweet stout, an english ale yeast allowed to run at its fruity wheelhouse temperature for the first week actually contributes a background character I find desirable in my stouts. I don't think I'd want to suppress that...

Cheers!

Thanks kindly! That makes sense. I'm sure irish ale yeasts also generate subtle berry esters that I wouldn't want to miss out on. I was thinking a lower pressure ferment to start might allow for those esters to show up without generating too many fusels.... but maybe I'm overcomplicating it and should just ferment in a carboy in a temperature controlled fridge. Maybe I'll get a kolsch going at room temperature in the FermZilla around 1 bar with WY1007 and do the oatmeal stout in more controlled conditions.

 

[day_trippr]

I believe for most strains any noticeable ester production happens earlier versus later. In any case, as long as you keep the fermenting wort temperature inside the strain's recommended range you should avoid fusels. I regularly brew a ~1.107 sweet stout and avoiding a runaway fermentation is always a concern in that regard, but kept on a tight temperature-control leash they do just fine, no pressure needed...

Cheers!

 

[luckybeagle]

Update: Ever the experimenter, I went ahead and brewed it anyway. I did a split batch with 5 gallons fermented in my chamber at a controlled 64F, and 5 gallons in the FermZilla at room temperature (a constant 70F in our house) and 8psi +/- via the spunding valve. I used Wyeast 1318 London Ale III in both.
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The traditional beer took nearly a week longer to reach FG and has berry esters that I find to be a little distracting. I haven't kegged and carbonated that one yet, so these are just carboy samples at the moment. Still tastes good, though. I'm crashing that one right now and am due to keg it later today, so if it's remarkably different/better after that, I'll update below.

The pressure-fermented-at-room-temperature beer is excellent. No fusels, limited but still present berry esters in the background--the levels compliment the beer beautifully rather than overwhelm it for me. Day_trippr, you're correct above in that pressure mutes those esters, but it seems like there might be a sweet spot depending on style, preference, and yeast related to pressure/gravity/etc. The beer also had a nice roastiness without being over the top. The beer is anything but muted or dull--it's surprisingly much better than any other porter or stout that I've brewed in the past.

Currently I've got a weird hybrid beer fermenting at 6 psi in the FermZilla--it's a Pilsner malt grist with just about 3 ozs of Acidulated malt, Magnum for bittering and an ounce of Mittelfruh at 10 minutes. The yeasts used are 50% 1007 German ale and 50% 3787 Trappist High Gravity. Sort of a Kolsch meets Single. I wanted to see if fermenting under pressure would strip the beer of its 3787 yeast character and make it more clean like 1007, or if it would have some elements of 3787 in it.

I guess my big curiosity is whether or not there's a generally applicable sweet spot/balance in pressure fermenting between OG, temperature, and pressure that allows the yeast to express itself well without bringing through the high temperature-caused undesirables. For example, if harsh fusels can't be produced in any beer at room temperature and pressure above 10psi, but esters still show up, that might allow one to brew high gravity beers using yeasts that traditionally throw fusels at high temperatures. My first Scotch Ale was about 8% ABV and tasted like rocket fuel after fermenting it at 70F ambient in a closet (who knows what the internal beer temp was). Wonder if that beer fermented under pressure would've turned out.

 

[micraftbeer]

This is an interesting discussion. I had been thinking previously of pressurized fermentation as binary- either on or off- and you either get all of changes or you don't want them. But this thought of tuning the tastes for particular yeasts in particular beers/recipes is an interesting concept. Maybe we don't all need yet another knob to turn to adjust flavors, but it seems like a cool tool.

My initial reaction of fermenting Wyeast 1318 under pressure was- "No way, the whole point of that yeast is the flavor." But similarly, I would've said "A Stout with 1318? No way." The thought of there being a knob there that using some level of pressure you could get some of that flavor, is very interesting. For sure, some will say to just use a different yeast and be done, but this gives you something else.

I was already thinking somewhat of this for Ales, that I would let the first half of SG drop to be under no pressure, then I'd spunding it up to take advantage of jump-starting carbonation, and trying to retain dry hop character more. But with the above reference of Kolsch yeast, a lightbulb went off. I recall loving Kolsch in Cologne, but whenever I brew it, the yeast sweetness (ala wine grape-y) doesn't fit with my memory/palate. So I have written off trying to recreate that. But now I'm thinking of trying that same Kolsch recipe under pressure to see if I can keep that yeast sweetness more subdued and out of the way for me.

 

[luckybeagle]

But with the above reference of Kolsch yeast, a lightbulb went off. I recall loving Kolsch in Cologne, but whenever I brew it, the yeast sweetness (ala wine grape-y) doesn't fit with my memory/palate. So I have written off trying to recreate that. But now I'm thinking of trying that same Kolsch recipe under pressure to see if I can keep that yeast sweetness more subdued and out of the way for me.

I really should've updated this after my last post. The hybrid pitch of 3787 + 1008 created one of the best beers I've brewed to date. I absolutely love Kolsch but haven't brewed one I've really enjoyed until this one. It turned out so clean with just a hint of yeast flavor contribution from the 3787--not enough to breach style guidelines. IIRC it was around 10psi for all of fermentation. It was perfect in every way, and the keg kicked in under a week (I shared some but admittedly drank it like water). I really need to try recreating this one.

Lately I've been contemplating a Voss Kveik under pressure at 90F and 15psi to see if I can suppress some of those intense citrus flavors but still take advantage of the crazy fast fermentation. I might give that a whirl soon with a simple smash recipe.

I think there is a lot of undiscovered--or at least unquantified-- potential (to my knowledge), regarding specific temperature schedule, pressure conditions, and pitch rate, and how these three variables can work harmoniously to create a fast turnaround beer that preserves the right yeast driven flavors without spinning off the undesirable ones.

Here's a pic of that gorgeous, wonderful beer: