I’m about to conduct an experiment to compare pressure fermentation without temp control to a standard temp controlled unpressurized fermentation. The only problem is that I’ve never done a pressure fermentation, so I’m looking for advice from those of you that have. Beer will be a pretty standard German pils using either Diamond or 34/70. My main questions are…
what pressure do I set my spunding valve to?
pressure from the start, or wait til after yeast is active?
Thanks for your thoughts.
The standard Weihenstephan protocol for lagers during a classic cold fermentation is no pressure during the growth phase (24h approx), then 0.3bar for 12-18h, then 1bar until end of fermentation.
Some ramp up temperature mid fermentation, some ramp late for diacetyl rest, some don’t ramp and go to lagering.
For an experiment, I would keep temperature constant and do 3 arms:
Ideally, monitor gravity throughout.
Drop in pH over time would be interesting as well.
Calibrate instruments if you can.
“It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts.” - Sherlock Holmes (A. Conan Doyle)
Thanks for that. You say for a cold fermentation, but I’ll be doing pressure without temp control. Many pressure advocates say that’s one of the main benefits. Would you say I should follow the same procedure?
I wait at least 24 hours, or until the top is covered in Krausen, before allowing pressure to build. After that, I ramp it up over another 12 to 24 hours, depending on how busy I am. About 12 psi is my final setting. Because I exhaust the CO2 through an empty keg, I lose very little pressure cold crashing so end up with 9 to 10 psi at packaging time.
If you are doing an experiment, changing more than one variable at a time difficults the interpretation.
In this case maybe 4 arms:
-Low Temp, No Pressure
-Low Temp, Pressure
-High Temp, Pressure
-Pro pressure fermentation as I described
Another idea,:
If you just want to do two arms, you can normalize by CO2 concentration.
For example:
“It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts.” - Sherlock Holmes (A. Conan Doyle)
Thanks again, but the parameters of the experiment are set. I have a specific goal in mind. This is homebrew science, not real science.
I am not so sure that pressure ferment without any temperature control will give a meaningful result - if the temperature is still too excessive, I don’t think that the beer will be very good. I would think that 68-70F is as high as I would go with pressure, using a lager yeast. I pressure ferment almost all lagers and I use 54-58F as my temperature range and apply around 6-10 psi initially and then allow it to fall down to 4 psi as the pressure drops in cold crashing (I can cold crash that way and lose around 6 psi or so of pressure once cold crashing completes). I will often hit the fermenter with a few psi, if it gets all the way down to 0 psi in the cold crash process.
I appreciate that you want to pressure ferment in very warm conditions to establish the lack of ester formation, but with too high of a temperature it might lead to extremely quick fermentation that doesn’t serve the beer well. There are limits to everything, of course.
Good luck with the experiment.
What I am testing are the claims from many homebrewers that with pressure you don’t need temp control. I intend to ferment it at normal room temps, nothing excessive.
So you pressurize all the way from pitching?
No problem.
Good luck with the experiment.
We can do real science too if we are strict with the design and control of variables.
BTW one more suggestion if you are using tasters as your instrument.
Don’t do side-by-side-by-side like in a BOS, but evaluate one beer, clean your plate, then the other (then the other if triangle test); like in a regular competition.
There’s quite a bit of carryover effect when drinking side-by-side.
Cheers!
“It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts.” - Sherlock Holmes (A. Conan Doyle)
Thanks for the tasting tip. Great idea.
I love experimentation.
I dare you to also ferment a batch with lager yeast at room temperature, that would be a most interesting comparison with 3 different versions and not just 2. Admittedly, perhaps that is better suited for a Phase 2 of this line of experimentation.
That’s your experiment. I have mine. Just testing homebrewer claims of the benefits of pressure.
A guy from my Homebrew club did a presentation on pressure fermentation. He is a master lager brewer who has won awards in NHC and when he had a commercial brewery for a short stint. He served us a German Helles that he made at 1 bar and room temperature. The beer was delicious without any esters, diacetyl, or any other off flavors. I found it hard to believe until I tasted it. There is some information from Josh Weikert (Craft Beer & Brewing) and tests conducted by White Labs with WLP 833 Bock Yeast.
The challenge is going to be determining if any of these results can be extrapolated from one strain to any other.
I should have mentioned that the beer I had was with Diamond lager yeast fermented in the high 60’s with 1 bar. He has used 34/70 and Diamond in the high 60’s to low 70’s with no ill effects. I can’t say if I would pick it over a lager fermented in the 50’s without pressure in a triangle tasting. I think it is an interesting experiment.
Yes. I add pressure as the yeast is pitched, because otherwise it seems to me that the yeast will start working without the pressure, so the benefit of pressure fermenting is at least diminished (ester formation, etc…will be happening). My typical pitch is done at about 58-62F (where my groundwater and immersion chiller can get it to) and then the fermenter goes into the chamber set at 50-56F, where it ferments with its exothermic heat a few degrees warmer. If it were easier to get the wort below pitching temp, I’d be inclined to naturally allow the pressure to build, but even then, you might be losing some benefit of pressure fermenting while the yeast begin working.
By the way, I monitor temp and fermentation progress with a Tilt hydrometer.
For those interested, the real life schedule for pressure fermentation is in Werner Back’s book.
“It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts.” - Sherlock Holmes (A. Conan Doyle)
I brew my lagers at whatever temps my basement is holding (60-68F ambient generally, depending on season). I ferment 3 gallons in a 5 gallon keg, with a spunding valve set to 15 PSI. I attach the PRV at pitching and let fermentation build pressure naturally. After 10-14 days, I jump the beer to a purged keg and cold condition in my beer fridge.
Since I’ve moved to this procedure for my lagers, I have used 34/70 dozens of times, Diamond 3 or 4 times, WY2278 3 or 4 times, and WY2633 2 or 3 times. I have not noticed a change in the quality of my lagers since moving from a more traditional cold lager fermentation schedule. I definitely don’t pick up any esters or fusels. If I felt it made a better beer, I’d move back to cold-fermented lagers in a heartbeat, but I just don’t see a reason to.
To be honest, I’m not sold that the pressure is what’s making my lagers come out so clean. I think many lager strains are far more tolerant of warmer temperatures than what is traditionally believed. A healthy, sizeable pitch of quality yeast goes a long way towards making a clean beer.