How I learned to stop worrying and ferment under pressure.
Pressure fermentation is nothing new, breweries have been experimenting with pressure fermenting since the 1960s. Only recently has the home brewing community taken notice of some of the benefits of this practice. While I only just started experimenting with pressure fermentation, there are plenty of folks out there that have been doing it for a while. If you are looking for more information David Heath has some excellent videos if you are looking to get into it (Easy Guide, Safety Guide, Spunding Valve info).
I won’t be going into an exhaustive explanation of pressure fermentation the links above do a much better job (plus they probably have better grammar skills). However I will explain the process I used and you can take it with a grain of salt.
The recipe I used was a basic Munich Helles recipe made with…dear I say…extracts! Yep! I did not have time to make a full all grain batch. My brewing rig really runs well if I am doing 10 gallon batches and if this went south then I didn’t want 10 gallons hanging around haunting my nightmares. The process was pretty straight forward boil extracts add hops, kettle finings, cool, toss into fermenter. Nothing special, but the process changes a bit as I do not have any fermenters that hold pressure. I do however have cornelius (corny) kegs and the last time I checked these do hold pressure. The issue with kegs is the pickup tube goes all the way to the bottom and would be square in the middle of the yeast cake. Unless I like drinking a big ol’ glass of vitamin B and trub I need to cut that pickup tube. As any brewer knows, that have stuff they hold on to “just in case”, I dug out my spare pickup tube and hacked off about 3 inches from the bottom of it. Boom! Perfect it sits just above the yeast cake.
I have the fermenter set up and ready to rock and roll but how am I going to regulate the pressure? I can’t just pull the pressure relieve valve each time I think it might be at pressure. Enter the spunding valve, this valve is a regulator that will only off gas pressure once a certain psi has been reached. Blackstone Valley Brewing Supplies does sell spunding valves in store (nice plug, right?). When you are pressure ferementing you cannot put just any amount pressure and call it a day. The yeast are still sensitive to being crushed just as much as you are. Most yeast are pretty happy anywhere between 5-15psi. It is still recommended that you take the proper steps to ensure yeast health, growing a starter or even adding yeast nutrient, some yeast can be stressed from the pressure and under attenuate. All pitfalls aside, I used the Whitelabs Munich Helles yeast. I grew a 2L starter 4 days before I pitched. Once the yeast was pitched I added ~10psi of head pressure, affixed the spunding valve and dialed back the pressure to 8psi… and waited.
The keg sat at room temp chugging away for 3 weeks then was transferred to the serving keg. I added keg fining and it has been sitting in the fridge. After 2 weeks of cold conditioning (this was for clarifying not flavor) the beer dropped out and honestly you would never know it only aged for 5 weeks instead months.