Brü Crew member Greg Foster was interested in the impact higher pressure fermentations had on beer, particularly in terms of hop character. He performed a cool xBmt to test it out, the results are in!
Very good write up by Greg. Keep 'em coming Marshall!
Interesting. Nice job.
Thanks, Amanda! I thought this was a really interesting topic that I haven’t seen much about in terms of homebrewing. I’m most curious about how pressurized fermentation impacts lager fermentation, which means I’ll likely be building a spunding valve fairly soon 
That would be an interesting follow up to the fast lager method you use.
I’ve been doing the fast lager ferment (although a bit slower) at home with great results. It’s not that I need more beers on tap faster, it’s just nice to know that I can.
I’m actually rather flexible on my times when it comes to lager fermentation-- I just started ramping temps on a BoPils that’s been sitting at 50˚F for the last week. It’ll still likely be ready by 3-4 weeks, though. I end up blowing through beer pretty quickly dues to taking growlers with me everywhere I go to collect xBmt data.
Good read. As to regards to Bell’s, on a tour of Bell’s they said they ferment pretty hot, how hot was not mentioned. Their house yeast gives an orangey aroma, and I wonder if that is accentuated with higher temps. They also ferment dry hopped beers in 400 bbl fermenters, and others can be in 400 or 800 bbl fermenters.
A local brewery used to use Ayinger’s strain before White Labs offered it, but switched to the high pressure lager yeast to minimize tank time. So many of the folks around Ann Arbor know this.
There are still production breweries that use open fermentation, and many of the Franconian lager breweries use open fermentation. Maybe tradition, or maybe better tasting beer? As I have many fermenters, I am not usually in a big hurry (my fermentations go pretty fast).
Just so happens there are instructions for one on pg. 66 of Experimental Homebrewing!
I’ve got it bookmarked!
BTW, as I said on your website, I think the exbeeriment perfectly demonstrated why so few breweries ferment under pressure.
For sure, at least intentional added pressure. I am really curious if the pressure created by the huge volumes of beer is really the reason commercial brewers can run warmer ferm temps… or if our thinking about ferm temps is just a bit askew.
Then again, what is the temperature in a big tank? At the 2011 NHC Terence Sullivan said Sierra Nevada had a multiple probe array made and put into a 800 bbl fermenter. They saw about 8 degrees F difference from bottom to top.
Which direction was warmer? Since heat rises, you’d think the top would be warmer. If its the other way around then something is going on.
My understanding is that the bottom is actually warmer because of the pressure… but as I am often, I could totally be wrong.