Reading up on all the variables in effects on yeast fermentation, I see that internal pressure on a closed fermenter has a negative effect. Has anyone done any studies, or experienced any studies, on subjecting a closed fermenter to negative pressures?
I have a 22-gallon Brewhemoth cylindriconical fermentor, and am interested in experimenting in this realm. I am able to maintain fairly close temperature control, and I can keep other variables (colony size, oxygenation, OG, mash temperatures, etc.) stable through different trials.
Please let me know any documentation or experiences you may have.
I would be careful in defining “negative effect”. I think that is yeast-strain dependent, and depends on what effect you are looking for (more esters, less esters, attenuation, etc.).
If you are fermenting in a vacuum, how do you get oxygen to the yeast for replication?
In essence, brewing at high altitude is an example of this phenomena. Sean Terrell is the head brewer at the second highest commercial brewery in the country (2 Mile High Brewing). He has told me some of the activity he’s seen. He says the beers do attenuate very well. Hopefully Sean will pipe up on this subject.
He has been doing his homebrew test batches. The bottle of his Belgian Pale was pretty nice, got that last Oct. when we drove thorough and met him for lunch. His page says he is not open yet, the final build out was to start when the weather breaks this spring.
It turns out another place has opened, looks to be one six blocks up the street. Periodic Brewing, the logo is “Pb”. I get it! IIRC there was a nano in planning when we visited. Some friends from MI were just at Periodic.
It is named Leadville for a reason. There was a big superfund site there to clean up the lead mine tailings in California Gultch near town. Maybe just stay away?
A long time ago I realized that there was a myth concerning the pure Colorado water. Mining left tens of thousands of shafts that leak toxic heavy metals into the streams.
The mention of “negative effect” references higher levels of pressure in a closed fermentor. Since this is deemed detrimental, I was curious about the opposite effect.
I would, of course, attempt a vacuum at low levels on the fermentor after 24 hours. This should give the yeast ample time to finish the lag and enter the exponential phase of attenuation.
My concern is with any damage to the yeast cell walls, or would the yeast react positively. Potentially a higher attenuation? Or a quicker finish?
Go for it. I know I’ve seen attachments for vacuum sealers designed to help degas wine. The hardest thing would be creating a steady vacuum that isn’t so high it sucks all of be headspace out pulling wort and foam with it or collapsing/shattering the fermenter.
I will check vacuum rating on the Brewhemoth fermentor.
At this time, my thinking on vacuum fermentation is to assess the effects on attenuation (as already mentioned), yeast health, final flavors, and anything else I can categorize. I am thinking about doing initial DOE using small batches split from an early primary fermentation.
I have multiple vacuum generators which can be set at different negative pressures. I can split into several 1-gallon or even 1/2 gallon glass jugs, and set pressures at atmospheric and below. Being at an initial altitude of 880 MSL (mean sea level), I can even pressurize one at true 0 MSL and then reduce from there.
I will not venture to begin this DOE tomorrow, or even this Spring. I need to find time and, hopefully, assistance from friends in the area. Whatever I can discover, I will pass on. Any hard data regarding setup and ongoing results will be also posted.
For me, the concept is just a quick brain fart. I understand about the problems with yeast functioning properly at higher pressures - especially in stronger brews. I thought a lower pressure might prevent the alcohol from forcing itself so greatly on the yeast walls and thus penetrating and “stupefying” the yeast.
Wonder if they ever experimented on this stuff in the ISS way up above us.
I don’t see it that way. More of a curiosity and he has the ability to do it. I still say go for it.
Looks like they have tried it on the space station. I remember this from before but didn’t think about it until you mentioned it. Micro gravity and a vacuum are two different things.
as I understand it, osmotic pressure and atmospheric pressure are two different animals.
Osmotic pressure is caused by higher concentrations of various compounds one one side of a permeable membrane, this forces too much/not enough sugar/salt/alcohol to cross the membrane which can hurt the yeast, especially at various points in their life cycle.
Atmospheric pressure can also hurt the yeast but for different, more mechanical reasons, just too much stuff pressing in on them from all directions.
Bigger brewers ferment under some positive pressure because it inhibits certain yeast character expressions, primarily ester formation, so you can ferment warmer without getting ester bombs. warmer fermentation temps lead to faster attenuation.
Brewers also choose open fermentation to reduce the atmospheric pressure on the yeast to encourage yeast expression. This is done by Sierra Nevada for Bigfoot and Anchor Steam across the board. Also many british brewers.
it’s an intriguing question and if you have the time and inclination I’d have at it. It would probably be worth your time though to review the literature that already exists in the trade to see what others have done around this already. not to say you shouldn’t do it if someone has already tried it but just so you have all the info you can going in.
I would be nervous using glass containers for this experiment myself but that’s up to you.
There is also hydrostatic pressure, which is the type of pressure I hear most commonly referred to as being detrimental to yeast. This is basically the pressure from the column of liquid squeezing down on the yeast as it settles out. It is a function of both gravity and surface area, and is mainly a concern in large cylendro-conical fermenters that most pro brewers use. I don’t thing fermenting under a vacuum will address that type of pressure.