Fermenting under pressure

[Sadu]

So I got into a discussion on Facebook with a supplier who makes pressure-keg style fermentors for homebrewers.

One of their main selling points is that you can turn beers around within 6 days - largely because the carbonation happens as part of primary fermentation. I'm not disputing the benefits of this and there are many - less oxidation, no having to wait for bottle conditioning, less cleanup etc.

But one of the big downsides is that these vessels are expensive and if you have to have them tied up lagering or ageing before you serve then you need several of them. These things are 10x the price of a secondhand corny keg so any sort of lagering/ageing schedule means you need more of them. The time from grain to glass becomes critical when you have expensive gear tied up. A problem I suspect commercial brewers have to deal with much more so than homebrewers.

So I asked how they account for lagering time in respect of a Pilsner or Doppelbock, or ageing time in respect of a RIS or Belgian strong.

The response was that ageing/lagering is a myth and beer is best fresh and the grains start degrading straight away bla bla. They also pointed out that Guinness gets brewed in 5 days, which I'm not disputing, but Guinness is not quite the same thing as a RIS.

Thing is, lagers that I brew, 100% no doubt in my mind taste better after a few months. RIS and bigger styles, plenty of my beers have gone from barely drinkable to very nice over 6+ months. Even the humble pale ale, in my view, continues to improve well after it's fully carbonated.

So what is it about pressure fermenting that eliminates this need to age the beer?

I actually tasted one of their blonde ales and my first thought was that while it was fine it tasted a bit green and a few more weeks wouldn't hurt it - so my gut feeling is that the 6 day turnaround is all marketing propaganda and the pressure-fermenting eliminates the need to wait for carbonation but you still need to allow for flavours to mellow (in styles that require it).

Does anyone actually own a pressure fermentor? I understand that carbonation time is eliminated, but how good to the pilsners / Vienna lagers / doppelbocks and higher gravity styles taste straight out of primary?

I'm not trying to troll these guys, genuinely interested if this process speeds up lager brewing as much as they say it does.

 

[acidrain]

I ferment under pressure in 1/4 bbl sankes,
The pressure (for me) is not enough to actually carbonate the brew since (at least for ales) 65F beer is not cold enough to absorb enough carbon dioxide.
If you let the fermenting wort get high enough pressure to fully carbonate, the yeast are damaged.
There is no magic that happens by using a pressure FV.
Honestly, Lagers can be made and ready to drink in 3 to 4 weeks in any vessel.
The reason I ferment under pressure is to keep oxygen out, and do pressure transfers.
I highly recommend fermenting under pressure... just not for the reasons they've given.
Want to build your own? Get a Sanke (or several) and use the adapter or cut a hole to accept a Corny lid & add a SS transfer tube gas inlet, and PRV.
Check this out: https://www.homebrewtalk.com/showthread.php?t=44344&page=213

 

[DaWhip]

I ferment under pressure in corny kegs. My quickest beer was turned around in 9 days. It was finished fermenting and fully carbed 2 days prior to that, but something magical happened with the aging between day 8 and day 9 and it went from tasting pretty bad to amazing. There is a lot of anecdotal evidence and some hard science that indicates that yeast produces fewer flavor compounds under pressure, but it does not replace appropriate aging. Along the lines of what you were saying, I can finish drinking a keg of IPA less than 2 weeks after I pitched yeast (with help of friends), but I would still let a RIS sit for weeks/months.

The pressure does not directly lead to the quicker fermentation. The difference is that the yeast will produce fewer flavor compounds under pressure, which in turn lets you ferment at higher temperatures, which leads to quicker turnarounds (i.e., ferment at 60*, 0psi tastes the same as ferment at 70*, 8psi). That is where things get tricky though, because their is not a lot of experience out there to determine what temperatures are ideal under pressure so it is kind of guess work if you want to push temperature limits. Since switching to pressure, I have gone from fermenting at the bottom of the yeast's advertised temp range to the middle of the yeast's advertised temp range, because I don't want to push it and make a bad beer and I don't mind my fermentation taking 2 more days or whatever, especially since I have already cut out the carbing wait.

Overall, The big pros for me are:

1. Fully sealed from the time the brew is done to the time I kick the serving keg. I'll even brew and leave it sealed up for a week before I pitch yeast with no problems.
2. Free CO2. I use fermentation pressure to carb the beer. I keep it around 7 PSI and use a krausening calculator to determine when to close off the relief valve to hit my final carb pressure, usually 3 or 4 points from finish. I also save the CO2 in my empty kegs and can use them to push beer instead of my CO2 tank. Also, all of my empty kegs are already flushed with CO2 for free.
3. Easier handling than my buckets or my fastferment; Easy sampling, Just hook up a picnic tap; fit more in my fermentation chamber; easy yeast collection...I guess that is more than 3, but the list could go on.

 

[BrewManChoo]

You can get a cheap headstart with carbing in primary with a balloon on top of the airlock. Put one tiny hole in the balloon. I don't like a lot of carb anyway, so it works for me.

 

[Brendos]

Sadu, I have two of these fermenters/kegs and brew under pressure. Although the 6 days is claimed, this is more relevant to ales for me as I still haven't built up the nerve to ferment at the suggested 24 degrees Celsius with lagers. The commercial users are said to brew at this temp though whether lager or ale.
With lagers I have been starting around 22-24 degrees day 0 and dropping gradually down to 15 by day 2. I'm finding its more like 10-12 days for lagers.
Re: lagering I'm finding you don't really need extended periods. Im my opinion beer seems to be at its peak in the first week after crash cooling, clarifying and holding at 1 degree for 3-4 days after.

 

[bboots]

I keep it around 7 PSI and use a krausening calculator to determine when to close off the relief valve to hit my final carb pressure, usually 3 or 4 points from finish.

I'm trying to figure out the final pressure to set my Fermentasaurs at and have a hard time finding what it should be. I tried a "force carb. pressure calculator" but set the temp to 70F (21.11c) Could you share what you would suggest for an ale?

 

[Sadu]

I brew mostly lagers in my Fermentasaurus and start off at 5psi ramping up to 15-20psi at the end which drops back a bit once I crash cool. This gets them "mostly carbed" and it's no big deal to finish off force carbing in the keg.

Ales are warmer so you need more pressure, I don't know that you want too much more pressure since the yeast and the Fermentasaurus might not like that. But I'd aim to finish around 20-25psi and expect to force carb the rest of the way.

 

[bboots]

I know the Fermentasaurus says it can go to 35 psi but I don't want to test that. That calculator says 28 psi but for forced carb. I know I'm going to have more than what fits in the keg and don't want to waste 1/2 gallon. The plan was to bottle the extra but if I use the carb tablets on top of fermentation carb I might blow bottles.

 

[JohannesAdielson]

I am brewing a Mangrove Jack NZ Pilsner kit in my bathroom.

Room temp ~28°c(82°f)
Pressure 2bar(30psi)
OG 1057

California Lager yeast
Tossed in those dry hops at start to simplify.

After two days it dropped shockingly to 1020. Now it slowed down the last days. Waiting for the last points to go down. Today, day 4 GR is1015 pressure is 2.4bars(35 psi). During 24-48 the wort temp was, actully 30°(86f). Have been sampling and no off flavours detected.

Planning to coldcrash att 5°c if i can in the fridge as soon as it hits GR~1008(ask wifey first..)