Pressure fermenting

[Tombo]

Hi, could someone explain the basics of pressure fermenting to me please?

I have been lucky enough to buy a HUGE job lot of gear which includes multiple pressure fermenters, far too many for me so I will have offload some but I obviously want to try them and see what difference it makes. I am not new to brewing, I have been doing that for over 40 years, on and off, but not this way and I do know it’s not for every beer style and I do have spunding valves.

I specifically want to know:-

1:- When do you put the wort under pressure i.e from the start of fermentation or do you let it get going first, if so for how long?
2:- How much pressure do you need and how much is too much?
3:- I know they can be used at higher temperatures with no off flavours but is there a rule for the yeast being used i.e if the max temp range of a yeast is up to 22C or 28C etc do you just go to the max or can you go 10%, 20% etc higher?
4:- Any other things I should know?

Also does anyone have an idea what the fermenters might be worth when I come to list them please? They are a mix of 35 litre fermenter king snubs and 20 litre fermenter king juniors all are like new and all have pressure caps.

Thank you for any advice

 

[Rodcx500z]

I can't help with most of your questions, what i do know is pet pressure fv's have a shelf life i have 2 all rounders they say 2 years max, which i suppose covers them if one goes off so, after 2 years you can bin it take a chance or use as a normal fv, fermenting i let my brews get going then apply 8psi, if for instance i am using us-05 yeast i will set temp at 20c,

 

[Sadfield]

My understanding is, dissolved CO2 suppresses ester production. So, with pressure fermenting, less CO2 is off gassed, suppressing esters which allows for warmer and therefore faster fermentation. Pressure needs to be applied at the point CO2 is being produced, which is the Exponential Growth stage of fermentation (see following link). I believe 5-15 psi is the usual range.
I only ever use it for lager fermentation at 5 psi to allow fermentation at 4-5°c higher than the lowest temp recommended for the yeast, so can't really answer the max temperature question.

https://byo.com/article/fermentation-time-line/

 

[hoppyscotty]

When I've done it in the past I've let the pressure build naturally and ramp up temp as pressure builds. Happens pretty quickly really, day to a day and a half really. I've not really done that many as I really struggle to see the benefits but going to start putting under pressure at the tail end of fermentation purely to carbonate the beer, though not quite sure how to ramp up temp as the pressure builds. Last thing I want to do is to cause the fermentation to stall in those final stages or to start stressing the yeast at that point.

 

[Andrew Booth]

I’ve been pressure fermenting for a while for normal ales I ferment at 10 psi for pseudo lagers I ferment at 15 psi you would need a spunding valve.

I have a larder fridge which I have converted to a fermentation chamber I can fit a fermenter king chubby or two juniors into it at once.

 

[foxy]

Hi, could someone explain the basics of pressure fermenting to me please?

I have been lucky enough to buy a HUGE job lot of gear which includes multiple pressure fermenters, far too many for me so I will have offload some but I obviously want to try them and see what difference it makes. I am not new to brewing, I have been doing that for over 40 years, on and off, but not this way and I do know it’s not for every beer style and I do have spunding valves.

I specifically want to know:-

1:- When do you put the wort under pressure i.e from the start of fermentation or do you let it get going first, if so for how long?
2:- How much pressure do you need and how much is too much?
3:- I know they can be used at higher temperatures with no off flavours but is there a rule for the yeast being used i.e if the max temp range of a yeast is up to 22C or 28C etc do you just go to the max or can you go 10%, 20% etc higher?
4:- Any other things I should know?

Also does anyone have an idea what the fermenters might be worth when I come to list them please? They are a mix of 35 litre fermenter king snubs and 20 litre fermenter king juniors all are like new and all have pressure caps.

Thank you for any advice

Where it all began, and before it went awry.
https://www.terifahrendorf.com/Closed-Pressurized-Fermenatation.pdf

 

[Andrew Booth]

I started pressure fermenting exclusively back in 2021 in basic terms I pressure ferment ales at around 20 degrees and lagers around 22 degrees (pseudo lagers) also I use spunding valves set at 10 psi for ales and 15 degrees for lagers.

I keep the spunding valves closed until co2 registers on the dial and the set to the correct pressure this also has the side effect of carbonating the the beer.

Once fermentation is done I close transfer to a Cornelius keg using a keg jumper which is two liquid disconnects with a length of pipe.

You could also harvest co2 to a keg from fermentation I’ve done this in the past until I sourced a co2 cylinder

 

[dtashmore]

yeast is fairly hardy and will work who into the high 30s and maybe higher but will create a lot of esters the higher the temperature goes, pressure prevents these esters forming as it suppresses the yeast activity which is the cause of the esters, I ferment at 28 to 35 degrees as that it's the general summer temperatures in South Africa and get good results at 16psi.

 

[foxy]

yeast is fairly hardy and will work who into the high 30s and maybe higher but will create a lot of esters the higher the temperature goes, pressure prevents these esters forming as it suppresses the yeast activity which is the cause of the esters, I ferment at 28 to 35 degrees as that it's the general summer temperatures in South Africa and get good results at 16psi.

So the labs who produce the yeast have got it wrong when they generally state for ales 15 to 20C below 20C is better? What about the health of the yeast when pressure is applied?
That's probably the reason why all the commercial brewers are rushing to order tanks which will hold more than 15 PSI.
Yeast is by no means hardy, it is a delicate organism which needs to be nurtured to make a good beer, temperatures need to be within the yeasts favourable working capabilities, and pressure at one atmosphere. By all means raise the pressure when within a couple of points of being finished to carbonate the beer, but don't for one minute think that pressurising a beer from the start and raising the fermenting at high temperatures is going to make a get good results because it's not.
Esters are an important part of an ale and like malt and hops add to the flavour, a reason why there are so many different strains. Brewing an American ale fair enough they aren't big on esters and NEIPA same thing. But please don't call a pseudo lager a pseudo lager because it isn't within a bulls roar of a lager.
As I said in my previous post since Teri Fahrendorf an accomplished commercial brewer wrote the article about applying pressure at the end of fermentation it has been taken completely out of context.

 

[dtashmore]

no yeast has been around far longer than humanity, it is hardy and will survive battery acid fairly high temperatures and very high pressures, it will go into a dormant state of stressed to much but will work once it's environment returns to normal. the manufacturers parameters do not cover pressure environment, if you ferment normally above the manufacturers parameters then the results will be poor unless pressure is applied.

 

[hoppyscotty]

I really struggle to understand why to pressure ferment too. I just cant see any benefits as far as the resulting beer is concerned. I can see where it can fix some issues people might have, for example if you don't have temperature control so want to ferment at a higher temp, but the trade off with that is less flavour and as far as flavour and benefits to the end result I cant find anything documented that extols the virtues of it and my personal experiments with it have failed to display any benefits...on the contrary the flavour of the beer is negatively impacted when I've pressure fermented beers I've brewed several times and know well.

As for the hardiness of yeast then I've tasted many a homebrew that has horrible off flavours because people have stressed the yeast out during fermentation in some way. Luckily none of my brews as the best bit of advice I got when I started homebrew was about centring everything around the yeast...brewers don't make beer, yeast makes beer and our only job is to create the best environment for the yeast to do their thing.

Yeast may be hardy in terms of its survivability as an organism... but as an ingredient that is a major contributer to the flavour and quality of a decent beer then yeast is extremely fickle and demanding. I've been to Belgium and tasted their famous Limbics brewed from natural yeasts that have been exposed to the stresses, trails and tribulations of survival of the fittest out in the wild instead of being grown in a lab in perfect conditions for the sole purpose of giving the best contribution to beer, and I cant say I enjoyed them. In fact I didn't enjoy them very much indeed.

 

[foxy]

no yeast has been around far longer than humanity, it is hardy and will survive battery acid fairly high temperatures and very high pressures, it will go into a dormant state of stressed to much but will work once it's environment returns to normal. the manufacturers parameters do not cover pressure environment, if you ferment normally above the manufacturers parameters then the results will be poor unless pressure is applied.

Completely wrong, but you are entitled to your opinion, you are happy brewing the beer you are brewing that is fair enough but an opinion that it is good doesn't really cut the cloth.

 

[Sadfield]

More pressure, either hydrostatic* or top applied, reduces esters. Increase in temperature increases esters. The two can be modulated as desired. Simple.

*Commercial brewers are probably brewing under more pressure than you are.

http://edsbeer.blogspot.com/2018/07/fermenter-geometry.html?m=1

There's a few references at the bottom of this, on applying pressure.

http://scottjanish.com/fermenting-dry-hopping-pressure/
Someone must be doing it as there are pressure fermentation specific yeast.

https://www.whitelabs.com/yeast-single?id=233&type=YEAST&style_type=2
https://www.mdhb.com/product_info.php?products_id=620394
If we're getting all prissy about 'Ale' fermentation and esters, if your using a cylindrical FV and an airlock, you're doing it wrong.

 

[hoppyscotty]

I've done a fair few brewery tours in my time in the UK amongst craft micro breweries and more traditional breweries and yet to see anyone brewing under pressure. not saying there aren't those who do it, but It seem far from commonplace in the industry in the UK at least. Pressure fermentation is definitely a thing but seems to me to be far more prevalent within the homebrew scene and I'm still unsure what the benefits are in terms of its contribution to the beer apart from suppression of esters. It's certainly not helping hop utilisation and its a very efficient method of blowing the hop volotiles out of the spunding valve at a far higher rate than with conventional fermentation - my fermentation fridge smells lovely when I've pressure fermented....which is nice if you forget the fact you actually want all that aroma in the beer.

The single biggest development in the industry over recent years, apart from the explosion in the hop varieties available, is in the yeasts....what the yeasts fundamentally bring are flavour profiles from esters they product even in more 'modern' American IPA's and NEIPA styles. What would be the whole point of that if you're going to brew under pressure and suppress all that Esther character and contribution of the yeast? might as well stick with the more established and blander yeast varieties.


For me it's about brewing the beer I want to drink with a specific target in mind and I'll choose the right methods, ingredients and processes to achieve that. in that context I'm struggling to think where pressure fermentation would be the 'right tool for the job'. Not saying pressure fermentation is bad in any way shape or form...it produces a different result and that may be what you're after or chasing, and in that case its the right tool for the job. But pressure fermentation for the sake of it doesn't make any sense whatsoever other than for the fun of it.

 

[dtashmore]

in my experience, I find pressure fermentation has a number of advantages, I use a lot less CO2, I start with fully gassed ale when I bottle(counter pressure) or keg my ale, also there is zero possibility for oxygenation. I usually run with around 16psi and cold crash when finished before bottling or kegging. the disadvantage is that it is difficult to add finings or dry hop. if esters are wanted then you would just run the ferment at a low pressure until near the end then build up.

 

[hoppyscotty]

I've just started spunding during the tail end of fermentation more for the purposes of carbonating the beer as much as anything. Early days yet so not drawn any firm conclusions form this but so far so good. Got a few of my 'core' beers coming up over the next few weeks so will be a better test as I know those beers well.

 

[Sadfield]

I've seen plenty of these in UK breweries. 1-2 Bar is 15-29 psi.

https://store.ssvlimited.co.uk/products/spunding-valve

 

[Braufather]

I've just started spunding during the tail end of fermentation more for the purposes of carbonating the beer as much as anything. Early days yet so not drawn any firm conclusions form this but so far so good. Got a few of my 'core' beers coming up over the next few weeks so will be a better test as I know those beers well.

how Does dry hopping fit with that? Would you nor have to de pressure again for your dry hop?

 

[foxy]

I've seen plenty of these in UK breweries. 1-2 Bar is 15-29 psi.

https://store.ssvlimited.co.uk/products/spunding-valve

Just because the spunding valve goes up to 2 bar doesn't interpret that a brewery bangs the SOP TO 2 bar during fermentation SOP is set when the beer is almost complete usually 1 to2 degrees Plato.

 

[hoppyscotty]

I only dry hop after Ferm

how Does dry hopping fit with that? Would you nor have to de pressure again for your dry hop?

I dry hop after fermentation has finished. I have two brew systems...a brewzilla and Fermzilla and a larger 3 vessel system and a stainless conical fermenter

With the smaller system I'll push the beer out of the fermenter and into a purged keg containing the hops so dry hop in the keg off the fermentation trub,then after contact time will push into a serving keg.

On the larger system I'll ferment out, dump trub and then dry hop via a hop bong.