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Fermenting Under Pressure

Discussion in 'General Brewing Techniques' started by wobbly, 12/7/12.

 

  1. pcqypcqy

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    Posted 17/12/17
    @benken25 cube fermenting as discussed yesterday
     
  2. wide eyed and legless

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    Posted 17/12/17
    Will do mardoo, my PRV is from your home country so I have to get a 1/4 NPT tap which I will get tomorrow.
     
  3. wide eyed and legless

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    Posted 17/12/17
    Further on what I have read, my main concerns are of the stripping of esters and the viability of the yeast from the pressurised fermentation, dissolved CO2 is BAD. Anecdotal evidence is never a good reason for going along with something that looks like it could be a good technique, pressurised fermentation is very good as long as it's administered almost at the death knoll of the fermentation.
    From now on this is the route I will take, (applying the pressure towards the end of fermentation) and gleaning the benefit of free and pure CO2 .
    Fast pressurised ferments aren't for home brewers, reason being we don't or can't agitate the wort to keep the yeast in suspension, we could re divert the CO2 produced to lift the settled yeast off the bottom of the fermenter, but that is going to be as good as it gets.
    All the empirical evidence I have read there is nothing which endorses pressure fermenting, sure they have done the research for the big commercials allowing them to produce a lager in half the time by over pitching, specialised yeast strains, and agitation of the wort to keep the yeast in suspension.
    Brewers are trying different ways to prevent dissolved CO2 being in the wort, (hence the resurgence of open fermentation) and here we are purposely putting it in. Put it in by all means but leave it till a couple of degrees plato to go.
    Just my opinion after reading a lot of material, especially material regarding dissolved CO2 during fermetation. A lot of it is over the head of this home brewer, but I think I manage to get the gist of it, here is a blog from a craft brewer. If you are interested in reading the scientific views just google effects of dissolved CO2 during fermentation of beer.
    https://wildflowerbeer.com/blogs/blog/process-e1-primary-fermentation-geometry
     
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  4. Coldspace

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    Posted 17/12/17
    You can read, you can do.

    I've done countless pressure lagers, all turned out spectacular.

    Latest one, was a simple Aussie style, 45 ltrs, o2, pitched 5 ltr decanted stepped starter s189, ran at 18 degrees @14 psi ,3 days from 1048 to 1012, cranked up to 20, shut spunding down, leave for 3 days to carb up and finish off at 1008.
    Biofine, cc for 1 week. Although had several schooners after 3 days straight off the kegmenter , so 9 days from pitch.
    Guzzling great, clear Aussie lager in 2 weeks.

    Clean as a whistle.

    Does work :)
     
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  5. Dan Pratt

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    Posted 17/12/17
    Hi Wide Eyed,

    I just had a read through that link and what I got from that was mainly aimed at yeast driven beers, esters profiled beers which benefit from fermentation without the pressure to get the full formation of esters. As we understand the pressure prevents the esters forming so for the Belgian styles and English ales avoiding that pressure during fermentation makes sense.

    I would not be applying that same theory into beers which are malt driven or hop forward styles, the pressure we can achieve is, I think creating a cleaner final beer "ester free" , which enable the true ingredients to pull through and shine, like the pils malt on a lager or the distinct hop aromas on a ale.
     
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  6. wide eyed and legless

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    Posted 17/12/17
    I am not trying to pour cold water on pressurised fermentation, if it was so good why aren't the craft brewers embracing it, I would have liked to have found some scientific evidence for it, but it was all to the contrary. 25% of beer drinkers cannot detect VDK's add a load of hops to that percentage and it will rise add to that a cold serve of 2 or 3 degrees and then you are close to a 100%.

    Dan I was going to apply it to a lager, but as I said what the big commercials are doing are using huge starters of particular yeasts, stirring the yeast to keep it in suspension things that we can't do. If it is useful anywhere it is only on the lager strains, even lagers need esters as a distinguishing flavour. For me personally I will continue to use pressure but only at the end of fermentation.
    Don't just read the blog by the brewer at Wildflower, there is plenty of scientific reading at The institute of Brewing.
     
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  7. Dan Pratt

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    Posted 17/12/17
    I'm wondering that too, why the craft brewery are not doing it as common practice. Locally Six String have moved to pressure ferment but I haven't had a chance to Chris and the brewers some questions about pressure and times applied etc. I have noticed their beers are much cleaner than before, possibly a mental placebo.

    I'm yet to use the pressure at the end of ferment to carbonate, usually because 90% are dryhopped but i can see some benefits to using the pressure naturally like discussed.
     
  8. Coldspace

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    Posted 17/12/17
    The cleaner beers are from better ferments unless chasing esters, you could run higher temps although to achieve these if you desire plus early ferment at say 6-10 psi which is bugger all , most craft brewery fermenters stand tall and the natural pressure anyway at the bottom or lower portion of these fermenters would be at least this anyway :) Having a similar effect on yeast as say my my 50 cm kegmenter at 7-10 psi,( every 10 mtrs or so of water is approx 1 bar of pressure,)but Smaller carb bubbles are another main reason you will find it's better beer ,initially from pressure ferment versus more soda like carb bigger bubbles with carbonic acids formed at fast carb techniques etc from forced carb.which will smooth out with time, but natural el carb is far superior ,especially in the early days of the beer try it one day , you will like.

    One of the main reasons I employ this in most of my brews now, all lagers upto doppelbocks, most ales, Irish reds and stouts really go well.

    Saisons, never tried only done these styles in ambient ferments .

    I always preferred my natural bottle carbed batches than force carb kegs, initially , now pressure ferments allow best of both worlds .

    That is one main things that makes a better beer, more palet friendly and allows more of the malt/hops flavours to shine through as the smoother carb is more taste bud friendly. Once you have employed and dialed in this technique you will kick yourself over forced carb and question yourself, why did I not do this earlier.

    Another benefit , is smoother creamier heads from the smaller bubbles, it generally laces the glass all the way to finish, if you get it right in the technique.


    Plus, plus plus, no oxygen hassles etc:). And can try a schooner or 4 a couple of days after cc.

    That's why most premium champagne producers carb el natural, gives a nicer finished product

    I'm no scientist ,and respect the science behind it, but also when employing these thing in a practical way, good things happen as well , seen and tasted with my many batches, but am also a qualified beverage tech and refrigeration tech and have worked in the beverage industry for nearly 30 years, brewed piss for as long, and understand carbonation, temps and pressures ,but pressure ferments are great and have deff improved my beers to the next level across most styles.

    Yes agree, science plays apart, but on the small scale, pressurised ferments can improve all or nearly all your beers if employed correctly . Just don't over do the primary ferment pressure , keep at 1 bar or just under, alittle less if you desire the yeast flavours and for the carbonation benefits ( allow to rise between 19 and 28psi depending on style and finished temp, usually 20-22 degrees before cc )of the finished product make for a nicer smoother beer.

    Cheers
     
    Last edited: 17/12/17
  9. Dave70

    Le roi est mort..

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    Posted 17/12/17
    Cost perhaps? Whats the average size of a micro fermentation tank, 1500 - 2000L? I'd imagine screwing on a sealed lid and somehow converting your giant tank into a giant pressure vessel might land you in hot water with OH&S types, so thats the kind of kit you would need to consider at startup. If it were a case of tripling your revenue or production it may be worth the investment for an established brewery, but pressure fermentation wont corrector for shit beer in the first place. Only aggressive advertising can do that. Hard earned thirst anyone?..
    Thats my theory anyway.
     
  10. bradsbrew

    Who's up for a pint?

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    Posted 17/12/17
    [QUOTE="wide eyed and legless, post: 1493948, member: 31016"

    stirring the yeast to keep it in suspension things that we can't do..[/QUOTE]
    Oh yes it is. Try quickly dropping the pressure out of a fermentasaurus and watch those yeasties go for a swim.
     
  11. pcqypcqy

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    Posted 17/12/17
    I'd disagree that craft brewers aren't jumping on this - the handful of craft breweries I've visited recently have all been using pressure vessels. Tonnes more that I know of are using unitanks, which are pressure vessels.

    I agree that they're not necessarily chasing pressure to begin with for the reasons WEAL have stated, but the evidence is there that they give you much quicker/cleaner lagers, and let you carbonate naturally.

    They're several times the cost of a non-pressure fermenter of the same size though so I'd imagine small start up type breweries might steer clear purely on a cost basis.
     
  12. bradsbrew

    Who's up for a pint?

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    Posted 17/12/17
     
  13. wide eyed and legless

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    Posted 18/12/17
    There is only one reason the commercial breweries (only in lager fermentation) pressurise their systems is not to make a better lager but to make it faster. It is agitated throughout and the pressure isn't applied until 40 hours after pitching the yeast. Pro Brewer where a lot of the craft brewers have their threads also have pressure fermenting vessels, I did read where one stated the the maximum pressure of these vessels is 15 psi. I have not seen where any one of them actually pressurises their vessels until the end of fermentation to utilise the CO2 gas for carbonating the beer.
    For me the best use of the pressure is for transfer and carbonating, and that could well be why as pcqypcqy states that a lot of the craft brewers are getting pressure vessels may not be to apply back pressure to the fermenting wort but to capture the CO2.
     
    Last edited: 18/12/17
  14. pcqypcqy

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    Posted 18/12/17
    Yeah, agreed. From what I've read about pressure schedules, a lot of people only do a few minimial psi for the primary ferment, and then close it right up for the last few points to carbonate.
     
  15. wide eyed and legless

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    Posted 18/12/17
    Manifold build, although I have 5 inlets one may be used for venting the gas dependent on how close together the brews are. So at this stage for 4 ferments.
    Adding more meat to the bone for tapping out, doubled this for the 1/4 NPT thread.
    002.JPG
    Spunding valve and gauge.
    003.JPG
    other end of manifold.
    004.JPG
     
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  16. malt junkie

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    Posted 20/12/17
    The 15psi, is likely vessel limit, I know Glacier do 30psi but that ain't cheap.

    How many of the Pro brewers that pressure ferment their Lagers actually also produce an Ale? Or have stated they use different technique for Ale regarding pressure?
    Pretty much I brew for the taste, the pressure fermented Ales I have done (and tasted from other brewers) have been better, cleaner, than their side by side non pressure fermented same batch beers.
    I aerate, pitch, cap and spund (15psi). No my beer will never go under a microscope. Pretty certain it won't kill me. As to the poor yeasties, well once fermentation has finished they end up on the garden, so their ongoing health is of little consequence.

    Now all this maybe anecdotal, but I brew to/for taste, I don't need a scientist to tell me what tastes good.
     
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  17. wide eyed and legless

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    Posted 20/12/17
    We are all plebs when it comes to brewing, but in the fundamentals of brewing we know we have to have a vigorous boil and a robust ferment to get rid of sulphur compounds and anything else that isn't wanted. Applying back pressure, (nothing to do with hydro static pressure from the volume of liquor in a tank) the gasses are dissolving back into the fermenting wort, hence all the posts about foaming during transfer.
    Where all this started was a guy on HBT in 2007 after reading an article from a master brewer, called Closed System Pressurised Fermentation by Teri Fahrendorf.
    After 10 years and 57 pages, if you google that same article you can see how the original poster got it wrong on HBT, the pH will be lower than what it should be in a finished beer and it isn't about what I have read which concerns me. It is what I haven't read, all the writers of blogs on brewing, Chris Colby, Palmer, Zainasheff, Aquilla, Oliver, etc not one has come out and endorsed this method. Byo has printed an article but very much the same as what Teri Fahrendorff stipulated. Vent the pressure until you are 1 or 2 degrees Plato from finishing the beer then use the spunding valve, this is the same as what the Pro Brewers are doing on their web site. You will still get a good mouth feel and taste from the naturally fermented beer or lager and a clean finish. But if you are happy with what you are producing thats fine.
     
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  18. Jack of all biers

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    Posted 20/12/17
    I think that is pretty much what most brewers with experience in pressure fermenting are doing to a certain extent. At least from what I have read on this forum. They set their spunding valves to low pressures, 5-15psi seems to be the general range, and vent at that pressure until 1 to 2 Plato prior to FG when they might if they do so, up the pressure and temp to get natural carbonation, whilst ensuring complete attenuation and D-rest is covered. I wouldn't think that at pressures of 5-15psi there would be a lot of sulphur that is remaining in the beers, though taste would soon tell the brewer. Anyone who pressure ferments come across this problem before?
     
  19. Coldspace

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    Posted 20/12/17
    No sulphurs detected, the cleanest beers I've ever made , mine and shit loads of friends /family agree, we are brewing about 200 ltrs a month and all now with this method.

    Pressure only between 10-14 psi depending on spunding valve accuracy. Then carb up.

    When weal gets into it I think he will surprise himself...
     
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  20. wobbly

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    Posted 20/12/17
    Well I'm sure that I will get it for posting this but here goes!!!!
    The standard procedure in the WilliamsWarn Systems call for setting the variable pressure relief valve (VPRV) equal to a setting that will hold around 1.5 bar (20psi) and allow the yeast activity to build to and hold at that pressure for the full ferment. So in practice the vessel starts at zero pressure and builds to the 1.5 bar (20psi) over the next 12/18 hours. That is for fermenting an Ale at 23C Similar procedure but slightly different temperature setting for Lager/Pilsner.
    There are reportedly 100's of these systems in use and from what I can gleam from their user forum there isn't too much departure from this setting and no reported issues with off flavors etc.

    Cheers

    Wobbly
     
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