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Fermenting Under Pressure

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

 

  1. Hpal

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    Posted 14/12/17
    It doesn't have to be a great amount of pressure, just do it an 5-10psi and I'm sure there would be no ill effects.
     
  2. malt junkie

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    Posted 14/12/17
    When doing beers of this magnitude, multiple health yeast cakes are required, if you have multiple pressure ferment vessels or are able to rack off used yeast and add fresh yeast in the same vessel.
     
  3. rossbaker

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    Posted 14/12/17
    I'll be using Zurich lager yeast which is designed for this kind of gravity, but I was thinking of over building the starter, keeping some aside then culturing that up and adding it if needed to keep the ferment going. It will be a 15l batch and the fv will just be a corny so it should be easy enough to rack to a second vessel if I need to use more yeast. Will go with low pressure, good advice.
     
  4. wide eyed and legless

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    Posted 14/12/17
    If you are pressure fermenting you have to choose your yeast carefully, White Labs have cultured a special Lager yeast for pressure fermenting WLP 925, keeping pressure under 1 bar
     
    Last edited: 14/12/17
  5. malt junkie

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    Posted 14/12/17
    I know there is a popular belief that yeast can suffer detrimental effects under pressure. But follow me for a minute here.
    Lets take a small/medium craft brewer like Wayward for instance Brew length of 40HL, FVs of 40 and 80HL. Now for every vertical meter of height water will exert 10KPA of static pressure(the gravity of wort would change this but not dramatically), most of Wayward's FVs are near 4m tall, so any lager they produce has 40kpa of static pressure on the yeast where they are working.
    Waywards beers taste fine to me. Now if you then think about the static pressure in the vessels CUB, Lion, or even Coopers are using.....
     
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  6. Mardoo

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    Posted 14/12/17
    The research I've seen says that yeast health starts to suffer above 200 kPa/30 psi/2.1 bar. That's part of why large commercial breweries with said tall fermenters use such high pitching rates. Re-pitching health starts to suffer above 30psi as well, so again, high initial pitch rates help ameliorate that.

    Has anyone seen any information on pressure rates and phenol production? I'm wondering about using Belgian yeasts under pressure. I'm doing some saisons soon. I've seen plenty of work on esters and fermentation, but don't recall seeing any on phenols.
     
  7. pcqypcqy

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    Posted 14/12/17
    40kPa is about 6psi, which is the number I've seen around the place quite a bit as well. I think the commercial guys aren't necessarily aiming to do a pressure ferment like we do, but are naturally achieving some pressure on the wort and yeast due to their tanks. An offshoot of this is that it does provide some benefits for lagers, so probably before the research was done, brewers realised that if they used vertical tanks of a certain height to ferment in, lagers were easier/quicker to produce.

    A lot of people talk about the 30psi limit. For reference, this is about 200kpa, which is about 20m of static water head. I imagine even the big boys would be stopping short of this height as it gets impractical - the structure required to support that is getting significant.
     
  8. malt junkie

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    Posted 14/12/17
    There was some good info linked in the earlier pressure ferment threads that charted time/gravity/ester formation/diacetyl levels during pressure ferment. There were also some papers linked that got right down into the why and how of what pressure was doing. Including the damage to yeast above 30psi (cell wall damage), if I get the chance I'll chase it down this arv' but the search function may well again be my nemesis.
     
  9. Mardoo

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    Posted 14/12/17
    Yep. I’ve read about 15 studies on the question. I need to rearrange my links listings as it’s very hard for me to find them these days. I know I’ve linked some somewhere on the site, but am unsure where.
     
  10. wide eyed and legless

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    Posted 14/12/17
    What you are talking about there is hydro static pressure which the yeast can tolerate up to around 10MPa, CO2 pressure is around 50KPa


    Stationary phase yeast cells exhibit an increased resistance to high hydrostatic pressure
    compared to exponential phase cells. Research studies indicated the profound cellular changes
    triggered by high pressure stress, which are maintained even after the stress has ended. For
    example, in yeast cells pressurized at 50MPa for 30 min. cellular recovery appears only after
    120min. Comparing yeast cell response to high pressure with the one after thermal stress
    (30min at 40ºC) showed that the pressure stressed cells need a longer period of time for
    recovering after stress (37). Recent studies indicated an advantage of high pressure stress for
    alcoholic fermentation: at 10 MPa the fermentation of glucose to ethanol by Saccharomyces
    cerevisiae proceeded three times faster and gave a slightly increased yield when compared
    with the same fermentation at ambient pressure (38). Resistance to high hydrostatic pressure
    can be attained either by a moderate pressure treatment or by exposure to moderate thermal
    shock. Most probably, high pressure tolerance results from a combination between membrane
    fluidity preservation (rich in cholesterol) and trehalose accumulation.
    High hydrostatic pressure stress in the brewing industry
    Most yeast resist to hydrostatic pressures stress, but the brewing yeast strains cannot
    withstand hydrostatic pressures higher than 10MPa and gaseous pressure up to 50kPa. The
    simultaneous effect of high gaseous pressure and ethanol stress increase the negative effects
    upon brewing yeast cells. High gaseous pressure negatively affects cellular membrane
    integrity and cellular division cycle, which further influences the aroma of the final product,
    beer

    Overview on Brewing Yeast Stress Factors (PDF Download Available). Available from: https://www.researchgate.net/publication/258323942_Overview_on_Brewing_Yeast_Stress_Factors [accessed Dec 15 2017].
     
    Last edited: 14/12/17
  11. Dave70

    Le roi est mort..

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    Posted 14/12/17
    Cool, I think I've got one of those Zahm devices tucked away in my wardrobe somewhere..
     
  12. wide eyed and legless

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    Posted 14/12/17
    You've got a penis pump with a gauge? What pressure you going to!
     
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  13. Dave70

    Le roi est mort..

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    Posted 15/12/17
    It is, in fact, supposed to a vacuum gauge, not *pressure. Which may explain my somewhat disappointing results.

    *Made in PRC.
     
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  14. rossbaker

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    Posted 15/12/17
    Well the Zurich lager yeast has arrived today so I'll start building the starter up with that. I'm still contemplating swapping the spunding valve for a blow off to let this one breath for the first few days. Never done a beer this big.
     
  15. Coldspace

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    Posted 15/12/17
    Christmas 2018, spunding valve deff on the blow off keg in post , with jumper lead on gas post of primary and liquid of blow of keg, pressure just run at 10-14 psi, all other constraints at normal , my dopplebocks from end of last summer at pressure fermented are just coming into their own last couple of months although they weren't this big, good luck.
    Did 2x 40 ltr batches aged in 4 cornies , all turned out great, German friend was out few months ago, we had a blinder night on one corny , he said, " this reminds me of home"
    Best feed back I've got from brewing piss.

    Cheers
     
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  16. malt junkie

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    Posted 15/12/17
    Not as bad as building a 1km tall FV 10mpa??? When Inbev truly do take over the maybe....
     
  17. wide eyed and legless

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    Posted 15/12/17
    There are some good posts on
    Thats a big beer Ross, you will need a big starter, even if it takes a few days to make it, I wouldn't be putting any CO2 pressure on it at all until you have 2 or 3 degrees plato left to go then capture the CO2 to carb the lager with. Big beers take time, and time before you can start to drink them, so there is no rush.
     
  18. rossbaker

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    Posted 16/12/17
    Good advice, cheers.
     
  19. wide eyed and legless

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    Posted 16/12/17
    Transferred my beer to secondary on Friday arvo, lost a couple of points on final gravity which I put down to the 10 psi pressure on the first day of fermentation. Apart from that extremely happy with the out come, beer has cleared nicely (not even cold crashed yet) and got carbonation, (enough for an English bitter) Making a manifold now so I can ferment 4 or 5 brews at the same time using the one PRV
    and gauge.
    001.JPG
    Bladder slowly filling with CO2 (on the right)
    002.JPG
    005.JPG
     
  20. Mardoo

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    Posted 17/12/17
    I like the manifold idea! That hasn't yet occurred to me. Can you post pics as/after you build it?
     
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