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  1. #1

    Pressure Fermentation


    I am thinking of of dabbling in this a little bit, but my research has brought about pretty contradictory view and experiences.:

    A. On one hand it says the extra CO2 held in the wort/ beer decreases the pH to levels the yeast dont generally like, and they slow down and it adds 2 or 3 days to fermentation

    B. On the other hand the theory is that you do a pressure ferment for a quicker ferment at a higher temp with less fusals and estery flavours.


    'A' above might just be a comparison between pressure and non pressure at the same temp, which makes sense. Im not sure specifically how pressure would affect the esters.

    But what are the real world experiences from you guys who use spundings?. Are there no other unwanted flavours compared to normal fermentation? Is the yeast/ ferment flavour profile completely different or not even noticeable?
    Cheers,
    Lang
    ~~~~~~~~~~~~~~
    "Dudddde...Hold my beer!".... ; "I wonder what will happen if I ...."
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  2. #2
    Senior Member JIGSAW's Avatar
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    Well, unless you ferment without a lid, you are actually fermenting under pressure ....

    A fermenter builds up quiet a bit of pressure before it pushes an air bubble through the airlock.

    But yea, controlling that pressure with a spunding valve (Blowtie) I cannot commend on, as the couple of YT vids I've seen on this, all says they're fermenting faster.
    Someone else might have the correct answers.
    The Problem With The World Is That Everyone Is A Few Drinks Behind.!


  3. #3
    Quote Originally Posted by JIGSAW View Post
    Well, unless you ferment without a lid, you are actually fermenting under pressure ....

    A fermenter builds up quiet a bit of pressure before it pushes an air bubble through the airlock.
    A good point! I dug a bit and estimates are that retained pressure from a bubbler equates to about 0.003 bar, so not too significant compared to the up to 1bar on a spunding But hell maybe retaining the 'atmosphere' alone gives very different results versus an open ferment?
    Cheers,
    Lang
    ~~~~~~~~~~~~~~
    "Dudddde...Hold my beer!".... ; "I wonder what will happen if I ...."
    www.ginormity.com

  4. #4
    Senior Member JIGSAW's Avatar
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    Quote Originally Posted by Langchop View Post
    A good point! I dug a bit and estimates are that retained pressure from a bubbler equates to about 0.003 bar, so not too significant compared to the up to 1bar on a spunding But hell maybe retaining the 'atmosphere' alone gives very different results versus an open ferment?
    That sounds a little low to be pushing up against the atmospheric pressure from the outside, or am I confusing my apples and oranges here?
    The Problem With The World Is That Everyone Is A Few Drinks Behind.!


  5. #5
    I'm waiting for groenspook to come in here with all his vast experience on pressure fermenting...

    Quote Originally Posted by JIGSAW View Post
    That sounds a little low to be pushing up against the atmospheric pressure from the outside, or am I confusing my apples and oranges here?
    No, you are right. Correctly speaking it's 1.003 bar absolute pressure inside the fermenter. That 0.003 is the pressure difference when a bubble pops through the bubbler. I think it assumed the fluid lifts about 1 inch before that happens. I might have converted it wrong from psi too.
    Cheers,
    Lang
    ~~~~~~~~~~~~~~
    "Dudddde...Hold my beer!".... ; "I wonder what will happen if I ...."
    www.ginormity.com

  6. #6
    Quote Originally Posted by Langchop View Post
    I'm waiting for groenspook to come in here with all his vast experience on pressure fermenting...



    No, you are right. Correctly speaking it's 1.003 bar absolute pressure inside the fermenter. That 0.003 is the pressure difference when a bubble pops through the bubbler. I think it assumed the fluid lifts about 1 inch before that happens. I might have converted it wrong from psi too.
    Lol, fill yer boots

    https://www.youtube.com/watch?v=W7WSFn6bNoA

  7. #7
    Cool vid, thanks. Does that all correlate with your practical experiences?
    Cheers,
    Lang
    ~~~~~~~~~~~~~~
    "Dudddde...Hold my beer!".... ; "I wonder what will happen if I ...."
    www.ginormity.com

  8. #8
    Trusted information for sure, I don't have a need to pressure ferment at the moment. My kveiks run fast enough tbh, on the horizon is pressure transfer in lieu of c02 purge. However I do need to add more kegs to my line up, then delve deeper into distilling with the alembic. T500 distilling is too easy, verges on boring actually - then again I don't drink a lot of hard tack so the clean spirit from the T500 will be piling up, planning to run it via the alembic / botanical basket for some gins. I have a feeling that lost keg to tonic will take quite a while to empty too. I digress, right now I'm not going to pursue pressure fermentation.

    on a side note. my replies are going to be slow until the tapatalk / forum thing is resolved
    Last edited by groenspookasem; 10th October 2019 at 08:36. Reason: and some

  9. #9
    Great vid with all the essential info.

    I initially started FUP (fermenting under pressure) to eliminate exposure to O2 and contamination. Beer quality has always been more important to me than brewing faster, not that the time saving when fermenting under pressure is not a bonus but imho speed should not be the main priority when brewing.

    0c7e23e62ba0616e3547e1c00bf43d47.jpg

    Munich Helles: BIAB, No-chill. 17L into sanitised corny keg.

    2 x packets of 34/70 Lager yeast 12 psi @ 20 C
    OG 1.048 - FG 1.012. attenuation 74% abv 4.7 % pH 4.2

    No starter and no yeast hydration. Sealed keg with 7 psi, set the spunding for 12 psi and let the yeast do their own thing, around 18 hour the pressure increased to 15 psi and stayed there. Did not raise the temp at the end of fermentation.

    Some additional points ito prosess:

    When FUP in a corny its very easy to take a SG reading
    Pro - just hook up your liquid out post with a piece of hose and a picnic tap.
    Con - the sample is carbonated (a milk frother whisk thingy will sort that out quickly)

    Your beer is never exposed to O2 during transfer from fermenter to keg
    Pro - Transver from FUP keg to CO2 purged keg via the 2 liquid out posts by adding pressure to FUP keg or releasing pressure in the serving keg.
    Con - you need a additional serving keg and additional out connector

    Your beer is already partialy carbonated at the end of fermentation (15 psi @ 20° = 1.7 Vol.)
    Pro - Time saving
    Con - You will lose 1st 500ml when doing the closed transfer to serving keg as there will be about 150 ml of
    yeast in 1 st 500 ml that comes out of the FUP keg.

    20190929_075819 - Copy.jpg
    Day 8 - 1st 500ml out of FUP keg 1st SG reading 1.012

    20191002_090159.jpg
    Day 10 - 1st 500ml out of FUP keg 2 nd SG reading 1.012

    Adding gelatin to clear the beer in serving keg need to be done in the serving keg before it is purged with co2. To dry hop you need to depressurize and seal the keg again unless you do "dry hopping" bmo a hop tea. There must be a few other thjngs that Im missing now but will catch up on it later

    Day 10 - Added gelatine to the serving keg, filled it with co2 and purged the keg a few times. Transferred the beer to from the fermentation keg to the serving keg and cold crashed for 2 days at 4 C.

    Day 12 - I hooked up the co2 at 15 psi and left the keg in keezer to carbonate

    Day 14 - Fully carbonated and ready to serve

    IMG-20191007-WA0000.jpg


    Who knows I might be doing no-chill in the keg and then do FUP in the same keg next
    Last edited by Harhm; 10th October 2019 at 15:28.
    I value your experience more than your opinion Time is on your side, never rush a beer Have fun, its only beer

  10. #10

    OK, only saw this tread now. Thanks Harhm.
    After reading up some more on kegging and keg components, I assume the spunding valve connects to gas in post, also thats what it looks like on the pic.
    Everyone must beleive in something, I beleive I'll have another beer

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