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Thread: Diacetyl in Belgian ales... again

  1. #1
    Join Date
    Apr 2005
    Location
    Montréal, QC
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    160

    Diacetyl in Belgian ales... again

    When we brew a Belgian ale (except Saison) it's always a gamble. We tried many fermentation patterns, but somehow, 50% of our batches develop a huge diacetyl aroma. The smell is awfull, starting with the usual caramel-butter aroma then ovetime... like over-the-hill cold cuts. Urgh!

    The strange thing is that this will only happen in our Belgian ales !

    We tried most WY + WL strains with the same results

    In most cases, we pitch at 18c/20c (66F) and let naturally rise to 23c/24c (74F) or higher

    We also tried to keep it at 20c, then let it rise higher at the end of fermentation like we do with our English ales

    We tried overpitching, underpitching. More oxygen, less oxygen.

    We tried leaving the beer naturally crash for a few days, even for a week or two before cooling with jacket.

    We tried alot of things!

    Lab analysis showed no infections in some batches sampled with that problem.

    Beer is fine in the fermenter even when crashed. Then once transfered to BT and kegged, WHAM! It's there.

    Any suggestions?

    Zb

  2. #2
    Join Date
    Jul 2008
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    25
    Hoses , pump , sanatation of bolth ?

  3. #3
    Join Date
    Apr 2005
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    Montréal, QC
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    As I said "Lab analysis showed no infections in some batches sampled with that problem"

    but thanks

  4. #4
    Join Date
    Jun 2007
    Location
    Solon, IA
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    250
    [QUOTE=Zucker Bee
    Lab analysis showed no infections in some batches sampled with that problem.
    [/QUOTE]

    Apparently, I don't know how to use the quotes.

    My first thought here is that you should try to sort out your data a bit. I would probably throw out the infected batches from your data set. Then see if you can nail down a pattern between fermentation temp, O2 levels, pitch rate, etc. I have a feeling that there is some correlation between these factors and your diacetyl. A good statistical guide to brewery lab work can be found in Brewing, Second Edition by Lewis and Young.

    If there isn't any pattern that presents itself with these parameters, then my next question would be where does your yeast for pitching come from, and how do you handle it? I've seen some anecdotal evidence that acid washing reduces lag time in our house lager strain when we get a fresh batch from our bank. We've theorized that washing affects the cell membrane in some fashion. Nothing to back that one up, though.

    Good luck, and happy brewing,
    Bill

  5. #5
    Join Date
    Apr 2005
    Location
    Montréal, QC
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    then use quotes like this

    "nail down a pattern between fermentation temp, O2 levels, pitch rate"

    I do collect data daily, wich allowed me to try different patterns and explore. I also drawn my cells/pH/T curves on a daily basis with all those experiments.

    ---

    After sleepless hours this week end and some hints by Chris White (of Whitelabs) I now realize there's something I didn't take in account. Pushing the my fermenters to the extreme limit by using the headspace I may end up with not enough yeast to reabsorb diacetyl: stuck to the walls and top dome dish, it's often spit out of the CIP arm.

    Also, this action might be amplified since we're doing two double batches in two days. Therefore, the already fermenting head is lifted and in way, "ecouraged" to stick up there. I'll reduce my volumes in the upcoming sessions.

    TBC!

    PS: with the ongoing spoiled batch, I'll try to add new yeast and wort and let naturally carb in the kegs (read more)

    Zb
    Last edited by Zucker Bee; 02-16-2009 at 11:42 AM.

  6. #6
    Join Date
    Dec 2008
    Posts
    1
    Possible scenario -

    If your beer tastes fine initially (fermenter), and then gets the diacetyl taste later (kegged) your problem might be with the diacetyl precursor - acetolactate. If your pH is to high, this could happen. Check your pH in the fermenter. You should also test fresh beer for acetolactate, right out of the fermenter before it turns into diacetyl. If your problem is acetolactate, the normal diacetyl remedies will not really work.

  7. #7
    Join Date
    Apr 2005
    Location
    Montréal, QC
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    I find it strange that this would happen only with my belgian ales... but notheless, I will investigate. Thanks!
    Last edited by Zucker Bee; 02-20-2009 at 08:09 AM.

  8. #8
    Join Date
    Aug 2005
    Location
    Nashville, TN
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    258

    Diacetyl

    I'm glad you talked to Chris White, he has enough knowledge to explain the formation to you. I just want to give my 2C.

    Basiccaly, Diacetyl formation is closely related to amino acids. If you have not enough VALINE, for example, you will end up with lots of Diacetyl. Keep in mind that if you have a low level of FAN, you also will have a low level of LEUCINE and VALINE. Now, second important factor is that yhe yeast used is healthy enough to use the FAN as food source. Why do I mention LEUCINE and VALINE in regards to FAN? These two amino acids are slowly uptaken by yeast with problems, i.e., to much death cells, and so on.
    Respiratory-deficient mutants represent an extreme example of this. In all such cases the inevitable result is elevated diacetyl levels.
    I observed that when DIACETYL appears spontaneously, the yeast used had a viability < 80%! The yeast used tend not to metabolize all the acetolactic acid in the wort and the acetolactic acid spills over into the finished beer and later is oxidized to diacetyl.
    So, what this means is you have no Diacetyl observed through tasting, and than BINGO, all at ones, there it is!

    Cheers,

    Fred Scheer

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