Acetal flavors & how to remove them

Discussion in 'General Brewing Discussions' started by 56 Firedome, Jan 28, 2020.

  1. 56 Firedome

    56 Firedome Active Member

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    Due to my typo, I allowed the Development of Acetal flavors. My Fermenter temps ran in the 70s & the kegged beer has a sharp bite.
    I had used Wyeast 1056 American Ale.
    So, my question is, Is there any way to clear up the Acetal flavor or am I looking at 5 gal of overly bitty beer?
     
  2. Nosybear

    Nosybear Well-Known Member

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    Same questions as on the "catastrophe" post - can you be more specific about "acetal?"
     
  3. 56 Firedome

    56 Firedome Active Member

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    Sorry to be repeating as I hadn't read you catastrophe post when I wrote this one.
    I took a bottle up to BH for some input.
    The general comment was Tastes like you have "acetal flavor" probably caused by the initially hi temp at the beginning of the fermentation. I reviewed the original recipe & found I had transposed the beginning & ending ferm temps. Should have started at 50 & ended the last 2 days at 70 to "clean up the acetal at the end of the fermentation."
    I wasn't entirely sure I heard/remembered exactly what they said.
     
  4. Nosybear

    Nosybear Well-Known Member

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    Ah, diacetyl! Buttery flavor, can be nice when fresh, rancid when old. It can also create a "slick" feeling in your mouth. There's nothing you can do about it now that it's in the beer. But here's the thing: It's considered "bad" in most styles but it's kind of the defining flavor in Czech lagers! It shouldn't be overly bitter due to diacetyl and if you can drink it, enjoy. Cause is generally an incomplete fermentation so if you dropped the temperature at the end from 70 to 50 degrees F, you likely stunned the yeast so that they couldn't clean up after themselves. The high fermentation temperature should have produced a fruity ester flavor more than diacetyl.
     
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  5. thunderwagn

    thunderwagn Well-Known Member

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    I'd also say that the diacetyl comment is thrown out like candy. Could be your beer is still young/green, or may even be a bad hop schedule.
     
  6. 56 Firedome

    56 Firedome Active Member

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    Nosybear & Thundrwagon Thanks for the reviews. Reading your posts it occurs to me that they were saying diacetyl not acetal. I'm a little deaf & I fear I misunderstood what they said in the 1st place.
    So, their observations regarding the Fermenter Temp 70 to 55 was likely to produce Diacetyl Flavors & that is the likely source of the "bitey" taste.
    Not sour or acid. I taste it on the tip & at the back of my tongue.
    I used Wyeast 1056. I've used it many times before.
    Any observations welcomed.
     
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  7. Mase

    Mase Well-Known Member

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    As @Nosybear stated in this and the other thread, towards the end of fermentation, raise the temp to encourage the yeast to now eat their vegetables (which includes diacetyl precursors) now that they’ve ate all the consumable sugars.
     
  8. Yooper

    Yooper Administrator
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    Diacetyl is buttery, “slick” in the mouthfeel and can leave an oily feeling on your tongue and teeth. Is that what you are getting from the beer?

    Your description does NOT sound like diacetyl at all, but some other issue. “Fruity”, yes- that could be because of the high temperature (those are called esters).

    When you taste the beer, what words come to your mind to describe it? Bitter, harsh, fruity, medicinal, solventy, burnt, grassy, etc? YOu don’t have to use official descriptions at all, just tell us what you taste and we can give you much better advice.

    Just because someone told you they tasted diacetyl doesn’t make it so- so many people use descriptors that aren’t accurate for tasting. And this is weird, but some people don’t have the ability to taste diacetyl at all- so if you don’t taste it, but the beer still feels slick on your tongue, you probably DO have it.
     
  9. 56 Firedome

    56 Firedome Active Member

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    Yooper & Mase - Thanks for the input. Taste descriptors are a whole new vocabulary.
    As best I can do to describe the taste experience is to say, "Tart" & on the tip & back of the tongue. Not as sharp as "Acid" about on the level with Sweet Tarts but not sweet at all.
    No "Slick" or tooth coating, not "Fruity".
    No doubt the Fermentation temp profile was wrong & probably generated diacetyl flavors which were buried by the "Tart" flavor.
    Heavy Sanitation was observed on the Keg, Fermenter & Secondary. All hoses, siphon & thief, the same. I tasted the SP Sample & did not get the bite I experienced in the finished beer.
    The Keg has been in the kegerator for 3 weeks. I used gelatin to fine in the Secondary before I transferred the beer to the Keg which I had first flushed with CO2.
    I have tried to maintain Sanitation Procedures as best I am able but I'm willing to change any processes neccessary.
    Thanks again for any input.
    Later
     
  10. Yooper

    Yooper Administrator
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    It doesn’t sound like diacetyl to me, but “tart” can be a yeast characteristic from fermentation temperatures being too high.
     
  11. Mark Farrall

    Mark Farrall Well-Known Member

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    This could also be a mountain being made out of a tiny slip up that may not have had any effect either. About what point in the fermentation did you hit the 70s? If it was later in the fermentation the chances are that it isn't the cause of any off flavours.

    If there's really anything wrong I'd be going with the raise at the end of fermentation to help clean up things, rather than hitting something in 70s during fermentation.

    And as thunderwagn has pointed out a lot of people when asked for a comment are unable to say fine, good, ok, etc. They have to give you some feedback they see as constructive (or they feel better if they point out a fault), so they'll say diacetyl, or astringency or DMS. Nosy thinks they know their stuff, so maybe it's not that, but it's a pretty common thing to look out for when you're getting feedback.

    I've done tasting sessions with brewers, cicerones, etc. that have that same impulse. They know their stuff, but they still have to pick out a fault. It gets worked out of them once they've done enough tasting sessions with someone experienced, especially with someone who gives them flights without any problems, but just because they're a pro brewer doesn't mean they've got the tasting/diagnosing side of the game down yet.
     
  12. BOB357

    BOB357 Well-Known Member

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    I'm with @Mark Farrall on this. You ended up with a beer that didn't meet your expectations. You can't pin down any particular flaw on your own, so you grasp the first straw offered by someone you think knows better. Brew the beer again and follow the proper procedure. If the flaw is gone, you now know it was caused by your error. If it's still present, try to pin it down using the descriptions you've read here.
     
  13. Mase

    Mase Well-Known Member

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    Couldn’t agree more, and take a lot of notes on every step and temperature, etc. etc.
     
  14. 56 Firedome

    56 Firedome Active Member

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    could also be a mountain being made out of a tiny slip up that may not have had any effect either. About what point in the fermentation did you hit the 70s? If it was later in the fermentation the chances are that it isn't the cause of any off flavours.
    Thanks Mark Ferrall. If only it was that easy. The folks I talked to at my LBS was with 2 sr guys I have worked with for the last 10 years. Both Nosybear & I highly respect both for their experience, willingness to provide honest review & their candor when their opinion is requested.
    This is not a small flaw. Regarding the Fermenter Temperature, the Fermenter Temperature Started at 70 & held for 2 days & reduced to 50 for the last 6 days of fermentation.
    This was a stupid failure on my part & I should have recognized the problem from the start. So, skip over that part.
    The flaw is a "sharp taste on the tip & back of my tongue, it's a "tart" taste on the scale of Sweet Tarts without the sweet."
    Bob357 so, not clutching at straws, looking for suggestions as to how to avoid making this mistake again.
    I've made this beer 6 times before with great results. It had been 4 years since I made this beer last & I was transferring the recipe from an old SS to a new one & transposed the fermentation profile.
    So, I know this was a failure not of the recipe or process as both have worked admirably in the past.
    I'm willing to publish the process but I have done that in the "How do you brew" post. I'll include the recipe but it's on my laptop, doable but it will take a minute.
     
  15. BOB357

    BOB357 Well-Known Member

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    Sounds like you're confident that you knew what caused the problem all along, so why ask for opinions here? As I stated earlier:

    "Brew the beer again and follow the proper procedure. If the flaw is gone, you now know it was caused by your error. If it's still present, try to pin it down using the descriptions you've read here."
     
  16. J A

    J A Well-Known Member

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    That doesn't describe diacetyl or acetaldehyde. That describes a highly acidic compound somewhere in the mix. Citric acid, malic acid, ascorbic acid are some of the compounds used in Sweet Tarts. Phosphoric acid and lactic acid are probably the ones most commonly associated with brewing in the form of Star San and water adjunct.
    If there's a possibility that a large quantity of Star San ended up in the mix or your amount/concentration was way off in a lactic acid addition, that might account for it. Sweet wort could mask an excess of acidic flavor but it would jump out in the finished beer, lacking the sugars to balance it. Otherwise, lactobacillus present in the fermentation would certainly make an acidic flavor.
    Hope you track it down.
     
  17. 56 Firedome

    56 Firedome Active Member

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    Thanks for the input one & all. I plan to drink it & make it again. I've made it before but a long time ago.
    My neighbor doesn't mind. I'll scrub the equipment while I wait it out & try it again.
    Thanks again.
     
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  18. Daniel Parshley

    Daniel Parshley Active Member

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    Would changing yeast type help? I have to ferment at 72-74F here in the SE USA and use Safale -05. Also, had a batch that tasted as described and a 4 week conditioning greatly reduced the bitter/tart. My problem was caused by adding high AA hops to early in the boil.
     
  19. Yooper

    Yooper Administrator
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    Is the 72-74 the actual fermentation temperature, or the room temperature? I ask because an active fermentation can be as much as 10 degrees higher than the room temperature. Fermentation itself produces heat, and so you may want to look into a small cooling chamber or something like that.

    You can try kviek yeast, which can be (should be) fermented at higher temperatures. That’s my plan if I brew here in Florida, instead of a fermentation chamber.
     
  20. Daniel Parshley

    Daniel Parshley Active Member

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    The fermenter temperature is 72-74. I use the color temperature sensitive adhesive strips on my fermenting buckets (and a thermometer before pitching yeast). A 2-3 degree increase above room temperature is what I usually observe. The selection of the Safale -05 yeast was made after visiting micro-brewers in the area and asking what they used. Thanks for the Kviek Yeast suggestion for our toasty region of the country.
     

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