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So THAT's what diacetyl tastes like!

Discussion in 'Homebrewing' started by good_gracious, Dec 6, 2012.

  1. Hot damn, I can cross diacetyl off the list of things I might not be able to recognize in a beer.

    I pulled a sample from a brown ale I just brewed on Sunday and whiffed/tasted the most distinct butterscotch. I hope assume the yeast will to go town in the next week or so and clear it all up. I never, ever open a fermenter before the two week mark, but I thought I'd give it a shot this time to see how effective my starter was with respect to gravity after 3 days.

    Now I guess I'm stuck trying to cross other stuff off the list, such as determining whether the beer is oxidized/contaminated/full of tannins/etc.
  2. barfdiggs

    barfdiggs Savant (420) California Mar 22, 2011

    You will also get a slick mouthfeel from diacetyl. Its one way for people who can't taste diacetyl to detect it in a beer.

    If you want to experience all those without brewing beers with the off flavors, buy an off flavor kit from the Siebel Institute, something along the lines of 20+ off flavors. We used it for an off flavor beer class, was very useful and pretty fun.
  3. koopa

    koopa Champion (765) New Jersey Apr 20, 2008

    Just do a diacetyl rest for a few days and then resume fermenting at your normal temperature. I will usually ferment my beer for say 3-5 days, then do the diacetyl rest by raising the wort temperature up to around 69-70F for 2-3 days, then resume the original fermentation temperature for another 1-2 weeks. You want to engage the diacetyl rest when you are about 80% - 85% fermented from what I've read. That usually takes me 3-5 days (mainly 3).
  4. Eriktheipaman likes this.
  5. As much as I would love fermentation temperature control right now, alas this is not an option. The fermenter is sitting in the guest bathroom tub right now though, so I guess I could go the redneck approach and fill it up with maybe 80F water to raise them temp. Ambient in my condo right now is 66-68.
  6. koopa

    koopa Champion (765) New Jersey Apr 20, 2008

    If your ambient temp is 66-68 then I'd assume your fermentation temperature is warm enough to force diacetyl to dissipate, as I believe that 64-72F is the recommended range for a diacetyl rest. Just give your beer the normal 2-3 weeks on the yeast cake and it should clean up somewhat.
  7. My first taste of diacetyl actually came from an IPA that I brought to a professional brewer. He immediately detected it while I never did until he said something. His first question was actually how long I left it on the yeast to which I responded 3 weeks and he said that was too long contrary to what most homebrewers say. I now just do 1 week primary, 2 weeks secondary, and however long it takes to force carb.
  8. yinzer

    yinzer Savant (385) Pennsylvania Nov 24, 2006

    I think that this thread will get a bit busier.

    Ok, not everyone can do temperature control for fermentation or is trying to make an award winning beer. Some people just like to brew. But that aside with most yeast and the correct conditions, you really shouldn't be making diacetyl. I try to do a diacetyl rest with every beer, but it's more just to try and let the yeast finish for attenuation and general cleaning up. But due to my work schedule I travel a lot and sometimes will pitch yeast and have to leave it for a few weeks on the cool side. I really don't notice any difference between when that happens and I can baby-sit my beer and do a proper rest.

    I wonder if the pro-brewer ever actually homebrewed. They are two different worlds. The yeast act totally different in a large fermentor vs a small carboy. Also he seems to be saying that diacetyl is being made post-active fermentation. Which isn't true.

    I think that this also speaks to why in another thread people said that it was okay to open bottles that might not of conditioned or be fully carbonated. It always good to taste, taste, taste.
    jlpred55 and cavedave like this.
  9. The pro brewer has definitely homebrewed many batches and actually some distributors that know about brewing are surprised that they actual give their beers enough time in the fermenter while many breweries do not.

    While it may be good to taste, taste, taste, IMO its pretty easy to pick out a green beer that needs some time.
  10. yinzer

    yinzer Savant (385) Pennsylvania Nov 24, 2006

    "and actually some distributors that know about brewing are surprised that they actual give their beers enough time in the fermenter while many breweries do not."

    Who is "they"? The pro-brewer? Distributors are surprised that they give their beer enough time while others give less time?


    Did he tell you to more it to a secondary after one week? Or that one week is all that needed? I don't see the need for you to use a secondary if you keg. You can condition in the keg.

    Yes, pro's can finish beer in a short time. So can homebrewers. Some pro's and some HB'ers can not. It's all process. And if the beer need time, then give it some more. But "green beer" really is used to describe something other then diacetyl.
    cavedave likes this.
  11. He said when homebrewing his process was always 1,2,3. 1 week in primary, 2 in secondary, and 3 to carb (less if you keg and force carb obviously). The fact is that even a decent amount of breweries rush their beers out (less than 3 or 4 days after fermentation is complete) and can lead to less than stellar beer.

    I know "green beer" is completely different from diacetyl. What I was saying is that many breweries rush their product out because of such high demand, which doesn't always necessarily display flaws in the beer but can result in "green" beer.
  12. yinzer

    yinzer Savant (385) Pennsylvania Nov 24, 2006

    Fair enough, thanks for the clarification.
  13. barfdiggs

    barfdiggs Savant (420) California Mar 22, 2011

  14. cavedave

    cavedave Champion (930) New York Mar 12, 2009

    Haha we used Coors Light for our demonstration as well. All of us are aware now of what are the true tastes of some of the off flavors, and the need to avoid them, and easy ways to do so. Sour Coors Light was actually not too bad (been on sour kick lately), but Coors light with diacetyl, or tannins, uggghh. Funniest thing was our club President and the member who presented arguing over how to pronounce diacetyl.
  15. You mean you didn't just have some laying around?? ;)
  16. pweis909

    pweis909 Advocate (695) Wisconsin Aug 13, 2005

    What yeast did you use? I've never had an issue with an ale yeast, but a couple of them do have a reputation.

    Here's a "Just in Case" tip: This summer I had a big issue with a lager yeast and the original yeast I had pitched did not clean it up with time, even at raised, diacetyl rest temperatures. After discussions with other BAs, I ended up making a small starter with a new pack of dry ale yeast (dry ale yeast is all I can get at my LHBS) to get the yeast active and then I pitched it and allowed the yeast to work on the diacetyl.
  17. VikeMan

    VikeMan Advocate (740) Pennsylvania Jul 12, 2009

    I hope he only homebrews a narrow range of styles and perfectly replicates all his processes every time. Otherwise, this 1/2/3 approach would not always result in the best possible beer.
    rocdoc1, koopa and jlpred55 like this.
  18. pweis909

    pweis909 Advocate (695) Wisconsin Aug 13, 2005

    It's not clear to me how leaving it on the yeast too long would lead to a diacetyl presence in a beer. In fact, one might predict exactly the opposite, that diacetyl declines with duration of yeast contact. Sometimes homebrewers experience diacetyl problems because they follow the advice you gave. By transferring from primary at a prescribed time rather than based on hydrometer readings and sensory perceptions (especially in the case of diacetyl and acetaldehyde), one invites problems associated with premature transfer.
    koopa, JrGtr and jlpred55 like this.
  19. VikeMan

    VikeMan Advocate (740) Pennsylvania Jul 12, 2009

  20. wlp002. Is this strain known to have an issue? If nothing else I can definitely attest to its ability to flocculate. Not a single remnant of the krausen after only 3 days.
  21. premierpro

    premierpro Savant (290) Michigan Mar 21, 2009

    There is one brew pub in my area that lets their beer sit on the yeast for 3 weeks ( so I've been told ) and another that pulls it off after 3-4 days. Guess witch brewery makes better beer?
  22. good_gracious likes this.
  23. Were you at terminal gravity when you pitched the second starter?
  24. Diacetyl will clear up at warmer temperatures -- high 60s and into the 70s -- no need for special technology to reach a diacetyl rest. Just move it to a warm part of the house. Or you could hug your fermentors for a while.

    That whole 1-2-3 approach is dated and really unnecessary.
  25. jlpred55

    jlpred55 Savant (270) Iowa Jul 26, 2006

    My kid who is 16 months old can say 1-2-3. Good for him, no so much for my beer. :)
    francisfilion likes this.
  26. pweis909

    pweis909 Advocate (695) Wisconsin Aug 13, 2005

    Yes, more or less. The new yeast had the sugar in the starter, and when that ran out, they consumed the diacetyl. Or at least that was the hypothesis. The beer cleaned up during a 2-3 week period. I do not know if it took this long; I just tried to forget about for a while.
  27. pweis909

    pweis909 Advocate (695) Wisconsin Aug 13, 2005

    I've never had big diacetyl with any ale strain, but several English strains are noted for leaving a bit of diacetyl. One could imagine how the strong flocculation could leave some residual diacteyl behind. I thing the one with worst reputation is the Ringwood strain, which is WLP005 British Ale yeast and WY1187. I used WLP005 once to make a brown ale and I did not detect diacetyl. It could have been present to some extent, perhaps disguised a bit by specialty malts and below my personal detection threshold. In any event, it was not the butter bomb that I had with the lager I referenced earlier.
  28. Well I make sure I am at my final gravity when I transfer to secondary so it is based on a length of time and hydrometer readings. The yeast was US-05.
  29. This is a highly flocculant yeast. When it drops out, it is not doing its job cleaning up as well. It is recommended to rouse the yeast to clean up the beer, or do an extended rest.

    http://www.whitelabs.com/beer/strains_wlp002.html

    Same strain. Both are said to be the Fullers yeast.
    http://www.wyeastlab.com/hb_yeaststrain_detail.cfm?ID=22
    good_gracious likes this.
  30. One more thing. Now that you know Diacetyl, drink a Samuel Smiths and see if you pick it up. I can, and my threshold is fairly high.
    Naugled and mattbk like this.
  31. pweis909

    pweis909 Advocate (695) Wisconsin Aug 13, 2005

    I strongly recommend tasting that hydrometer sample. If it tastes OK, then proceed with racking to secondary (or better yet, skip secondary, give it some more time to clear, and then package). But if it tastes like there is something for the yeast to clean-up (diacetyl - butterscotch; acetaldehyde-green apple) then permit the beer to stay in contact with the yeast for a few more days.

    As always, "your milage may vary." Perhaps you have things so dialed in that you don't need this advice, but just note that you can use sensory evaluation to make good decisions in the brewery.
  32. Some diacetyl is to style. Which (or all) Sam Smiths are you talking about?

    If you don't want to buy a kit, you can do it this way too:
    http://www.bjcp.org/course/Class5Lesson2OffFlavors.php

    However... it won't give you all of them and it may cost just as much in the end.

    Diacetyl I know from butterscotch candy! Funny, though -- I had an IPA with scotch soaked oak in it that came back with lots of Diacetyl comments... it didn't do well because of it, but there was definitely no Diacetyl in it (at least none I could taste).
  33. You've just crossed the minimum threshold for pushing me to try a beer. It's not very high. :)
    Beerontwowheels likes this.
  34. I think it was the Pale Ale or India Ale in a judging class. "Some" is to style. This was beyond some.
  35. barfdiggs

    barfdiggs Savant (420) California Mar 22, 2011

    That was one of the surprises of the night. I liked the Coors light with lactic acid spiked in, as well as some of the esters dosed in (isoamyl acetate (banana) and ethyl hexanoate (apple/fruity)). The capryllic acid, mercapatan and indole spiked ones were absolutely foul though.
    cavedave likes this.
  36. All beer yeasts create diacetyl (with the peak occurring during the exponential growth phase). If you permit the yeast to complete the primary fermentation, the yeast will metabolize the diacetyl into other compounds.

    Some folks refer to the post exponential growth phase as being a “diacetyl rest”. For ales I prefer to think as this timeframe as just being the completion of primary fermentation. If you are fermenting at ale fermentation temperatures you really should not have to increase the fermentation temperature; simple letting the fermenter stay in the appropriate fermentation temperature range (e.g., 68°F) for an appropriate amount of time should permit the diacetyl to be metabolized.

    WeaponTheyFear used the Fullers yeast strain (WLP002/WY1968) which as hopfenunmaltz noted has a tendency to flocculate quickly. I have not used WY1968 in quite some time but when I did use it I always roused the yeast during the primary ferment. I did this rouse process because I have read posts from homebrewers recommending this for this ‘lazy’ yeast strain:

    “The White Labs website has a lot of information about all their yeast strains including WLP005, the lazy yeast. This yeast is a fast starter and highly floculant producing malty ales in a relatively short period of time. There is also much discussion among homebrewers about stalled fermentations and the manufacturer suggests rousing the yeast may be needed to re-suspend the yeast.”

    My motivation for rousing was to obtain full attenuation with this yeast (not specifically to ‘manage’ the diacetyl). I am very sensitive to diacetyl and I never tasted diacetyl in the beers I made with WY1968; it would appear that rousing was helpful in this regard.

    So, WeaponTheyFear permitted his beer to primary ferment for three weeks but my guess is that the yeast flocculated quickly (e.g., after a few days) and then was not actively metabolizing the diacetyl. He needed to rouse the yeast for this process to occur for his beer.

    The Ringwood strain (WY1187) has a reputation for creating diacetyl. Perhaps this strain makes more diacetyl than other strains but if you permit this yeast to have a complete primary fermentation then you will not notice diacetyl in your resulting beers. I have a local brewpub that uses WY1187 as their house ale strain and none of their ales have any diacetyl taste; they simple permit the yeast to complete its work before serving their beers.

    Cheers!

    P.S. A good article by Chris White on The Diacetyl Timeline: http://www.whitelabs.com/beer/Diacetyl_Time_Line.pdf
  37. If you want to minimize the D, pitch the correct amount into wort that is 5F below the fermentation temp then let it free rise, have it aerated when you pitch, and keep the temp up at the end of fermentation. Leave on the yeast, and if you can't taste it in a warmed sample, you are good to go.
  38. good post Jack Horzempa. One of the reasons I like WL 013 (WY1028 I believe) best for english styles is that it is slower to flocc out than WL 002. Therefore drier (while still plenty malty) than 002. WL002 almost always needs a good rousing after about day 4 or 5, sometimes even sooner.

    BTW in my opinion & experience the whole extended primary thing is not necessary with these yeasts (002 and 013, I'm talking about); even if 1-2-3 is outdated I think 002 is almost always fully attenuated and finished w/in 10 days at the latest, usually 7 in my experience. If I were going to dry hop (and I would in every english pale or IPA I made with this yeast) I'd probably check gravity on about day 7, would expect it to be at terminal gravity, and would accordingly rack to a clean sanitized fermenter for the dry hop, for probably another 7. Then rack to a keg and prime for carbonation (probably with a keg addition of hops), whole thing probably more describable as 1-1-2 than 1-2-3, or whatever the new thing is (4-3 I guess)
  39. Better yet, let the beer's taste say when the beer is done.

    British brewers often have a quick turn around of the real ale from brewing to serving.

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