Why do I have such a problem with diacetyl??

It seems like every beer I brew these days has too much diacetyl. My experience so far:

- The first time I noticed diacetyl was a Dogfish Head 90min IPA clone I brewed. This was a double IPA that I left in the secondary for 4 weeks. I believe the problem was that I only left it in the primary for 4 days because the fermentation was so rapid that it was at its target gravity by then. I regret racking it so early because I believe I didn't give the yeast long enough time to clean up. Perhaps I also overpitched?

- The next diacetyl problem I had was with an American lager. I chilled the wort to 50 before pitching, but I had made the starter at room temperature. I didn't check gravity until almost 2 weeks after I pitched and by that time I had hit my target gravity and it was too late for a diacetyl rest. The aroma of butter was overwhelming. I tried to remedy it by adding more wort (basically DME plus water) and letting it ferment again at room temperature. I did this 3 times over two weeks at 65 degrees and ended up using nearly a pound of golden light DME. It seemed to help at least a little bit although I have yet to taste the finished beer as it is still lagering.

- The next beer I made was another double IPA (Oskar Blues Gordon clone). It perhaps fermented slightly warm (got up to 74-75 when it should have never gone above 72) and I noticed a moderate amount of diacetyl after the first week in primary. I pitched a little bit of sugar and prayed that it would clean up. It is sitting in secondary now and I hope it will turn out ok.

- Finally, I made a very straightforward hefeweizen (40% pilsner, 60% wheat and wyeast 3068). I fermented it a little warmer than usual (70-72) because my last hefeweizen was fermented at 62-64 and it was rather bland. I was hoping for a more flavorful beer at a warmer temp. No, I didn't get a banana bomb but instead I got more dreaded diacetyl. I want a weihenstephaner clone and I'm always so far off (I use decoction mashes and everything!). Diacetyl again... its not so bad that the beer is undrinkable, but I wouldn't call it a great beer. Certainly it is nothing like Weihenstephaner (I wonder if they use any light crystal malts or something because it seems to have so much more substance and flavor).

So basically ever beer the past couple months except for my Belgian quads seem to end up with at least some diacetyl. The only thing I can guess is that my fermentation temperatures are slightly higher nowadays now that it isn't winter anymore. Or maybe I am just really really sensitive to diacetyl. To put things in perspective a friend had a keg of dock street pilsner recently and I felt it was completely disgustingly undrinkable because of the amount of diacetly in it. Imagine taking a bag of uncooked microwave popcorn, filling it with warm water and pouring it into a glass. Yeah, that's what it was like. At least it makes me feel better that this happens to commercial brewerys too. The question is now what can I do to avoid it?? Any suggestions?

Are you kegging or bottle conditioning?

If it's getting worse over time it could be an infection taking hold. Also, some of my lagers have reached terminal gravity, but I still did an effective diacetyl rest. The key is to be patient and let the yeast clean up before you rack.

Also, do you often pick it up in commercial beers, or just in the Dock Street beer? It sounds like you are very sensitive to it.

blizzard said:

If it's getting worse over time it could be an infection taking hold. Also, some of my lagers have reached terminal gravity, but I still did an effective diacetyl rest. The key is to be patient and let the yeast clean up before you rack.

Also, do you often pick it up in commercial beers, or just in the Dock Street beer? It sounds like you are very sensitive to it.

Click to expand...

I'm bottle conditioning, btw.

In my experience, once target gravity is reached and the primary phase of fermentation is finished, diacetyl never gets better, and in fact, usually gets worse with age. I gave my lager a 2 week diacetyl rest and the diacetyl only got better each time I added more wort and therefore got the yeast to reactivate.

I notice in commercial beers frequently but it really depends on the style. I don't often notice it in Belgian beers. I never notice it in mass produced American lagers (PBR, miller high life, etc) as they are blends on many batches and produced with consistency as a goal rather than flavor or quality. I do notice in IPAs from smaller breweries rather frequently though and lagers from microbreweries and craft beers (for example, fairly commonly although not consistently from Dogfish Head).

The reason you are having diacetyl problems is because you don't understand yeast. Some searching on this site, other sites or looking into the number of podcasts out there that focus on understanding yeast would help you a lot.

- You racked a DOUBLE IPA after four days. This is not handling yeast properly. Overpitching is doubtful.

- It isn't uncommon for a lager to have some diacetyl after two weeks. You mentioned it was too late to do a diacetyl rest because the beer had reached terminal gravity. Why? Where do you think the yeast went? After two weeks you have an UNBELIEVABLE amount of yeast left still suspended in that beer. Especially, if it was a common lager strain which tend to drop out slower than commonly used ale yeasts. The traditional diacetyl rest is NOT used to drop points of gravity. It's done to clean up diacetyl. Also, if the diacetyl seemed strong at two weeks in comparison to other similar lagers you've done in the past it's a good indication you may have under pitched. How much yeast and what was the gravity?

-Again a DOUBLE IPA and your messing with it 7 days into the ferment. The yeast needs time to do it's work. This beer might not even have been complete (unless you didn't temp. control the ferment and just let it run it's own course) and even if it was complete they hadn't given sufficient time to clean up any off flavors. Also, 74-75F is way too high and if that is room temp (not beer temp) then a beer with an OG as big as an IIPA, the beer likely hit 84-86F. Common ale yeast begin to do poorly as you pass 68F in the typical homebrew carboy.

-Hefe. What yeast did you pitch? You mention 70-72F. Was this the temperature of the room or the temperature of the fermenting beer?

gio said:

In my experience, once target gravity is reached and the primary phase of fermentation is finished, diacetyl never gets better, and in fact, usually gets worse with age. I gave my lager a 2 week diacetyl rest and the diacetyl only got better each time I added more wort and therefore got the yeast to reactivate.
.

Click to expand...

I had a summer job in the lab at a large commercial brewery and one of my jobs was to test for diacetyl (quite time consuming BTW) and i can tell you that it definitely lowers over time. With all yeast strains during fermentation off flavours, esters, diacetyl etc. are produced after all of the sugars are fermented the yeast go back a 'clean up' the beer getting rid off most of the off flavours, esters and diacetyl.

I recommend the following if you think you have high diacetyl:

1) taste your beer before racking and if you can taste diacetyl wait at least 3 more days or until you can't taste it any longer (whichever is longer)

2) control your fermentation temperatures better

I will finish with the following:

Diacetyl is produced during fermentation as a by-product of valine synthesis, when yeast produces α-acetolactate, which escapes the cell and is spontaneously decarboxylated into diacetyl. The yeast then absorbs the diacetyl, and reduces the ketone groups to form acetoin and 2,3-butanediol, relatively flavorless compounds.

How are you controlling fermentation temperature? What yeast strains are you using?
It could be an infection since its across multiple beers with different yeast strains.

My guess on the hefe is that you pitched too warm (crucial to pitch low for the weihenstephan yeast), the temp increased a lot during fermentation, and once the builk of fermentation is was cooled too quickly. Like if room temp was 65, you pitched at 70, temp rises to 75+, then goes drops down to room temp. It would be best to pitch at 60 to 65, let it rise to 67 or so, and hold it there, or even raise the temp a little bit as time goes on. That's just a guess. There is so much yeast in suspension you shouldnt have much diacetyl. This makes me think it could be caused by an infection, and not a product of fermentation.

If you are only controlling ambient temps, than the tale end of your fermentation might be too cool to clean up what was produced during the earlier stages.


On a side note for your hefeweizen, consider adding a little munich malt, or carahell - I started adding some carahell and have been very pleased with the results. Mine scored a 43 in the 1st round of NHC. Also pitch low, I pitched near 60, fermented at 65, raised it up for 68 for the very end. Lots of banana (almost too much) but very balanced.

All I read in your explanations was that you are bottling too early.

I'm also suspicious of your detection of diacetyl and whether it's not just esters you are noting.

I bottle condition as well, and have found that the beers change considerably within the first month of conditioning. I usually start drinking a batch after one week (low carb, slightly sweet, lots of esters and maybe diacetyl), but find a much better beer later on. There should be plenty of yeast in suspension to do a d-rest in the bottle, my ales condition between 70-80 deg f.

Also noticed you participated in this thread:

https://www.homebrewtalk.com/f13/preventing-diacetyl-hold-butter-please-70438/

did you try 'the test'?

"How can you tell if the diacetyl rest is complete? There's an easy “forcing” test that will only cost you a few ounces of beer. Pull a sample from your fermenter and split it into two covered containers. Refrigerate one and heat the other to 140°F for an hour, then taste them both. If they taste the same, you're ready to rack your beer out of the fermenter. If you can taste butter in the heated sample, your yeast is still at work, and you should give it another day or two. "

Morning_Dew said:

The reason you are having diacetyl problems is because you don't understand yeast. Some searching on this site, other sites or looking into the number of podcasts out there that focus on understanding yeast would help you a lot.

- You racked a DOUBLE IPA after four days. This is not handling yeast properly. Overpitching is doubtful.

Click to expand...

I've read a ton about brewing but there is a lot of misinformation out there. It is hard to know what to believe.

One rule I've read time and time again is that if you are going to rack to a secondary, do it as primary fermentation is winding down. That is, 2-6 days after pitching, or when the bubble rate has drop to 1-5 bubbles per minute. This is from "How to Brew" by John Palmer but this rule also appears several other places too both on the internet and in books. So racking to a secondary after 4 days when the target gravity has been hit and all visible fermentation has stopped (no bubbles) is not unreasonable at all.

I do not agree with this anymore and though I have no definitive proof that was the cause of my diacetyl problems, I think it is a definite possibility. There are still many people out there who follow those recommendations. Personally, I don't feel the gains of racking early outweigh the potential risks, and I nowadays I usually let my beers sit in primary for 2 weeks.

- It isn't uncommon for a lager to have some diacetyl after two weeks. You mentioned it was too late to do a diacetyl rest because the beer had reached terminal gravity. Why? Where do you think the yeast went? After two weeks you have an UNBELIEVABLE amount of yeast left still suspended in that beer. Especially, if it was a common lager strain which tend to drop out slower than commonly used ale yeasts. The traditional diacetyl rest is NOT used to drop points of gravity. It's done to clean up diacetyl. Also, if the diacetyl seemed strong at two weeks in comparison to other similar lagers you've done in the past it's a good indication you may have under pitched. How much yeast and what was the gravity?

Click to expand...

The yeast is still there but it is not longer in its active primary fermentation phase and thus is not consuming diacetyl. I gave it a good 4-5 days at 66 degrees with no measurable reduction in diacetyl. The only thing that helped reduce the diacetyl was pitching more wort and letting the yeast reactivate and begin a new fermentation cycle. I did this three times and each time the diacetly was reduced a little more.

The OG of the beer was about 1.052. I pitched a one gallon starter which was made over a period of 8 days with 3 wort additions at room temperature. That is the amount that was recommended by MrMalty.

-Again a DOUBLE IPA and your messing with it 7 days into the ferment. The yeast needs time to do it's work. This beer might not even have been complete (unless you didn't temp. control the ferment and just let it run it's own course) and even if it was complete they hadn't given sufficient time to clean up any off flavors. Also, 74-75F is way too high and if that is room temp (not beer temp) then a beer with an OG as big as an IIPA, the beer likely hit 84-86F. Common ale yeast begin to do poorly as you pass 68F in the typical homebrew carboy.

Click to expand...

That double IPA won't be racked to the secondary until 14 days anyways. It had already hit its target though and you might disagree but I've found diacetyl doesn't go away that much once primary fermentation is over.

I measure both bucket temperature (externally with a stick on thermometer) and internally with a electronic thermometer on a wire. I find that typically the internal temperature is about 2 degrees warmer if there is active fermentation going. The room temperature was nowhere near that warm and was about 64-66. The plan was to let fermentation gradually raise the temperature to 72 but my fermentation was much more active than I had expected and it had already hit 75 overnight before I had a chance to cool it down.

-Hefe. What yeast did you pitch? You mention 70-72F. Was this the temperature of the room or the temperature of the fermenting beer?

Click to expand...

Again, that was the temperature of the wort itself. I fermented my last hefe (identical recipe) at 62-64 and I was not happy with it. I was hoping I could get more banana esters with the higher temperature.

kinghellsfire_NZ said:

I had a summer job in the lab at a large commercial brewery and one of my jobs was to test for diacetyl (quite time consuming BTW) and i can tell you that it definitely lowers over time. With all yeast strains during fermentation off flavours, esters, diacetyl etc. are produced after all of the sugars are fermented the yeast go back a 'clean up' the beer getting rid off most of the off flavours, esters and diacetyl.

I recommend the following if you think you have high diacetyl:

1) taste your beer before racking and if you can taste diacetyl wait at least 3 more days or until you can't taste it any longer (whichever is longer)

Click to expand...

My first IPA (with diacetly problems) spent 4 weeks in secondary. That did nothing to clean up the diacetyl and I'm guessing that that was because there was no longer enough yeast in suspension after I racked to clean it up. The other possibility is that I overpitched and so fermentation was vigorous and too warm. Fermentation started fast and was over in 48 hours. That seems pretty quick for a 9% ABV beer.

2) control your fermentation temperatures better

Click to expand...

Oh, I try, but it is easier said than done with limited equipment. Without any kind of automatic temperature control I can have wort at 66, go to bed, and wake up 8 hours later and it's at 72! I'm getting better at predicting how fast and warm fermentation will be depending on the yeast and I've been adjusting the ambient temperature and initial pitching temperature to compensate. I have great success with my belgians, though, as those usually require adding additional heat to get them nice and warm. It's generally easier to heat than it is to chill.

I will finish with the following:

Diacetyl is produced during fermentation as a by-product of valine synthesis, when yeast produces α-acetolactate, which escapes the cell and is spontaneously decarboxylated into diacetyl. The yeast then absorbs the diacetyl, and reduces the ketone groups to form acetoin and 2,3-butanediol, relatively flavorless compounds.

Click to expand...

ReverseApacheMaster said:

All I read in your explanations was that you are bottling too early.

I'm also suspicious of your detection of diacetyl and whether it's not just esters you are noting.

Click to expand...

I don't think I've ever bottled too early. Every beer I've made has had a minimum of 3-4 weeks from pitching to bottling. The IPA I made had 5 weeks. The hefeweizen had 3 (2 in primary, 1 in secondary) but hefeweizens taste better young and you don't typically secondary them at all. The lager still hasn't been bottled and it's been 10 weeks since pitching now. The second IPA I made won't be bottled until 6 weeks (2 in primary, 4 in secondary).

It's definitely diacetyl. I make a lot of belgians tripels and quads with all sorts of strange esters from the yeast and fermenting at warm temperatures (>80 degrees) and this is an unmistakeable fake butter aroma. Some beers it is not as noticeable as others and it can be a good thing in some styles at low levels (like in the belgians), but I can usually quickly tell if it is there.

Hex said:

Also noticed you participated in this thread:

https://www.homebrewtalk.com/f13/preventing-diacetyl-hold-butter-please-70438/

did you try 'the test'?

"How can you tell if the diacetyl rest is complete? There's an easy “forcing” test that will only cost you a few ounces of beer. Pull a sample from your fermenter and split it into two covered containers. Refrigerate one and heat the other to 140°F for an hour, then taste them both. If they taste the same, you're ready to rack your beer out of the fermenter. If you can taste butter in the heated sample, your yeast is still at work, and you should give it another day or two. "

Click to expand...

I've done that test many times actually but I've learned it really isn't necessary. If there is any appreciatable amount of diacetyl in there, you can tell if the beer is even slightly warm. In other words, the diacetyl might only be slightly noticeable when the beer comes out of the fridge at 35 degrees, but as the beer warms up to 50 it slowly becomes stronger and at room temperature there is no question. Actually heating the beer makes the diacetyl unbearable if there is any diacetyl in it at all. Its a useful test if you don't know what diacetyl smells like or you aren't particularly sensitive to it but once you know what you are looking for it's not necessary.

You could have a Pediococcus infection in your brewery. Some strains of pedio create tons of diacetyl. I'd recommend replacing all of you plastic equipment.

Hex said:

I bottle condition as well, and have found that the beers change considerably within the first month of conditioning. I usually start drinking a batch after one week (low carb, slightly sweet, lots of esters and maybe diacetyl), but find a much better beer later on. There should be plenty of yeast in suspension to do a d-rest in the bottle, my ales condition between 70-80 deg f.

Click to expand...

I tried to do some research and find out whether diacetyl tends to increase or decrease and the results were very mixed. It seems the consensus is that it ultimately will increase as time goes on although it might decrease if the beer is stored at cold temperatures. I find that beers definitely taste better with age (especially belgians and stronger beers) but that diacetyl tends to gradually increase. At least my first IPA has more diacetyl in it now (2+ months after bottling) than it did right at bottling. It's possible that the yeast will slowly eat some of the diacetyl left but more of the precursors of diacetyl are converted to diacetyl as the beer ages which will result in a net gain of diacetyl in a bottled beer.

gio said:

I tried to do some research and find out whether diacetyl tends to increase or decrease and the results were very mixed. It seems the consensus is that it ultimately will increase as time goes on although it might decrease if the beer is stored at cold temperatures. I find that beers definitely taste better with age (especially belgians and stronger beers) but that diacetyl tends to gradually increase. At least my first IPA has more diacetyl in it now (2+ months after bottling) than it did right at bottling. It's possible that the yeast will slowly eat some of the diacetyl left but more of the precursors of diacetyl are converted to diacetyl as the beer ages which will result in a net gain of diacetyl in a bottled beer.

Click to expand...

Perhaps other flavors fade, especially in an IPA, causing the diacytel to be more prevelant, and now youre also looking for that flavor because you know its there.

I think the advice on here would be to get a fermentation frig and temp controller and, at least until your problems are solved, consider ditching secondaries (which it sounds like you may have already done).

gio said:

The yeast is still there but it is not longer in its active primary fermentation phase and thus is not consuming diacetyl. I gave it a good 4-5 days at 66 degrees with no measurable reduction in diacetyl. The only thing that helped reduce the diacetyl was pitching more wort and letting the yeast reactivate and begin a new fermentation cycle. I did this three times and each time the diacetly was reduced a little more..

Click to expand...

As I said earlier, diacetyl is not consumed during its active primary fermentation. The vast majority is consumed once visual fermentation has stopped. Another poster replied with this same fact yet you repeated your belief once again?

gio said:

. . . and you might disagree but I've found diacetyl doesn't go away that much once primary fermentation is over.

Click to expand...

I do disagree. Another poster indicated that he/she did lab work on completed beer and it indeed showed that diacetyl was reduced after visual fermentation had completed. This fact is nothing new and is supported in several texts (Fixx, etc) with supporting research data. It's relatively well known and why I stated it without supporting evidence.

Both of the statements I quoted above again are clear indications that you need to gain a better understanding of how yeast behaves.

gio said:

I find that typically the internal temperature is about 2 degrees warmer if there is active fermentation going. The room temperature was nowhere near that warm and was about 64-66. The plan was to let fermentation gradually raise the temperature to 72 but my fermentation was much more active than I had expected and it had already hit 75 overnight before I had a chance to cool it down..

Click to expand...

You need to reread what you just wrote. No, the temperature of the fermenting beer is NOT typically 2 degrees warmer than ambient as you say in the first sentence. You even prove that it is not in your own words two sentences later.

If the temperature of the fermenting beer only rides 2 degrees higher than ambient, how did you ever expect it to get to 72F when you said the ambient was 64-66? And then you say you found it at 75F after overnight (9-11 degrees over ambient. What happened to your 2 degrees higher?). Just as I said, fermenting beer will easily ride 6-12 degrees over ambient for a typical starting OG (1.048 - 1.058) depending on other factors; i.e. yeast strain, amount of yeast pitched, etc.

I had an ale with an O.G. of 1.092 sitting in my fermentation chamber in an air conditioned basement (68F ambient) and I left for a road trip. Four days later I returned to find that I had never plugged in my PID temp controller. The beer temperature was 89F (21 degrees over ambient) and the activity was just slightly past the peak.

I now believe you are mistaking off flavors from fermenting too hot (or even typical young fermentation flavors) for diacetyl.

Finally, you came seeking advice as to why you were tasting diacetyl in all your recent beers. You got a general concensus:

1. May not be even tasting diacetyl
2. Not controlling fermentation temperature (at all)
3. Moving / judging your beer to quickly.

Yet you seem to disagree with everyone.

Good luck and I hope you find a solution.

I nice starting point is the following article by George Fix. If you only read one section, please read the section titled "The Effect of Yeast".

http://www.brewingtechniques.com/library/backissues/issue1.2/fix.html

First 2......... Your assumptions are wrong. You can't go by a pitching date of 2 to 6 days or by bubbling of 1 to 2 seconds. You need to know the starting og then the f/g and plan the rest in between. Don't you love it ! More math and more watching temp and controls.

I have tested in a lab the mg/L of diacetyl in a wide variety of beers and I can tell you that MOST people won't notice anything under 0.2mg/L which is the level of most beers that i tested after 8-10 days in the primary. However some that had a too vigorous/warm fermentation have level up to 0.6mg/L at 10 days however this dropped very quickly and by 14 days was normally around 0.2mg/L.

I believe it is an indicator of how diacetyl is cleaned up in that we didn't even start testing until 140 hours after pitching and that there was VERY minimal drop in diacetyl once the beer was transferred into a secondary (<0.02mg/L).

Moral of my story is that I never transfer into a secondary/bottle until 10-14 days AND after a taste test.

P.s the stronger the flavour of the beer the more diacetyl it can hide.
P.P.s Lager yeast seem to be more efficient at cleaning up diacetyl.

gio said:

I've read a ton about brewing but there is a lot of misinformation out there. It is hard to know what to believe.

One rule I've read time and time again is that if you are going to rack to a secondary, do it as primary fermentation is winding down. That is, 2-6 days after pitching, or when the bubble rate has drop to 1-5 bubbles per minute. This is from "How to Brew" by John Palmer but this rule also appears several other places too both on the internet and in books. So racking to a secondary after 4 days when the target gravity has been hit and all visible fermentation has stopped (no bubbles) is not unreasonable at all.

Click to expand...

John Palmer has repented for his sin of suggesting that racking after 1 week is desirable, but the damage has been done. That piece of terrible advice is still repeated in many pieces of literature and by pretty much all kit instructions. Just do what the majority of us do here: don't secondary (except for very exceptional circumstances like long-term aging or using fruit). The yeast can make foul tasting compounds when it ferments, but it will clean it up if you let it. If you remove 99% of the yeast before these compounds are gone, it will take a while before the beer is drinkable.

Here is Palmer begging forgiveness for his terrible advice:

https://www.homebrewtalk.com/f163/secondary-not-john-palmer-jamil-zainasheff-weigh-176837/

None shall come from me.

Morning_Dew said:

As I said earlier, diacetyl is not consumed during its active primary fermentation. The vast majority is consumed once visual fermentation has stopped. Another poster replied with this same fact yet you repeated your belief once again?

Click to expand...

My understanding has been that diacetyl is typically produced by yeast at the beginning of fermentation and reduced by the yeast towards the end of fermentation. I've read that it is possible to miss your opportunity for diacetyl rest if fermentation is too far along (from Palmer and others). The question is when is too late. Palmer implies that if you have hit your target gravity it is too late. He may be wrong. Others say to do it when you are 2/3s through your primary fermentation (as indicated by measuring your gravity) (see http://www.brewingtechniques.com/library/backissues/issue2.1/miller.html). I assume they are talking about "Narziss fermentation" as described in the article you linked in your post. So my question is whether I missed my chance for a diacetyl rest? If not, why did my lager end up with so much diacetyl (it was fermented at 50 btw).

I do disagree. Another poster indicated that he/she did lab work on completed beer and it indeed showed that diacetyl was reduced after visual fermentation had completed. This fact is nothing new and is supported in several texts (Fixx, etc) with supporting research data. It's relatively well known and why I stated it without supporting evidence.

Both of the statements I quoted above again are clear indications that you need to gain a better understanding of how yeast behaves.


You need to reread what you just wrote. No, the temperature of the fermenting beer is NOT typically 2 degrees warmer than ambient as you say in the first sentence. You even prove that it is not in your own words two sentences later.

If the temperature of the fermenting beer only rides 2 degrees higher than ambient, how did you ever expect it to get to 72F when you said the ambient was 64-66? And then you say you found it at 75F after overnight (9-11 degrees over ambient. What happened to your 2 degrees higher?). Just as I said, fermenting beer will easily ride 6-12 degrees over ambient for a typical starting OG (1.048 - 1.058) depending on other factors; i.e. yeast strain, amount of yeast pitched, etc.

Click to expand...

I think you misunderstood me. I was comparing the temperature on the outside surface of the fermenting bucket (as measured with a stick on thermometer) with the internal temperature of the wort as measured with a digital thermometer on a wire. The internal temp is 2 degrees higher than the outside of the bucket. I only mentioned that to show how I have been able to get the temperature of the fermenting wort even when there is no digital thermometer (which are extremely prone to failure). The ambient temperature is far lower than either of those temperatures.

I had an ale with an O.G. of 1.092 sitting in my fermentation chamber in an air conditioned basement (68F ambient) and I left for a road trip. Four days later I returned to find that I had never plugged in my PID temp controller. The beer temperature was 89F (21 degrees over ambient) and the activity was just slightly past the peak.

I now believe you are mistaking off flavors from fermenting too hot (or even typical young fermentation flavors) for diacetyl.

Finally, you came seeking advice as to why you were tasting diacetyl in all your recent beers. You got a general concensus:

1. May not be even tasting diacetyl
2. Not controlling fermentation temperature (at all)
3. Moving / judging your beer to quickly.

Yet you seem to disagree with everyone.

Click to expand...

1. It's definitely diacetyl. I've even taken the beer to my local homebrew store for them to taste and they agree.
2. The first IPA had no temperature issues. The hefeweizen never went above 72 which is within the range of the yeast. The second IPA got to 75 which is why I believe it's possible it was due to high temperatures. The lager fermented at 50 degrees and never varied more than a degree up or down from that. So for all the beers with diacetyl problems, only one I suspect could be due to high temperatures which I'm reluctant to think that is the cause.
3. Its my understanding that diacetyl is not going to get better when lagering which is why I let my lager rest at room temperature until I could get the diacetyl down to a reasonable level. As for the IPA I'm making now, it still might turn ok, we'll see in a few weeks. I will have to rack it to a secondary tomorrow to get it off the dry hops so I will test it then. The other beers are long done and are not going to get any better.

Good luck and I hope you find a solution.

I nice starting point is the following article by George Fix. If you only read one section, please read the section titled "The Effect of Yeast".

http://www.brewingtechniques.com/library/backissues/issue1.2/fix.html

Click to expand...

Thank you for the link, very informative.

RIT_Warrior said:

John Palmer has repented for his sin of suggesting that racking after 1 week is desirable, but the damage has been done. That piece of terrible advice is still repeated in many pieces of literature and by pretty much all kit instructions. Just do what the majority of us do here: don't secondary (except for very exceptional circumstances like long-term aging or using fruit). The yeast can make foul tasting compounds when it ferments, but it will clean it up if you let it. If you remove 99% of the yeast before these compounds are gone, it will take a while before the beer is drinkable.

Here is Palmer begging forgiveness for his terrible advice:

https://www.homebrewtalk.com/f163/secondary-not-john-palmer-jamil-zainasheff-weigh-176837/

None shall come from me.

Click to expand...

Yeah, I know how he repented for his sin of recommending a secondary. I still usually have a reason for using a secondary though because 90% of my beers fall in one of these categories:
- I add fruit
- I dry hop in the primary and need to get the beer off the hops to age it in the secondary
- It's a strong belgian that I plan on cold conditioning for an extended period of time (6-8 weeks or more). This is 50% of my beers.

I don't see anything wrong about a secondary other than the potential risk of infection if you have given your beer plenty of time in the primary (I now give at least 2 weeks). There is also the practical concern that I have a lot of 5 gallon glass carboys and fewer large buckets available at any given time.

kinghellsfire_NZ said:

I have tested in a lab the mg/L of diacetyl in a wide variety of beers and I can tell you that MOST people won't notice anything under 0.2mg/L which is the level of most beers that i tested after 8-10 days in the primary. However some that had a too vigorous/warm fermentation have level up to 0.6mg/L at 10 days however this dropped very quickly and by 14 days was normally around 0.2mg/L.

I believe it is an indicator of how diacetyl is cleaned up in that we didn't even start testing until 140 hours after pitching and that there was VERY minimal drop in diacetyl once the beer was transferred into a secondary (<0.02mg/L).

Moral of my story is that I never transfer into a secondary/bottle until 10-14 days AND after a taste test.

P.s the stronger the flavour of the beer the more diacetyl it can hide.
P.P.s Lager yeast seem to be more efficient at cleaning up diacetyl.

Click to expand...

Thanks, this is very informative and seems to be in line with my experience so far. It explains why my first IPA had diacetyl (racked too early) and why my second IPA had some (fermented too warm and tasted too early before the yeast was finished cleaning up). The second IPA will be 3 weeks old tomorrow and so I will taste it for diacetyl again.

windbreaker123 said:

First 2......... Your assumptions are wrong. You can't go by a pitching date of 2 to 6 days or by bubbling of 1 to 2 seconds. You need to know the starting og then the f/g and plan the rest in between. Don't you love it ! More math and more watching temp and controls.

Click to expand...

I always check the gravity. The 2-6 days and bubbling thing I quoted from Palmer. It is useful to watch that to know when you should be checking your gravity though.

Morning_Dew said:

As I said earlier, diacetyl is not consumed during its active primary fermentation. The vast majority is consumed once visual fermentation has stopped. Another poster replied with this same fact yet you repeated your belief once again?

I do disagree. Another poster indicated that he/she did lab work on completed beer and it indeed showed that diacetyl was reduced after visual fermentation had completed. This fact is nothing new and is supported in several texts (Fixx, etc) with supporting research data. It's relatively well known and why I stated it without supporting evidence.

Both of the statements I quoted above again are clear indications that you need to gain a better understanding of how yeast behaves.

You need to reread what you just wrote. No, the temperature of the fermenting beer is NOT typically 2 degrees warmer than ambient as you say in the first sentence. You even prove that it is not in your own words two sentences later.

If the temperature of the fermenting beer only rides 2 degrees higher than ambient, how did you ever expect it to get to 72F when you said the ambient was 64-66? And then you say you found it at 75F after overnight (9-11 degrees over ambient. What happened to your 2 degrees higher?). Just as I said, fermenting beer will easily ride 6-12 degrees over ambient for a typical starting OG (1.048 - 1.058) depending on other factors; i.e. yeast strain, amount of yeast pitched, etc.

I had an ale with an O.G. of 1.092 sitting in my fermentation chamber in an air conditioned basement (68F ambient) and I left for a road trip. Four days later I returned to find that I had never plugged in my PID temp controller. The beer temperature was 89F (21 degrees over ambient) and the activity was just slightly past the peak.

I now believe you are mistaking off flavors from fermenting too hot (or even typical young fermentation flavors) for diacetyl.

Finally, you came seeking advice as to why you were tasting diacetyl in all your recent beers. You got a general concensus:

1. May not be even tasting diacetyl
2. Not controlling fermentation temperature (at all)
3. Moving / judging your beer to quickly.

Yet you seem to disagree with everyone.

Good luck and I hope you find a solution.

I nice starting point is the following article by George Fix. If you only read one section, please read the section titled "The Effect of Yeast".

http://www.brewingtechniques.com/library/backissues/issue1.2/fix.html

Click to expand...

Awfully opinionated, when it could very well be an infection too. A hefe with diacetyl? People rack those in a week. I dont think its the yeast, too frequent with different strains. Either detecting thr wrong flavor, super sensitive or infection, imo.

The hefe does seem odd. Those yeast are powdery and good diacetyl reducers.

I wouldn't rule out infection.

I do think the OP is correctly diagnosing diacetyl as he quickly and correctly named a craft brewer (DFH) whose beers frequently have fairly high levels of diacetyl.

People get all excited about early racking, but then every commercial beer has the yeast cone dumped well under a week after pitching and those beers are generally pretty clean. Long primaries may fix some problems but eventually you want to think about avoiding the problems in the first place if you want to improve.

gio said:

Yeah, I know how he repented for his sin of recommending a secondary. I still usually have a reason for using a secondary though because 90% of my beers fall in one of these categories:
- I add fruit
- I dry hop in the primary and need to get the beer off the hops to age it in the secondary
- It's a strong belgian that I plan on cold conditioning for an extended period of time (6-8 weeks or more). This is 50% of my beers.

I don't see anything wrong about a secondary other than the potential risk of infection if you have given your beer plenty of time in the primary (I now give at least 2 weeks). There is also the practical concern that I have a lot of 5 gallon glass carboys and fewer large buckets available at any given time.

Click to expand...

Just my $0.02:

1. I have done one fruit beer - not much of a fruit really - a habanero beer. But I added the peppers right to the primary after I had a stable gravity.

2. I dry hop on occasion. When I do, I confirm stable gravity and then dry hop in the primary.

I'm not saying this is absolutely the way to go. But I am saying that I don't have infections yet (knock on wood) and I do not rack to secondary for 2 of your 3 reasons for racking. And as for the 3rd, I will say I'm doing a lager on Monday and after my diacetyl rest, it's staying in the primary bucket for lagering.