Help, I think I've got 9 gallons of diacetyl IPA..

[brobeman]

I'm pretty new to brewing but have been all grain for the last 3 months or so. I brewed an extract Pliny the Elder kit from Austin HB early on that started out great, but ended up with a taste that I couldn't stand. Not sure how to describe it, other than it's kind of a toasted caramel flavor that to me is pretty cloying. I know diacetyl is supposed to taste like butterscotch or margarine, and although that's not exactly what I'm getting, I'm afraid that's what I've got.

Having choked the Pliny keg down I'm now on to a 5 gal Corny of a Zombie Dust clone and another of Firestone Walker's Union Jack (Can You Brew It). I hit my numbers in both cases and ran primary fermentation in both cases somewhere in the high 60s (probably around 65, but as low as 60/61). Primary fermentation ran on the ZombieDust about 23 days, and for the UJ 15 days. I don't recall raising the temp, but I may have pulled them both upstairs for a few days where they would have seen temps in the low 70's.

In both cases I cold crashed in my kegerator for 24 hours at 37 before racking to secondary. Both beers saw 10-14 days of dry hopping at 54F, another 24 hour cold crash at 37F before racking to keg.

The ZD has been carb'ing up for the last week and half and the Union Jack for a little less than a week.

I'm afraid if got a diacetyl issue from fermenting too cold. Both beers used Wyeast 1968 which I built up using a 1300ml starter with 1 cup of DME for ~18-24 hours (no stir plate) before cooling and decanting.

The off taste appears to be getting worse as the kegs carb up. Am I screwed, or is there some means of saving them? Is 1968 susceptible to Diacetyl at these fermentation temps?

Both beers have a great hop aroma and are the clearest I've made to date. I just can't stand the damn taste I'm getting on the mid palate.

Sorry for rambling. Any guidance would be greatly appreciated.

Regards,
Brobeman

 

[Devils_Chariot]

Does it smell like popcorn butter? If so its diacetyl. The best way to get rid of it is to let the beer sit on the yeast longer and ramp the temp up to 70-72 f. If its hard to smell in cold beer put a little beer in a glass and cover with plastic wrap. Nuke it in the microwave for 15 seconds. When its warm the diacetyl butter smell will jump out at you. If it still smells like caramel it might be oxidation.

 

[bobbrews]

Usually diacetyl would be apparent from fermenting with 1968 too warm, not too cold. I also don't think that's the yeast of choice for Union Jack or Zombie Dust.

 

[TwoDrunkenDogs]

As far as I know, the two main ways to get Diacetyl is if your wort cooled too slowly, say overnight, and the other way is if the beer was racked into secondary carboy too soon which means the yeast did not have enough time to absorb the Diacetyl. It looks as though you allowed enough time in the primary. But I'm just wondering, if you have three batches that have all come out with off flavors maybe you just need to do a huge clean/sanitize of all your equipment.

 

[Cape Brewing]

As far as I know, the two main ways to get Diacetyl is if your wort cooled too slowly, say overnight, and the other way is if the beer was racked into secondary carboy too soon which means the yeast did not have enough time to absorb the Diacetyl. It looks as though you allowed enough time in the primary. But I'm just wondering, if you have three batches that have all come out with off flavors maybe you just need to do a huge clean/sanitize of all your equipment.

That's not accurate...

diacetyl is a natural compound that is given off by every yeast in at least some quantity during the fermentation process and doesn't have anything to do with cooling or racking.

When you primary ferment, the yeast will automatically produce some levels of diacetyl (some yeasts toss off much more than others), once fermentation is complete and the yeast has consumed all of the sugars they are going to consume, they'll go back and start "eating" the diacetyl.

One common practice with yeasts that toss off a lot of diacetyl is to do a "diacetyl rest"... which is nothing more than taking the beer (regardless if it is in primary or secondary) and warming it up a bit so the yeast get a little extra active and finish the job quicker.

Typically diacetyl is caused from fermenting at the low end of the yeasts range and NOT then bringing it up to a warmer temp so they can get active and clean out the diacetyl.

An example would be fermenting with US-05 at something like 60 degrees... and then just going straight into bottling/kegging. Like I was saying, once primary fermentation is done, bring that beer up to 67ish for a day or so and the yeast will kick-start and eat up any remaining diacetyl and the problem is solved.

All of that said... if you simply ferment for a long enough time at a temp in the middle or towards the top of the yeast's range, the yeast will typically do all of this clean up work on their own.

 

[brobeman]

I hadn't considered oxidization, but maybe that's it. I've got a bottle that I'm going to run by the Northern Brewer this afternoon for some expert opinion. Other than whirlpooling my wort over my immersion chiller during cooling I don't touch my hot wort. I keg, and always bleed off a few times upon initial pressurization, so I don't know where that would come from. My equipment is all new (sans re-conditioned Corny kegs) and I'm a stickler for sanitation, so I don't know how there could be any infection. The keg lines on both of these kegs have never pushed any other beer.

Puzzled, but I still suspect that maybe I cold crashed too soon and ended up with a little diacetyl. If I pull the kegs out of my kegerator and put them at say 72-73F for a few days, will it make a difference?

Thanks for the replies.

Regards,
Brobeman

 

[Cape Brewing]

It might... depends on how much yeast is still in suspension. If the beer was crystal clear when you kegged it off the yeast cake, there might not be enough yeasties there to do the job. If it is truly a diacetyl problem it is at least worth a shot. It ain't going away any other way.

 

[TwoDrunkenDogs]

Question though, can Diacetyl only happen in lagers?

 

[BoogieBrandBooze]

it's kind of a toasted caramel flavor that to me is pretty cloying.

Maybe what you're tasting can be described more like a toffee flavor? I've heard this can often be confused for the buttery flavor of diacetyl. What was your boil like? It's possible you may have carmelized the wort a bit.

Just a thought...

 

[brobeman]

Question though, can Diacetyl only happen in lagers?

From what I understand, no. It does come from colder fermentation temps where the yeast are not vigorous enough to clean it up. With the colder fermentation temps required for lager yeasts it is necessary to warm them up a few days before racking.

 

[TyTanium]

Question though, can Diacetyl only happen in lagers?

No, it's usually just more noticeable with the crisp, clean flavors. Ales hide it better, usually.

OP - the warming thing may work, but IME only if the yeast are still active. You could pitch a quart or two of actively fermenting yeast and that'll clear it right up. Similar gravity & IBU to your beer, same yeast, pitch at high krausen. (DON'T stirplate...not trying to grow yeast, just get them active)

The other thing about diacetyl is the mouthfeel - oily slick, kind of coats your mouth, gross feeling...have any of that?

 

[TwoDrunkenDogs]

My brewing society has been talking about Diacetyl for some time now. This is what we have posted that is straight out of "How To Brew"

Diacetyl is not actually produced by the yeast. The vicinal diketones diacetyl and pentanedione are created chemically by oxidative decarboxylation, (i.e., removal of hydrogen and carbon dioxide) of the acetohydroxy acids. Warm temperatures and the presence of oxygen promote this reaction. The ability of the yeast to remove diacetyl is about ten times the creation rate, but as the wort temperature finally gets to the primary fermenatation temperature, the yeast activity decreases, and they biochemically reduce it more slowly. The result is a buttery/butterscotch flavor in the lager, which is considered an off-flavor. Some amount of diacetyl is considered good in other styles such as dark ales and stouts but is considered a flaw in most lager styles. To remove any diacetyl that may be present after primary fermentation, a diacetyl rest may be used. This rest at the end of primary fermentation consists of raising the temperature of the beer to 55 to 60 degrees F (13 to 16 degrees C) for 24 to 48 hours before cooling it down for the lagering period. This makes the yeast more active and allows them to eat up the diacetyl before downshifting into lagering mode. Be careful to minimize oxygen contact during racking, because this will generate still more diacetyl. Some yeast strains produce less diacetyl than others; a diacetyl rest is needed only if the pitching or fermenatation consitions warrant it.

It supports what Cape Brewing was saying.

 

[tre9er]

As of 4 brews ago I always raise the beer up (by removing it from temp control environment) to room temp, ~68*, after active fermentation has ceased...usually 5 days or so (Gravity reading will tell you). I let them rest there for nearly another week, but 48 hours is widely considered plenty of time. I brew all ales thus-far.

 

[cperry7467]

I brewed a Blonde Ale a few months back and had a really strong butter flavor after I kegged it. I waited a few more weeks with the keg in the fridge and tried it again and it was about the same. I set it back at room temp and waited a couple weeks and the taste got worse. I ended up making a new small yeast starter and put it in the keg to see if the active yeast would clean up the diacetyl. I set the keg on it's side and would rotate it every few days and just let it sit for 3 weeks or so at room temp and the flavor finally went away. Not sure if it was just letting it sit longer or if the new yeast helped cleaned it up but either way it did get fixed and turned out to be a good beer.

 

[cperry7467]

Another thing worth mentioning though... I didn't know what the off flavor was when I first tasted it. I had my wife try it and she said "It kind of tastes like popcorn" and then it hit me like a ton of bricks that the flavor was butter and there was no mistaking it. So if you're not sure it's a butter flavor, you might want to consider other possibilities. There was no doubt in my mind the off flavor was butter.

 

[fpweeks]

Diacetyl is not actually produced by the yeast.

Some yeast strains produce less diacetyl than others;

Not trying to be a jerk here.....but isnt this a contradiction?

 

[NordeastBrewer77]

It sounds like it could be a caramelized extract thing to me. Like the LME was boiled too long. I've had that happen and it tastes like burnt caramel. 1968 will kick diacetyl, but at warmer temps. Ferment cool with it and it's an amazing yeast, no to very very low diacetyl.

 

[brobeman]

The brew was all grain and I had what I would call a medium boil. I just stopped by Northern Brewer and the opinion on the Zombie Dust was that it's actually a good clone. They too noticed the weird sweetness on the mid-plate, but nobody thought it was diacetyl. The only suggestion offered was that it could have something to do with the hop schedule and suggested making sure there was a mid-boil addition. Not sure about that, but I'm going to take a look.

Just in case I'm going to pull both kegs out of the kegerator and will let them sit at 73 over the weekend. Can't hurt. Thanks again for all the guidance. This is a great community.

Regards,
Brobeman

 

[brobeman]

No, it's usually just more noticeable with the crisp, clean flavors. Ales hide it better, usually.

OP - the warming thing may work, but IME only if the yeast are still active. You could pitch a quart or two of actively fermenting yeast and that'll clear it right up. Similar gravity & IBU to your beer, same yeast, pitch at high krausen. (DON'T stirplate...not trying to grow yeast, just get them active)

The other thing about diacetyl is the mouthfeel - oily slick, kind of coats your mouth, gross feeling...have any of that?

No slick mouthfeel that I've noticed, but I've never had something I know to be Diacetyl so have no clear point of reference. If warming over the weekend doesn't work I'm going to split a pack of 1967 and brew a small batch with similar gravity to mix and pitch into the kegs.

 

[tre9er]

The brew was all grain and I had what I would call a medium boil. I just stopped by Northern Brewer and the opinion on the Zombie Dust was that it's actually a good clone. They too noticed the weird sweetness on the mid-plate, but nobody thought it was diacetyl. The only suggestion offered was that it could have something to do with the hop schedule and suggested making sure there was a mid-boil addition. Not sure about that, but I'm going to take a look.

Just in case I'm going to pull both kegs out of the kegerator and will let them sit at 73 over the weekend. Can't hurt. Thanks again for all the guidance. This is a great community.

Regards,
Brobeman

I'd let them sit longer than just the weekend. Heck, if you have any yeast lying around it might make sense to pitch a tad bit in both kegs and let them sit for a week at room temp.

 

[daksin]

If you look it up, 1968 is actually pretty well known for making diacetyl when it's stressed (hot, cold, low O2, or high alcohol). You really need to use excellent aeration (pure O2 will work best) and ferment warm-ish with it, generally treat it nice, don't let the temp swing around. I made some serious butter-bomb ESB with it, and had to krausen it in the keg to get rid of the flavor. To do that, ferment a batch of beer with S-04 (my preference) and take a quart or two of that beer at high krausen and add it to your buttery beers at room temp. Once they're done working on the sugar in the beer you transferred over, they'll set about cleaning up your IPA. This has worked great for me in the past.

 

[brobeman]

If you look it up, 1968 is actually pretty well known for making diacetyl when it's stressed (hot, cold, low O2, or high alcohol). You really need to use excellent aeration (pure O2 will work best) and ferment warm-ish with it, generally treat it nice, don't let the temp swing around. I made some serious butter-bomb ESB with it, and had to krausen it in the keg to get rid of the flavor. To do that, ferment a batch of beer with S-04 (my preference) and take a quart or two of that beer at high krausen and add it to your buttery beers at room temp. Once they're done working on the sugar in the beer you transferred over, they'll set about cleaning up your IPA. This has worked great for me in the past.

Thanks, I'll go that route. It's actually more like 7 gallons now though. My friends didn't seem to mind the Zombie Dust all that much last night.