I brewed a pale ale on 12/6 to have on tap New Years Eve. Basic recipe, 95% 2 row, 5% Crystal 60. Fermented with US-05. Centennial and Citra hops. It tasted good, no hint of diacetyl. Fast forward a month and I’m now getting definite diacetyl in the aroma and a hint in the taste. It’s possible the diacetyl was there a month ago and I didn’t notice it and only notice it now as the hop flavors have muted a bit. Assuming it wasn’t there before, thoughts on why it has reared its ugly head now?
Not really. When I have it, I notice it right away and wince immediately. You can move the keg to someplace warmer and let it sit for 3-4 days and hit the PRV on the keg a few times. Then put it back on tap and it should be okay. Funny you mention this because I had some ales recently with the same issue and my only guess is that it’s winter and these beers never warmed up towards the end of fermentation. I got diacetyl from 1056! I had to leave the kegs warm for a bit and it took care of it. Beers I’m making now (still with 1056) are placed in a warmer spot while still in the fermenter to avoid the dreaded D.
EDIT: I should mention our tastebuds are weird. I can drink a beer one day (multiple pints) and not pick up diacetyl. Then the next time I drink it I pick it up. You’re not alone.
did you dry hop?
I’ve had a couple of beers go through a diacetyl phase after I put them on tap, but then clear up on its own after a few weeks. I’ve wondered if I somehow end up rousing the yeast and kicking off a small/slow wave of fermentation that then slowly cleans itself up. But that’s just a guess. It’s still pretty mysterious to me.
If you’re referring to hop creep, it’s hard to make it happen.
My current Czech Pils has minor diacetyl and is now out of the fridge sitting in a warm spot. It never got over 57F due a cold front that cooled my garage and didn’t let it rise when I wanted it to. I kegged it during dry January so I didn’t taste it then.
I am sure it will be better in a few days.
No I didn’t dry hop. (but considering it to mask the diacetyl a bit before poker night next week). Good idea bringing the keg into the house for a few days
I had the same issue … cool here and I was using an ale yeast that has never produced diacetyl when I used it. It’s my own fault and I should have taken steps to resolve it earlier. With many lager strains, I automatically give the beer a chance to warm up when fermentation is close to done. I do it with S-04 too because it can be a diacetyl bomb. But getting diacetyl with 1056 tells me that I need to warm things up with every yeast strain I use especially in cooler weather. I suppose these 1056 beers would have turned out fine if I brewed them in July or August. The good news is that the batch(es) is not ruined … some time spent warm should take care of it.
OP - did you expose the beer to O2?
Diacetyl is formed when the precursor oxidizes. Yeast can reasorb the Diacetyl and convert it to a nonoffensive compound. Higher temperatures speed that process up.
I’ve gotten Diacetyl after bottling from a keg. No Diacetyl in the keg, O2 exposure caused it.
But if yeast cells need some amount of O2, how to determine how much O2 is enough or too much? Even the LO guys run wort into their fermenter with some amount of splashing so there is O2 in solution for the yeast.
I think Hopfenundmalz is talking about late O2 exposure, rather then pre-ferment oxygenation. I have found that, like others here, time will heal most diacetyl, if it is fermentation related/arising…but, infection by, say, pedio…that is another matter.
Okay, understood. Once my wort is in my fermenter I feel like the chance of “late-in-the-process” O2 pickup is pretty low. I purge my kegs with the CO2 from fermentation and then do a closed-loop transfer into the purged keg. What you say makes sense because he mentioned packaging from a keg … late O2 pickup.
Only O2 exposure was when transferring from fermenter to keg via gravity transfer. I purged keg with CO2 like I always do. I haven’t opened the keg again since this transfer on 12/23. Obviously my method isn’t foolproof but I’ve been using this procedure for 5+ years and have never had diacetyl show up so late in the game. I’ve had it before with a couple different lager strains early in the process, but never this late. I have the keg inside now sitting on a hot pad. Will test again in a few days.
Where are you located? Between your location and the fact that the beer was fermenting in December is possibly all you need to know … diacetyl formed and was not reduced by warming up the beer. I feel like many of my beers may have diacetyl but if the weather is warmer it’s reduced or removed before I even knew it was there. FTR, when this happened to me I left the kegs next to the furnace for 3-4 days and hit the PRV a couple times per day. Thas was enough. Good luck.
Yes, post fermentation.