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Diacetyl Issue in Keg

Hi guys,

I have been having lots of issues with daicetyl lately in lighter beers such as pales, ipas etc.
Using mostly cali ale yeast and my beers are always in primary for up to 2 weeks in a temp controlled fridge at 67.

My most recent beer that turned out great I let go for 5 days and then bumped it up to 72 slowly and let it chill there for another week and came out super clean but i don’t know if that is the fix or not.

In the beers I’m getting diacetyl i usually don’t taste it until its been in the keg a few days. I stopped racking to a secondary fermentor b/c i thought i might have been having a sanitation or oxidation issue so now i just dry hop in the keg. Because it takes longer to show up i almost think it could be pedio or a sanitation problem.

I dont purge my kegs with CO2 prior to kegging but they are usually filled with star san and i just empty it out. Could i be getting oxidation so strong that it causes diacetyl just from that? i don’t think so but i could be wrong.

I have been super crazy about sanitizing everything on the cool side but i feel like if you have a beer at 67 for 2 weeks there is no need for a diacetyl rest.

I seem to never get this off flavor when i do stouts or when i do beers that i don’t dry hop. My dry hop regiment has been soaking the hop sack in a star san solution before.

Also as a side note i don’t think i have any issues with contaminated fermentors b/c i have had good beers without diacetyl from each of my carboys.

Any thoughts on whats going on here or what I can do to resolve this issue.

Yes, it could be from oxidation. It could also be an infection.

So should i be emptying the keg of starsan and then put the lid back on and blast it with some c02 for 30 seconds and then release some pressure take the lid off and fill it with beer?

Whats a good practices?

…i personally think its a pedio infection or oxidation since the diacetyl doesn’t come through when i taste it when racking to the keg Just not sure whats causing it. If it were just straight up diacetyl id think id taste it during the transfer.

It doesn’t sound like Diacetyl. You’d taste that even before racking. Diacetyl tastes like imitation butter. Like the crap they use at movie theaters. You’ll know that taste when you taste it and you won’t ever forget it. Also diacetyl isn’t a contamination issue. It’s a yeast by-product that will usually get cleaned up by the yeast. It’s not very common in ales, but is possible. Either way, it doesn’t sound like that’s your problem.

Since you mentioned dry hopping are you sure the flavor isn’t just green beer or harsh hop flavor? Highly hopped beers especially dry hopped beers can have a harsh “green” flavor that will mellow with time.

It could be oxidation from not purging your kegs before/after filling.

I don’t think it’s an infection issue because infections take some time to grow and then impart flavor to a beer. Maybe some are quicker than others, but I doubt you’d be tasting it 2 weeks after pitching.

[quote=“cheddahbiscuits”]So should i be emptying the keg of starsan and then put the lid back on and blast it with some c02 for 30 seconds and then release some pressure take the lid off and fill it with beer?

Whats a good practices?

I purge the keg before racking buy attaching the gas to the beer out post for about 10-15 secs with the lid off to push the oxygen out. I then rack the beer in and once full, crank the gas to 30psi and push more gas in (gas in post) while securing the lid. This ensures most/all of the oxygen is out and also helps get a nice tight seal on the lid.

Sweet thanks or your help, I will purge the keg through the beer out post. It could be a green beer taste but i find it strange that one day the beer sample tasted like pure dry hop awesomeness and the next the smell is quite different. I bottled a few of these beers and maybe i can try one of those thats quite old but i think i remember the taste not going away.

I didn’t think it was diacetyll at first b.c i didn’t get slickness or a tun of butter. But when i took it to my brew club a few of the guys were convinced it was diacetyl.

Maybe I’m just being impatient or maybe it is oxidation. Thanks for the feedback…Ill keep trying to be more on point in every step. I don’t think its a sanitation issue and agree that an infection would take much longer to develop.

any additional feedback is appreciated.

Is it butterscotchy? And it’s happening a few days after you keg, but on gas? If so, check your disconnects, see if they’re dirty. Don’t shake your kegs to carbonate, make sure to purge keg after seating the lid when hooking up co2 to carbonating pressures to avoid backing up beer into your co2 lines. I had an issue for almost 2 years that was causing IPA’s to turn butterscotchy after about 5 days in the keg on gas. It was FRUSTRATING. I almost quit brewing because I couldn’t figure out where it was coming from. Check your co2 system if this is something you’re getting post fermentation. Otherwise, it may be an oxidation issue.

I think you may have hit the nail on the head…i didn’t think about this and usually don’t sanitize my c02 lines. but ill purge them after putting the lid on and then allow it to fill up again…I think this may be whats happening. I will also soak my line distributer lines and all that stuff…

Good catch on this…

Also why do you think it was only happening with IPAs and not darker beers like stouts…maybe the flavor wasn’t strong enough to come through in a darker beer?

Because the butterscotchy flavor actually goes well in an amber beer or darker beer, which I think is why I only really noticed it with my IPAs. It just ruins hop flavor and aroma, so it’s much more obvious in hoppy beers, I think.

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