Diacetyl Taste

[losp]

Hi guys,
i have a slightly unpleasant aftertaste (a little butterscotch-like i guess...) which i dont think was very present during fermentation. is it possible that this taste can be come present during carbing?
cheers.

 

[DUANNE]

hey losp i have had this happen a few times.the beer comes out of the fermenter clean and in the bottle picks up diacetyl. all the ones i had do this i just left a bit longer and they eventually clean themselves up. i dont know if this would work if the diactyl was present before bottling though cause the yeast can only take up so much.

 

[dr K]

Probably not unless your beer is infected then probably so.
Diacetyl is produced in every ferment, you takes steps at the end to reduce it.
If you fermented low (say a lager) you increase the temp for a DA rest, if your ferment went high temp you drop it 18 +- for a day so..show clear it.
Bacterial infections also lead to diacetyl, but also a tart to sour taste depending on how advanced it is.

K

 

[Bribie G]

I've had a few diacetyl brews and generally only notice it in the bottle. Personally I like it in a UK bitter, especially the darker ones, and deliberately 'push' it with yeasts such as 1768. To avoid it, give the beer a good rest for two or three days at a slightly higher temp (e.g. low 20s)

When I first got it, I took a bottle along to BABBs for some advice. When I opened a bottle, Troydo who was sitting at the next table sung out "who opened the diacatyl brew?" then later in the evening a guy came up and said "have you got any more of that butterscotch beer, I really like it" :icon_cheers:

A touch of diacetyl is common in UK bitters and part of the style

 

[losp]

Its a lager, cold conditioned for a month. Didnt do a diacetyl rest.

 

[Thirsty Boy]

it probably was present before bottling.. but its a bit of a skill to translate the taste of uncarbed fermenter samples into the final product. Let is sit in its bottles for a while, that might help... and learning that your fermenter sample has diacetyl that needs to be dealt with is unfortuantely just a matter of practise.

Could be a mild infection - with pedio for instance you might well notice diacetyl well before any sourness.. the sourness may never develop if its a really low level infection.

TB

 

[losp]

Thanks for your help guys. It is really appreciated! I am a little confused now! do i drink more of it or less!?
I am definitely going to put a diacetyl rest in my process out of good practice. Cheers

 

[dr K]

TB is correct, on both counts, though he treads into territory I dare not (suggesting that an infected beer might just be infected and not gas spewing shat smelling sour old vinegar, many an infected beer is pronounced clean).
You can do a litlle trick called DA gonogo, take two samples of of your freshly fermented wort, smell the first,if it is clearly DA then do a DA rest, if you cannot pick DA (you may not, there has to be a lot for me and others to pick it) then take sample two and heat it to about 40C, if you still cannot smell it, its clear..go go, if you can its no go, back to the rest.
DA in lager = naaah
DA in ale (esp lighter styles) no worries, at a low level.

K

 

[RdeVjun]

I remember asking about diacetyl being processed post- bottling a while back, can't find the thread, it wasn't one of mine. IIRC, responses weren't unanimous though, some said yes so I left a few bottles on top of the hot water system and they got to high- 20s. Did the diacetyl go away? I honestly can't recall what the results were, I think spousie may have nabbed some of them before I got a chance!!! Thankfully the crazy Geordie doesn't do that any more...

These days I often do a room temp rest for a day before bottling, seems to take care of it, but I'm like BribieG and don't mind a bit in my mainly English styles anyway so I am not bothered by my own laziness if I skip the rest.

Agree with Thirsty too, some quite profound changes take place from the fermenter to bottled/ kegged finished product, I wouldn't be surprised if any diacetyl then present was masked.

 

[bigfridge]

I remember asking about diacetyl being processed post- bottling a while back, can't find the thread, it wasn't one of mine. IIRC, responses weren't unanimous though, some said yes so I left a few bottles on top of the hot water system and they got to high- 20s. Did the diacetyl go away? I honestly can't recall what the results were, I think spousie may have nabbed some of them before I got a chance!!! Thankfully the crazy Geordie doesn't do that any more...

These days I often do a room temp rest for a day before bottling, seems to take care of it, but I'm like BribieG and don't mind a bit in my mainly English styles anyway so I am not bothered by my own laziness if I skip the rest.

Agree with Thirsty too, some quite profound changes take place from the fermenter to bottled/ kegged finished product, I wouldn't be surprised if any diacetyl then present was masked.

Diacetyl doesn't go away - it is either re-absorbed by active yeast or continues to convert into more rancid and objectional products.

Yeast actually don't produce Diacetyl, they produce pre-cursor products that are converted into diacetyl when exposed to oxygen. This is why it shows up after bottling.

If it is in your bottles and the yeast is sleeping on the bottom of the bottle then there won't be much change.

HTH,
David