# diacetyl?



## fletcher (24/10/14)

i've made a very light summery beer and two days ago, it was tasting amazing. no off flavours and super clean. literally within 2 days it's taken a detour and i feel as though there is an ever so slight hint of butter.

how quickly does diacetyl kick in if it's the culprit?

the recipe was:

20L
4.15kg joe white vienna
90gm joe white cara-malt
45gm hallertau mittelfrueh (pellets, 3 aa%, 60 mins)
20gm hallertau mittelfrueh (pellets, 3 aa%, 5 mins)
11.5gm DCL yeast US-05 - american ale
1 tablet whirlfloc
0.5 tsp yeast nutrient

at 18 ibu.

i wonder if the IBU is too low for the small amount of caramalt sweetness? or if it's the onset of something like diacetyl? i didn't d-rest it, as i've not often needed to with other ales but i've often had at least 25-40 ibu as well which may have masked it. it's been in the keg about a month now at 3C and been tasting really nice for close to 2 weeks until now.


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## verysupple (24/10/14)

Hmmm, it's strange that it's only coming on after a month in the package. If it was diacetyl created by the yeast then it would have been more obvious earlier as the yeast would have been slowly metabolising it the whole time - more time = less diacetyl.

Another option is an infection of one of the types of bacteria that creates diacetyl. 

A third option is that it's not diacetyl.

If you're confident of your sanitation I'd be thinking the third option.


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## Online Brewing Supplies (24/10/14)

Take a sample cover the top and leave it out overnight and have a good snip when its warmed up next day, should confirm or put your mind at rest.
Nev


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## fletcher (24/10/14)

verysupple said:


> Hmmm, it's strange that it's only coming on after a month in the package. If it was diacetyl created by the yeast then it would have been more obvious earlier as the yeast would have been slowly metabolising it the whole time - more time = less diacetyl.
> 
> Another option is an infection of one of the types of bacteria that creates diacetyl.
> 
> ...


super confident of my sanitation. i'm always my worst critic when it comes to my own beers and i scrutinise them. perhaps you're right, it's just some sort of flavour that isn't unpleasant but i just can't explain it any other way


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## indica86 (24/10/14)

Mmmm butter beer.


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## verysupple (24/10/14)

Online Brewing Supplies said:


> Take a sample cover the top and leave it out overnight and have a good snip when its warmed up next day, should confirm or put your mind at rest.
> Nev


Good idea. Diacetyl will become more obvious at warmer temps. Nev's suggestion is pretty much a daicetyl force test and you should be able to tell pretty easily.


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## fletcher (24/10/14)

i'm new to kegging too, and it could also possibly be the beer that has been sitting in the line or my line just not being clean if it's had stale beer sitting in it after a while? inside the font? as in, i've poured a beer, tried it, poured another one and then left it for 2 days, then poured this one today. could the beer that's in the line somehow 'stick' to the line or somehow taint the beer coming through it from the keg?

have just read a BYO article that talked about diacetyl flavours coming from unclean keg lines so i'll completely clean them out too before re-testing. thanks all.


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## manticle (24/10/14)

You're super careful about sanitation but have dirty lines?
I bet 10c the problem goes away.


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## fletcher (24/10/14)

manticle said:


> You're super careful about sanitation but have dirty lines?
> I bet 10c the problem goes away.


i meant sanitation with my brewing processes. this is the first beer i've had in my own keg/kegerator. i meant dirty as in, i haven't poured a beer in about 2 days so there is beer sitting there quite warm in the lines in the font. i was wanting to see if THAT beer could somehow taint the line so that the fresh beer poured through it (after you get rid of that warm-line beer initially) would be affected taste-wise.


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## Dan Pratt (24/10/14)

hey Flecher,

I love that you're your worst critic :beerbang:

As part of the "pour a beer process" I always clear the line into a cup/glass/anything that holds liquid as I have about 400mm of beer line that is not inside the fridge at cool temps, this way you get only fresh cold beer from the keg without any off flavors.


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## fletcher (24/10/14)

Pratty1 said:


> hey Flecher,
> 
> I love that you're your worst critic :beerbang:
> 
> As part of the "pour a beer process" I always clear the line into a cup/glass/anything that holds liquid as I have about 400mm of beer line that is not inside the fridge at cool temps, this way you get only fresh cold beer from the keg without any off flavors.


thanks mate. yeah i usually do the same. i still feel like this beer though has still 'stuck' to the inside of the lines (for want of a better phrase) and has affected the taste of the fresh beer poured through it. i'm a MASSIVE newbie with kegs and kegging, but i just flushed my lines with star san, let it sit for a while, then re-attached the keg, let the star san finish pouring through, and poured myself a glass. tastes a lot better. i think it was that for sure. manticle guessed it. 

it's not dirty though, as in, this is literally the first beer i've had in my new kegerator, but in the past month, i have poured a beer, tried it, then left it for a week or so, then done the same thing and so on etc. so would this be something to remember for future batches? or just the very lager-like ones? 

does this make sense?


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## Midnight Brew (25/10/14)

How often have you used the JW vienna? I found it had this odd sweetness to it that I wasnt quiet sure of and could be that. It's been a long time since I've used any but I do remember this odd sweet character that wasnt the vienna type that Ive tasted in other home brews using the wey vienna.


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## fletcher (25/10/14)

Midnight Brew said:


> How often have you used the JW vienna? I found it had this odd sweetness to it that I wasnt quiet sure of and could be that. It's been a long time since I've used any but I do remember this odd sweet character that wasnt the vienna type that Ive tasted in other home brews using the wey vienna.


that's one thing i was thinking too. i think the beer could potentially be unbalanced toward the malt, and therefore exhibiting a bit of sweetness due to the vienna and the caramalt. i've cleaned the lines and did Nev's suggestion and the character is still there. as i said, not really bad tasting, just a subtle sweetness (butter was probably the wrong word to describe it).


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## dent (25/10/14)

Diacetyl can come about later on even when there wasn't any when you racked the beer to keg or whatever. Have a read about AAL here.


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## JasonP (25/10/14)

Got to be careful not to introduce o2. This can lead to diacetyl production after fermtation is long done.


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## /// (25/10/14)

AAL can sit in the beer for eons and convert if the beer is warmed up. Excess bound oxygen can also be the culprit working with any AAL over time. We had he issue in pack beer at 30 and 60 day taste samples and had to add an enzyme that chases the excess O2 prior to packaging. 

If beer is in a keg you can reintroduce yeast to mop up at warm temps for 48 hours. We never release beer without a force test, my 2ic is extremely sensitive to it where I like it weirdly enough.


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## fletcher (29/10/14)

after thoroughly cleaning the lines and doing the diacetyl test Nev mentioned, i've found the problem was an unbalanced beer and sweeter than expected vienna malt. not bad, but not really what i wanted. others have said they liked it, but being my own worst critic, i'm saddened about it. will re-brew it and increase the IBU or perhaps stick to weyermann for my mostly-vienna style beers like this one.

thanks everyone for their help.


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