Diacetyl in Rye Kolsch

[Simonpyman]

So i did a Rye Kolsch a few weeks ago and from the few samples from the keg I can detect a slight corn taste and its sweet. This was an experimental brew so I wasn't sure what to expect. All in all its pretty tasty and creamy though sweeter than I expected.

after cold crashing + 2 day Diacetyl rest, its been 2 weeks now lagering in the keg... Will this flavor decrease with longer lagering time?

 

[MaxStout]

Diacetyl causes more of a buttery or butterscotch flavor. A "corn" taste is more likely dimethyl sulfide (DMS), which is a natural byproduct of the grain from mashing. Boiling the wort usually allows that to dissipate--if you keep the lid off. The DMS--actually, DMS precursors--are volatile and will readily boil off. If you detect the flavor in the fermented beer, it might be possible for the yeast to "clean up," but that would require warm temps, when the yeast is active. Lagering will cause the yeast to go dormant. It's hard to say if the off-flavor will diminish during lagering.

Did you notice this off-flavor before or after the D-rest?

 

[Donoroto]

What Max said ^^

The diacetyl rest needs warm temperatures, several degrees above fermentation temperatures. Cold crashing it first stops the yeast activity, so this batch did not have a diacetyl rest at all.

 

[Simonpyman]

I didn’t sample before i did the rest. I say corn but it’s probably more a buttery/sweet flavor.
I am lagering in the keg so I can’t do another rest.

 

[Simonpyman]

What Max said ^^

The diacetyl rest needs warm temperatures, several degrees above fermentation temperatures. Cold crashing it first stops the yeast activity, so this batch did not have a diacetyl rest at all.

I cold crashed after the rest

 

[Donoroto]

I cold crashed after the rest

Ah, ok.

You wrote "after cold crashing + 2 day Diacetyl rest" and I read it wrong.

 

[Simonpyman]

Ah, ok.

You wrote "after cold crashing + 2 day Diacetyl rest" and I read it wrong.

Sorry my mistake

 

[Donoroto]

Sorry my mistake

No worries sir! It's all good.

 

[Minbari]

Don’t attack me….I also have not done it BUT, Not all German breweries do a diacetyl rest. Holding longer at cold temps gets rid of it according to multiple articles from breweries I’ve read about. Time is the friend of a lager. But I assume if you taste it your pitch rate could have been low, temp of pitch and fermentation may have been high. THIS IS FROM READING SINCE I ALWAYS DO A REST.

that is pretty much what I have read too. a D-rest simply speeds up the process

 

[Josh Hughes]

Don’t attack me….I also have not done it BUT, Not all German breweries do a diacetyl rest. Holding longer at cold temps gets rid of it according to multiple articles from breweries I’ve read about. Time is the friend of a lager. But I assume if you taste it your pitch rate could have been low, temp of pitch and fermentation may have been high. THIS IS FROM READING SINCE I ALWAYS DO A REST.

I know kolsch isn’t a lager but it is laggered

 

[Simonpyman]

Don’t attack me….I also have not done it BUT, Not all German breweries do a diacetyl rest. Holding longer at cold temps gets rid of it according to multiple articles from breweries I’ve read about. Time is the friend of a lager. But I assume if you taste it your pitch rate could have been low, temp of pitch and fermentation may have been high. THIS IS FROM READING SINCE I ALWAYS DO A REST.

I know kolsch isn’t a lager but it is laggered

Interesting, good to know!

 

[The Brew Mentor]

You could pull the keg out and warm it up. Even add some yeast and a bit of simple sugar to it.
Give it a week warm and then try it

 

[The Brew Mentor]

Obviously you'll need to vent the keg to prevent it from over carbing

 

[HighVoltageMan!]

You could pull the keg out and warm it up. Even add some yeast and a bit of simple sugar to it.
Give it a week warm and then try it

You will need the yeast to be active. BM is advice is probably the best way to get rid of it. Keep in mind that the yeast need to be active, so it sounds like it may have some fermenting to do, so warming it up will allow the rest of the sugars to be consumed along with the VDK. Once again BM is correct to advise venting the keg to avoid over carbonating and excessive pressures.

The yeast can be active at refrigerator temperatures, but it needs to be brought down to slowly to keep the yeast in suspension. It also needs to be a lager yeast. The other alternative is adding an enzyme to the beer. ALDC can be added to the beer post fermentation to break down the VDK compounds. It's better to add it before fermentation. I now add it to every beer I make as an "insurance policy".

https://www.morebeer.com/products/cellarscience-aldc-enzyme-1-fl-oz.html

 

[The Brew Mentor]

The yeast can be active at refrigerator temperatures, but it needs to be brought down to slowly to keep the yeast in suspension. It also needs to be a lager yeast.

Just to clarify what HVM was saying here is that if you want to do it cold, then you would need to use a lager yeast.
If you warm it to ~70°, an ale yeast will clean it up pretty quickly and after it's clean, you can then cool it down again.
Good Luck
Brian

 

[Nosybear]

So i did a Rye Kolsch a few weeks ago and from the few samples from the keg I can detect a slight corn taste and its sweet. This was an experimental brew so I wasn't sure what to expect. All in all its pretty tasty and creamy though sweeter than I expected.

after cold crashing + 2 day Diacetyl rest, its been 2 weeks now lagering in the keg... Will this flavor decrease with longer lagering time?

Sweet corn is DMS, not diacetyl. Generally DMS is s a boil problem, not vigorous enough or covered boil.

 

[Simonpyman]

Sweet corn is DMS, not diacetyl. Generally DMS is s a boil problem, not vigorous enough or covered boil.

I may have misspoken or at least described the flavor wrong. I did a 90 minute boil and it is definitely diacetyl not DMS

 

[MaxStout]

The D-rest takes advantage of the bump in temp and the large amount of active yeast in suspension in primary fermentation, such that it will "clean up" the diacetyl and its precursors. But I'm wondering if there will be enough yeast remaining in the keg to clean it up at that point.

I don't keg, but it has been my experience with bottle-conditioned beers that once diacetyl is produced it tends to persist, regardless of the aging period. On two occasions I have uncapped and poured 50 bottles down the drain.

 

[The Brew Mentor]

The D-rest takes advantage of the bump in temp and the large amount of active yeast in suspension in primary fermentation, such that it will "clean up" the diacetyl and its precursors. But I'm wondering if there will be enough yeast remaining in the keg to clean it up at that point.

I don't keg, but it has been my experience with bottle-conditioned beers that once diacetyl is produced it tends to persist, regardless of the aging period. On two occasions I have uncapped and poured 50 bottles down the drain.

That's why it was suggested to add yeast to the keg.
Also a bit of simple sugar to get the yeast active.

 

[Simonpyman]

After 4 weeks the beer cleared up nicely and the “off” flavor I think I perceived is gone.