Author Topic: Diacetyl question.  (Read 580 times)

Offline Oiscout

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Diacetyl question.
« on: February 24, 2021, 02:10:28 AM »
Through all of my reading and research I still feel like I'm a little bit confused by Diacetyl production and clean up.

I've only ever gotten Diacetyl when I didn't make a starter or had suffered a bad spell of temperature fluctuation.

Would you say Diacetyl is a byproduct of stressed yeast?

I also understand that some strains more than others produce more Diacetyl than others.

 For my Ales I wait till I'm about 1/2 way to Terminal gravity and begin my Diacetyl rest at 68-70 degrees or allow the fermenting wort slowly ramp up 4 days after the beginning of fermentation. I ferment in buckets and do not like the idea of opening them up occasionally.

Is there something I'm missing or anybody have some links to a few articles on Diacetyl production in strains of yeast used for making Ales?

Sorry if it seems like I'm rambling just wanting to make sure I am on the right track with this. I recently had a kveik beer that was a total Diacetyl bomb and was a dumper.

Thank you

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Offline majorvices

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Re: Diacetyl question.
« Reply #1 on: February 24, 2021, 02:29:30 AM »
Lot's of things cause diacetyl. Stressed yeast can be a cause if the yeast is not healthy enough to clean up the diacetyl it forms.

Infection can cause diacetyl. Oxidation can cause the diacetyl to "reform" if the precursor is still there after fermentation.

Some strains do produce more diacetyl than others. I didn't think kviek was a diacetyl producing strain. But I may be wrong.

Offline Oiscout

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Re: Diacetyl question.
« Reply #2 on: February 24, 2021, 02:43:14 AM »
I could be wrong aswell. I'm pretty careful and clean but contamination happens.

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Offline ttash

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Re: Diacetyl question.
« Reply #3 on: February 24, 2021, 03:27:06 AM »
When in doubt, you can run a diacetyl force test. Once fermentation is complete (at least 2 days same gravity) take about 200 ml and put it in a flask, cover with foil and put it in a 150*F water bath for 15 minutes. Cool it down to room temp in a cold water bath, remove the foil and smell it. If you detect diacetyl, give the beer more time on the yeast. It may seem like a bit of work, but it's actually very simple, and way better than dumping an entire batch.
It's also known as a  VDK test. VDK is the precursor to diacetyl and can be reabsorbed by the yeast given enough time. If you suspect that the diacetyl may be caused by contamination, run the same test but with an additional cool non-heated sample. If you detect diacetyl in both samples, it's most likely a contamination problem.
This procedure is detailed in the Yeast book by White and Zainasheff.

Offline Saccharomyces

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Re: Diacetyl question.
« Reply #4 on: February 24, 2021, 04:23:43 AM »
Diacetyl is often the result of under aeration or premature flocculation.

Online dmtaylor

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Re: Diacetyl question.
« Reply #5 on: February 24, 2021, 11:53:44 AM »
Diacetyl is primarily a lager thing, and only certain strains produce it very much in detectable levels.  You shouldnt need a d rest for most ales because they are fermented warmer. Yeast eats diacetyl but it takes time. At colder temperatures it takes more time, especially if you cold crash and expect s nice clean beer. Yeast will eat the diacetyl but not at ice cold temps. I think this is a common mistake with brewers who advocate for cold crashing. You need to be sure that theres no diacetyl before you do that.
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Offline BrewBama

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Re: Diacetyl question.
« Reply #6 on: February 24, 2021, 01:11:59 PM »
Diacetyl Formation Facts Written by Dr. Chris White

Some yeast strains produce a lot of diacetyl, while others produce less. Choose yeast that produces less, unless you are brewing a style that allows for the presence of diacetyl.

High fermentation temperatures promote diacetyl production.

Low aeration levels when yeast is pitched will produce less healthy yeast, which are prone to higher diacetyl production.

Ale fermentations produce more diacetyl because ales are fermented warmer than lagers, but the reduction happens much quicker.

Lager fermentations need to be given a “diacetyl rest” by increasing the fermentation temperature just before completing fermentation.

A hydrometer should be used to measure the specific gravity to calculate when to start the diacetyl rest. Begin when the beer reaches two to five points of final gravity.

The fermentation should never be rushed. Give the beer ample time for maturation.

Sanitize well, particularly when bottling, to limit the effect of diacetyl from bacterial contamination.

https://byo.com/article/brewing-science-controlling-diacetyl/


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Offline majorvices

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Re: Diacetyl question.
« Reply #7 on: February 24, 2021, 02:11:41 PM »
Hop creep and introduction of oxygen post fermentation can cause diacetyl as well.

Offline erockrph

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Re: Diacetyl question.
« Reply #8 on: February 24, 2021, 06:24:43 PM »
Diacetyl is primarily a lager thing, and only certain strains produce it very much in detectable levels.  You shouldnt need a d rest for most ales because they are fermented warmer. Yeast eats diacetyl but it takes time. At colder temperatures it takes more time, especially if you cold crash and expect s nice clean beer. Yeast will eat the diacetyl but not at ice cold temps. I think this is a common mistake with brewers who advocate for cold crashing. You need to be sure that theres no diacetyl before you do that.
I will say that diacetyl can also be a problem with certain highly flocculant English strains on occasion as well. If they drop out before they clean up all the diacetyl then you can end up with some diacetyl in the finished product.

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Offline Oiscout

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Re: Diacetyl question.
« Reply #9 on: February 24, 2021, 07:51:12 PM »
Thanks so much y'all!!!!

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Online dmtaylor

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Re: Diacetyl question.
« Reply #10 on: February 24, 2021, 09:10:59 PM »
Diacetyl is primarily a lager thing, and only certain strains produce it very much in detectable levels.  You shouldnt need a d rest for most ales because they are fermented warmer. Yeast eats diacetyl but it takes time. At colder temperatures it takes more time, especially if you cold crash and expect s nice clean beer. Yeast will eat the diacetyl but not at ice cold temps. I think this is a common mistake with brewers who advocate for cold crashing. You need to be sure that theres no diacetyl before you do that.
I will say that diacetyl can also be a problem with certain highly flocculant English strains on occasion as well. If they drop out before they clean up all the diacetyl then you can end up with some diacetyl in the finished product.

Good point.
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Online dannyjed

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Re: Diacetyl question.
« Reply #11 on: February 24, 2021, 11:32:05 PM »
Hop creep and introduction of oxygen post fermentation can cause diacetyl as well.
This happens to me sometimes after I dry hop my Barleywine. Thank goodness, it fades away with time.


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Offline Homebrew_kev

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Re: Diacetyl question.
« Reply #12 on: February 26, 2021, 10:45:28 PM »
From my exeperience - some yeast strains produce more diacetyl than others. My last exeperience was with WLP095 Burlington Ale. I did a 1L starter (with a reasonably fresh pack) and gave it pure O2 before pitching. I fermented in the mid 60s and it had a strong fermention. I got big peachy easters like it promised - but I didn't raise the temp to clean up diacetyl. Took me about half a keg to realize it had a butter note to it!

I would have kicked up the temp to the 70s for about 48 hours to clean it up - then crash cool it to help flocculation.

Big thing here is that you'd need some temperature control to help clean it up.

Offline Oiscout

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Re: Diacetyl question.
« Reply #13 on: February 27, 2021, 12:08:31 AM »
I was worried my process was flawed, or I had an infection in my system just pulled sample off my Dunkelweisen I brewed a week ago and tastes good. Very happy

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Offline narcout

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Re: Diacetyl question.
« Reply #14 on: March 01, 2021, 01:48:18 AM »
Lager fermentations need to be given a “diacetyl rest” by increasing the fermentation temperature just before completing fermentation.

That particular one is definitely not true.
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