Author Topic: The Big D (Diacetyl) - Contamination or Fermentation Issue?  (Read 1208 times)

Offline amichuda

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The Big D (Diacetyl) - Contamination or Fermentation Issue?
« on: February 08, 2017, 03:23:54 PM »
Can anyone convince me the hint of diacetyl I'm getting is NOT from contamination? It is NOT extremely evident in the aroma outside of a faint honey like sweetness and muting of the hop aroma. There is a certain fullness and slickness to the mouthfeel. I did warm some up in the microwave and the aroma got much stronger. Again, sweet and rich smelling, but not butterscotch or popcorn.

If this is a maturation/fermentation issue I'll sleep much better at night. My concern is that this is from a wild yeast or bacteria infection, since the source will be much more difficult to track down.

My main question is how long do pedio and other lactic producing bacteria (or wild yeast) take to produce noticeable diacetyl? My understanding is that with reasonable sanitation procedures and traditional beer yeast fermentation, it would take a while for the spoiling agent to make an impact. This beer is only 2 weeks old. If it was indeed infected, wouldn't I also notice a lack of body and other offensive aromas and flavors?

Does any one have any methods which I use to eliminate infection as the potential cause of the big D? I've been brewing for 6 years and am obsessive about sanitation. Any ideas?

Offline Phil_M

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Re: The Big D (Diacetyl) - Contamination or Fermentation Issue?
« Reply #1 on: February 08, 2017, 03:28:41 PM »
What yeast did you brew with? Style of beer? If it's infected, I'd expect diacetyl levels to keep increasing until it's terrible.

If it's not infected, and it tastes good, I wouldn't worry about it. If it's a British style I certainly wouldn't worry about it. Diacetyl isn't the boogeyman it's made out to be.

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Corn is a fine adjunct in beer.

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Offline amichuda

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Re: The Big D (Diacetyl) - Contamination or Fermentation Issue?
« Reply #2 on: February 08, 2017, 03:56:17 PM »
Definitely not a dumper. Just don't want all my beers to start having this issue. Over the last 6 years it seems to get harder and harder to make a perfect beer. Maybe my palate just sucked back then.

Its a 1.052 pale ale with 150B cells (from a 1.6L starter) of WLP001. Hit it with O2, pitched and fermented at 64. Day 7 let it free rise. Up to 72 by day 10.   

Its in a keg at 38. Wouldn't it take a long time to get worse?

Only other thing I can think of is to sanitize the line and tap and fill a sterile bottle. Then leave it out at room temp (77) with some foil over the top. That should speed things along.






Offline reverseapachemaster

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Re: The Big D (Diacetyl) - Contamination or Fermentation Issue?
« Reply #3 on: February 08, 2017, 04:09:52 PM »
If it doesn't taste like butter it's not diacetyl.

What you describe sounds far more like an issue with oxidation. Possibly water issues.
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Offline denny

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Re: The Big D (Diacetyl) - Contamination or Fermentation Issue?
« Reply #4 on: February 08, 2017, 04:14:27 PM »
If it doesn't taste like butter it's not diacetyl.

What you describe sounds far more like an issue with oxidation. Possibly water issues.

Not necesarily.  I ofetn don't taste butter from diacetyl, but I can always detect it via mouthfeel.
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Offline Phil_M

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Re: The Big D (Diacetyl) - Contamination or Fermentation Issue?
« Reply #5 on: February 08, 2017, 04:20:18 PM »
If it doesn't taste like butter it's not diacetyl.

What you describe sounds far more like an issue with oxidation. Possibly water issues.

Not necesarily.  I ofetn don't taste butter from diacetyl, but I can always detect it via mouthfeel.

Same. When faint a certain slipperiness on the roof of the mouth is how I can detect diacetyl. Samuel Smith's Nut Brown Ale has a good amount of diacetyl in it, I use this to "recalibrate" every so often. Very easy to notice the slickness in that beer.
Corn is a fine adjunct in beer.

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Offline amichuda

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Re: The Big D (Diacetyl) - Contamination or Fermentation Issue?
« Reply #6 on: February 08, 2017, 04:22:08 PM »
Appreciate the thoughts Apache. I should clarify that the warmed sample did have some artificial butter aroma. Its hard to perceive in the serving temp beer through the hops. Kind of a distraction in the background.

RO water + gypsum  + CaCl + Lactic Acid (1 ml) in the mash. Sulfate and Chlorides balanced and within reasonable ranges. Don't think its a water issue.

Oxidation? maybe. Cooled the fermenter down to 40 with foil over the top. Replaced with an airlock when temp stabilized. Purged keg with CO2 before and after racking. Only things I could do to reduce oxygen pick up would be to have a steady trickle of C02 into the headspace while cooling, and purging the siphon hose before racking.

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Offline klickitat jim

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Re: The Big D (Diacetyl) - Contamination or Fermentation Issue?
« Reply #7 on: February 08, 2017, 04:25:39 PM »
I'm sensitive to diacetyl and have detected it as Carmel, butterscotch, and theater butter. It's not until it's in the butterscotch-butter level that I get the slickness.

It's nearly impossible to detect over the Internet though, so we can only assume you are correct and it's diacetyl. The two prime causes I have experienced are racking to package prematurely and pedio. If it's pedio it should become more and more obvious, and not just diacetyl.

Offline JJeffers09

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Re: The Big D (Diacetyl) - Contamination or Fermentation Issue?
« Reply #8 on: February 08, 2017, 04:27:28 PM »
I'm with denny, I detect the 'slick' feeling before I taste buttered popcorn.  To me a big difference in bacterial infection causing D and just D from yeast, is if it tastes vegetal.  The only time I have experienced it was in my 2 wild ales.  One that is my back yard brettanomyces and the other was a dumped batch. 

As far as method of detecting an infection is a mini batch, fast ferment at higher Temps for 001 IIRC ~72f

How did the fermentation go?  Was it a slow starter? How long was it in primary?

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Offline amichuda

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Re: The Big D (Diacetyl) - Contamination or Fermentation Issue?
« Reply #9 on: February 08, 2017, 04:47:21 PM »

How did the fermentation go?  Was it a slow starter? How long was it in primary?

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Fermentation was normal. Not as violent as some batches I've made though. Krausen fell after 3 days.

Warmed it up on day 7 until cooling on day 10. Packaged two weeks after pitching.

Think I'm going to let my next few beers mature/condition around 70F a bit longer, and see if that solves the problem.

Offline klickitat jim

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Re: The Big D (Diacetyl) - Contamination or Fermentation Issue?
« Reply #10 on: February 08, 2017, 04:50:19 PM »
How did the two final gravity samples taste? Lately I always warm my FG sample in the microwave just to be sure there's no diacetyl. Why not? It's right there anyway

Offline amichuda

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Re: The Big D (Diacetyl) - Contamination or Fermentation Issue?
« Reply #11 on: February 08, 2017, 04:59:45 PM »
How did the two final gravity samples taste? Lately I always warm my FG sample in the microwave just to be sure there's no diacetyl. Why not? It's right there anyway

I don't do final gravity samples. Mostly because I'm lazy, but I don't like to poke around in my beer and risk contamination.  If my 1.052 wort isn't fully attenuated after 10-14 days, I've got some major issues.

But given my current situation, a forced diacetyl test should definitely be in my routine before cold conditioning.

Offline klickitat jim

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Re: The Big D (Diacetyl) - Contamination or Fermentation Issue?
« Reply #12 on: February 08, 2017, 05:06:20 PM »
It can be fully attenuated but still not done up taking things like diacetyl. My bet is now on  unfinished rather than contamination.

Offline denny

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Re: The Big D (Diacetyl) - Contamination or Fermentation Issue?
« Reply #13 on: February 08, 2017, 05:17:22 PM »
It can be fully attenuated but still not done up taking things like diacetyl. My bet is now on  unfinished rather than contamination.

Actually, Jim, according to Palmer the cleanup phase does and should take place while there are fermentables, not at the end of fermentation.
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Offline klickitat jim

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Re: The Big D (Diacetyl) - Contamination or Fermentation Issue?
« Reply #14 on: February 08, 2017, 05:38:16 PM »
It can be fully attenuated but still not done up taking things like diacetyl. My bet is now on  unfinished rather than contamination.

Actually, Jim, according to Palmer the cleanup phase does and should take place while there are fermentables, not at the end of fermentation.
I wouldn't doubt Palmer. It's just that I've seen beer improve after final gravity is reached. It must have been for some other reason then. But in this particular case, I am not seeing any evidence that the beer was actually done.