Diacetyl problem - getting discouraged

Brewed a pliny the elder clone and it spent a week in the keg before becoming a butter bomb.

I'm desperate here. I want to brew the beer that I want to drink. I can brew low gravity ales no problem. IPAs kick my butt though... I can't brew a high gravity IPA to save my life.

Here are some vital stats:

Starting Gravity 1.072
Pitched at 62F, let free rise to 66F and let it sit there for 3 weeks.
Finished out at 1.006

2 packs rehydrated US-05

Dry hopped after 17 days (final gravity confirmed after 2 samples over 4 days). Sat out at ambient temps (68-72F) for a week and a half while dry hopping.


Samples tasted clean, even tasted clean while carbonating. I should have drank it all super early (hindsight being 20/20).

Diacetyl shows up today after 1 week in the keg.

Whats up??? How can I fix a buttery keg?

 

I don't keg. But I've heard that dirty lines can cause diacetyl.

 

My friend sometimes has this problem, and while I still have no idea as to the cause, it does tend to dissipate after a while.

 

If the diacetyl wasn't in your hydro sample at the time that you kegged it and instead showed up a week later, I think I'd be inclined to suspect infection.

 

I know of no way that could actually happen. Infection or other off-flavors, sure. Diacetyl, highly doubtful.

Unfortunately, ale yeast (including Chico strain) can and sometimes does kick off some alpha acetolactate (the chemical precursor to diacetyl). Next time, try starting and holding the ferment at 64-65*F until it begins to slow down then begin to raise it up slowly so that it spends the last 5-7 days at 70-72*F (sort of a mini d-rest)

I'm afraid that there's no way I can suggest to "fix" it at this point other than to set that keg aside at room temp for a few months and see if it persist. If it's an infection (although I can't recall one that tastes like butter), it will be even worse over time.

 

Do you use the same kegs and beer lines for your other beers that aren't buttery? Is it really just IPAs that you develop this buttery flavor? Very strange.

 

This time I sampled using one of these. The lines won't be the issue this time around. I clean my kegs with oxy clean and rinse with water. I do a final rinse with star san right before the transfer with a starsand auto siphon. I'm stumped.

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Have you tried breaking down your kegs to clean all of the poppets and dip tubes (including using a brush to clean down inside the tubes)?

 

Yep, every time. Some of my poppets don't separate from the posts though. Not this particular keg though.

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These folks seem to think it is because of oxygen.

http://crafthomebrewclub.org/forums/index.php?threads/diacetyl-forming-in-the-keg.384/

Are you purging O2 from the headspace? Perhaps try flushing the keg with CO2 before racking.

 

Good read but I did that this time as well. I have a feeling I'm doing something wrong on the cold side.

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Beer Smith

 

I'm out of ideas. The only thing I can say is that your FG looks a little low. Hopefully someone else can help you out.

 

Diacetyl
Diacetyl is most often described as a butter or butterscotch flavor. Smell an unpopped bag of butter flavor microwave popcorn for a good example. It is desired to a degree in many ales, but in some styles (mainly lagers) and circumstances it is unwanted and may even take on rancid overtones. Diacetyl can be the result of the normal fermentation process or the result of a bacterial infection. Diacetyl is produced early in the fermentation cycle by the yeast and is gradually reassimilated towards the end of the fermentation. A brew that experiences a long lag time due to weak yeast or insufficient aeration will produce a lot of diacetyl before the main fermentation begins. In this case there is often more diacetyl than the yeast can consume at the end of fermentation and it can dominate the flavor of the beer. — Palmers book

Spoilage

The second-most influential way diacetyl is produced in beer is through bacterial infection. Two main bacterial culprits are to blame for this: Pediococcus and Lactobacillus (Gram-postive/catalase-negative cocci and rods, respectively). Both of these bacteria produce lactic acid, so when the buttery aroma is detected along with a sour character, it is pretty certain that an infection has occurred. The most common source of contamination comes from contaminated pitching yeast, as the bacteria hitch a ride with the yeast from brew to brew and gradually accumulate into populations which wreak havoc on your beer.

How to limit diacetyl production

So how can the small-scale brewer or homebrewer use this information to limit diacetyl in their own products?

Use high quality malt (high nitrogen)
Use healthy yeast at a good pitching rate (10^6 cells/ml/Plato), with good oxygenation/aeration after cooling
“Diacetyl rest” at the end of fermentation (possibly including rise in temperature, especially for lagers)
Good sanitation practices to prohibit infection
Limited oxygen in packaging and minimized mechanical agitation — From here

 

How do you clean your draft lines? A caustic line cleaner or just oxiclean or PBW? In my experience, caustic cleaners work way better than oxiclean or PBW for draft lines. Caustic cleaners actually wick into the lines and clean deep in there. I used to clean with a sodium percarbonate cleaner (PBW) and found that caustic line cleaners work significantly better. The only draw back is that you really need to make sure that your lines are rinsed good since caustic chemicals are no joke. You probably know this already, but improperly cleaned draft lines can be a cause of off flavors and can even be the cause of an infection. This may or may not be your issue but it is certainly an avenue that you should explore.

The only other thing that I can think of is a Pedio infection. Pedio throws a bunch of diacetyl. Your low FG of 1.006 combined with a long primary of 4 weeks shows that an infection might not be out of the question. That being said, this scenario is probably a long shot since you didn't mention a pelicle, but I figured that I would mention it since the usual suspects have already been addressed in previous posts.

If you really want to check if the diacetyl is from an infection you could send a sample to White Labs to check for contamination. Or you can send a sample to see if the off flavor is really diacetyl.

http://www.whitelabs.com/other-products/test-kits


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Interesting. I learned somethin new today.

 

Here's a test you can do for the pre-cursor:
http://www.winning-homebrew.com/diacetyl-test.html

 

My working theory is that oxidation from dry hopping or racking to secondary (or in this case kegging without purging) causes the diacetyl pre-cursor (alpha acetolactate) to convert to diacetyl. I have read that this is a spontaneous reaction so trying to prevent conversion isn't as effective as just giving your beer good time at room temp after any sort of oxidation so the AA will convert to diacetyl and be cleaned up by the yeast. I can't help but feel like alpha acetolactate in beer is a ticking time bomb. My new strategy is to warm my IPA's up to ~69-70 before dry hopping and leave them there for about a week after my latest dry-hop addition.

 

OP, if this is still an issue, check your co2 lines. I had a recurring diacetyl issue that would develop after a week in the kegs for years. And it was because I backed up beer into one of my co2 lines and didn't know it. So, beers here and there would develop a buttery/butterscotch flavor, mainly noticeable in IPAs as the hop character would be completely destroyed. You don't notice it in darker beers, it might even enhance those, and I didn't brew a whole lot of lighter beers. I was on the verge of quitting. I still often contemplate just ditching the kegging system altogether.

But that's a place you should check also.

 

+1 on changing out the gas line and fitting.

You might, in addition to replacing the gas line, warm the keg up to room temp and pitch in a 2 liter starter and give it a week to clean up your diacetyl.

Repitching an active starter has cleared up that problem in a lager for me before. This will not help though if you are pushing in bugs from the gas line.

 

Yep, just ripped out all my gas lines. Replaced. Carbing a new keg right now. Will know in about a week.

 

Ive been experiencing the same problem. Never had this problem when I bottled. Did tearing out the gas lines solve the problem? How do you clean out a gas line?


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No, replaced all that and still persisted. I am redoing my Kegerator at the moment and bought new regulator and then more lines again.

I am carbing a hoppy beer right now. I believe I have finally narrowed it down to my tank. If it isn't that I'm going to rage quit homebrewing I think.

 

Do you rack to a secondary vessel at all? If done improperly this can introduce oxygen. Also cold crashing can be a culprit because of the vacuum it creates. I used to have a similar problem but now I dry hop and cold crash in the keg.


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What is the grade of CO2 you're using? If it's industrial (98-99% CO2, or 1-2% air), you're adding a crapload of O2 to your beer during carbonation (look up tapintohach for more info). Keg conditioning may solve your problem. I kind of doubt that your issue is infection. I think you'd get other off-flavors as well over time, and you sound like you have sanitation under control anyway. I have had diacetyl develop in beer after I've bottled it, but it's gone away after 10 days or so of conditioning. Most people don't drink their bottled beer after 4 days in the bottle, but I like to check it out early (and often) to see how things are going. Oxygen will definitely cause diacetyl formation if you've got some of the precursor hanging around. And if you're kegging, you aren't going to have very active yeast present to clean up the diacetyl, which is why I would suggest getting some priming sugar in there to clean things up. You may even save the current beer just by letting it sit at room temperature for a few weeks, and also shaking the keg periodically to re-suspend the yeast that you do have in there.

 

FarmerTed,
Thank you. This sounds like a possible cause of my problems. I buy my CO2 from a welding supply store. I have no idea what the purity is and never considered it to be honest. I am so meticulous about keeping EVERYTHING sanitary and clean, which is part of the reason that I'm losing my mind over this problem. My kegged beers have never been as flavorful/hoppy as when I use to bottle. All my beers are so blah now.
So what's the solution? I there a place where I can look to buy a higher grade CO2? Is there a food grade CO2 in existence as opposed to industrial grade? Looking forward to hearing more about this potential answer to my insane dilemma here. Thank u!


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NAILED IT! I was just going to post almost exactly this, but I'm happy to see that someone beat me to it.

A lot of great information here but boil it all down to some recommendations. Typically Diacetyl is considered a problem for impatient brewers but yes, Pediococcus and Lactobacillus infections can both create diacetyl and they just happen to be the two most prevalent microorganisms that infect beer taps/lines. (Fruit flies, which are attracted to ethanol and therefore beer taps, carry pediococcus and when they sip a drink of your beer, your tap and lines get infected.)

Other than avoiding infection and having good sanitiziation here's the recommendations:

• Leave the beer on the yeast for 2 weeks
• Perform a "diacetyl force test" before crash cooling, transfering off of the yeast, or filtering

You can taste the beer say a week into fermenting an ale and say "hey I don't taste any diacetyl and more and the air lock stopped bubbling 3 days ago; it must be done. I'm going to transfer / chill / filter now." BUT- You can't taste the diacetyl pre-cursors and you have to WAIT to let the precursors form diacetyl so that the yeast can convert it.

You can check for the presence of the diacetyl precursors, known a "Vicinal diaketones" (or VDK) using a multiple thousand dollar gas chromotography piece of lab equipment OR by doing the "diacetyl force test". -Just pull a sample of your seemingly-finished-fermenting beer and pour it into a glass, cover it, and let it warm up to room temperature for a good 20 minutes, THEN taste it for Diacetyl. -The VDK precursors will convert into diacetyl in the presence of oxygen and the reaction is accelerated at higher temps and then you can actually just use your tongue as a free instrument vs. the gas chromotography equipment... -I do the 10 minute version of the test where I put the glass sample into a sink of hot water and heat it up to 80-90F and then chill it back down again and then taste for diacetyl.


The combination of good sanitization, preventing fruit flies from getting to your taps, and leaving the beer on the yeast until it passes the VDK/diacetyl force test will get diacetyl out of your life.

-There's also a chemical additive you can add prior to fermentation and it will prevent the formation of diacetyl completely as it contains an enzyme that will immediately convert the diacetyl precursors into ethanol directly and skip the diacetyl interim stage. It's now available at home brew quantities but I can't remember the name of the product to save my life... "BioFerm" or something like that maybe..

[Edit] I should note that this additive will only solve your problem if the diacetyl results from fermentation; not infection. The additive is useful if you're going to be brewing a lager with a diacetyl-prone yeast strain such as some of the Malt-focused German Lager strains and the Budwar Bo Pils strain; big commercial breweries use it to speed up lager production schedules as they don't have to wait for diacetyl reduction so they can immediately filter instead of performing an extended cold lagering that ties up fermentation tanks and limits throughput.

-I LOVE the Weihenstephaner lager strain for Oktoberfests and other malty German lagers but it's SOOO slow at reducing diacetyl and although krausening works wonders, I'm already tieing my fermenter up for a good month when I ferment a lager and I just don't want to deal with it being tied up any more so the enzyme is a cheap way to ensure that I get my fermenter back on my schedule and I get to brew again when the month is done.

Adam

 

What sanitizer are you using to try and kill the pedio/lacto infection that seems to be the problem?

-Remember these two strains are both "Lactic-acid producing bacteria" so they have pretty high tolerances for acidity; use multiple sanitizers when you get a major infection like this. Use an alkaline cleaner followed by a good acidic sanitizer (starsan) at high temp with extended soak times, THEN go with a sanitizer that kills with something other than acid like a iodine or chlorine cleaner but not chlorine if you have stainless equipment or at least don't SOAK it in a chlorine sanitize and rinse thoroughly and quickly.

Also remember that even beer line cleaner, which is really ideal for this scenario, is designed to have a long contact time and be circulated so pay attention to not only dosage but contact time; also if you have very hard water sometimes you need to increase your sanitizer dosage.

Adam

 

I would ask them what grade the CO2 is next time you get a re-fill. I'd also give keg conditioning a shot. Or, just go back to bottling, lol.

 

Gonna give keg conditioning a shot, dismantle and thoroughly clean/sanitize with oxy and starsan and see if this solves it. Thanks to all for sharing your knowledge and experience. Ill report back when it's all said and done.


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I found anytime I put in a keg and lose my hoppy taste I'll add 1 oz of whole hops in a hop bag with some dental floss tied to bag and it's small enough to seal the gasket on a corny keg, I buy hops from the local brew store and have had 2 ounces of magnum that did nothing while one ounce of summit completely destroyed my IPA, you never know the freshness of home brew shop hops, I've had one pound of Saaz 6.5% in freezer for a year that will out produce hop flavor of any high alpha hop, gotta love home brewing-alcohol-good friends-and unexplainable mysteries that will haunt or amaze us


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At my wits end here. New regulator and lines, problem persists.

Soak fermenters/kegs in pbw, rinse with water and then rinse with starsan right before filling.

Left a 1.045 beer on the yeast for 3 weeks and raised temps to 68 as fermentation was finishing (S05 yeast).

I do not use a secondary vessel.

I don't taste diacetyl when I keg it or as its carbonating. It happens about a week after its carbonated. I got my tank filled at a fire extinguisher place. Like several of my other homebrew buddies.

Help.... I'm desperate now.

 

Try bottling a batch and see what happens

 

Well Magnum is pretty much a bittering only hop, and Summit has a HUGE alpha so that explains those two.

 

Sounds like some pedio in the lines, I would swap those if you could. Other things to check are the QD's and maybe the regulator (if you've ever blown beer back in to the regulator that might be where the flavor is coming from)

 

He has replaced all that stuff, but didn't say he replaced the quick disconnects. Did you check the disconnects, OP? I took mine apart when I had this issue and noticed some green mold in there.

Otherwise, if this isn't happening until after packaging, it HAS to be something happening somewhere in the transferring process or the keg. Did you try replacing your racking cane and tubing as well? I had an issue recently with an unclean stainless racking cane that didn't cause diacetyl, but caused an off flavor that seemed to develop in the keg. Stopped using it, problem solved.

I hope this doesn't drive you to quit brewing. I know the feeling, believe me! Brewing is such a great hobby and is worth pursuing for life, I think. Even through all the trials and tribulations.

 

Thanks I brought in a consultant (trusted homebrew friend) to ferment something I brewed. Still trying to figure it out though.

I did replace the disconnects though fwiw

 

All,
I wanted to update the thread on what I've determined to be the cause of all my problems - lack of CLEANING. I dismantled all my kegs and cleaned the parts with pbw and then starsan.
I had been sanitizing everything like a madman but hadnt been as thorough with the cleaning. I have learned the hard way that killing the bugs that kill your beer is a two step process - cleaning AND sanitizIng everything at every step. I have now employed pbw/cleaning as step one and starsan/sanitizing as step two every step of the way.
I've brewed three beers since incorporating this method and the brews have been phenomenal! I hope this helps someone who is confronting the same issues which were driving me insane.
Good luck and happy brewing!


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Found the issue HERE.


TL;DR - Crusty ball valve

 

Great to hear that you finally got to the bottom of the issue.