Ongoing Diacetyl ? off flavour

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Bandit24

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Check out caravan water filters on eBay, not the best but 2 are sub $20 and have the standard ouch to connect garden house coupling male side nipples inclided.
Get some food grade hose and new fittings at the big green shed and run them both inline and use a low flow rate, renters delight.
I drain them spray with sanitiser and keep them in a bag in the fridge when not in use. Don't have any water data but the taste is greatly improved over straight from the tap (which is still drinkable).
Best budget and ghetto option I've found dollars for doughnuts.

Thanks, this looks like a good idea
 

Bandit24

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Jaycar have a few options.

I've got 3 of these Katabat fans, ($16.95 each) been running 2 of them in my fermenting fridges for about 3 years now. The other one I use in my Kegerator. I disconnected the shit fan that came with it and put one in its place.

The only other thing you'll need is a longer USB cable, as the one that comes with it is only about 500mm long. I bought a 1.5m.

Cool, saw these at Jaycar yesterday, good to know they won’t blow up. I was thinking they looked a bit similar to my camping fan that burnt out. In theory though if I want to use a 240v option the target fan I linked above can’t be too far off the Katabat fans right? How are you constantly powering the Katabat? A powerboard with USB charging ports?
 

Thomas Wood

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I can't remember each individual thing I bought but all up it was $40 from JayCar and the fan is overpowered. I wish I got a smaller fan and saved some $$$ but it definitely does the job.
I basically got this fan: https://www.jaycar.com.au/90mm-12v-dc-2-wire-fan/p/YX2521 (maybe I got 120mm I can't remember)
An adapter to go from the fan to the powerpack (~$5), then the powerpack to plug into the powerpoint (~$10-15).

I have it running for a month at a time and it works fine, since it's a proper computer fan.

I can take a better look when I am home tonight and send pictures of each part tonight if you want? But I told the JayCar guy what I wanted to do and he sorted me out easy enough.
 
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Cool, saw these at Jaycar yesterday, good to know they won’t blow up. I was thinking they looked a bit similar to my camping fan that burnt out. In theory though if I want to use a 240v option the target fan I linked above can’t be too far off the Katabat fans right? How are you constantly powering the Katabat? A powerboard with USB charging ports?

You could use that, I've got a USB adapter plugged into an HPM safety powerboard

The 2 that are in my fermenting fridges are running nearly all the time, with the only exceptions being when I'm not fermenting. Which usually happens when I've kegged and it takes me a few days to get sorted to get the next batch going again.
The one I run in my kegerator goes 24/7.
 

mongey

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I'm in the Gong too. thirroul. I'm def no expert on off flavors and what they are though . you should hit up the IBU brew club page . sure someone would sample for you and tell you if it is diacetyl or an infection. they knowledgeable and have been super cool in my dealings with them.

you said the kit and kilo tasted better. Have you tried just doing a kit and kilo ? I have def had mixed results with FWK's over the years I have used them .

I have had beers which had off flavors in my 4 years for sure , . but never out of the fermenter .its something that develops after bottling .and often improves with time in the bottle
 

Deepregret

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Hey guys, I'm new to this forum (First post!), and this is one of the first posts I've read so I hope you don't mind me putting my 2 cents in.
My understanding of diacetyl is that it is in fact a flavour compound created by the fermentation process, that is reabsorbed by the yeast once fermentation is finished. Hence the phrase often used by brewers, "Diacetyl rest". That is, the time after fermentation has finished to allow the yeast to finish what it started and reabsorb these funky flavours!
Is it possible that you just haven't left your beer in the fermenter long enough? Just because your beer reaches its FG doesn't necesarily mean that the fermentation proces has completely finished.
A good way to test for diacetyl after fermentation, and to determine whether or not the diacetyl rest has finished is to put about 100mls of wort into a small conical flask (if you have one) and heat it up to about 80 degrees on the old cooktop! Once it's heated up, if diacetyl is still present you should be able to pick up that buttery/butterscotchy smell. If it's there, let your beer chill out in the fermenter for another day or so. As long as it's clean and air tight, infection won't be an issue. I generally leave my beers sit in the fermenter for at least a week after fermentation has stopped.

Anyway that's my thoughts on the issue. Let me know what you think!
 

raturay

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Deepregret
In my opinion you are 100% correct. This is pretty much exactly how it was described to me by my LHB (a very experienced, and I understand, qualified brewer). I have left some lagers on the yeast for almost a month for this purpose. I currently have a dark ale that fermented out to its FG (3 days at the same SG) two days ago. While there’s no evidence of diacetyl I have chosen to leave it on the yeast while we enjoy a week away at Evans Head!
A great resource about diacetyl is the podcast from Beersmith where he discusses the subject with the Pope of Foam Dr Charlie Bamforth. Great listening.
 

pirateagenda

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i'm pretty sure ive picked up a pedio infection in one of my taps. Had a lacto sour on tap for a couple of months, then the next beer (an XPA) was great tasting for the first 2 weeks, but has since developed a diacetyl taste. I swapped taps thinking it may have just been a dirty tap, but the beer is gone in the keg. The infection must have travelled down into the keg through the lines.I'm worried now that the tap I swapped the beer

I've ordered new beer lines and disconnects - just going to chuck the old ones. but what's the best way to nuke the bugs in the kegs and taps. Boiling or chemicals?
 

MHB

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Hey guys, I'm new to this forum (First post!), and this is one of the first posts I've read so I hope you don't mind me putting my 2 cents in.
My understanding of diacetyl is that it is in fact a flavour compound created by the fermentation process, that is reabsorbed by the yeast once fermentation is finished. Hence the phrase often used by brewers, "Diacetyl rest". That is, the time after fermentation has finished to allow the yeast to finish what it started and reabsorb these funky flavours!
Is it possible that you just haven't left your beer in the fermenter long enough? Just because your beer reaches its FG doesn't necesarily mean that the fermentation proces has completely finished.
A good way to test for diacetyl after fermentation, and to determine whether or not the diacetyl rest has finished is to put about 100mls of wort into a small conical flask (if you have one) and heat it up to about 80 degrees on the old cooktop! Once it's heated up, if diacetyl is still present you should be able to pick up that buttery/butterscotchy smell. If it's there, let your beer chill out in the fermenter for another day or so. As long as it's clean and air tight, infection won't be an issue. I generally leave my beers sit in the fermenter for at least a week after fermentation has stopped.

Anyway that's my thoughts on the issue. Let me know what you think!

Good first post!
You are right, up to a point, what you covered is pretty much on the money for Diacetyl produced by yeast during fermentation. If you have a good population of healthy yeast and give it the chance it will reabsorb all VDK's (Diacetyl is a member of a group of chemicals collectively known as Vinyl Di-Ketones). Where people run into problems is when there isn't enough good healthy yeast - two sides to that, stressed yeast well produce more VDK and be less able to get rid of it.

There are also a fair number of bacteria that can produce VDK, we have to work out whether the VDK are a byproduct of fermentation or infection - then manage the cause.
Mark
 

Bandit24

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RE: Fan inside fridge.

I'm starting my cold crash and as usual I'm getting some condensation in the fridge on the back wall. Is it safe to keep running the fan under these conditions?
 

altone

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Hey guys, I'm new to this forum (First post!), and this is one of the first posts I've read so I hope you don't mind me putting my 2 cents in.
...
A good way to test for diacetyl after fermentation, and to determine whether or not the diacetyl rest has finished is to put about 100mls of wort into a small conical flask (if you have one) and heat it up to about 80 degrees on the old cooktop! Once it's heated up, if diacetyl is still present you should be able to pick up that buttery/butterscotchy smell.
...
Anyway that's my thoughts on the issue. Let me know what you think!

Well Deepregret my friend, I've never noticed diacetyl in any of my beers and was wondering if I'm one of those people who have a really high tolerance to it.

My nose works well [It should do with the size of it :)]
so I'll try this little titbit in a few days when the next brew is at a stable SG.

Thanks, I've never seen this mentioned before (unless I forgot of course)
 

Bogan333

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Here is an Article I did in 2016 on diacetyl

Note: new studies after I did this article are saying now when dry hopping, second diacetyl rest is needed.




A lot of brewers would consider it a flaw.

All through some classic beer styles call for low levels of diacetyl. Which gives off a buttery or butterscotch aroma and flavour. Some beer drinkers actually find diacetyl to be enjoyable

So what is Diacetyl,

It is a small organic compound that belongs to the ketone chemical family that is derived from yeast in the fermentation stage as a by-product.


0

Formual (CH3CO)2

In the 1950's diacetyl levels were found in the range of 0.2 to 0.3mg/l. Today it's about 0.05mg/l

So how does it happen,

All brewers yeast stains produce it, some more than others like high flocculent yeast stains. And others have the ability to absorb and reduce diacetyl. Fermentation problems like control of temperature can also affect the diacetyl levels.

Higher the temperature results in faster yeast growth and acetolactate. The higher the acetolactate peck, the higher the diacetyl peck but higher temperature also increases diacetyl reduction.

Lower yeast growth rates can reduce the amount of acetolactate produced, it can result in higher level of diacetyl in the finished beer if the lower growth rate results in lacklustre fermentation.

It is often beers that ferment more slowly and produce less acetolactate that have problems since to yeast are still slowly producing acetolactate late into fermentation.

The vanilla tone which is often confused with caramel flavouring, definitely adds to the smoothness of the beer. The problem is that diacetyl at these levels is unstable and eventually will turn into headspace air. As consequence, these beers typically have a short shelf life and do not travel well.

The other ketone of interest is 2,3 pentanedione which together with diacetyl forms a beer's vicinal diketones (VDK) aromatic volatile compounds.


So what can I do prevent it


  1. As always go overboard with your sanitation from start to finish
  2. Make a healthy yeast starter at least four days out from brew day,
  3. BeerSmith is a great program that gives you the recommended stater size.
  4. Two days out from brew day chill your stater to 6c to settle the yeast.
  5. At the end of brew day when chilling your wort have it 2c below your target Fermentation temperature.
  6. When Pitching only pitch the yeast slurry.
  7. 24 hours after pitching increase the temperature by 1c, 48 hours again by 1c. You how should be at your target temperature.
  8. On the last two days of Fermentation increase the temperature by 2c, this will absorb the diacetyl.
  9. Carry out force diacetyl test or VDK
  10. At the end of Fermentation cold crash, your beer slowly over days down to 3c and hold or another day.
  11. Bottle or keg your beer as normal.

I hope this has helped you in your pursuit of brewing better beer

Cheers

Sandgroper

(George Copley)
 

peterlonz

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One potential problem I don't see mentioned here is your water source.
Most home brewers use tap water treated by the local authority.
But quality does vary substantially from region to region & sometimes within a region.
The problem disappears if all water is boiled to pasteurize, but that takes ages & takes a lot of time.
An alternative (which I have used for years) is to purchase a high quality water filter.
Generally they use two coupled filters. one to remove particles bigger than about 5 microns & a second "Carbon Block" filter to filter down to 0.5 microns. If you restrict the flow rate to about 2 litres per minute & change filters annually this should make a vast improvement.
Of course trial & error is the only way to know unless you have access to a lab for such testing.
For other reasons many years ago, I suspected our local water was infected with Gikaria. I called the local council & they promptly came, took water sample & within a week reported all clear.
Worth thinking about!
 

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