# Diacetyl In Your Beer



## Voosher (6/11/06)

I have recently subjected fellow brewers and beer drinkers to a beer with strong diacetyl. Granted it was probably a little stronger ( :excl: ) than "ideal" and I will be taking further steps to reduce it in future but the range of opinions I have found quite surprising as indicated by the questions in the poll above.
I'd love to hear more opinions, er... especially from fellow participants in the SA Christmas Case.


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## pint of lager (6/11/06)

The online magazine Brewing Techniques has an article on diacetyl. I don't have the specific link, but have a browse through their index, it is not hard to find.

Link.


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## Steve (6/11/06)

I dont like it. If I wanted to taste butterscotch i'd buy a bag of worthers. I want to taste the malt n hops n yeast.
Cheers
Steve


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## Kai (6/11/06)

A little is ok depending on the beer, a lot is not. I don't mind some faint caramel notes and a tiny bit of that buttery slickness, but only a little bit. I'm sure by xmas yours will have toned down a fair bit.


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## Fingerlickin_B (6/11/06)

I'm not willing to vote yet, as I'm not entirely sure that I know how to detect it :huh: 

There were two extract brews recently that had an odd taste that I couldn't explain.

They were in different fermenters, but in the same box together at the same time when fermenting, so both would have been subject to the same temperature variations. 

I hated it and one of my mates that tried the beers said they tasted normal for my beer and couldn't pick any difference. 

Quite possibly it was Diacetyl and he's one of those people I've read about that cannot detect it. 

I wouldn't call this taste "butterscotch"...more like "musk"...is that Diacetyl?

PZ.


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## THE DRUNK ARAB (6/11/06)

Voosher, what yeast has given you diacetyl?

I have had it a few times, with Wy 1028 and 1056 also with US 56. In the two cases with the Wyeast I had actually bottled the beer and I found that after a month or so in the bottles the diacetyl had disappeared.

C&B
TDA


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## Asher (6/11/06)

I aim to produce none.... but fall back on the relevent style guide as the reason it's there when it does appear


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## Voosher (6/11/06)

THE DRUNK ARAB said:


> Voosher, what yeast has given you diacetyl?
> 
> I have had it a few times, with Wy 1028 and 1056 also with US 56. In the two cases with the Wyeast I had actually bottled the beer and I found that after a month or so in the bottles the diacetyl had disappeared.
> 
> ...



'twas the 1187 Ringwood.
It was fermented at 18-19C and not given a thorough diacetyl rest mainly because I had no idea what was required for a rest for ale yeasts. I have since discovered from Wyeast that 72 hrs @ 21C should give sufficient rest for this and most other diacetyl prone ale yeasts (eg 1968 and the 1469 Timothy Taylor has thrown a little during ferment as well.) It should also subside with time - I was told about 6 weeks - but this particular brew had 2 weeks each primary and secondary, 2 weeks conditioning and now at 6 weeks in the bottle it's still more than evident.
The current diacetyl prone brews (another Ringwood and the Timothy Taylor) are getting a thorough rest so I'll see how it goes.

Fingerlickin_B
Brew with the 1187 and I reckon you'll find it.  
Having 'discovered' it - and I find it more on the nose than the palate - it's now easy to detect elsewhere as well.

I think this is possibly the actual article to which POL referred.
Diacetyl: Formation, Reduction, and Control
I haven't read it yet but will as soon as poss.

And for what it's worth I voted "Good for a change or a distinctive flavour". I don't mind it but as I said earlier it's not too heavy for me on the palate. Having said that I've made some recipe adjustments this time around to get a better balance.

Cheers.
:beerbang:


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## nifty (6/11/06)

I'm not sure what it tastes like. I think I'd need someone to specifically say that this beer has diacetyl before I recognized it.

nifty


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## Voosher (6/11/06)

> I think this is possibly the actual article to which POL referred.
> Diacetyl: Formation, Reduction, and Control



Interesting article.
Of particular interest - especially with regard to diacetyl prone _ale _yeasts - are the increased tendency of diacetyl production for high flocculating yeasts into which category both 1187 and 1968 fall; and the role of oxygen in diacetyl production. A heavily and properly oxygenated wort should limit diacetyl production.


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## Steve (7/11/06)

Fingerlickin and nifty....next time you are at the movies buy a bag of popcorn....then you will know what diacetyl tastes and smells like.
Cheers
Steve

P.S. also for whats its worth, I voted for: If I hold my nose I can just get it down


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## Fingerlickin_B (7/11/06)

Steve said:


> Fingerlickin and nifty....next time you are at the movies buy a bag of popcorn....then you will know what diacetyl tastes and smells like.
> Cheers
> Steve
> 
> P.S. also for whats its worth, I voted for: If I hold my nose I can just get it down



Well, after that one I'm pretty sure it _was_ Diacetyl. 

Voted the same as you Steve...it was the closest option I could find to "didn't like it, but still forced myself to drink both kegs" :lol: 

PZ.


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## Steve (7/11/06)

Fingerlickin_B said:


> Steve said:
> 
> 
> > Fingerlickin and nifty....next time you are at the movies buy a bag of popcorn....then you will know what diacetyl tastes and smells like.
> ...



:lol:


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## Trev (7/11/06)

Diacetyl can also arise from an infection, pediococcus(sp) as well as technique/yeast. You can rest it and bottle condition it till you're blue in the face and it's still there.

I had the pleasure(?) of serving a butterscotch ale to a group of brewers last year. If I could have distilled it, which of course I wouldn't because that's illegal, and made the nicest butterscotch liqueur  

Mind you, I've also made Banana Ale (damn Isoamyl Acetate - a bit too warm fermentation with a Weiss yeast) as well as a couple of Band Aid ales (damn phenolics - gotta watch that sparge temp).

Trev


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## delboy (7/11/06)

i agree with nifty in post 9 but i do not totally agree with steves comment in post 11 . NO DISRESPECT STEVE but popcorn allways tastes a bit card boardy to me and if my beer had tones of that i would say it was oxidised .but then if you got butter flavoured popcorn the i would say oxidised and may be diacetly .
i have never really come across a diacetle taste in anybeer but then again we all taste things a little differently and i have more than likely drank loads of it and never thought any different because it was a home brewed beer . unless someone put a beer under my chin and said that taste like diacetle is in that beer then i might know it .

can anyone tell me do the major brewers have this problem or is it only us hbrs .

delboy 
brp


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## Voosher (7/11/06)

delboy said:


> can anyone tell me do the major brewers have this problem or is it only us hbrs .
> 
> delboy
> brp



Coopers Pale Ale has been known to have diacetyl around Christmas time when they're pumping it out at near maximum capacity.
That doesn't surprise me. Many have had diacetyl in beers made with recultured Coopers yeast... myself included... now I know what to look for.  

There are beers which legitimately show signs of diacetyl - certainly several Brit ales. I wouldn't use them as a definitive guide out here though. I find the quality of British bottled ales is too variable though having said that you'd likely find diacetyl in the Fullers beers (1968 yeast) and I generally think the ESB is of good quality by the bottle out here.


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## dr K (7/11/06)

Diacetyl, like many other components in beer is produced as part of the fermentation process. Some beers will exhibit more than others and in many beers I believe it is an important part of the flavour balance.
If you are making a lager you will often do a diacetyl rest (?) after fermentaion has pretty much finished by bringing the fermenting chamber up to say 18C, this will invigorate the sleepy old yeast who will feel like a bit of breakfast and as most of the sugars have gone they will happily eat the diacetyl.
Ale yeasts though, tend to produce higher levels of diacetyl full stop so if you package (bottle or keg) too early the yeast may have eaten the bread but not the butter !!!!
Another cause of diacetyl is gravity racking, you will introduce some oxygen and kick off a genuine secondary fermentation with resulting diacetyl.
Bottom line is that diacetyl is not a bad thing, too much is a worry.

K


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## delboy (7/11/06)

SO IF THIS IS NOT A MAJOR CONCERN to Coopers why do we cringe at the thought? I know that producing the perfect beer is the goal here but that would be near impossable as most of us have different expectations.
I tend to take the art of beer making simply that an art and try not to worry to much about the cloning factors but i rather like to take a style and customise it for me .hey you guys here are a wonderful resorse and this is a great place to learn and i love the site so there is no disrespect here .

keep up the work 
DELBOY BRP


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## Voosher (8/11/06)

delboy said:


> SO IF THIS IS NOT A MAJOR CONCERN to Coopers why do we cringe at the thought?



It's not so much that it not a major concern for Coopers... it's more that supply and revenue are BIGGER concerns.
Coopers Pale Ale is better WITHOUT diacetyl.


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## AngelTearsOnMyTongue (8/11/06)

I just dont know.... I'm really curious though as I have no doubt that some (or all) of my brews must have diacetyl.

I have been curious about Diacetyl ever since I became a member of this site and am still none the wiser. Cant someone just make little taster tubes and circulate them to members?

Maybe a "Lick and taste" card?

Is there a beer that has a signature diacetyl flavour. ie a beer I can go and buy to taste this elusive character?

cheers in confusion

ATOMT


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## Voosher (8/11/06)

AngelTearsOnMyTongue said:


> I just dont know.... I'm really curious though as I have no doubt that some (or all) of my brews must have diacetyl.
> 
> I have been curious about Diacetyl ever since I became a member of this site and am still none the wiser. Cant someone just make little taster tubes and circulate them to members?
> 
> ...



As I mentioned earlier, I reckon you'd find it in Fullers beers primarily because of the 1968 yeast but they're never going to allow it to be obvious and dominant. Looks like I'm just going to have to grab some London Pride and ESB to check. Damn you.  

Taste and smell are notoriously individual senses. Two people can taste the same thing and describe it in completely different ways. I remember reading somewhere that every human's sense of taste is essentially unique albeit with some peoples' senses of taste being closer than others.

I was never convinced that I knew the diacetyl flavour until recently. I wouldn't describe it as "butterscotch" which is the most common description I've heard. I think the "buttered popcorn" description is closer for my palate. The mouthfeel is buttery and the taste is caramelly for mine. And yes, I know a lot of people will say "that's butterscotch". :blink:

I don't think that diacetyl is common in most home brews. Most home brewers use yeast which is not prone to heavy diacetyl production and ferment at temps which discourage diacety retention (20-22C)


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## pint of lager (8/11/06)

A little diacetyl can compliment the flavour profile of a beer. Doesn't matter if it is BJCP guidelines or not. A lot of diacetyl is nasty.

Join a strong brewclub that has plenty of mashers on board. That way, you can learn more about the beers you are making and tasting. Mashers tend to use yeasts and brew styles that have diacetyl in the profile.

If you are really keen, study for the BJCP where diacetyl is covered thoroughly.

Refresh your memory of butterscotch. Go buy a packet today. The popcorn that used to be called Lolly Golly Bliss Bombs (popcorn covered with a caramel/sugar glaze) was full of diacetyl aromas and flavours.


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## DJR (30/11/06)

OK to bring back an old thread...

I'm wondering when we actually have to do a diactetyl rest for lagers - ie. is it necessary when pitching cold with a big cell count? Last night i racked a Boh Pils into a CC cube after a 48 hr diacetyl rest. Before this, i had made the lager with the slurry from a 3L starter of WLP802 and pitched and fermented at 8C. The fermentation happened great guns, 1050 to 1020-odd in 7 days (i also added half a chelated zinc tablet at the start of fermentation which also probably explains the speed). It tasted pretty sulfury at that point and had quite a whack of butterscotch flavour. I then took the fermenter out and did a diacetyl rest at 18-20C for 48 hrs.

Now, what i think i'm reading is that 1) the WLP802 yeast creates low diacetyl so i may not have needed the rest and 2) pitching cold with a big starter minimises diacetyl production. So if i'd have kept the beer in the primary ferment till it was done and then racked&lagered at 2-4C i might have got a better beer, without the diacetyl? At the moment it tastes like most lagers taste just after CCing - starting to clear up but a good 2-3 weeks at least to go.


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## newguy (30/11/06)

AngelTearsOnMyTongue said:


> I just dont know.... I'm really curious though as I have no doubt that some (or all) of my brews must have diacetyl.
> 
> I have been curious about Diacetyl ever since I became a member of this site and am still none the wiser. Cant someone just make little taster tubes and circulate them to members?
> 
> ...



I've noticed that women tend to be more sensitive to diacetyl than men. It has to be very strong before I notice the taste and aroma, and a lot of the brewers I know are the same way.

Anyway, the way I tell if a beer has low levels of diacetyl is by the slickness on the tongue & teeth. The beer also seems "colder?" when it has a bit of diacetyl. By colder I'm thinking of the "ice" chocolate and the cool sensation you get from it. I tend to notice the coldness first, then the slickness (but I have to look for that).

If you think you notice some diacetyl, ask your wife/girlfriend. Chances are she'll be able to pick it out if it's there.

Finally, attend as many homebrew club meetings as you can as well as competitions. This will greatly increase your chances of running across a strong diacetyl example.


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## marky_mark (30/11/06)

As a test for diacetyl and for anyone who wants to find out what it tastes like...

- take one of your lagers (or ales if you wish, but more of an issue in lagers) as its coming toward the last 1/3 of fermentation cycle (around SG of 1.025-1.020)
- take out two samples (in two shot glasses or something similar)
- place one sample in a tray with boiling water up to the level of the sample so as to heat the sample, and leave it for half an hour. Once time is up, place this sample in the fridge.
- refridgerate the other sample
- take both samples out and give them a taste test each. If you've got some diacetyl in your beer you WILL know about it. It'll taste like off, oxidised butter. 

This is what I do for most of my lagers just to see if I need a diacetyl rest, because it all depends so much on how the fermentation has gone so far. 
But its a good newbie introduction to diacetyl as well.

Cheers,

Mark


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## Stuster (30/11/06)

DJR, not sure if you've read it, but Trough Lolly's post on diacetyl might be a good read.


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## DJR (30/11/06)

Stuster said:


> DJR, not sure if you've read it, but Trough Lolly's post on diacetyl might be a good read.



I did read it along with about 10 other information pages i found in a google search on the topic - so much conflicting information i'm wasn't sure what was going on! Some people say wait for terminal gravity, some say 50% of the way, other say 66% or 75%! But i couldn't find anything about whether the diacetyl rest is required when pitching cold! I'll just assume that it is and after lagering my boh pils should taste quite nice!


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## voytekl (30/11/06)

I find if I taste my bottle carbonated beers early (like a week in or so - for the sake of science honest!) I get a taste that I'm assuming is diacetyl that then clears. Which makes sense based on how diacetyl's sposed to work from the reading I've done.

Although I only figure that's what it is based on how people describe it rather than anything like knowledge.

cfm


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## DJR (30/11/06)

Well it seems that if you pitch cold there should be little diacetyl - counter to what i thought before, diacetyl levels increase if the temperature is higher than what it should be. So if you pitch cold a diacetyl rest shouldn't be needed. In any case it should clear up a couple of days after fermentation finishes anyway. I found this good study http://www.mbaa.com/TechQuarterly/Articles/2002/0916-05.pdf but the fermentation that they show in the graphs was carried out at 14C - of course it's going to throw diacetyl, and considering the point of their research (trying to sell Maturex to large breweries) it's not surprising they chose that temperature! Raising the temp of fermentation/pitching seems to be the killer. If you do the classic homebrew "pitch at 20C and drop to 8-10C" trick, chances are you need a diacetyl rest, if you pitch cold, don't bother.

If someone has more info, i'd love to hear it...


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## matti (30/11/06)

I don't worry about it in my ales as its generally disguised as fuller flavour. Even though my avatar suggest i like Urqell, I find it annoyingly lingering even in this fine drop.
The butterscotch taste doesn't quench you thirst like a Munich dunkel or Carlsberg.  

matti


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## Pennywise (21/4/10)

Rather than starting a new thread I'll revive this one.

I believe I can now taste diacetyl  , I've never picked up on that buttery coating down the back of the throat that lingers for a minute or so. Unfortunatly I don't go much on it at all and I'm struggling to get through a keg of dark ale fermented with Wyeast 1084 Irish Ale, it was fermented quite warm, 20 degrees from memory. Funny, I've made this same beer quite a few times and never had an issue, although last time I made it was about 8 months ago, so maybe I'm picking up on different flavours since quitting smoking? I can actually feel the thickness of it as it goes down the back of my throat. Just sharing my dissapointment.
I vote, If I hold my nose I can just get it down


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## Bribie G (21/4/10)

To me, diacetyl just tastes a bit like werthers butter drops. Maybe that buttery thing down the back of your throat is something else? I like a bit of diacetyl and next time I can get some Wyeast 1768 I'll put through a quick batch to encourage some Diacetyl :icon_drool2:


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## Pennywise (21/4/10)

Not sure BribieG, first time I've noticed it, but it is alot like those worthers lollies, it just feels like it's a syrupy texture as it goes down, the beer itself isn't syrupy though. I have another batch on the go so I'll see how that goes. Hoping It is something else really


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## Thirsty Boy (24/4/10)

excessive diacetyl will (can) give you a slippery/oily/greasy mouthfeel. I find it quite mouth coating when its excessive - which is most of the time for me. I'm relatively sensitive to D and not all that fond of it in most circumstances.

Perhaps thats the syrupy texture.


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## MHB (24/4/10)

> Refresh your memory of butterscotch. Go buy a packet today. The popcorn that used to be called Lolly Golly Bliss Bombs (popcorn covered with a caramel/sugar glaze) was full of diacetyl aromas and flavours.


POL

That's showing your/our age, Google couldn't even find a pick of the packet but I remember the old cardboard box and a flood of memories.

Problem with Di-acetyl is that there are two peaks on the sensitivity graph; some people can detect it at low levels and some need much higher amounts before they notice it; I'm one of the latter.

For me Di-acetyl is an integral part of British beer and it takes reasonably over the top amounts to be too much, but like I said that's genetic and you can't pick your parents so we are all stuck with what we have. For others I can appreciate that much smaller amounts can overshadow the other flavours in a beer and become quite annoying.

Still can't find any excuses for the amount in Fat Yak enough that it ruins the beer for me.

MHB


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## Caelum (24/4/10)

The only commercial beer i've found to have a very 'in your face' Diacetyl flavour is Cascade Export Stout.

In this case, it gives the beer a really nice full buttery/butterscotchy flavour - in any other beer i'd be questioning how suitable it really is, but for this style of stout, i approve.


I tend to find the flavour diminishes somewhat after the first stubby... Perhaps your tastebuds just get diacetyl overload 


Though the website seems to suggest otherwise, cascade make two stouts, with the normal 'stout' being less diacetyl flavoured than the export stout.. The "Export Stout" has a shorter maturation time, which brings out those diacetyl flavours quite strongly.

Apparently the export stout is part of the tasmanian range - maybe it isn't available on the mainland, wiki states that it is only brewed in small quantities.



Regardless, the Export stout, along with coopers best extra, and ofcourse guinness, are my 3 favourite black beers...


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## Thirsty Boy (24/4/10)

I was talking to the Cascade brewer about 6 months ago and he was telling me they work quite hard to get that Diacetyl profile in there - most sweeter stouts have a decent chunk of the stuff.



> Still can't find any excuses for the amount in Fat Yak enough that it ruins the beer for me.



not meant to be in there - and it _usually_ isn't. But then again, it is often enough to shit me to tears. Completely out of place in that sort of beer. There is no excuse for it in my book. Cascade is a big enough and complex enough brewery that they should have this crap under control. I think Fat Yak is a perfectly reasonable crossover APA.. when its right. It _should_ be all the time and isn't.


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## lespaul (29/12/11)

so, ive made a rice beer that i fermented with us05 at low temperatures, mainly because i didnt want to wait the time for a lager yeast.
Ive ended up with a bucket load of diacetyl, which, given the type of beer is pretty much all you can taste. Never had this problem before, and the only thing i think that could have caused it is over pitching (yeast spewing out the airlock).
Did a diacetyl rest but hasnt really cleared up that much.

What would you do?

1. lager and hope it dies down
2. get mates over for free piss
3. water the garden
4. possibly add bitterness to the beer to try and drown some of it out (currently the beer is only ~ 20IBU)
5. unknown solution?

Cheers


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## felten (29/12/11)

warm it up, diacetyl rest.

ed: i am stupid and can't read


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## mika (29/12/11)

lespaul said:


> .....
> Never had this problem before, and the only thing i think that could have caused it is over pitching (yeast spewing out the airlock).
> .....



Nope, that's just US-05.



lespaul said:


> .....
> Did a diacetyl rest but hasnt really cleared up that much.
> .....



Describe how you did this, tend to think you did it wrong, or it's not diacetyl that you're tasting


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## lespaul (29/12/11)

was fermenting at 17... then heated it up to 21-22 for a couple of days
not diacetyl?


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## mika (30/12/11)

Would have thought that would of done it, though 6 above ferment temp is recommended. You didn't filter it to clear it up, or anything like that to remove the yeast before you discovered the diacetyl type flavour ?


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## mika (30/12/11)

Quick after thought, another source of diacetyl is a Pedio infection, which would persist and not be re-absorbed. Not sure how quickly the pedio produces diaceytl though.


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## lespaul (2/1/12)

so should the diacetyl get worse over time?


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## mika (5/1/12)

If it was due to a Pedio infection, yes, up to a point before it starts going all sour on you as the Pedio converts the Diacetyl into whatever chemical is responsible for the sour (don't think it's pure lactic with Pedio, but don't know enough to be sure)


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