Yet Another Diacetyl Question

[Goose]

Apologies for yet another diacetyl question.

I brewed up 2 kegs of lager, pretty much identical processes, had the luxury of being able to lager them in a keg (carbonated) for 4 months +. One was absolutely magnificent, but the other other had a distinct diacetyl taste, but otherwise faultless. I am confident there is no infection, so unsure what was the cause, though it is possible that the pitching temperature was a little too high for the second brew.

Nonetheless, have tried warming the beer to 20 deg C for 3 days but to no avail. The reason this didn't work is likely because there is no residual or active yeast remaining in the brew. I have read I could try pitching some active krausen or a yeast starter into the keg bit loathed to try that since beer is sparkiling clear after so many months of lagering.

I have heard that bubbling CO2 through the beer can do the trick. To do this I was thinging maybe injecting CO2 at 2-3 psi through the liquid outlet and releasing the gas out the safety valve. I dread to think what foamining issues I may end up with and no idea for how long I'll need to do this.

Does anybody have any experience bubbling CO2 to remove diacetly ? I am curious as to the mechanism of this as did not realise diacetly could enter the gas phase so readily (???) ...

 

[Fourstar]

I have heard that bubbling CO2 through the beer can do the trick. To do this I was thinging maybe injecting CO2 at 2-3 psi through the liquid outlet and releasing the gas out the safety valve. I dread to think what foamining issues I may end up with and no idea for how long I'll need to do this.

By doing this, you will remove the aroma of Diacetyl but also strip any hop aromas and other phenols as well. Personally i would do the follwing.

Drop a small amount of dextrose into the keg at ambient temps (say 1/4 of what would be used to force carb the keg. The yeast will become active, eat the fermentables, then go dormant. Following this the yeast will then absorb the diacetyl they produced and hopefully the excess left from the 1st fermentation cycle. If that fails, you can always send the keg my way and i will give you an empty one i have. The true meaning of 'mykegonlegs'

Cheers,
Fourstar

 

[newguy]

Throw in a packet of dried yeast - S04 or Nottingham would be okay - stay away from any 'funky' or wheat beer yeasts. The new yeast should consume the diacetyl without adding new ale-type flavours. Leave it at 18-20C for 3-4 days and sample again. The diacetyl should disappear. If not, it may be pediococcus.

 

[Bribie G]

I accidentally made a batch of buttersotch burton ale and ended up liking it so much I'm going to try to make it again! Yup, rush it into secondary, bottle early.... I've got a sample of the yeast in the fridge.

 

[eamonnfoley]

By doing this, you will remove the aroma of Diacetyl but also strip any hop aromas and other phenols as well. Personally i would do the follwing.

Drop a small amount of dextrose into the keg at ambient temps (say 1/4 of what would be used to force carb the keg. The yeast will become active, eat the fermentables, then go dormant. Following this the yeast will then absorb the diacetyl they produced and hopefully the excess left from the 1st fermentation cycle. If that fails, you can always send the keg my way and i will give you an empty one i have. The true meaning of 'mykegonlegs'

Cheers,
Fourstar

Does this mean that Ross's carbonation method strips the hop flavour from the beer? I have a kegged beer with little flavour (despite decent american hop additions).

 

[buttersd70]

Does this mean that Ross's carbonation method strips the hop flavour from the beer? I have a kegged beer with little flavour (despite decent american hop additions).

No, because it is in a sealed keg....the method mentioned is done with the pressure valve open, so the co2 passes through the liquid, then escapes the keg, carrying the volatiles with it.

 

[Goose]

No, because it is in a sealed keg....the method mentioned is done with the pressure valve open, so the co2 passes through the liquid, then escapes the keg, carrying the volatiles with it.

thanks chaps, I know that bubbling CO2 removed DMS but thought diacetyl a bit too complex a compound to be removed in the gas phase. a bit of googling and I come away with the undertanding that the purpose of the CO2 bubbling is to agitate the yeast back into suspension. But in my case, having racked this beer carefully am pretty sure their aint any residual yeast, let alone active yeast.

will give the CO2 a shot first....

 

[Fourstar]

Does this mean that Ross's carbonation method strips the hop flavour from the beer? I have a kegged beer with little flavour (despite decent american hop additions).

No, because it is in a sealed keg....the method mentioned is done with the pressure valve open, so the co2 passes through the liquid, then escapes the keg, carrying the volatiles with it.

Butters is correct, Ross force carb method does not strip hop FLAVOUR from the beer. Although you would be stripping hop AROMA from the keg if you are forcing CO2 into the keg and continually purging. As hop aroma degenerates over time its probably already quite subtle in your kegs anyway.

If i can avoid it, any kegs i have with big hop aroma additions i will not touch the pressure relief valve until im going to open the lid to clean it. I'd prefer to be undercarbed than overcarbed

 

[Goose]

Tried the bubbling mthod by attaching a liquid out connector to the gas hose and attaching it to keg, bubbling at 2 psi for 30 minutes with safety valve locked open for gas release. No change to taste or specifically to diacetyl taste. Tried then increasing to 3 psi and bubbling for another 1/2 hour.... still zero effect.

Conclusion: Diacetyl prefers to stay in the liquid phase and will NOT scrub out with CO2 in the gas phase.

No surprise really. Going to try to pitch some yeast slurry next, maybe a teaspoon or two and warm to room temperature for a few days to see if that will chew it up.

 

[Goose]

Just to complete the thread.

7 days ago I pitched three tablespoons of yeast slurry from a brew that I had just finished, and raised the keg to room temperature.

Chilled an tasted, wow, those active yeasties really did soak up that diacetyl :icon_cheers:

Beer now tastes clean as a whistle though I expect it will take a week or so to settle and clear properly. Oh well, alot better that the drain which is where it was headed initially.

Goose

 

[razz]

Did you identify the minor changes in the two brews Goose?

 

[cozmocracker]

what does this diacetyl taste like, i have a lager i have done and conditioned for weeks, and all through the process( from fermenting to now) it has had a sulphury taste and smell like the vapour coming out the airlock from the Saflager S23 yeast i used. is this the diacetyl? i was hoping more cold conditioning would get rid of it. tempted to dump it if i cant get rid of the taste.

 

[Goose]

G'day Razz, the only difference was that I used yeast from the first brew to make the second. Otherwise , the process was pretty much the same, which suggests that the as you re-use yeast the chances of it throwing diacetly increase perhaps ?

comocracker, taste is a difficult thing to describe. The most common description of the taste is akin to buttered popcorn but damn if I can associate it that way (I love popcorn but diacetyl is plain vile). Once you taste it you will never forget the taste and trust me you do not want it in your beer.

It is not sulphury like you describe and in fact the rotten egg smell is normal for S23 during fermentationif I recall, though you may have a dose of DMS (di methyl sulphide) of in an extreme case a bacterial infection which can create sulphury smells and taste. If its DMS then you can try bubbling CO2 threough the beer if you are kegging.

 

[cozmocracker]

mmmm, infection you say, i will look up DMS, but as i said its been there through fermentation and i used some of the yeastcake for the next brew i did and it doesnt have the same taste or smell?? so that leads me to think its not an infection, of course im new and could be totally wrong, but thanks for the reply goose.

 

[Kai]

Butters is correct, Ross force carb method does not strip hop FLAVOUR from the beer. Although you would be stripping hop AROMA from the keg if you are forcing CO2 into the keg and continually purging. As hop aroma degenerates over time its probably already quite subtle in your kegs anyway.

The two are part & parcel, if you are stripping aroma then you are stripping flavour too. One end of the spectrum is just more volatile than the other.

 

[kook]

The two are part & parcel, if you are stripping aroma then you are stripping flavour too. One end of the spectrum is just more volatile than the other.

Exactly. It's amazing the difference it can make to the perception of flavour.

Anyone who has lost their ability to taste properly with a cold realises the importance of aroma in taste.

 

[Goose]

The two are part & parcel, if you are stripping aroma then you are stripping flavour too. One end of the spectrum is just more volatile than the other.

yep ..in the case of diacetly you can smell it before you taste it which is why I gave the CO2 bubbling a shot. I have not noticed any hop aroma loss though this lager was pretty light on and dry to start...

Goose

 

[Online Brewing Supplies]

Tried the bubbling mthod by attaching a liquid out connector to the gas hose and attaching it to keg, bubbling at 2 psi for 30 minutes with safety valve locked open for gas release. No change to taste or specifically to diacetyl taste. Tried then increasing to 3 psi and bubbling for another 1/2 hour.... still zero effect.

Conclusion: Diacetyl prefers to stay in the liquid phase and will NOT scrub out with CO2 in the gas phase.

No surprise really. Going to try to pitch some yeast slurry next, maybe a teaspoon or two and warm to room temperature for a few days to see if that will chew it up.

"Conclusion: Diacetyl prefers to stay in the liquid phase and will NOT scrub out with CO2 in the gas phase",
Just as I suspected, if it was that easy there would be no Diacetyl around.Where did you guys get this idea from? I have no science to say this so called method removes Diacetyl, I have seen it used to remove volitiles in green beer though.
GB

 

[tommygun]

a little OT but just came across a interesting diacetyl explaination if anyone is interested.

http://www.whitelabs.com/beer/Diacetyl_Time_Line.pdf

tom :icon_cheers: