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Naturally Carbing Kegs

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gryphonkd

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I've just realised why my beer doesnt fully carbonate in keg.

I've been trying to carbonate in keg. I lookup the right amount of priming sugar to achieve 2.5vols eg. Add to the whole batch in secondary, then keg half and bottle the rest.
The bottles are carbed perfectly. The kegs maybe land at 1.5 vols and taste a little sweet. So it's not fully fermenting out.
Then it dawns on me; I am transfering to keg carefully so as not to oxengenate, and the purging the headspace and laying CO2 on it.
Of course it won't ferment out! theres almost not oxygen for the yeast to work with!

I am now trying to remedy this by using a (air filtered) beer stone down the liquid line, to dissolve oxygen into the beer so it will ferment out the residual priming sugars.
Of course it still won't reach desired C02 vol (as i have blown it all out while airating) and rather than add more sugar, force carbing the rest with guess work.

In future, I could either airate on transfer to the keg, and seal with CO2, or just transfer to keg, not purge and let the headspace in the keg feed the yeast.
What do you guys do?
 

mxd

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no don't aerate your beer, is your keg full ?
 

gryphonkd

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Keg is only half full -- but question applies whether its full or half full.
Is the oxygen in the headspace enough for secondary fermentation to process all the priming sugars?
I suppose if it's a good enough approach for the bottle, should be good enough for keg.

The thing that makes me nervous; is without blasting some CO2 into the keg.. i'm never sure if it's sealing properly. Don't want to find out 2 weeks later when I go to serve flat beer. Hence I though oxygenating the liquid and then then blasting in some CO2 to seal.
Although now I think of it, I could always drive some normal (filtered) air under pressure in there to up the O2 count in the headspace, and skip the aeration.

** correction on first post - just driving filtered air down the liquid line -- no beer stone involved.
 

GalBrew

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I wouldn't pump oxygen into your fermented beer, you will oxidise it.....

You need to have a full keg you want to force the CO2 generated by yeast in conditioning into solution, otherwise it will just occupy the headspace in the keg (to a certain degree).
 

Rodolphe01

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When I have naturally carbonated a keg I use about half that I would use for bottles due to the decreased total headspace. I purged the air from the keg and it was carbonated fine. Oxygenating fermented beer is just about the worst thing to do to it AFAIK.
 

mxd

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gryphonkd said:
Keg is only half full -- but question applies whether its full or half full.
Is the oxygen in the headspace enough for secondary fermentation to process all the priming sugars?
I suppose if it's a good enough approach for the bottle, should be good enough for keg.

The thing that makes me nervous; is without blasting some CO2 into the keg.. i'm never sure if it's sealing properly. Don't want to find out 2 weeks later when I go to serve flat beer. Hence I though oxygenating the liquid and then then blasting in some CO2 to seal.
Although now I think of it, I could always drive some normal (filtered) air under pressure in there to up the O2 count in the headspace, and skip the aeration.

** correction on first post - just driving filtered air down the liquid line -- no beer stone involved.
your problem is the amount of head space you have, all the CO2 your generating is filling the headspace then trying to carb.

Why do you keg carb ?
 
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You've pretty much described the procedure I use when naturally carbonating my kegs and I always get good carbonation.

In my opinion you need to pump co2 into the keg to get a good seal, purging the oxygen isn't necessary, but I do it (habit from when I force carbonated) and have never had a problem.
 

gryphonkd

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I have deliberately oxidised the beer -
I am hoping there is enough residual priming sugar to ferment out the batch; not to achieve carbing in this case, but to remove the undesirable sweetness I could taste (compared to conditioned bottles of the same batch)
Could have been a dreadful mistake.... will find out in a few days.
 

RobW

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Could this have been a dreadful mistake....

Almost certainly
 

mxd

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gryphonkd said:
I have deliberately oxidised the beer -

Could have been a dreadful mistake.... will find out in a few days.
yes, you oxidise wort not beer. you'll get a nice cardboard flavour

your sweetness may be related to under carb, tasting too early, you can ferment yor wort without oxygen (will probably have some off flavours)

Do a gravity test, that'll tell you if it's fermented out.
 

MaltyHops

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gryphonkd said:
...
Of course it won't ferment out! theres almost not oxygen for the yeast to work with!
...
Yeast need oxygen to reproduce themselves and when the O2 level is low,
they switch mode to produce CO2 so I reckon if your beer in the keg is low
in yeast numbers, then it will take time for the yeast that is there to carb up
your beer.

As others have said, adding extra O2 to your beer is not a good idea.

Might have been better to have added rinsed yeast from the yeast cake
instead so you have an instant significant amount of yeast to carb away
from the start.
 

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