How does beer carbonate in keg?

MBM30075 · 11-17-2009, 07:28 PM

No, I'm not asking how pressure forces the CO2 to dissolve into the beer.

I don't like to "force" carb my kegs in the traditional method. I think I shake it too hard or something, but my first two kegs I shook the crap out of didn't taste right. Since then, I've gone with the following method:

1. Purge air from keg.
2. Stick keg in fridge.
3. Put keg under ~25-30 psi
4. After 4 or 5 days, sample 1/2 to 1 glass of beer per day until ready

This usually takes about 10 days to finish, but of course the beer in the mean time isn't so bad!

I've got 2 kegs that went in the fridge last Thursday night. One keg seems to be about halfway to being carbed, the other is coming more slowly.

It's gotten me thinking, though: Is the beer on top more carbed than the beer at the bottom?

Since the pressure is coming from up top, you'd expect the CO2 to dissolve up there first, and only later make its way down to the beer at the bottom.

Is that a correct theory or bunk?

If I shook that keg gently, just to swirl it, would the carbonation diffuse throughout the beer and noticeably alter the beer I'm drawing off?

Anybody know why the two kegs, both hooked to the same regulator would carb at such different rates?

I pulled a 2 liter of beer from one of them to carb up separately. Would the extra head space allowed by that combined with the smaller volume of beer to carbonate make it carb up faster? Makes sense to me; is it right?

Thanks!

Suthrncomfrt1884 · 11-17-2009, 07:45 PM

Different gravity beers carb differently. I always hook my beers up to the gas at about 12-15psi and let it sit for 3 weeks before I touch it.

JesseRC · 11-17-2009, 07:48 PM

25-30 psi for more than 2 days is gonna cause overcarbonation. Most folks only do that for 24-48. Still at 5 days I still consider th beer young and will have some carbonic bite to it.

MBM30075 · 11-17-2009, 08:06 PM

Jesse,

I hate to do it, but I have to disagree. I've done it this way for 6 or 8 batches now, and I can tell you for SURE, based on my latest batch, that the beer being served isn't over-carbonated. The top may be, but not the bottom.

Should I crank it down to 12-15 and let it sit?

Why would it be "young" at 5 days on the gas? Wouldn't its "age" be determined by how long it was in primary and secondary, not how long it's had gas in it?

Thanks

JesseRC · 11-18-2009, 12:55 AM

Quote:

Originally Posted by MBM30075

Jesse,

I hate to do it, but I have to disagree. I've done it this way for 6 or 8 batches now, and I can tell you for SURE, based on my latest batch, that the beer being served isn't over-carbonated. The top may be, but not the bottom.

Should I crank it down to 12-15 and let it sit?

Why would it be "young" at 5 days on the gas? Wouldn't its "age" be determined by how long it was in primary and secondary, not how long it's had gas in it?

Thanks

Well you just just said that the top is. I don't want to deal with any kind of over carbonation. I shoot for equilibrium, which can be accurately achieved by leaving it on gas for 3 weeks at serving pressure. Your beer will only get better the longer it sits on gas. Despite the aging in the Carboy, the beer willbenefit from a few weeks on gas..

**Yooper** · 11-18-2009, 12:59 AM

Quote:

Originally Posted by MBM30075

Jesse,

I hate to do it, but I have to disagree. I've done it this way for 6 or 8 batches now, and I can tell you for SURE, based on my latest batch, that the beer being served isn't over-carbonated. The top may be, but not the bottom.

Should I crank it down to 12-15 and let it sit?

Why would it be "young" at 5 days on the gas? Wouldn't its "age" be determined by how long it was in primary and secondary, not how long it's had gas in it?

Thanks

Yes, we're not really talking about the age of the beer. We're talking about that carbonic acid bite that comes from quick carbing.

I usually quick carb mine- 30 psi for about 36 hours, then purge and set at 12 psi. It's drinkable in two days, but better after a week. The carbonic "bite" seems to mellow by then.

MSOE_HomeBrew · 03-30-2011, 03:04 AM

How does letting the beer sit on gas affect the taste? I have a stout that I plan to keg tomorrow and it has been aging in the secondary for 3 months now.

WPen · 03-30-2011, 01:08 PM

Quote:

Originally Posted by MBM30075

If I shook that keg gently, just to swirl it, would the carbonation diffuse throughout the beer and noticeably alter the beer I'm drawing off?

Anybody know why the two kegs, both hooked to the same regulator would carb at such different rates?

I pulled a 2 liter of beer from one of them to carb up separately. Would the extra head space allowed by that combined with the smaller volume of beer to carbonate make it carb up faster? Makes sense to me; is it right?

Thanks!

There are many factors that contribute to the carbonation level, pressure, temperature etc. The fact that you shook one and it also had more headspace means that the beer should be more carbonated than if you had just "set it and forget it". What I normally do is force carb at 30 psi for 24 hrs then drop to serving pressure. I do it with the beer cold and also with some rolling of the keg to give more beer to CO2 surface area, resulting in faster equilibration. The beer always tastes great after a week at serving pressure.

Jaysus · 03-30-2011, 01:12 PM

Quote:

Originally Posted by Yooper

I usually quick carb mine- 30 psi for about 36 hours, then purge and set at 12 psi. .

Do you shake the keg during the 36 hours? If so, how often?