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itsernst · 10-04-2012, 06:46 PM

Quote:

Originally Posted by feinbera

Idunno, itsernst... at the end of conditioning, carbon dioxide is carbon dioxide, no matter where the yeast are getting the sugars that produced it.

You might see very slight variations in flavor, but think about it in terms of your total grain bill. In a five-gallon batch, you've got somewhere around a 4.5 ounces of priming, or, a quarter pound of corn sugar/cane sugar/extract/honey/whatever, versus pounds and pounds of grain and/or extract. Even in a 1.040 OG lawnmower beer, that's only something like 5% of your grain bill. Unless you're doing something crazy like priming with wort made from black patent, you're not using something that's strong enough to be very noticeable in such a small dose.

You are absolutely correct, however the variables that contribute to how the sugar becomes carbon dioxide is what I am arguing. Monosaccharids versus Polysaccharides are quite different and their molecule count can change depending on the yeast used in your brew.

BuddyWeiser · 10-04-2012, 07:27 PM

There's also not anywhere near the same amount of oxygen in a freshly bottled beer versus freshly pitched wort.

**Bobby_M** · 10-04-2012, 07:32 PM

Quote:

Originally Posted by RhesusPuffs

There's also the time it takes for the CO2 to be forced into solution. Some beers are carbonated sooner, but three weeks is a safe estimate.

Myth I say. What exactly do you mean?

**Bobby_M** · 10-04-2012, 07:36 PM

Quote:

Originally Posted by DrummerBoySeth

It only takes a week or 2 for the yeast to eat the priming sugar. The rest of the time allows the gas to be absorbed into the beer. Sort of like force-carbing a keg. You pressurize the keg and put it in the fridge, but you still have to wait a week or 2 for that gas to become carbonation. During the first part of bottle conditioning, the yeast eat the priming sugar and make CO2. Then, during the second part, that gas absorbs into the beer and becomes carbonation.

Myth I say. The process of bottle conditioning is nothing like force carbing. The origin of CO2 in bottle conditioning is IN the beer already at a molecular level which is the opposite of putting CO2 into the head space.

**AnOldUR** · 10-04-2012, 07:50 PM

Quote:

Originally Posted by Bobby_M

Myth I say. The process of bottle conditioning is nothing like force carbing. The origin of CO2 in bottle conditioning is IN the beer already at a molecular level which is the opposite of putting CO2 into the head space.

hmmmm . . . Though I saw something about someone putting a gauge on a bottle and the pressure building and then stabilizing supposedly as the CO2 from the head space went into solution. Or did I misunderstand something?

So would this also debunk the reasons for not bottling in a growler? Seems like the CO2 in suspension once sealed would be putting out the same pressure if it was bottle conditioned or filled from a keg (as long as you didn’t over prime.)

**Bobby_M** · 10-04-2012, 08:00 PM

Quote:

Originally Posted by AnOldUR

hmmmm . . . Though I saw something about someone putting a gauge on a bottle and the pressure building and then stabilizing supposedly as the CO2 from the head space went into solution. Or did I misunderstand something?

So would this also debunk the reasons for not bottling in a growler? Seems like the CO2 in suspension once sealed would be putting out the same pressure if it was bottle conditioned or filled from a keg (as long as you didn’t over prime.)

I commented on this in another thread. My criticism of that experiment was lack of temperature logging. That is the variable that I believe accounts for the spike above equilibrium. Until it is repeated with strict temp control or temp logging along with the pressure, i can't buy in.

**AnOldUR** · 10-04-2012, 08:33 PM

Quote:

Originally Posted by Bobby_M

Until it is repeated with strict temp control or temp logging along with the pressure, i can't buy in.

Sounds like an interesting experiment to try, but do you think that strict temp control is necessary? If you posted a temperature reading along with the pressure reading, could you use a kegging chart to compensate for any minor fluctuations?

How about an extreme experiment? Put a DME solution and some yeast in a high pressure vessel and monitor both pressure and temperature for a week or so? If the CO2 from the fermentation is not going to the head space before being absorbed it should be evident.

I have one of these in the shop that's rated to something like 200psi that might be up to the task with a few modifications.

**Bobby_M** · 10-05-2012, 03:06 AM

I agree. I'd prefer to see the temp logged along with the pressure. If temp can't be monitored, the lo fi version would to immerse the container including the headspace in a water bath for buffering. Ideally the temp probe would be in a thermowell in the vessel itself.

**helibrewer** · 10-05-2012, 05:23 AM

Hmmm, seems to me that the CO2 is absorbed into the liquid as it is produced. It doesn't make sense that the CO2 gets produced, then some how gets into the head space then is absorbed. If that was the case we should be able to observe the CO2 bubbles rising into the headspace.

**AnOldUR** · 10-05-2012, 09:45 AM

Quote:

Originally Posted by helibrewer

If that was the case we should be able to observe the CO2 bubbles rising into the headspace.

I'm not so sure that is the case. During vigorous fermentation in a carboy, I've observed a lot of activity as the yeast convert the sugars into alcohol and C02, but I don't know that I've seen actual bubbles raising through the wort. By the airlock activity, you know that large amounts of C02 are being produced that can't be absorbed because of the temperature and pressure restrictions.

There is probably someone on HBT who could explain this in scientific terms, but I don't have that education and have not been able to find it. For now, I am only looking at it as a mechanical thing. To me, there is logic that either way is possible. I wouldn't argue that some or even most of the C02 is absorbed as it is being formed because of the rate and area over which it is being created during bottle conditioning. But I also haven't ruled out that some of it can make its way into the headspace and is then absorbed over time.

I hope to be able to do the experiment with enough control to satisfy everyone, but I'd still like to hear the science behind why it happens. Is there an instant molecular bonding as Bobby says, or after the sugars are converted, is there a lag time during which some C02 could make its way to the surface?