Quick question about bottle conditioning and bottle size

[Mothman]

In an earlier thread I posted about a bad bottling day, where one of the issues was batch priming for 3.25 gallons of beer at about 2.4 vol. of CO2, but only managing to collect about 2.2 gallons, which I figured would actually put me somewhere around 3 volumes of C02.

I was advised to let the bottles condition for about a week (rather than the usual 2+), then refrigerate one bottle and try it.

I just had a thought though.... most of the bottles are 650ml bombers, a few are the standard 350ml bottles.

Maybe this is a dumb question, but do the larger bottles take longer to carbonate?

If so, are we talking twice as long?

 

[Mothman]

Now that I've posted this, I see several similar threads shown down below.

Like many homebrew questions, it seems the answer is "maybe". lol

 

[doug293cz]

The yeast and fermentable concentrations should be the same in any size bottle. Since the fermentation occurs in the bulk beer, there should be very little, if any, volume effect. Other things will have a larger effect on carbonation time, such as: yeast concentration, fermentable concentration, alcohol content, yeast strain, temperature, etc.

Brew on

 

[interference]

I regularly bottle different sizes from 1 batch and have more variety between bottles of the same size than different as far as I can recall.

Also, since fermentation is an exothermic bottle, wouldn't bigger bottles make slightly warmer beer in the bottle causing slightly faster carbing, making slightly warmer beer...?

 

[doug293cz]

I regularly bottle different sizes from 1 batch and have more variety between bottles of the same size than different as far as I can recall.

Also, since fermentation is an exothermic bottle, wouldn't bigger bottles make slightly warmer beer in the bottle causing slightly faster carbing, making slightly warmer beer...?

The yeast count is low enough, and the fermentation slow enough during bottle conditioning, that you would be hard pressed to measure at temp rise due to the exothermic activity.

Brew on

 

[Mothman]

Thanks!

 

[SlitheryDee]

I know that when priming a keg or similar large volume container it's normally recommended that you use less sugar than you normally would when using bottles. Unless there's some other factor at play, that suggests that container size must have at least some effect on carbonation.

 

[doug293cz]

I know that when priming a keg or similar large volume container it's normally recommended that you use less sugar than you normally would when using bottles. Unless there's some other factor at play, that suggests that container size must have at least some effect on carbonation.

It's a common recommendation, but no one has been able to offer an explanation why a keg should require less priming. According to the physical chemistry, volume makes no difference, as long as the headspace to beer volume ratio is similar (which it is for kegs and bottles.)

Brew on

 

[Yooper]

It's a common recommendation, but no one has been able to offer an explanation why a keg should require less priming. According to the physical chemistry, volume makes no difference, as long as the headspace to beer volume ratio is similar (which it is for kegs and bottles.)

Brew on

The explanation I've heard is that indeed it is headspace to beer volume.

In a bottle, you'd have maybe 1.5 inches for 12 or 22 ounces. In a keg, you'd have several inches, and it's a bit wider across, but the volume is much bigger. My keg holds about 672 ounces (5.25 gallons). That would be 56 bottles. I didn't measure the headspace, but I have a very short gas diptube and I fill up to that. Maybe 2(?) inches, about 8 inches in diameter. So the headspace is much less, per volume.

 

[doug293cz]

The explanation I've heard is that indeed it is headspace to beer volume.

In a bottle, you'd have maybe 1.5 inches for 12 or 22 ounces. In a keg, you'd have several inches, and it's a bit wider across, but the volume is much bigger. My keg holds about 672 ounces (5.25 gallons). That would be 56 bottles. I didn't measure the headspace, but I have a very short gas diptube and I fill up to that. Maybe 2(?) inches, about 8 inches in diameter. So the headspace is much less, per volume.

I actually measured the headspace in both a 12 oz bottle, and a 5 gal ball lock keg. For the bottle, I filled to the brim with a bottling wand, extracted the wand, and then measured the difference in volume (weight actually) in that bottle and a bottle filled to the brim. The completely full bottle contained 12.81 fl oz, and the "standard" fill bottle contained contained 12.09 fl oz. The ratio is 1.06, or 6% headspace.

For the keg, I first added 5 gal of water (by weight), and then determined that it took 5 cups (0.3125 gal) of additional water to fill the keg to the rim. The completely full to "standard" fill ratio again came out to 1.06, or 6 % headspace.

The beer volume to headspace volume is almost exactly the same for a bottle and a keg. The variations in fill that can occur are not nearly enough to account for the 33% to 50% less priming I have seen recommended for kegs. I am still waiting for someone to come forward with something that I am missing.

Brew on

 

[Yooper]

I actually measured the headspace in both a 12 oz bottle, and a 5 gal ball lock keg. For the bottle, I filled to the brim with a bottling wand, extracted the wand, and then measured the difference in volume (weight actually) in that bottle and a bottle filled to the brim. The completely full bottle contained 12.81 fl oz, and the "standard" fill bottle contained contained 12.09 fl oz. The ratio is 1.06, or 6% headspace.

For the keg, I first added 5 gal of water (by weight), and then determined that it took 5 cups (0.3125 gal) of additional water to fill the keg to the rim. The completely full to "standard" fill ratio again came out to 1.06, or 6 % headspace.

The beer volume to headspace volume is almost exactly the same for a bottle and a keg. The variations in fill that can occur are not nearly enough to account for the 33% to 50% less priming I have seen recommended for kegs. I am still waiting for someone to come forward with something that I am missing.

Brew on

What about the width? I know the keg is much wider than a bottle (duh), but maybe not 56 bottles wide.

 

[doug293cz]

What about the width? I know the keg is much wider than a bottle (duh), but maybe not 56 bottles wide.

Carbonation level is all about quantity of CO2 per volume of beer (1 volume is equivalent to 1.9768 g/liter.) Surface area exposed to the headspace does not affect the final carbonation level. When force carbing, the exposed surface area does affect the rate of carbonation (rate of CO2 absorption by the beer), but not the final level of carbonation. When naturally carbonating, the CO2 is formed in the bulk of the beer, so rate of carbonation does not depend on absorbing CO2 from the headspace.

When you naturally carbonate, you add a specific amount of priming sugar, which will ferment 100%, and create a known amount of CO2. The total carbonation is then the amount of created CO2 divided by the volume of beer (converted to volumes), plus the residual carbonation level of the beer (in volumes) after fermentation.

Brew on

 

[Yooper]

Carbonation level is all about quantity of CO2 per volume of beer (1 volume is equivalent to 1.9768 g/liter.) Surface area exposed to the headspace does not affect the final carbonation level. When force carbing, the exposed surface area does affect the rate of carbonation (rate of CO2 absorption by the beer), but not the final level of carbonation. When naturally carbonating, the CO2 is formed in the bulk of the beer, so rate of carbonation does not depend on absorbing CO2 from the headspace.

When you naturally carbonate, you add a specific amount of priming sugar, which will ferment 100%, and create a known amount of CO2. The total carbonation is then the amount of created CO2 divided by the volume of beer (converted to volumes), plus the residual carbonation level of the beer (in volumes) after fermentation.

Brew on

Well, yes- but.....................


Did you ever have a little beer left over, say, half a bottle? And go ahead and bottle it with the other 55 bottles of the batch? I have. And, believe it or not- that bottle will have explosive carbonation compared to a full bottle.

There IS something about the headspace and dissolution of the gas. I'm definitely NOT the science type, well, at least not physical science type, but while it's not intuitive, it's a real thing.

And in my experience, 2.5 ounces of corn sugar DOES carb up a 5.25 gallon batch in a keg just fine. It's not a bit undercarbed, and actually is on the high side (like 2.5 volumes of c02 or thereabouts if I remember correctly).

I tend to force carb most of my beers, but I do prime a few kegs when I have something that needs a bit of age anyway.

 

[doug293cz]

Well, yes- but.....................


Did you ever have a little beer left over, say, half a bottle? And go ahead and bottle it with the other 55 bottles of the batch? I have. And, believe it or not- that bottle will have explosive carbonation compared to a full bottle.

There IS something about the headspace and dissolution of the gas. I'm definitely NOT the science type, well, at least not physical science type, but while it's not intuitive, it's a real thing.

And in my experience, 2.5 ounces of corn sugar DOES carb up a 5.25 gallon batch in a keg just fine. It's not a bit undercarbed, and actually is on the high side (like 2.5 volumes of c02 or thereabouts if I remember correctly).

I tend to force carb most of my beers, but I do prime a few kegs when I have something that needs a bit of age anyway.

Yes, I have bottled 1/2 bottles, but never noticed that they carbed to higher levels than the other bottles. I keg everything now, and running a 1/2 bottle experiment isn't interesting enough to get me to bottle a batch, just to test a 1/2 bottle.

Headspace volume can affect carbonation since at equilibrium the CO2 partial pressure in the headspace is determined by the carb level of the beer, the temp of the beer, and the amount of CO2 in the headspace initially. This can all be calculated for different headspace volume to beer volume ratios, and different assumptions for starting CO2 levels in the headspace.

Your statement about getting a fully carbed keg from 2.5 oz of corn sugar in 5 gal is typical of the anecdotal experiences I see reported. But, no one has shown any physical chem based math to show how this can occur.

2.5 oz (70.9 g) of corn sugar will create 36.4 g of CO2 when fully fermented. If you distribute that CO2 in 5 gal (18.9 L) of beer, you will get 1.663 g/L of CO2, which is equal to 0.84 volumes of carb. Beer after fermentation at 68˚F contains 0.84 volumes of CO2, assuming that the CO2 in the beer has come to equilibrium with the CO2 in the fermenter headspace. So, the total carb level after naturally carbonating with 2.5 oz of corn sugar would be 0.84 + 0.84 = 1.68 volumes. Even if the beer has not had enough time to equilibrate with the headspace, and has 1 volume of residual carbonation, that would still only be a final carb level of 1.84 volumes. Still way below the "observed" 2.5 volumes of carb. Where does the extra CO2 come from? This is the question that no one has been able to answer.

The only possible source for the extra CO2 is additional fermentation of the original beer, meaning that fermentation had not completed when the beer was packaged. You could try to argue that adding the priming sugar triggers additional attenuation in the keg of the original beer, but then you have to explain why you get additional attenuation in a keg but not in bottles. The only plausible explanation that I have been able to come up with is that folks aren't as careful about actually attaining FG when kegging, since they don't have to worry about bottle bombs.

I'll freely admit that I might be missing something, but if I am, someone should be able to point out just what I'm missing. If I do have things incomplete, or just plain wrong, I really want to know what the correct answer is.

Brew on

 

[SlitheryDee]

Yes, I have bottled 1/2 bottles, but never noticed that they carbed to higher levels than the other bottles. I keg everything now, and running a 1/2 bottle experiment isn't interesting enough to get me to bottle a batch, just to test a 1/2 bottle.

Headspace volume can affect carbonation since at equilibrium the CO2 partial pressure in the headspace is determined by the carb level of the beer, the temp of the beer, and the amount of CO2 in the headspace initially. This can all be calculated for different headspace volume to beer volume ratios, and different assumptions for starting CO2 levels in the headspace.

Your statement about getting a fully carbed keg from 2.5 oz of corn sugar in 5 gal is typical of the anecdotal experiences I see reported. But, no one has shown any physical chem based math to show how this can occur.

2.5 oz (70.9 g) of corn sugar will create 36.4 g of CO2 when fully fermented. If you distribute that CO2 in 5 gal (18.9 L) of beer, you will get 1.663 g/L of CO2, which is equal to 0.84 volumes of carb. Beer after fermentation at 68˚F contains 0.84 volumes of CO2, assuming that the CO2 in the beer has come to equilibrium with the CO2 in the fermenter headspace. So, the total carb level after naturally carbonating with 2.5 oz of corn sugar would be 0.84 + 0.84 = 1.68 volumes. Even if the beer has not had enough time to equilibrate with the headspace, and has 1 volume of residual carbonation, that would still only be a final carb level of 1.84 volumes. Still way below the "observed" 2.5 volumes of carb. Where does the extra CO2 come from? This is the question that no one has been able to answer.

The only possible source for the extra CO2 is additional fermentation of the original beer, meaning that fermentation had not completed when the beer was packaged. You could try to argue that adding the priming sugar triggers additional attenuation in the keg of the original beer, but then you have to explain why you get additional attenuation in a keg but not in bottles. The only plausible explanation that I have been able to come up with is that folks aren't as careful about actually attaining FG when kegging, since they don't have to worry about bottle bombs.

I'll freely admit that I might be missing something, but if I am, someone should be able to point out just what I'm missing. If I do have things incomplete, or just plain wrong, I really want to know what the correct answer is.

Brew on

What about the presence of oxygen in the headspace? From what I can tell through my incessant googling of the subject, respiration produces 3 times the Co2 (6 molecules per cycle vs 2) as fermentation. Perhaps there is something about the availability of oxygen in the headspace of a larger container that promotes the occurrence of respiration in yeast, creating more co2 and reducing the need for as much priming sugar.

I'm no expert here obviously, but like you I would like to understand this phenomenon. I know this gets us back to headspace considerations, but I'm at a loss for anything else to explain it.

 

[doug293cz]

What about the presence of oxygen in the headspace? From what I can tell through my incessant googling of the subject, respiration produces 3 times the Co2 (6 molecules per cycle vs 2) as fermentation. Perhaps there is something about the availability of oxygen in the headspace of a larger container that promotes the occurrence of respiration in yeast, creating more co2 and reducing the need for as much priming sugar.

I'm no expert here obviously, but like you I would like to understand this phenomenon. I know this gets us back to headspace considerations, but I'm at a loss for anything else to explain it.

I'll have to look at the respiration chemical equations, as I am not familiar with them. However, a properly purged keg will have almost no O2 in the headspace, and with most bottling processes, you will have almost atmospheric O2 levels in the headspace, so I don't think respiration is going to be the answer.

Brew on

 

[Yooper]

I remembered reading about this on the Beersmith forum a while back. I cut and pasted from there (so this is NOT mine!):

Carbonation is pretty mechanical...

The headspace in a corney keg can be measured as a percentage of the volume.
A Corney is 9" in diameter.
That means the headspace is about 96 in^3.
The beer is taking up the remaining 19.5 inches of height for a total of 1240 in^3.
Thus, the headspace represents 1.57% of the total volume.
Translated into ounces as a percentage of 5 gallons, the headspace holds 10 ounces.

Like I said, my experience holds that this is so. But I've always filled a keg to the brim, never less so I'm not sure that it's a linear thing.

 

[bleme]

The only thing I can think of is that when I package the keg, I pressurize with 30PSI to set the seal. Maybe the difference is that initial CO2?

Back to the OP's issue, the only difference I have seen between 12's and 22's is that the 22's are more likely to explode when over-carbed.

 

[doug293cz]

I remembered reading about this on the Beersmith forum a while back. I cut and pasted from there (so this is NOT mine!):

Carbonation is pretty mechanical...

The headspace in a corney keg can be measured as a percentage of the volume.
A Corney is 9" in diameter.
That means the headspace is about 96 in^3.
The beer is taking up the remaining 19.5 inches of height for a total of 1240 in^3.
Thus, the headspace represents 1.57% of the total volume.
Translated into ounces as a percentage of 5 gallons, the headspace holds 10 ounces.

Like I said, my experience holds that this is so. But I've always filled a keg to the brim, never less so I'm not sure that it's a linear thing.

That estimate leads to a total keg volume of (96 in^3 + 1240 in^3) / (231 in^3/gal) = 5.78 gal. I believe my actual volume measurement of 5.3 - 5.35 gal is more accurate, than that estimate. If you put more than five gal of beer in a keg, then of course the headspace to volume ratio will go down, as will the total amount of CO2 in the headspace. I'll do some calculations to show how headspace ratio affects carb level for a fixed priming sugar concentration, and starting level of carb in the beer, and post the results here when I get it done.

Brew on

 

[doug293cz]

The only thing I can think of is that when I package the keg, I pressurize with 30PSI to set the seal. Maybe the difference is that initial CO2?

Back to the OP's issue, the only difference I have seen between 12's and 22's is that the 22's are more likely to explode when over-carbed.

With a partially full keg (large headspace to beer volume ratio), the initial 30 psi headspace pressure would definitely affect the final carb level. However, with a small headspace to beer volume ratio there isn't enough CO2 in the headspace initially to make much of a difference, and the more you "overfill" the keg, the less difference it will make. In order for the initial headspace pressure to make a big difference, the absorption rate of CO2 would have to be extremely high, in order to push significant amounts of CO2 into the beer during the keg purging and sealing process.

Brew on