Bottle carbonation theory

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BrookdaleBrew

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I have noticed when I bottle carb that the beer generally stays hazy for about 24 hours and then drops completely clear. I can only assume that this means the yeast is done eating the priming sugar at that point. Also, most of my starters ferment out in 24 hours (granted, with a lot more yeast... but also a lot more sugar.)

I'm no scientist, but I've always assumed the reason it takes a standard gravity beer at least 3 weeks to carbonate is because that is the amount of time it takes for enough CO2 to be absorbed into solution at room temp.

So, assuming that yeast generally ferment out my priming sugar in 24 hours and knowing that CO2 absorbs into solution more quickly at colder temps (kegs generally carb after 1 week in the fridge at serving pressure), would it stand to reason that if I let a beer stay at room temp until it clears, then throw it in the fridge for a week, it would come out perfectly carbed since the CO2 is already in the headspace of the bottle and just needs to be absorbed into solution?

I decided to test this theory with my latest batch and will report back with results. If anyone else has tried anything like this, I'd love to hear your experiences.

NOTE: I am in no way saying you can speed up CONDITIONING time this way. I would only attempt this method with smaller, low ABV beers that can condition in a few weeks time. I am only attempting to speed up the carbonation process.
 
It's an interesting experiment. How many yeast (i.e., did you get any trub in there) would also have an effect on your results. Let us know how it goes. :)
 
I don't secondary but I am very careful not to disturb the yeast cake when I rack from primary to my bottling bucket, so I don't generally end up with a lot of sediment in my bottles.

That being said, it does not take much yeast to prime a 12oz bottle. Sierra Nevada is filtered then bottle conditioned (after adding more yeast of course) and the sediment layer in their bottles is barely noticeable.
 
No, traditionally you speed carb, by warming the beer up, not chilling it. Put your beer above your referigerator or near the furnace and you will have your beer carb faster than the 3 weeks @ 70 we recommend.

Chilling actually RETARDS the process of conditioning and carbonating.

And just because a beer appears to be dropping clear, doesn't mean what it is dropping is yeast, OR that just because some yeast may be falling that the ALL the fermentables needed to produce enough co2 to max the headroom and force the co2 into solution, has yet been generated. That is what truly causes a beer to carbonate, NOT the cold drawing the co2 into solution. Maxing out the headroom and not blowing the bottle up forces the co2 to take the path of least resistance and go into solution. Cold just later locks it in, it absorbs the rest of it, but not the brunt of it that truly carbs the beer.

All you will be doing is drawing out a natural process by slowing the yeast down and forcing them to dormancy in the fridge.

Don't forget there's other things in the solution that are also dropping out, and that too is what you are seeing. Not just yeast.
 
My guess is that it won't work. I tend to need about 7 days for normal gravity beers that spent less than 2 weeks in the primary and more time under other circumstances.

I believe Boulevard and Sierra Nevada both do one week warm and in their case they are repitching extremely vital/viable yeast. They do that storage at considerable expense and both are positioned at the low end of the craft beer price range. If you could do one day warm, they would be doing that.
 
Remilard's right about repitching, that's another way to speed up carbonation, OR to insure carbonation in higher grav beers.

I think "normal" grav beer is subjective. My normal beers tends to have a starting gravity of 10.60 or above. Where other folks normals could be milds, or things in the 1.040-1.060 range.

We tell folks 3 weeks @ 70, because that seems to be the average for beers around 1.060. Plus most folks keep their houses around 70 degrees year round. But beers take less or more time depending on several factors, mostly grav and carb temp.

For me, I'm not out to win a race, I don't care if my beer takes 3 weeks, or 8 weeks to be drinkable, so I don't try to do anything special. For the most part I brew relatively regularly, so I have a fairly deep pipeline, of stuff at all levels of maturation, from things bulk aging for 6 months or more, to stuff that I pitched yeast 2 weeks ago, to stuff that I bottled 3 weeks ago, to stuff I bottled over the summer. So I'm not necessarily rushing to drink everything I make. I wait 3 weeks minimum before trying ANYTHING I make these day...if it's ready, great, if it's not...back in the closet.
 
Would carbonating the bottles in warmer temps create any off flavors as it would during primary fermentation? Afterall, carbonating the beer in bottles is just a small scale fermentation in a sealed environment, is it not?
 
My closet where I am fermenting and carbonating is staying right at 64 degrees, is that too cold for ale? Should I warm it up or simply adjust my time.
 
DarkUncle said:
Would carbonating the bottles in warmer temps create any off flavors as it would during primary fermentation? Afterall, carbonating the beer in bottles is just a small scale fermentation in a sealed environment, is it not?
Click to expand...

I think the bigger danger at that point is bottle bombs, not off flavors.

Although freshly bottled beer tastes much worse than the flat beer that went into it the week before, I've observed many times.
 
DarkUncle said:
Would carbonating the bottles in warmer temps create any off flavors as it would during primary fermentation? Afterall, carbonating the beer in bottles is just a small scale fermentation in a sealed environment, is it not?
Click to expand...

It's too small a scale of fermentation, but too high may affect long term storage of the beer.

billf2112 said:
My closet where I am fermenting and carbonating is staying right at 64 degrees, is that too cold for ale? Should I warm it up or simply adjust my time.
Click to expand...

Just adjust your time...expect it to take longer. I have that issue in the winter in my loft.
 
Justibone said:
I think the bigger danger at that point is bottle bombs, not off flavors.

Although freshly bottled beer tastes much worse than the flat beer that went into it the week before, I've observed many times.
Click to expand...

You know, I think I noticed that as well. I tried my pumpkin ale a week and a half into carbing in the bottle for the hell of it and man, it did not taste so good. I remember it tasting better when I took a sample while bottling.

I hope that sorry excuse for a pumpkin ale turns itself around...
 
Thanks for weighing in guys, I appreciate the feedback. We'll see what happens. If the bottle doesn't carb up fully, I'm out 1 beer, so it's not a huge loss to me.
 
Revvy said:
That is what truly causes a beer to carbonate, NOT the cold drawing the co2 into solution. Maxing out the headroom and not blowing the bottle up forces the co2 to take the path of least resistance and go into solution.
Click to expand...

Ok I need to get a science rant off my chest now, because I have seen this written a hundred times on the forum and it makes me frustrated!

It must be complete rubbish that the headspace fills up with CO2 first, which then has to be forced back into the beer.
Yeast don't have air-breathing lungs, they live IN SOLUTION, respiring with any oxygen present IN SOLUTION (none in the case of anerobic fermentation) and giving out CO2 IN SOLUTION.

This means that the beer fills up with CO2 as the priming sugar is consumed, and as the amount of CO2 in the beer increases, some of the CO2 flows out of the beer into the headspace up to equilibrium pressure. The headspace pressure DOES NOT go above equilibrium pressure and force gas back into the beer, it is the opposite with the amount of CO2 in the beer increasing and the headspace pressure then increasing to match.

If your theory about headspace filling first was correct, then the yeast would somehow have to get the CO2 into the headspace without it being dissolved in the beer first. The yeast would have to have little air pockets inside them and somehow blow tiny bubbles into the beer! This is obviously impossible because a) the yeast would undoubtably explode and b) each yeast cell only produces a tiny tiny amount of CO2 and making a CO2 bubble that small would be energetically impossible.
 
That makes complete sense. Like I said, I'm not a scientist, I work in IT.

So the head space does fill with CO2 but only until it reaches equilibrium with what is already in solution, then as the yeast produces more CO2, equilibrium is maintained until there is no more sugar and the beer is carbed.

I guess that blows my theory of the bulk of fermentation in the bottle completing in 24 hours out of the water.
 
So are you saying that the beer carbonates first and becomes saturated before any CO2 is expelled into the headspace of the bottle?

If that's true than why would it be when I popped open a bottle after a week and a half that a little hiss can be heard, which I would assume to be the release of some CO2, but the beer is still flat? Shouldn't the beer be carbed up at that point if there is now CO2 in the headspace of the bottle?
 
markcurling said:
This means that the beer fills up with CO2 as the priming sugar is consumed, and as the amount of CO2 in the beer increases, some of the CO2 flows out of the beer into the headspace up to equilibrium pressure. The headspace pressure DOES NOT go above equilibrium pressure and force gas back into the beer, it is the opposite with the amount of CO2 in the beer increasing and the headspace pressure then increasing to match.
Click to expand...

DarkUncle said:
So are you saying that the beer carbonates first and becomes saturated before any CO2 is expelled into the headspace of the bottle?

If that's true than why would it be when I popped open a bottle after a week and a half that a little hiss can be heard, which I would assume to be the release of some CO2, but the beer is still flat? Shouldn't the beer be carbed up at that point if there is now CO2 in the headspace of the bottle?
Click to expand...

It's not "complete rubbish" it's not too different than force carbonating...why are kegs made to handle so much pressure....

And yet we KNOW that too much headspace can cause bottles to blow during carbonation.......AND that often some folks will attempt to bottle in growlers and THEY BLOW, yet folks can put carbed beers in them and have everything be fine. If your theory were totally correct we really wouldn't need to do through such extremes as crimping down a cap, clamping down a champagne cork as hard as we have to.

I never said it fills the headspace FIRST.

Poindexter first brought my "Rubbish THeory" :rolleyes: to my attention years ago in his video...Look at week 1 in this video.

We know co2 rises, we know there's a headspace for a reason (why don't we just fill to the top then) we also know that when folks open bottles to soon, there is a pfft and some gas but it still isn't enough to carb the beer. The HAS to be a mechanicism at play to get the all that gas under control



My take is it is a little bit of BOTH your theory and mine, BUT headspace and the fact that we have to Crimp or bottles so tightly DOES bear my "Rubbish theory" out.
 
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DarkUncle said:
So are you saying that the beer carbonates first and becomes saturated before any CO2 is expelled into the headspace of the bottle?
Click to expand...

No, he is saying that equilibrium is maintained. So even when you open a bottle after a week, there is some CO2 in solution as well as some in the head space (so you get the hiss) but the yeast has not produced enough CO2 yet to fully carb the beer.
 
DarkUncle said:
So are you saying that the beer carbonates first and becomes saturated before any CO2 is expelled into the headspace of the bottle?

If that's true than why would it be when I popped open a bottle after a week and a half that a little hiss can be heard, which I would assume to be the release of some CO2, but the beer is still flat? Shouldn't the beer be carbed up at that point if there is now CO2 in the headspace of the bottle?
Click to expand...

i think its because the beer and the headspace has to maintain a constant state of equilibrium. Not one or the other having more co2 than the other. Because the common knowledge here is the headspace fills first then when there's no where to go it falls into solution, therefore carbing the beer. did I get that right?
 
DarkUncle said:
So are you saying that the beer carbonates first and becomes saturated before any CO2 is expelled into the headspace of the bottle?

If that's true than why would it be when I popped open a bottle after a week and a half that a little hiss can be heard, which I would assume to be the release of some CO2, but the beer is still flat? Shouldn't the beer be carbed up at that point if there is now CO2 in the headspace of the bottle?
Click to expand...

The yeast produce CO2 which goes into solution. The amount of CO2 that can be held in solution is a function of the temperature of the solution and the pressure - basic gas laws here. As the yeast continue to produce CO2, the solution will reach its saturation point for the current pressure, so some of the CO2 escapes into the headspace. As the CO2 increases in the headspace, because the bottle is capped, the pressure inside the bottle builds up, which increases the amount of CO2 that can go into solution - you can think of the increased headspace pressure literally forcing the CO2 back into solution until the pressure of the CO2 pushing out of solution is equal to the pressure pushing back in - the system maintains equilibrium. At some point all the sugars are used up and no more CO2 is produced. Otherwise, if you add too much sugar, too much CO2 builds up, increasing the pressure inside the bottle until the glass cannot take it any more and explodes (the force of the CO2 inside exceeds the material strength of the glass).

Now, once the yeast are done converting all the sugars into CO2, there will still be CO2 in the headspace. When you then chill the beer down, more CO2 goes into solution since colder liquids can hold more gas. When you pop the top, you've released the pressure, which is the hiss you hear as CO2 escapes. With the pressure released, the beer is now out of equilibrium, so the CO2 dissolved in the beer comes out of solution once more as the system swings back into equilibrium, this time with the lowered ambient pressure. Hence, we get nice bubbles (and foam) when we pour. If you don't have a lot of CO2 dissolved in solution - either because you didn't add enough priming sugar or the yeast haven't had time to fully convert the sugar into CO2, the CO2 in solution quickly dissipates (come out of solution), and the result is flat beer (even though you heard a hiss when you popped the top)
 
Dark Uncle I agree with your observation - and I believe it is this observation which leads to the crazy headspace theory! The explanation is as follows...

Carbon dioxide does not dissolve very well in water. This means that the equilibrium point inside the bottle lies with 90% CO2 in the headspace, 10% CO2 in the beer. The beer stays fairly close to this equilibrium at all the time throughout carbonation/conditioning. This means that a beer which is only slightly carbonated still has considerable CO2 in the headspace, or in your instance, a beer which is perceived as flat still gives an illusional hiss!
 
jourelemode said:
i think its because the beer and the headspace has to maintain a constant state of equilibrium. Not one or the other having more co2 than the other. Because the common knowledge here is the headspace fills first then when there's no where to go it falls into solution, therefore carbing the beer. did I get that right?
Click to expand...

well, not according to markcurling, that's "utter rubbish," funny this is the first time in years anyone's challenged it, including some of our better known beer scientists on here..

*shrug*
 
JLem said:
The yeast produce CO2 which goes into solution. The amount of CO2 that can be held in solution is a function of the temperature of the solution and the pressure - basic gas laws here. As the yeast continue to produce CO2, the solution will reach its saturation point for the current pressure, so some of the CO2 escapes into the headspace. As the CO2 increases in the headspace, because the bottle is capped, the pressure inside the bottle builds up, which increases the amount of CO2 that can go into solution - you can think of the increased headspace pressure literally forcing the CO2 back into solution until the pressure of the CO2 pushing out of solution is equal to the pressure pushing back in - the system maintains equilibrium. At some point all the sugars are used up and no more CO2 is produced. Otherwise, if you add too much sugar, too much CO2 builds up, increasing the pressure inside the bottle until the glass cannot take it any more and explodes (the force of the CO2 inside exceeds the material strength of the glass).

Now, once the yeast are done converting all the sugars into CO2, there will still be CO2 in the headspace. When you then chill the beer down, more CO2 goes into solution since colder liquids can hold more gas. When you pop the top, you've released the pressure, which is the hiss you hear as CO2 escapes. With the pressure released, the beer is now out of equilibrium, so the CO2 dissolved in the beer comes out of solution once more as the system swings back into equilibrium, this time with the lowered ambient pressure. Hence, we get nice bubbles (and foam) when we pour. If you don't have a lot of CO2 dissolved in solution - either because you didn't add enough priming sugar or the yeast haven't had time to fully convert the sugar into CO2, the CO2 in solution quickly dissipates (come out of solution), and the result is flat beer (even though you heard a hiss when you popped the top)
Click to expand...

Gee isn't that what I've been saying that I just got told was utter rubbish????
 
markcurling said:
dspace fills up with CO2 first, which then has to be forced back into the beer.
Click to expand...

I see where the problem lies, I never said it fills the headpace FIRST. I just said it fills the headpace. Not when. Of course it is happening first in solution. But it is rising up and FILLING the headspace and then being forced back in solution.

If that's why you called it rubbish, then it's your mis reading of my explanation, not my explanation. That's flawed....
 
Thinking about all this raises another question in my mind. Is yeast less effective under pressure? Would that explain why it takes 3 weeks for a beer to carb?

I think the next time I bottle a batch, I will set aside 2 uncapped bottles. I will take a hydrometer reading from each bottle, return the samples to the bottles, cap one of the beers, then take another reading from both 24 hours later and see how much the gravity has changed and what the potential differences are.
 
BrookdaleBrew said:
Thinking about all this raises another question in my mind. Is yeast less effective under pressure? Would that explain why it takes 3 weeks for a beer to carb?
Click to expand...

Yeast are inhibited by high CO2 concentrations. I do not know what direct effect pressure has on them, but I don't think any, because liquid is not compressible and yeast are not airborne.
 
Gas only ever flows from high partial pressure to low partial pressure (i.e. towards equilibrium). Therefore CO2 will only flow into or out of the headspace in the direction of equilibrium. The CO2 is added by the yeast into the solution, which puts the CO2 in solution at a higher partial pressure than the headspace, forming a concentration gradient from the beer to the headspace.

Therefore I disagree with the wording where you say CO2 is "forced back in solution". This implies that the CO2 flows from solution, to headspace, to solution again. There can never be a time when the headspace has a higher partial pressure than the solution, so there can never be a net flow from the headspace to the beer. CO2 is added in solution, so the direction of flow can only ever be into the headspace. This is the exact opposite of force carbing, whereby you are adding CO2 to the headspace hence setting up a concentration gradient into the beer.
 
JLem said:
The yeast produce CO2 which goes into solution. The amount of CO2 that can be held in solution is a function of the temperature of the solution and the pressure - basic gas laws here. As the yeast continue to produce CO2, the solution will reach its saturation point for the current pressure, so some of the CO2 escapes into the headspace. As the CO2 increases in the headspace, because the bottle is capped, the pressure inside the bottle builds up, which increases the amount of CO2 that can go into solution - you can think of the increased headspace pressure literally forcing the CO2 back into solution until the pressure of the CO2 pushing out of solution is equal to the pressure pushing back in - the system maintains equilibrium. At some point all the sugars are used up and no more CO2 is produced. Otherwise, if you add too much sugar, too much CO2 builds up, increasing the pressure inside the bottle until the glass cannot take it any more and explodes (the force of the CO2 inside exceeds the material strength of the glass).


Now, once the yeast are done converting all the sugars into CO2, there will still be CO2 in the headspace. When you then chill the beer down, more CO2 goes into solution since colder liquids can hold more gas. When you pop the top, you've released the pressure, which is the hiss you hear as CO2 escapes. With the pressure released, the beer is now out of equilibrium, so the CO2 dissolved in the beer comes out of solution once more as the system swings back into equilibrium, this time with the lowered ambient pressure. Hence, we get nice bubbles (and foam) when we pour. If you don't have a lot of CO2 dissolved in solution - either because you didn't add enough priming sugar or the yeast haven't had time to fully convert the sugar into CO2, the CO2 in solution quickly dissipates (come out of solution), and the result is flat beer (even though you heard a hiss when you popped the top)
Click to expand...

That is the process as I understood it but which it seemed, at first, markcurling was refuting. In reading through his explanation again I'm not really clear on what he disagrees with. Perhaps it's a matter of semantics here?
 
Justibone said:
Yeast are inhibited by high CO2 concentrations. I do not know what direct effect pressure has on them, but I don't think any, because liquid is not compressible and yeast are not airborne.
Click to expand...

hydrostatic pressure definitely affects the yeast - I don't know the exact biology of it, but it is often talked about when homebrewers try to mimic/clone commercial recipes. The commercial guys often have tall cylindrical fermenters, which exert more pressure on the yeast (because of that tall column of liquid pushing down), which represses ester formation (somehow) and because of this they tend to ferment at higher temps than homebrewers do.

Just because something is incompressible doesn't mean it cannot be affected by increased pressure - ever had a sinus infection?
 
markcurling said:
Gas only ever flows from high partial pressure to low partial pressure (i.e. towards equilibrium). Therefore CO2 will only flow into or out of the headspace in the direction of equilibrium. The CO2 is added by the yeast into the solution, which puts the CO2 in solution at a higher partial pressure than the headspace, forming a concentration gradient from the beer to the headspace.

Therefore I disagree with the wording where you say CO2 is "forced back in solution". This implies that the CO2 flows from solution, to headspace, to solution again. There can never be a time when the headspace has a higher partial pressure than the solution, so there can never be a net flow from the headspace to the beer. CO2 is added in solution, so the direction of flow can only ever be into the headspace. This is the exact opposite of force carbing, whereby you are adding CO2 to the headspace hence setting up a concentration gradient into the beer.
Click to expand...

OK - i see your point. It's not that the headspace forces CO2 back into solution so much as the pressure in the headspace prevents CO2 from escaping from solution. However, once you lower the temperature, we've got another story - the partial pressure of the liquid will be decreased so the CO2 will flow back from the headspace to the beer...right?
 
JLem said:
OK - i see your point. It's not that the headspace forces CO2 back into solution so much as the pressure in the headspace prevents CO2 from escaping from solution. However, once you lower the temperature, we've got another story - the partial pressure of the liquid will be decreased so the CO2 will flow back from the headspace to the beer...right?
Click to expand...

Agreed :mug:

Though to be 100% correct, I think when you lower the temperature, rather than decreasing the partial pressure of the liquid, you are actually shifting the equilibrium position, giving a resultant gradient back into the beer.
 
JLem said:
OK - i see your point. It's not that the headspace forces CO2 back into solution so much as the pressure in the headspace prevents CO2 from escaping from solution. However, once you lower the temperature, we've got another story - the partial pressure of the liquid will be decreased so the CO2 will flow back from the headspace to the beer...right?
Click to expand...

I think this is why Revvy's explination is confusing. To me it makes it sound like CO2 created, fills the headspace and then is slowly forced back into solution over the course of 3 weeks, (which is what my entire theory was based on) when in reality, equilibrium is maintained and when the beer is chilled the equilibrium shifts.

Now I have a better understanding of what actually happens in the bottle. I'm glad I brought this up even if my theory wasn't sound.
 
markcurling said:
Agreed :mug:

Though to be 100% correct, I think when you lower the temperature, rather than decreasing the partial pressure of the liquid, you are actually shifting the equilibrium position, giving a resultant gradient back into the beer.
Click to expand...

we're just arguing semantics at this point, and I am no chemist, but, since total pressure is directly proportional to temperature and partial pressures are defined by the total pressure, doesn't lowering the temperature then also lower the partial pressures? :mug:

(Or am I erroneously using ideal gas laws to talk about aqueous solutions?)
 
JLem said:
we're just arguing semantics at this point, and I am no chemist, but, since total pressure is directly proportional to temperature and partial pressures are defined by the total pressure, doesn't lowering the temperature then also lower the partial pressures? :mug:

(Or am I erroneously using ideal gas laws to talk about aqueous solutions?)
Click to expand...

THIS is the can of worms.
 
JLem said:
hydrostatic pressure definitely affects the yeast - I don't know the exact biology of it, but it is often talked about when homebrewers try to mimic/clone commercial recipes. The commercial guys often have tall cylindrical fermenters, which exert more pressure on the yeast (because of that tall column of liquid pushing down), which represses ester formation (somehow) and because of this they tend to ferment at higher temps than homebrewers do.
Click to expand...

Yes, I remember getting involved in a "satellite" brewing discussion where this came up. It is not very relevant to bottling, unless someone is using a 6 ft tall bottle vs. 6 inches??

Just because something is incompressible doesn't mean it cannot be affected by increased pressure - ever had a sinus infection?
Click to expand...

The differences in pressure for sinus infection are mostly relevant because of nerve stimulation. The actual differences are usually of small magnitude. Until I see a patient with the hollow space in their skull actually blowing fragments out onto the pavement... I'm gonna say sinuses are not the best example. ;)

Deep sea submersibles... now there's an example.
 

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