Why does carbing take so long? Explain...

[Bobby_M]

If these experiences are correct, then something is happening beyond simply producing the CO2. It's possible that the evidence is simply flawed, though. It's hard to collect proper data about brewing, especially in homebrewing processes, and there are plenty of examples of even experts drawing incorrect conclusions. But I'm rather inclined to trust that the anecdotes at least indicate *something* is changing.

My non-scientific hypothesis on why bottle conditioned beers tend to require a stabilizing period is not related to where the CO2 molecules are, but rather where the nucleation points are.

Let's start with shaking up a soda bottle or beer bottle for that matter. When you open a carbonated beverage that has been shaken recently, it gushes. Why? It's certainly not related to an increase of co2 molecules or pressure. It's caused by the presence of bubbles that act as nucleation points that wouldn't be there in a restful state.

When you bottle condition, you have yeast and other foreign material floating around in the beer from the moment you bottle. These particulates settle out in the bottle, after the carbonation process is done and further (and faster) when you finally chill the beer. If you open the bottle after the CO2 was created but before the particulates settle out, you end up losing a lot of the Co2 due to the nucleation points. Now, let's not ignore that the chilling step is equally important due to colder liquids holding on to more CO2 when the system is opened. However, I'm specifically talking about why a bottle conditioned beer that has been in the fridge for a week or more obviously has a more stable carbonation than one that is simply made cold in 24 hours.

If the hypothesis of "the beer needs more time to absorb the co2 in the head space" held any water, it wouldn't cause gushing. Gushing is only caused from massive amounts of Co2 coming out of solution in a short time frame. In other words, it's contradictory.

I'd love to be able to experiment more on this stuff if I had the time.

 

[Nonyaz]

However, I'm specifically talking about why a bottle conditioned beer that has been in the fridge for a week or more obviously has a more stable carbonation than one that is simply made cold in 24 hours.

If the hypothesis of "the beer needs more time to absorb the co2 in the head space" held any water, it wouldn't cause gushing. Gushing is only caused from massive amounts of Co2 coming out of solution in a short time frame. In other words, it's contradictory..

So to try and summarize, is your current working theory that there are larger nucleation points in the short term cooled beer vs the long term cooled beer which presumably had more time to more finely disperse the co2 already in the liquid?

 

[Bobby_M]

Not exactly. More co2 will stay in the beer when the beer is cold and the particulates have had a chance to flocculate to the bottom of the bottle. That's it in a nutshell. Now I just need some ideas on how to test it. One idea I had was to bottle two identical beers with tiny stir bars in the bottle. Refrigerate both for a week, remove them both and put one of them on the stirplate for an extremely gentle stir so that the particulates go back into suspension without making bubbles. Open both and see how much head forms in the bottle.

 

[Nonyaz]

Not exactly. More co2 will stay in the beer when the beer is cold and the particulates have had a chance to flocculate to the bottom of the bottle. That's it in a nutshell. Now I just need some ideas on how to test it. One idea I had was to bottle two identical beers with tiny stir bars in the bottle. Refrigerate both for a week, remove them both and put one of them on the stirplate for an extremely gentle stir so that the particulates go back into suspension without making bubbles. Open both and see how much head forms in the bottle.

Ok I got you now.

How about you take a long term chilled bottle out of fridge, shake it (so particulates are now back in suspension), then let it return to room temp, then put it back in the fridge with a bottle that has never been in the fridge for 24 hours and test them both. If it was dependent on particles being suspended, both should foam equally, if the bottle that has been in the fridge for the long time before still doesn't foam, then that could mean its not dependant on particulates. Your idea sounds better, I'm just trying to think of a way around needing stir plates.

 

[jfr1111]

Most of my beers are ready within 7-10 days. A factor to consider is yeast strains. Some yeast strains do not work well at all under pressure and will take their sweet time to even eat the little bit of priming sugar, while others will happily go at it. And the higher the CO2 level, the harder it seems for the yeast to consume the sugars.

Another reason why a beer might still produce a head and be considered "flat" is that it takes very little CO2 to be produced by the yeast in order to produce head on the beer. 99% of my beers are carbed with 2 ounces or less table sugar (to get around 1.3 to 1.5), and as the pitcures I have very often posted on this forum can attest, my beers all have head.

 

[zeg]

One idea I had was to bottle two identical beers with tiny stir bars in the bottle. Refrigerate both for a week, remove them both and put one of them on the stirplate for an extremely gentle stir so that the particulates go back into suspension without making bubbles. Open both and see how much head forms in the bottle.

I have been thinking about how to test this as well. A simpler way to do this might be just to put one in the fridge upside down, then turn it right side up a couple hours before opening. If this one gushes/goes flat, then you have your answer.

If it doesn't, then it's inconclusive because the particles may clump and not return to their original distribution simply by falling from the top. A follow up would be to refrigerate two bottles the same amount of time, flipping one of them over every few hours to prevent everything from settling. This may also answer the question, but again a negative result is inconclusive.

While I think it's promising, I'm not totally sold on your hypothesis. The standard explanation for shaken bottles of soda (or beer) foaming up is that the shaking creates tiny bubbles to act as nucleation sites. It could be that yeast produce CO2 fast enough that this idea of instant solution is not quite right, and that instead the yeast cells actually produce tiny bubbles as they work. Given the vast size difference between a yeast cell and a CO2 molecule, this is actually pretty likely---they probably don't actually work on a single molecule at a time or produce individual separated CO2 molecules.

These are, of course, not mutually exclusive ideas for causes. Both could contribute to the overall effect.

Yet another possible test of your theory would be to produce two identical bottles of beer, then add some additional inactive sediment to one bottle. One might expect this to cause faster/stronger gushing. (This may be hard to gauge, though perhaps using multiple samples of each type could help.)

Anyway, just some thoughts.

 

[tj218]

Again, I am amazed at the level of depth on these responses. Where are the Mythbusters when you need them?

 

[kingwood-kid]

I don't know how long it takes for the vast majority of the bottle-conditioned CO2 to be pruduced, and certainly there is room for variance based on temps and whatever. But I'd guess 3-4 days at 70F will be sufficient to produce most of that CO2. If all of it was concentrated in one place--headspace, trub, right behind the blue mountains--wouldn't that part of the bottle give way pretty quickly?

 

[tj218]

BUMP!


Also....why is the standard advice @70F...say if I have a yeast that worked it's magic at 59F. Why can't I also condition at 59F?

 

[helibrewer]

It takes a long time because it's a damn harsh environment. Those yeast have basically gone dormant by the time you bottle. Now they need to come back, in a high alcohol, zero nutrient, zero O2 environment and start their lifecycle all over again. It's slow, it takes time and the higher temps (70's) help since metabolic processes proceed faster at higher temps (within limits).

You could certainly do it cooler but it will take much longer. We're not as concerned with the higher temps at bottling because there is not enough activity to negatively effect flavors.