Yup. We've proven popular theories wrong on here from our own experiments,myself included. It can def be a good thing that advances our understanding of the brewing process.
While I understand where you are going with this, the rolling bubbles in my fermenter are very strong evidence that not all of the CO2 is staying as individual molecules in solution from the get-go. They are bumping together, congregating, and rising. Lots of gas is obviously reaching the surface as bubbles and not just diffusing as individual molecules. If it were a pressurized environment like a bottle, that CO2 would slowly be reabsorbed into solution until it reached equilibrium.
I think it is fair to say that both processes (and probably a lot more) are happening simultaneously.
As you drop the temp, the beer can absorb more CO2, creating a vacuum (because the temp change does not affect gas as drastically as liquid). A little bit of CO2 will slowly move from the headspace into the beer as the temperature drops until a pressure equilibrium and constant temperature are reached. However, most of the CO2 (maybe 2/3rds or more) is/was already in the beer from the moment the yeast produced it/before the temp was dropped.
And since the head space in an average 12 ounce bottle is more like 10-15 ml the difference is even less. Serving temperature or room temperature, the volumes of Co2 in a bottle of beer are the same for practical purposes.The bottle was assumed to have 30 mL head space and 355 mL liquid.. . . Finally, the change in volumes is small: 2 volumes was 1.4 g dissolved, so we've only increased to 2.06 or so. I don't think many homebrewers carb to that level of precision. So Bobby_M is also right.
And since the head space in an average 12 ounce bottle is more like 10-15 ml the difference is even less. Serving temperature or room temperature, the volumes of Co2 in a bottle of beer are the same for practical purposes.
Although it makes sense, I'm still having trouble wrapping my brain around the CO2 formed during carbonation going right into solution, but Buddyweiser's statements are hard to take seriously.
Why not? Put something together this morning before work. Didn't have any beer ready to bottle, so threw some Munton carb tabs in water with yeast nutrient and added a little dry yeast. I’m not looking to draw any serious conclusions from this. Just want to make sure the system is sealed and will hold pressure. If this works out I’ll do it with some proper controls in place.This is why anoldUR should still do the experiment, as should anyone else with the means to graph pressure and temp.
...or the rate is much slower for absorption for some reason.
feinbera said:That reason is that you're dramatically changing the environment the beer is in. The amount of pressure in the air the beer is touching affects the amount of gasses the beer can absorb -- higher-pressure air forces more of itself into the fluid. The headspace in your bottles is at a much higher PSI than Earth's atomsphere -- this high-pressure air escaping is why the bottles hiss when you open them, even before the beer starts foaming. However, once the pressure is no longer "holding the absorbed gas in," it's free to escape the beer, and will do so much faster than it was forced in.
Think about blowing up a balloon -- the first few breaths are easy, but it gets harder and harder, and it can take a minute to really get it good and full -- but, if you accidentally let it go before you tie it, it will be empty again in a couple seconds, even with the air escaping from the same hole it entered through. The pressurized headspace takes the role of your lungs, forcing air in, and the beer itself takes the role of the rubber walls of the balloon, readily allowing more CO2 in initially, resisting more strongly the more CO2 is already in, and expelling the CO2 once the pressure is released.
That reason is that you're dramatically changing the environment the beer is in. The amount of pressure in the air the beer is touching affects the amount of gasses the beer can absorb -- higher-pressure air forces more of itself into the fluid. The headspace in your bottles is at a much higher PSI than Earth's atomsphere -- this high-pressure air escaping is why the bottles hiss when you open them, even before the beer starts foaming. However, once the pressure is no longer "holding the absorbed gas in," it's free to escape the beer, and will do so much faster than it was forced in.
Think about blowing up a balloon -- the first few breaths are easy, but it gets harder and harder, and it can take a minute to really get it good and full -- but, if you accidentally let it go before you tie it, it will be empty again in a couple seconds, even with the air escaping from the same hole it entered through. The pressurized headspace takes the role of your lungs, forcing air in, and the beer itself takes the role of the rubber walls of the balloon, readily allowing more CO2 in initially, resisting more strongly the more CO2 is already in, and expelling the CO2 once the pressure is released.
Yeah, like I said, I didn't bother checking what the headspace volume actually is. In any case, even if 100% of the gas dropped into solution, you'd have no appreciable difference in carbonation unless you left the bottle a couple ounces short.
I don't have any idea whether the idea that the CO2 is instantly insolution is correct. I do think you can get some idea of the timescales involved in absorption by looking at the reverse process: watching CO2 escape from solution after you've poured a beer and the CO2 partial pressure is ~0. Since that's about an hour (order of magnitude), the dissolving process is probably not grossly different (though there are complications, and it certainly could be). So I'm not sure how to connect that with the standard claim that it takes ~3 days of refrigeration for a bottle to be ready (or ~5 days for force carbing a keg), as both of those are ~100 times longer than the go-flat time. Either something else is going on, or the rate is much slower for absorption for some reason.
When you're watching bubbles escape from a beer into the atmosphere, it's not really the opposite of what happens when bottle conditioning. Yeast release CO2 as individual molecules. It's not like a huge cluster pops out that immediately would appear as a bubble. Since "dissolved" means the individual molecules intermingling with the solvent, doesn't it follow that CO2 expired by the yeast is already by definition "dissolved"?
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.
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?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..
Ok I got you now.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.
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.
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