Not inspired by the thread about how to add carbonation, but because I prefer my colas flat. (Just one of the quirks that make me amusing , I choose to believe.)
Other than by opening a can of pop (soda–terms to be used interchangeably) and leaving it for many hours, and other than by shaking it up or dropping in a tube of Mentos, is there an easy, non-taste-altering way to remove most or all of the carbonation from my Coke, Pepsi, or RC?
I was under the impression that the CO2 stays in solution because of pressure; that in canning, the pressure inside the can was above atmospheric pressure and that’s why the can would eventually go flat after being opened. But if this was the case, then applying a vacuum to a newly-opened can should cause it to flatten out faster. A few experiments seem to disprove this theory.
It’s Monday morning, I didn’t get enough sleep, and I’d like to caffeinate with an ice-cold, but flat, can of pop. While I’m cursing the school system that never had me take a chemistry class, I’d like to hear any suggestions that could lead to a solution. A solution with no carbon dioxide, that is. If the result doesn’t require metal fabrication and won’t make a story for the thread about “Things you don’t want in your obituary,” (http://boards.straightdope.com/sdmb/showthread.php?t=573788
)so much the better.
Well, removing the carbonation does affect the taste.
You could try cooking it. I’m not sure how commercial soda syrup is made, but when I make my own, it’s cooked, so that might not change the taste. You’ll have to add some more water to counter the vaporization. The hotter it is, the less capable it is of holding carbonation.
You could expose it to a vacuum. The less pressure there is, the easier the CO2 will come out of solution. Get yourself a CO2 tank and a venturi, and try to build vacuum that way. You could use any gas, but the CO2 has the advantage of being able to recarbonate should you have guests.
Many years ago I acquired an addiction to Root Beer Kool-Aid which became a problem after that flavor was discontinued. To approximate the goodness of Root Beer Kool-Aid, I buy the cheapest generic root beer and bring it to a simmer, cool it down, and rebottle* it. Delicious over crushed ice.
*I was going to say I recant it, but 10 seconds of research suggests “recant” isn’t the opposite of “decant”.
My wife and her father both prefer their pop de-carbonated.
He opens the bottle (if it is bottled) and holds his thumb over the opening, shakes it and slowly releases the pressure. He does this for a few minutes and the drink is pretty much CO2 free.
My wife usually just opens the can hours in advance and lets it sit in the fridge.
Last March when she was sick and wanted ginger ale I came up with the following method:
-Pour into a cup
-Pour from that cup into a second empty cup
-Pour back into the first cup
Do that for about 3 minutes or until it no longer bubbles up and your pop will be fizz-free.
A blender? Hmmm. Why do I have mental pictures of Lucy putting too much soap in the washing machine?
If anyone knows why the vacuum idea doesn’t seem to work, I’d like to hear that, too.
(I once tired experimenting with a vacuum container and a pump. Near as I could tell, it didn’t really do anything, contrary to my expectations that I would instantly de-fizz the whole thing.)
It should be fine - just fill it less than halfway and keep the top on, maybe with that little middle piece removed. Start it nice and slow , see if it erupts (jamming the piece back in if need be) - if it doesn’t (and I don’t think it will), then crank it. I’m guessing you’ll be CO2 free in less than a minute.
ETA: although it would be hilarious if it exploded…
I came in to suggest this. It ought to work – that’s how they get bubbles out of plastics they’re trying to set, and for removing carbonation from wine*. What are the details of your vacuum setup? Are you sure you were getting a real vacuum? (High vacuum shouldn’t be necessary – just what you could get with a roughing pump)
I think that the problem with a vacuum is that the partial pressure of CO[sub]2[/sub] is already pretty low in the air. Carbon dioxide makes up only 0.039% of the atmosphere so air is a pretty good vacuum as far as CO[sub]2[/sub] goes. Now if drinks were “nitrogenated” instead of carbonated, the vacuum idea would work much better.
Although that’s a little non-intuitive, it’s not all that surprising.
Carbonated beverages are already super-saturated, meaning there’s far more CO[sub]2[/sub] absorbed in the pop than it will hold at equilibrium (which, of course, is why pop goes “flat”). Dropping the external pressure to a vacuum just increases the driving delta-pressure, but not by a large percentage. You still need to drive the CO[sub]2[/sub] out of solution, which usually takes a little energy. Try applying a vacuum, and then giving the pop a brisk shake.
Alternatively, you can provide additional nucleation sites to give the solution more contact with the air, and more places for bubbles to form. Try pouring the pop through something like a filter pad or dry sand.
I think you could open it and stick it in the freezer, but you will have to wait for it to freeze. Also, you have to take into account expansion of the frozen liquid.
The partial pressure of CO2 in the atmosphere is irrelevant. If I put it in a vacuum, I’ve reduced the ambient gas pressure virtually to zero – the CO2 ought to come out in response to that, regardless of what the atmosphere on planet earth is.
Question: would your answer change if we were drawing a vacuum on your cup of soda on a planet with a CO2 atmosphere?
I believe his point is that with respect to the speed at which CO2 is coming out of solution, the presence of the 99.961% of air that is not CO2 is pretty much irrelevant. However, I’m not so sure that’s correct. To me, part the reason why the CO2 doesn’t quickly escape the solution is that the CO2 that does escape stays in close proximity to the solution due to the presence of other gasses that prevent it from zooming off. The equilibrium is harder to reach since the partial pressure of CO2 right at the boundary is higher than it is in the rest of the room. Removing the rest of the air will cause the CO2 to more quickly escape the area.
I can personally assure you that (at least with petroleum-based liquids and nitrogen) applying a vacuum won’t cause dissolved gas to spontaneously leave solution.
Why would reducing the external partial pressure to zero be different than reducing the external partial pressure to a small fraction of what it was originally?
