a pretty common action when closing half-full plastic bottles of pop is to squeeze them first, leaving as little air inside as possible. this is done to preserve the carbonation. i’m just wondering: does it really work?
I’ve never seen anyone do this - it seems like it would make the situation worse. You’d want to keep it under as high a pressure as you can, so that the carbonation doesn’t come out of solution. But if you squeeze the bottle before replacing the cap, the sides trying to pull outwards would actually cause the pressure in the bottle to be lower than ambient, so it would lose its carbonation even faster.
No, and it could cause more loss of carbonation. The elasticity of the bottle creates a slightly low pressure and could pull CO[sub]2[/sub] out of solution. To preserve the carbonation, you’d have to pump CO[sub]2[/sub] into the bottle at a fairly high pressure. It’s possible, but it’s not worth the cost or trouble.
There are inexpensive hand pumps that pump air into opened and resealed bottles of champagne, but they really don’t have much of an effect.
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If anything it might do the opposite. Keeping the contents of the bottle under pressure is what retains the CO2 in when it’s bumped or shaken. It may bubble out when it’s disturbed but now the bottle is under much higher pressure, forcing the gas bac into solution. When you squeeze the bottle it wants to return to it’s normal shape because of the memory in the plastic. That reduces pressure, literally pulling the CO2 out of the soda.
I do this myself, but it’s not to save carbonation. The idea is, that I don’t mind flat pop as much as I mind it fizzling all over the countertop when I open it. This way, when some more gas comes out of solution, it just pops the sides of the bottle back out, instead of pressurizing the contents.
The amount of gas dissolved in a liquid is proportional to the pressure of the gas exerted on the liquid. This is why carbonated drinks are sealed into cans under pressure, it keeps the CO2 in solution in the liquid. Reduce the pressure, more gas will go out of solution and try to reach a new pressure equilibrium.
HIJACK ALERT
I have a soda siphon at home that screws on to the top of a standard 2-liter soda bottle. It uses the pressure of the carbonated soda to drive the liquid out of the bottle, through a valve, and into my glass (sort of like a tap on a beer keg). It keeps the soda from ever going flat since there is still a lot of pressure in the bottle when the soda runs out. It works just like the soda siphons you see in classy bars (or old movies, in case you still don’t know what I’m talking about, when the three stooges got squirted with seltzer THAT is a soda siphon). The only problem is that the company that made my siphon did a really crappy job of it and I suspect that is why it disappeared from store shelves. What do you folks think, is a soda siphon that screws onto 2-liter bottles a viable product? Would you want one to keep your soda from going flat? The reason I’m asking is because I have considered trying to start a company to make such a product and make it right.
SarumanRex : Go for it I would by one. If it worked I would want more than one.
This topic was discussed a little here.
torq had this one right in the linked thread that Alphagene posted. But to make it short, yes, it does work… ------ IF ----- you squeeze the bottle so that it will retain its deformed state after the squeeze is released.
I think you’re forgetting something… Real soda siphons use little cartriges of CO2. You can put plain old water in them, and it will come out as soda water. The carts have CO2 in incredibly high pressure, when released into a closed chamber with a liquid, it will dissolve the gas into the liquid.
I know that real soda siphons use CO2 cartridges to carbonate plain water. Soda in 2-liter bottles is already carbonated and I have a cheap plastic soda siphon that works in the way I have described, just not very well (what can I expect for 3 bucks).
I once had a roommate that would not only squeeze the bottle, but would also shake it up before putting it back in the fridge. When I asked him what difference that would make he gave me some gibberish about the CO2 releasing into the air (from the liquid)in the bottle when he shook it, then being forced back into the liquid by the limited air space. I told him I didn’t see the point in releasing the CO2 into the air space in the first part. He wasn’t able to explain, so I told him to play Mr.Wizard with his own soda.
If you put the top back on tightly it doesn’t lose it’s carbonation for weeks. At least, that’s the deal with Dr. Pepper at my altitude (close to a mile high).