h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Supposing you've got a bottle of carbonated drink, say, oh, I don't know... some tonic water - purely for medicinal purposes and nothing to do with gin.

Any road up. Let's say that said bottle is plastic. Once opened you've got got to somehow retain as much of the fizz as possible. Do you think it would be best to squeeze the bottle and expel as much of the air as you can so that any gas in the bottle is almost all CO2, or should one leave it as is and just put the cap back on the bottle and leave it be?

I could go either way on this. If you squeeze the bottle the theory is that the bottle contains nothing but fizzy liquid and CO2 and the liquid should therefore stay fizzy, but I've found that next time you retrieve it from the fridge it's regained its original size because so much CO2 has escaped from the drink and filled the empty space, thus blowing the bottle back up, and if that much CO2 escapes from the liquid it must go flat more quickly.

If you just recap it though without squeezing the bottle you've got air in the bottle too, but that ought to mean that not so much CO2 can escape from the liquid because there isn't any room for it in the bottle, thus keeping it fizzier.

Or is there just likely to be no discernible difference? I drink a lot of tonic water you see, and I can only get it in litre plastic bottles.

Chin chin

The idea is that the CO2 absorbed by the liquid will slowly escape (in bubbles)until the pressure in the bottle builds up to a level sufficiently high to stop any more bubbles forming. Hence the reason fizzy drinks tend to fizz up suddently when you open the bottle and release the pressure insie.

So the best thing is to have the minimum of space available for the CO2 to fill... Squeezing the bottle won't work as the build up of pressure will just re-expand it. The other trick of shaking the bottle when you close it doesn't work either as it just accelerates the loss of CO2 (You'll get the same quantity of CO2 released, just faster than normal).

About the only thing I can think of is to avoid leaving space in the bottle for the CO2 to fill. If you could find something to replace the liquid removed (stainless steel ball bearings or something), then you could keep the volume of compressable air to a minimum thus minimising the quantity of CO2 released.

Jeez. How much is tonic water? About a dollar a bottle?

Loosen the purse strings, Gosho.

B

Nowt to do with wedge, B, as well you know. A ginnantonnix with flat tonic water is something I prefer to avoid.

I believe cooling down the drink will also make the liquid able to hold more dissolved gasses, so it should help keep it from going flat. Don´t squeeze the bottle though, that will just lower the pressure and let more CO2 escape.

But, if you cool the bottle, is the increase in the quantity of CO2 the liquid can contain greater than the increased loss due to the fact the cooling process would lower the air pressure within the bottle?

You could try one of two things.

1. Repressurise the bottle by some means sufficient to slow or stop the CO2 escaping from the liquid.
2. Squeeze all the air out of the bottle and put a weight on it back in the fridge. The weight would have to be heavy enough to have the same effect as in 1 above.

You could buy a Soda Stream and re-fizz the flat soda water or buy smaller bottles so that you have fresh each time or even drop an Alka Seltzer in the bottle .

Neat Gin over crushed ice is nice as is a White Lady (gin and Cointreau with a bit of lemon juice).

t.

Or I could just drink enough ginantonnix that the tonic water doesn't have a chance to go flat

There was a time when I started to design a bottle pressuriser (screw it on, pump it up) but gave up 'cos someone else put one on the market.

However, there had been a question in my mind about the effectiveness (partial pressures etc)...

That was a long time ago & can't remember much about it. Perhaps it didn't work? -or- Perhaps it's still available?

RtB

Oh and that's why we insist on buying the small (one glass' worth) tins of Ssh you-know-who, even though they're more expensive. Not always easy to find, either - we get 'em 3 or 4 boxes (of 12) at a time.
That usually lasts a week...

That long...?

t.

Oh, did I say 'of' 12? typo.

We bought one of those pump stoppers - works pretty well. Mostly we don't bother with it though, as any fizzy drinks get finished up before losing too much fizz, or the consumers put up with the loss!

Pumps are no good for fizzy drinks - they just pull the CO2 out even more. Those are for wine. We use these on the champagne bottles at work http://www.fyc.com/usr/catalog/bar/franmara-champagne-stopper.htm They work every bit as well as the screw top you get on a bottle of pop.

No, they are the opposite of the wine savers ones - you can get pump that puts more air into the bottle, increasing the pressure above the fizzy drink.

I can't be bothered most of the time and just tolerate flat tonic. These days I don't even get to have any G in my G&T so the tonic gets used up much faster which suggests I might previously have been putting far too much G in the glass...

i saw a program with Adam Hart Davis in and he said somthing about gasses not interacting with each other, so changing the pressure inside the bottle has no effect, the co2 would just leak out of the liquid untill it was at the correct pressure, so the way to preserve fizz is to put co2 back into the bottle, pour dink, exhale into bottle, put on cap.

hope this helps

Taff, that's partly true (I hinted at it post 9, 'partial pressures').
It'll take someone more knowledgeable than me to give a proper answer, but you'd be pumping *some* CO2 in, so you'd lose that much less from the liquid.
Breathing it back in would be a waste of good G fumes?