I am looking for some trick or gazzette to keep a bigger bottle of coke longer so that it doesn't lose all the fizz everytime it's opened again! Something which could keep the CO2 longer so that a bigger bottle could be used longer? Anything we have?
You can get a little pump that attaches to the top of the bottle.
It pumps in air to pressurize the bottle, thus preventing the carbon that makes the drink fizzy from escaping the liquid.
Something that will help a little is to get it very cold before it's opened, and don't let it warm up. Don't even let it warm up after you reclose it, as it will reach equilibrium faster when warm. I'm tempted to say it's because carbon dioxide is more soluble in cold water, but the physics of carbonation is much more complicated than simple solubility.¹ And while I don't know much about the underlying physics, the gas will escape faster if it is warm (and build up more pressure, assuming the container is closed).
Also, let it sit very still for some hours or days before it's opened. When you jostle or shake it, not only are nucleation sites introduced, but the (not quite) bonds between the carbon dioxide and the water are disturbed, and the solution is less able to bear the supersaturation until its former state is re-established.
If you want to cheat, you can buy a CO₂ canister from a welding supply store and make a lid with a nozzle glued into it. Top up the CO₂ by getting the soda nice and cold then pumping in some gas, keeping the pressure low so the plastic doesn't burst. When the pressure drops as the gas is absorbed, pump in some more. When the pressure is low enough, remove the nozzle and put a normal cap on. If you're really enterprising, you can produce CO₂ in a separate chamber with acid and baking soda.Regulating pressure will be a challenge.
1: Some brief further explanation here: https://winemakermag.com/1308-inert-gases-techniques
Colas go "flat" because of loss of CO2. The only way to keep the CO2 in solution is to prevent it from getting out. While the bottle is sealed, the liquid reaches an equilibrium where the partial pressure of CO2 outside the liquid (but still inside the bottle - the little "air" space at the top) is equal to the partial pressure of CO2 inside the liquid.
As soon as the bottle is opened, the partial pressure of CO2 in the "air" space drops and you see CO2 effervescing from the liquid. This is the liquid's attempt to reach equilibrium again. While the cap is off, equilibrium will not be reached until the CO2 in the liquid is equal to that of ambient air (about 0.04% - aka "flat"). Putting the lid back on helps limit this process, but will NOT prevent the liquid from losing its "fizz". The liquid will reach another equilibrium point after some time at which, the concentration of CO2 in the liquid has dropped in order to stabilize the concentration of CO2 in the air space.
The pressurization gadget mentioned at the very top of the responses does NOT work at all as it does next to nothing to add CO2 to the air space. Ambient air is about 0.04% CO2. You will not be able to pressurize the bottle with enough air to prevent the release of CO2 from the liquid. Not possible.
The only way to prevent the liquid form going "flat" is to introduce CO2 at the same rate at which it leaves. This means you need a system that injects CO2 into the bottle as the liquid is poured out. I'm not aware of anything that does this at the moment.
If you buy your soda in a big plastic bottle, I recommend squeezing out as much air as you can before you screw the cap back on. My theory is that the carbonation wants to leave the soda, but if there is nowhere for it to go (no big pocket of air in the bottle), then the carbonation will stay in the soda.
(I'll determine whether my theory is right by the number of thumbs up and thumbs down I get on this answer.)
Its a bit more involved, but you can get a carbonator cap. We use it in homebrewing to carbonate beer and to keep it carbed. It allows you to hook up a co2 tank to a 2 liter bottle. You would need the cap, a regulator and a co2 tank or cartridges.
A bottle of soda will lose it's fizz if it is opened when warm,so when you decide to open a large bottle,the first thing to do is to refrigerate it. When the bottle is cold, you can open it and pour the soda. Don't let it get warm after you open it. Pour the soda, re-cap it,then put the entire bottle back in refrigerator. From then on,the way to pour servings of soda will be:
- take bottle from refrigerator
- pour soda
- re-cap bottle
- put bottle in refrigerator
We all know that for each time it's opened some fizz escapes. Reducing the number of times it is opened (or handled) therefore reduces the amount of fizz escaping.
One way for a larger bottle to retain fizz can therefore be to divide the contents into several smaller bottles, so as to reduce the number of openings before actually being consumed.
Note that this should be done with the beverage being as cold as possible to reduce loss of fizz when pouring to the other container(s).
Keep the bottle cold and in an upright position. If you drink the coke within a day or two, it will keep fresh and sparkling, and you should hardly notice the difference.
Tip: The more coke there is inside the bottle (and the less air), the less CO2 will escape from the coke and into the (closed) bottle while it is stored in the fridge (results from Henry's law). Pour over coke from a half-full bottle over to a smaller container (or into another half-full bottle of coke, to fill one single bottle), and you will save space and loose less sparkling gas.
CO2 "evaporation" is a result of the gas trying to reach an equilibrium between what is solved in the liquid (coke) and what is in the air above (Henry's law).Keep in mind:
- Less CO2 escapes if the temperature is kept low (CO2 is more 'soluble' in low temperature, and less will escape from the liquid)
- Less CO2 escapes if the bottle is kept upright (smaller surface area than when the bottle is laid down, so this will slow down the 'evaporation' process)
- Less CO2 escapes if the bottle is almost full (smaller 'air' volume to fill with CO2 escaping from the liquid)
The moment you have opened a bottle of coke, then non-sterile air from the surroundings mixes with the content inside the bottle. An opened container will only keep fresh (without growth of bacteria or fungus) for a limited number of time (a week or two).