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Does taking an unopened can of soda out of the refrigerator and leaving at room temperature compromise the taste, flavor, or carbonation of the unopened soda can?

TFD
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Ambrose
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  • I'm confused—soda here is normally sold unrefrigerated. Maybe we're referring to different things as soda? You mean things like Coca Cola, right? – derobert Apr 30 '12 at 17:35
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    Not being able to find an applicable tag usually means that the question is off-topic. I'm open to arguments as to how this would be considered a culinary question. – Aaronut May 01 '12 at 02:01

4 Answers4

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In order to create sparkling beverages, a gas called carbon dioxide (CO2) is dissolved in them, a process that goes under the name of carbonation.

When dissolved in water, CO2 becomes carbonic acid (H2CO3), following the reaction:

 CO2 (g) + H2O <-> H2CO3    (1)

The double arrow means that the reaction is reversible, that is, you can go from left to right as well as from right to left. So, essentially you have two reactions going on at the same time:

 CO2 + H2O -> H2CO3          (2)

and

 H2CO3 -> CO2 + H2O          (3)

However (and here's the trick) the g next to CO2 means that it is a gas and, as such, is volatile and will leave the water when it is formed (that is why you see bubbles coming out of your soda).

There is a very important law of chemistry called Le Chatelier's principle which states that:

If a chemical system at equilibrium experiences a change in concentration, temperature, volume, or partial pressure, then the equilibrium shifts to counteract the imposed change and a new equilibrium is established.

If CO2 was not volatile, what would happen is that, at some point, you would reach a chemical equilibrium, that is, the amount of H2CO3 formed by CO2 dissolving in water would be exactly the same as that of H2CO3 decomposing into CO2. But, as we said, CO2 escapes the water in the form of gas... So what happens is that you are always removing CO2 from your reaction and, as Le Chatelier's principle tells us, the system will react to counteract this loss, by decomposing more carbonic acid to forming more CO2.

This is why, if you pour soda in a glass it will slowly become less and less sparkly, as CO2 will leave the water, be substituted by the decomposition of some more H2CO3 and so on, until no H2CO3 is left.

So, why does a closed bottle of soda stay sparkling until you open it? Simply because CO2 has only a small room to escape (the small empty space on top of the liquid). All I said before works also for a closed can/bottle of soda, but at some point the air on top of the liquid becomes saturated with CO2, that is, it cannot make room for any more CO2. This means that the CO2 will restart to go back into the water.

All of these reaction will be influenced by temperature. Carbonic acid decomposition is much faster at room temperature compared to 4°C, so what happens is that, at room temperature, reaction (3) will be more favoured compared to (2) and when the can will be opened more CO2 will exit the can, giving you a slightly less fizzy drink.

This effect is similar to that of shaking the bottle: in that case you are mechanically promoting the dissociation of carbonic acid and helping CO2 to escape from water.

Finally, carbonic acid is, as you may guess, an acid, albeit a very weak one!

It will therefore contribute to lower the pH of your drink in a more or less strong way, depending on the soda: the pH contribute of H2CO3 will be higher in sparkling water (bringing the pH down from 7 to between 3 and 4) than in Coca Cola, which already contains a strong acid (H3PO4, phosphoric acid) and has a low pH in any case.

nico
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    To the downvoter: could you please explain the downvote? – nico May 01 '12 at 21:53
  • So nitrogenated or hydrogenated water could have the same fizz but without the bitterness or acidity? – endolith Oct 06 '13 at 01:33
  • @endolith: not sure about what would happen with nitrogen... but definitely you don't want to put highly explosive gas into your soda! – nico Oct 06 '13 at 08:38
  • The answer to the actual question is only reached after a fairly long amount of text. And it's a little unclear - if I understand right, you're just saying that it'll be less fizzy and possibly more or less acidic (which?) at room temperature than chilled. But the OP was asking about refrigerating then bringing back to room temperature - is that any different from just leaving it at room temperature in the first place? – Cascabel Jan 23 '15 at 21:18
  • An soda that loses carbon dioxide tends to have less flavor than a one which hasn't lost any. –  Jan 23 '15 at 18:39
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    @Jefromi *he answer to the actual question is only reached after a fairly long amount of text* I have this bad habit of trying to explain things clearly rather than giving unsubstantiated answers... As for the difference between refrigerating and RT or directly RT, surely that is different. As I say in my answer, reaction is slowed down at lower temperature, therefore 1h in the fridge and 1h at RT is different from 2h of RT. However, if the bottle is closed the difference may not be that big on the long term. – nico Jan 23 '15 at 22:15
  • I read the question as asking asking about a can that'd come to equilibrium in the refrigerator, then came to equilibrium at room temperature. Is that any different from just leaving at room temperature? (I assumed the OP knew what soda at room temperature was like, could be wrong.) – Cascabel Jan 23 '15 at 22:28
  • @Jefromi not if you leave it long enough at room temperature, so that it reaches the equilibrium. As the system is closed, CO2 has no means to escape therefore the previous state (fridge or no fridge) will only affect how long it will take to reach equilibrium outside the fridge. – nico Jan 23 '15 at 22:31
  • @nico Exactly - those are the kind of practical statements I thought might be useful in the answer. As long as it's unopened, basically just the temperature matters, with warmer meaning slightly less fizz. – Cascabel Jan 23 '15 at 22:53
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If the question is asking if this impacts the integrity of the can, in my experience, the answer is no. You can chill and warm the can over and over and as long as it remains sealed it shouldn't have any noticeable effect on taste, flavor, or carbonation once you do finally open it.

Now if you freeze it, it will likely explode.

As others have mentioned the taste and flavor can be affected by temperature but a cycle of temperature changes shouldn't alter the end result compared to a can that did not experience those same cycles.

Ryan Elkins
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The temperature of food or drink can have a dramatic effect on the flavor, as described. Though I can also offer a counter-example from experience. When I made the switch from sugared sodas to no-sugar sodas I found that the colder the drink the more sweet the taste.

Cos Callis
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I've once experienced freezing a soda, and yes it exploded. As for I am doing a science experiment on "what's the fastest way to cool a soda" and it's pretty simple really and basic. I- in my opinion think whether you freeze the soda, place in a refrigerator, or place in any position the soda will have the same taste to it as long as the soda has not been opened and has had anything accidentally go inside it.

danielle hathale
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