Put a warm can of beer in the freezer last night. Forgot about it. Wife found it this morning frozen solid as a rock. She put it in the sink where it thawed, then hours later she put it in the refrigerator to chill. I got home from work tonight and popped open a nice cold beer.
But man, is it flat. it’s weird. Like beer flavored kool Aid. There were no leaks or openings in the can for the CO2 to leak out.
So what happened here? I’ve done the same thing with soda and it survived just as bubbly as ever.
I don’t know the answer, but in my experience, soda does go flat after being frozen, or at least loses most of its carbonation. ETA: though in my case, it’s with plastic bottles, so perhaps that has something to do with it.
Bottle or can? A bottle can leak gas (particularly a twist-top) even though it doesn’t leak liquid. It would be a slow leak, however.
If the CO2 cannot escape, then it is just a matter of it going back into solution. When it freezes, a lot of the CO2 comes out of solution and exists as a gas (at high pressure). The solubility of CO2 in beer (or water) is highly dependent on temperature; the lower the temperature, the more CO2 can go into solution. It does take time, perhaps several hours to a few days, for equilibrium to return.
I’m guessing that the beer did give the satisfying “Pffffft” when opened, indicating it was under pressure, and that if you had left in the refrigerator a day or two, it would have been fine.
I think excavating has it mostly right. Freezing the can pushed most of the carbon dioxide out of solution and into either bubbles trapped in the ice or into the void at the top of the can. When it melted, the CO2 started going back into solution. Leaving it in the fridge for a day or two would have allowed most of the carbon dioxide to dissolve again. But, having frozen the can, you probably also bulged the bottom of it. So after the ice melted, the void at the top of the can was bigger and the gas pressure in the can was a bit lower than it would have been with a normal size can. This means that not quite all the carbon dioxide would go back into solution. You never would have gotten all the fizziness back.
There may have been some ice left in that can, I have seen this in bottled drinks, they seem pretty flat as long as there’s some ice left. There’s also the possibility that there was enough of a leak somewhere to allow the gas to escape. The expansion of the ice could have opened up a pin hole around the pull tab.
I think Tripolar’s right. Aluminum cans have incredibly thin walls and are usually filled to the brim with little if any empty space at the factory. Freezing it, the expanding liquid causes the can to bulge out and probably ruptured the can somewhere. Then, when it thawed, all that pressurized CO2 just bubbled out of the ice and left.
Chances are it did leak. Probably through a tiny tear in the scored line where the pop tab is. Enough for the CO2 to seep out but not any appreciable amount of liquid.
I have forgotten a can of beer in the freezer and thawed it in the fridge for 24 hours and it was flat. I did the same thing recently, thought it was a lost cause, but left it in the fridge for 48 hours and it was fine.
A leak somewhere seems likely to me (was the can bulged?) - IME beer bottles I’ve forgotten in the freezer have invariably popped the top and made a mess.
You can also mix flat beer with carbonated beer, and it will be at least drinkable if not exactly back to normal. This is a homebrewer’s trick for when your whole batch comes out under carbonated.
I’ve frozen lots of beer cans before and found that if you leave it long enough (a day or two) the carbonation returns… it seems to take many hours for the CO2 to dissolve back in and if you open the can too soon the beer will be flat. My rule is to let the frozen can thaw and warm up to room temp, then put it back in the fridge and cool it back down. Generally by this time the carbonation has returned as if nothing happened. A ruptured can however, don’t even bother trying.
This may sound counter intuitive, but shaking the can when it’s cold (not frozen) should help the CO2 to re dissolve into the beer. Unless it’s light beer which shouldn’t ever be consumed because they’ve removed some of the alcohol.
