I have made a funny homemade experiment, repeatable, and with a high success rate over 6 bottles of cola. I haven't found any trace on internet.
It reminds me the Mentos-Diet Coke experiment, but I am focusing on the lemon.
Take a bottle of sugarfree cola, e.g. diet Pepsi in this case. Cut a lemon and put some through the bottle's hole to give some taste to the beverage (we are in the process of making Lemon Pepsi...). Seal the bottle. Put it in the fridge.
As soon as you do it, the lemon floats on top the cola. The next day, however, the lemon disappears. Apparently disappears. You can find it on the bottom of the bottle.
Now open the bottle. It obviously fizzes. And then the lemon almost instantly appears floating, with a huge amount of foam trying to break through the top. This is the part where this experiment reminds me about Mentos.
But the Mentos experiment differs because the reaction is instantaneous and the bottle is left open.
Question
What does happen inside the bottle so that
- The lemon sinks when the bottle is closed and refrigerated (I haven't trying air temperature)
- After opening the bottle, the lemon starts to float again, and won't apparently sink anymore again
- When opening the bottle, a large amount of foam is produced and a small eruption occurs
Number #3 is likely to be the same reason (nucleation) of the Mentos experiment, but of course a lemon has different physical features than the Mentos candy.And when the bottle is shut the air pressure inside the sealed bottle may be increased.
I don't know the rest. Enjoy your drink if you like to try yourself!