This is a topic I admit to knowing nothing about. This question relates to very old bottles of red wines where the fill levels significantly decrease over time. What exactly happens to the given alcohol content, as a ratio of remaining wine in these bottles? Thanks!
Well, I am no expert, but alcohol and water have different vapor pressures that vary with temperature, and relative humidity. At higher humidity alcohol is going to evaporate ever so slightly more. As to actual data… I’m not sure. It would be interesting to test a new batch of wine, and age them for a few years in different conditions to see what would happen.
Interesting science question that piqued my curiosity enough to do a quick google search.
I’m assuming, perhaps incorrectly, that the liquid level reduces essentially through evaporation via the cork. I’m also assuming that the cork (and/or other seal) doesn’t change the nature of the evaporation.
Wine is a mix of ethanol and water. One experiment showed that when the two are mixed, alcohol tends to evaporate more quickly than water.
If applied to wine, then presumably the alcohol level goes down with time.