I’ve been doing some research on the amount of alcohol that is present in wine after decanting. This is because I had expected that it goes down rather quickly when the wine is left exposed to open air. The reason to think that is because I feel the wine heat goes away when I decant. Do you recognise this observation?
In any case, it turns out that the alcohol content goes down very slowly. A nice set of data that I found, which correlates to a typical 750 ml bottle at 14% alcohol, for 100 ml of pure alcohol is the following:
As you can see, it takes about a day for the alcohol to reduce by 10 ml. In other words: if I decant a 14% bottle of wine early in the morning, at night the alcohol content will still be 13+%.
I’m curious as well. I would think the rate would vary considerably given temp and surface area though. Significant in the real world as decanters vary in size, cellar vs room temp decant, etc. Perhaps a spinning cone manufacturer would have this data?
Yes, I agree that there will be a sizable temperature dependance.
As to surface area: it will probably be determined by the smallest surface area that the wine ‘sees’ before being exposed to the outside world. As such, it will probably vary from around 2 cm in diameter (bottle of wine) to a few cm diameter more for a decanter. I don’t think that is too much of an effect. But interesting to study nonetheless… (science = cool
The plot above is for pure alcohol (and I think it’s for isopropyl alcohol rather than ethanol). Alcohol mixed with water evaporates at a different (slower) rate.
With all you guys with lab and lab equipment at your disposal, I would think this would be a pretty easy experiment to do with a few (to make the data more reliable) cheap bottles in relatively standard decanters just for fun and vague reference.
I would guess another factor could be at work, as well: Some wines flesh out with air, and that could mask alcohol to some degree. (Of course, that might be offset if the wine warms up, which typically highlights alcohol.)
I’m a little unclear. Are you assuming a full decanter with a narrow neck? What about a bulbous decanter where a lot of surface area is exposed to air?
Exactly. This experiment is a good idea, but it’s not executed well. Wine is mostly water and ethyl alcohol. Both are evaporating. Ambient humidity is going to be key in finding the tipping point at which ethanol evaporates faster than water. At sufficiently low humidity, water will evaporate faster than alcohol. It’s the partial pressure that matter, IIRC, and the partial pressure of water is what varies.
The other objection is the assumption that ethyl alcohol is the source of heat. Maybe it can also be VA or fusel alcohols that cause heat.
