One of the biggest ones is that since alcohol has a lower boiling point (78.4°C) than water (100°C), all the alcohol must evaporate first when added to a dish.
Sorry, folks, it doesn't quite behave that way as every physicist and chemist possibly knows.
Firstly, in general, you need multiple distillations to separate two liquids. This is just a consequence of how molecules behave. Energy transfer and evaporation are statistical in nature not deterministic.
Secondly, ethanol and water form an azeotrope so you can never truly separate them using just distillation.
So while the rate of evaporation of alcohol is higher than that of water at 100°C (cooking temperature), there's always going to be alcohol left behind in the mixture even after extended cooking. Particularly in a closed vessel where you have both evaporation and condensation taking place.
| Method | Percentage alcohol remaining |
| Added to boiling liquid + removed from heat | 85% |
| Alcohol flamed | 75% |
| Alcohol simmered 15 minutes | 40% |
| Alcohol simmered 30 minutes | 35% |
| Alcohol simmered 1 hour | 25% |
| Alcohol simmered 1.5 hours | 20% |
| Alcohol simmered 2 hours | 10% |
| Alcohol simmered 2.5 hours | 5% |
(Source: US Dept. of Agriculture Nutrient Data Lab.)
Note that we're talking miniscule amounts because generally only a small amount of alcohol is added to the dish but the myth that there is none left behind is just that.
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