Cooking with Alcohol

name         Keith
status       teacher
grade        9-12
location     CA

Question -    When cooking with wine and various forms of
alcohol, does the alcohol evaporate or burn off? What temperature
does this type of alcohol burn at?
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Keith,

The alcohol in alcoholic beverages is ethanol. In its pure form, 
ethanol has a boiling point of 78.3C. Since the boiling point of 
water is 100C one should expect that the ethanol can be boiled off 
before the water is completely removed from the cooking sauce.

You may have heard that ethanol and water form an azeotrope. At 95% 
ethanol to water, the vapor formed has the same exact composition as 
that of the solution, the two-component system acts as though it 
were a pure compound (at least as far as boiling point is concerned) 
and has a boiling point of 78.15C. At this point, no amount of 
distillation or careful heating can preferentially boil off the 
ethanol. However, wines and spirits are usually under 100 proof (50% 
ethanol). Thus this issue of azeotrope formation is not a concern. 
The sauce never gets to be 95% ethanol (quite the contrary).

Still, in most cooking processes, the length of time of heating or 
flambeing is not sufficient to remove *all* the alcohol. There will 
be a trace amount of alcohol in the sauce.

Greg (Roberto Gregorius)
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Depending upon the recipe, either/both processes can occur. 
Ethanol boils at about 78 C., so if wine or other alcoholic 
ingredient is simmered/boiled at a temperature of about the boiling 
point of water, 100 C. the  ethanol with evaporate. On the other 
hand, if the source of ethanol is in a more concentrated form, e.g. 
rum, brandy, or fortified wine, and the recipe is heated over an 
open flame, as is done in some recipes, the ethanol vapor can 
ignite and burn -- usually with a blue flame. No other alcohols 
than ethanol (C2H5OH) are used in cooking to my knowledge because 
other alcohols such as methanol or propanol are toxic, or taste bad.

Vince Calder
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Well, I don't think that they meant that it actually burns the alcohol off,
but rather that it boils off, as alcohol is more volatile than water.
Unless you flambé the stuff, the alcohol doesn't burn.

As it turns out, the view that cooking removes all alcohol is erroneous.
Some of the alcohol will boil away, but usually not all of it.  If you add
wine to a soup and only gently simmer the soup in a covered pot, most of the
alcohol will remain in the soup.  On the other hand, if you add brandy to a
sauce and heat it over high heat until the sauce is much thicker in
consistency, most of the alcohol will boil away.  Basically, it depends on
how thoroughly you cook down the liquid.

Richard Barrans
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