Any experienced cook knows you can add some flavor by putting a bit of alcohol in with sauces, and any experienced baker knows that squirting a cake with brandy and setting it on fire as it goes out to the table will eliminate any questions as to why it looks so crappy once the fire has been put out. With the many social events and potluck dinners in the holiday season, we all rely a little bit on alcohol to get us through.
What most chefs assure us, especially when serving dishes to children, is that the booze will "cook off." And some of the time it does. Other times, not so much.
We know that alcohol boils out of food before water does for the same reason we know that we don't get a big dose of antifreeze with our alcohol. The fermentation process — especially in liquor cooked in a still — produces methanol as well as ethanol. To get rid of the methanol, the concoction is heated, with a tube allowing steam to escape. Methanol's boiling point is 65 degrees centigrade, so the temperature of the boiling liquid will stall there, before climbing up to alcohol's boiling point of about 78 degrees centigrade. When the liquid boils at 78 degrees, there is no appreciable quantity of methanol left and it can be collected, bottled, and eventually served. Things should, in theory, go the same for food dishes containing both water and ethanol. Water boils at 100 degrees centigrade, at which point almost all of the ethanol should be gone.
But things get complicated. For one thing, boiling water and alcohol in a pan or pot is not the same easy temperature-measured process as boiling off methanol in a still. The mixture will boil somewhere between the boiling point of water and the boiling point of alcohol, meaning that, when you first see your dish boil, the temperature will still be quite low. The vapor rising up from the pan, though, will have a higher ratio of alcohol-to-water than exists in the pot. As more alcohol boils off, the mixture boils at a hotter and hotter temperature.
It still takes time. Bringing the liquid to a quick boil after you've deglazed a pan with alcohol won't take out the booze. One researcher found he had to boil a can of beer for 30 minutes before he took the alcohol content down to zero, but few people are willing to wait that long. A study on the leftover alcohol content of dishes showed that depending on the cooking method, up to 49% of the original alcohol was still in the pot when the dish was done. The dishes with the least alcohol in them were simmered in a wide, open pots, letting the alcohol freely boil away. As lids were put on deeper pots and dishes were cooked more quickly, the percentage of alcohol left over rose. Some dishes, baked in the oven with a lid over them, retained up to 85% of their original alcohol content.
Even setting things on fire doesn't completely work. Flambés barely take the edge off alcohol; generally, only the vapor above the dish catches fire, while the rest soaks into the food, leaving it very boozy. (Fatty dishes also kept a higher percentage of alcohol, since fat seems to hang on to it.) Any dish set on fire can retain 75-80% percent of the booze originally dumped on it.
So you were probably consuming a little more alcohol than you thought you were this season. That being said, if anyone has a good brandy cake recipe, lay it on me. It's almost a new year, and I'd like to start 2013 right.
Image: Taro Taylor