Sherry in the mushroom sauce

We were cooking up a storm of tortellini with wild mushroom sauce the other night. Not that we had tortellini kicking around, but some good old linguine did the trick. And not that the mushrooms were really wild… well, you get the picture.

Just before the sauce was ready to go I took one look and thought, eeeuh, that’s way too thick. The main liquid ingredient is Marsala wine, not that we… oh, forget it.

Anyway, we were using a pretty nice sherry. But just before splashing in more to thin the sauce my sous chef yelled, no, no, it won’t have time to burn off if you add it now, you swine (my sous chef is far from insouciant at times). So I applied my usual culinary strategy and just slipped it in when he wasn’t looking. We all thought it was pretty delicious nonetheless, but maybe that was because we’d been sipping the sherry throughout the prep.

In all fairness to my sous chef, that’s not the first time I’ve added some form of alcohol or another to a dish fairly late in the game and wondered the same thing myself. On occasion, we’ve also inadvertently sent dinner guests who happen to be alcoholic scurrying into the kitchen when they’ve spied us refining one dish or another with dashes of this or that from various bottles of booze.

I’d be among the first to proclaim that alcohol has a cherished place in the kitchen. I’m known to be quite liberal with the Cointreau bottle around fresh sliced strawberries, even on ridiculously early mornings. And the only time I was on a team that almost won a chili cook-off, right in Village Square I should note, we juiced our way into second place adding, no lie, about a six-pack of beer into the pot. But, hey, it was good beer, at least the judges must have thought so, and we added it gradually before reducing it over hours of cooking time.

At home, we’ve always blithely reassured guests fearful of any alcohol slipping into dinner, whether they be alcoholic or not – apparently there are varying degrees of sensitivity as to whether seven-year-olds should be enjoying spaghetti sauce nursed into full bloom with red wine. Oh, don’t worry, all the alcohol has burned off, we pipe, pouring ourselves another glass.

But has it?

While commonly-held wisdom is that booze used in cooking burns off after simmering some pronounced length of time – what is it, 10, 20 or 30 minutes in your household? My mom says about 40 – I was quite happy to learn a little more nuanced take on the subject from Robert J. Wolke’s excellent book, Kitchen Science Explained: What Einstein Told His Cook .

Wolke is professor emeritus of chemistry at the University of Pittsburgh and his Washington Post column has won several distinguished awards, including one from the James Beard Foundation. So I take his observations on the alcohol-in-cooking regime in full measure. They go something like this:

First of all, when cooks or cookbooks say that the alcohol "burns off" they really mean that it evaporates, since alcohol won’t burn unless you light it. That doesn’t mean over the years you’ve wrecked everyone’s sambuca that you served flaming, though I now hear that a cool thing to do is to ignite it right in your mouth and squelch the flames once you feel the burn, something I can’t even imagine anyone doing as I picture the hapless idiot in a burn unit, but like I said, it’s out there.

The "burning off" myth apparently arose from the rationale that alcohol boils at 173ºF, water at 212ºF, ergo the idea that alcohol will "burn off", meaning boil off, before the water-based liquid does.

But that’s not the way it works, according to Wolke. At least not when the two are combined, as they usually are in a recipe. A mixture of alcohol and water boils at anywhere between 173º and 212º degrees, closer to 212º if the mixture is primarily water, which is usually the case, and closer to 173º if it’s mostly alcohol.

As for that big waft of alcoholish fumes you inhale when the wild mushroom sauce or whatever is simmering, that is, the smell that assures you the booze is "burning off", well, that may not contain as much alcohol as you might think.

Since alcohol evaporates more readily than water, the vapour does contain more alcohol than water, but it’s far from pure alcohol. In fact, it may not contain much alcohol at all.

In a study, nutritionists from two U.S. universities and the USDA measured the amounts of alcohol in three dishes before and after cooking. They found that between 4 and 49 per cent of the original amount of alcohol still remained in the final products, depending on the type of food and cooking method. On average, a coq au vin recipe using three cups of wine lost about half the alcohol during 30 minutes of simmering. A boeuf bourguignon dish made with the same amount of wine and simmered for three hours lost about 95 per cent of the alcohol.

Factors such as higher temperature, longer cooking time, a wider pan and no lid all increased the amount of water – and alcohol – that evaporated.

As for those blue-flaming sambucas, Bailey’s Comets, crêpes suzettes or other occasions when you actually ignite the alcohol with an open flame, the same study also found that only about 20 per cent of the alcohol may be burning off. That’s because to sustain a flame the percentage of alcohol in the vapour must be above a certain level. When the amount of vaporized alcohol burns down below that point, the fumes may no longer be able to sustain a flame, but a substantial amount of alcohol can still remain in the dish of crêpes or whatever.

So if your sister squawks that you’re getting little Jack high on the kirsch or brandy in cherries jubilee as he ricochets off the ceiling, she might have a point. On the other hand, it could be the sugar or the fact that he’s up way past his bedtime having dinner with the big people.