What Einstein Told His Cook (25 page)

REAL COOL STUFF

UNFREEZING YOUR ASSETS

What’s the best and fastest way to defrost frozen foods?

I
know what you mean. You come home after a hard day’s work. You don’t feel like cooking, and you can’t face the hassle of going to a restaurant. Where do you turn?

To the freezer, of course. And like a crowd of football fans, a little voice in your head begins to chant, “DEE-frost! DEE-frost!”

Scanning your frozen assets, you’re wondering not so much about what is in there (“Why didn’t I label those packages?”), but about what would defrost in a minimum amount of time.

Your options are (a) leaving it out on the kitchen counter while you go through the mail, (b) soaking it in a sink full of water or (c) the best and fastest method of all, which I shall divulge in due time and which, I promise, will astound you.

For commercially packaged frozen foods, just follow the directions. You wouldn’t believe the armies of home economists and technicians who slaved away to determine the best methods of defrosting their company’s products in the home kitchen. Trust them.

While the defrosting directions on commercial packages often involve a microwave oven, that usually doesn’t work for thawing home-frozen foods, because it’s hard to keep the outer regions of the food from beginning to cook.

“Frozen food” is something of a misnomer. Technically speaking, freezing means converting a substance from its liquid form into its solid form by cooling it below its freezing point. But meats and vegetables are already solid when they are put into the freezer. It’s their water content that freezes into tiny ice crystals, and those ice crystals are what make the whole food hard. The job of defrosting, then, is to melt those tiny ice crystals back to their liquid form.

How do you melt ice? Why, you heat it, of course. Your first problem, then, is to find a source of low-temperature heat. If that phrase sounds paradoxical, please realize that heat and temperature are two very different things.

Heat is energy, the energy that moving molecules have. All molecules are moving to some extent, so heat is everywhere, in everything. Even an ice cube contains heat. Not as much as a hot potato, but some.

On the other hand, temperature, as I have pointed out earlier, is just a convenient number by which we humans express how fast the molecules are moving. If the molecules of one substance are moving faster, on the average, than those of another, we say that the first substance has a higher temperature, or is hotter, than the other.

Heat energy will travel automatically from a warmer substance into an adjecent, cooler one, because the faster molecules in the warmer one can bang against the molecules of the cooler one, making
them
move faster. Obviously, then, we could warm our frozen food most quickly by putting it in contact with a hot substance, such as the air in a hot oven. But that would cook the outer parts of the food before much heat could penetrate into the inner parts.

The air in your kitchen is at a very moderate temperature compared with the air in a hot oven, but it still contains a lot of heat that can be tapped to defrost frozen food. So should we just leave the food out in the air? No. It would take too long for the air to transfer its heat, because air is just about the worst conductor of heat that you can imagine. Its molecules are just too far apart to do much banging against other molecules. Besides, slow air-thawing is dangerous because bacteria can grow rapidly on the outside portions that are first to thaw.

How about soaking in water? Water is a much better heat conductor than air is, because its molecules are much closer together. If the food package is waterproof (and if you’re not sure, seal it in a zipper-top bag after pressing out most of the air), then by all means soak it in a bowl—or in the case of a whole chicken or turkey, a sink or bathtub—full of cold water. Since the frozen bird will make the water even colder, change the water every half hour or so and the whole process will go even faster.

The quickest method of all, I now reveal, is to place the unwrapped frozen food on an unheated, heavy skillet or frying pan. Yes, unheated. Metals are the champion heat conductors of all substances, because they have zillions of loose electrons that can transmit energy even better than clashing molecules can. The metal pan will conduct the room’s heat very efficiently into the frozen food, thawing it in record time. The heavier the pan the better, because thicker metal can conduct more heat per minute. Flat foods like steaks and chops will thaw fastest, because they make the best contact with the pan, so keep this in mind when making up your packages for the freezer. (Round, bulky roasts and whole chickens or turkeys won’t thaw much faster on the pan than on the counter; however, neither method is recommended because of the danger of bacterial growth. Thaw them either in cold water or in the refrigerator.) Nonstick pans won’t work, incidentally, because the coatings are poor heat conductors, nor will a cast-iron pan because it is porous.

I discovered the frying-pan gimmick while experimenting with one of those “miracle” defrosting trays sold in catalogs and cookware stores. They are reputedly made of an “advanced, space-age super-conductive alloy” that “takes heat right out of the air.” Well, the space-age alloy turns out to be ordinary aluminum (I analyzed it), and it “takes heat out of the air” exactly the way an aluminum frying pan does, and for exactly the same reasons.

So save the water method for the bulky stuff and just put that frozen steak or fillet on a heavy frying pan. It’ll be thawed before you can say, “Where did I put those frozen peas?” Well, not quite, but a lot sooner than you’d think.

HOW TO MAKE A COOL BUNCH OF DOUGH

Why do cookbooks recommend rolling out pastry dough on a marble surface?

P
astry dough must be kept cool during rolling so that the shortening—most often a solid fat such as butter, lard, or Crisco—doesn’t melt and soak into the flour. If it does, your piecrust will have the texture of a shipping carton. Flaky pastry is produced when many thin layers of dough are kept separated from one another by layers of fat. In the oven the separated dough layers begin to set, and by the time the fat melts, steam from the dough will have forced the layers permanently apart.

Marble is recommended for the rolling surface because, according to the books, it is “cool.” But that’s playing fast and loose with the concept of temperature, because the marble isn’t one bit cooler than anything else in the room.

But, you protest, the marble
feels
cold. Yes, it does. And so does the “cold steel” of your chef’s knife and every one of your pots, pans, and dishes. In fact, run into your kitchen right now (I’ll wait), pick up anything at all except the cat and hold it against your forehead. By George, everything feels cold! What’s going on here?

What’s going on is that the temperature of your skin is about 95ºF, while the temperature of your kitchen and everything in it is around 70ºF. Is it any surprise, then, that things should feel cold if they actually are 25 degrees colder than your skin? When you touch such an object, heat flows from your skin into the object, because heat always flows from a higher temperature to a lower one. Your heat-deprived skin then sends the message “I feel unusually cool” to your brain.

So it’s not that the object is cold; it’s that your skin is hot. As Einstein never said, “Everything is relative.”

But all things won’t feel equally cold, even though they are all at the same 70ºF room temperature. Go back to the kitchen, please. Notice that the steel blade of your chef’s knife feels colder than, say, the wooden cutting board. Is it actually colder? No, because the two objects have been in the same environment long enough to have come to the same temperature.

The steel knife blade feels colder on your forehead than the wooden cutting board does because steel, like all metals, is a much better conductor of heat than wood is. When in contact with your skin, it conducts heat away into the room much faster than the wood can, thereby cooling your skin faster.

Marble isn’t as good a heat conductor as metal, but it’s ten to twenty times better than a wood or plastic-laminate countertop. Just as marble feels cold to your skin because it steals away heat, the marble feels cold also to the pastry dough because it removes the rolling-generated heat rapidly. Thus, the dough doesn’t warm up enough to melt the shortening.

Okay, okay, so I’m splitting hairs. If something feels cold, acts cold, and does everything but quack like a cold duck, why the heck can’t we just say that it’s cold? So be my guest. Say that marble is cold. But take secret pleasure in the knowledge that it isn’t strictly correct.