What Einstein Told His Cook (22 page)

IT’S MAINE-LY A MATTER OF OPINION

Some people say the best way to cook a live lobster is to boil it. Others insist that steaming is better. Which method should I use?

T
o find an authoritative answer, I went to Maine and interviewed several leading chefs and lobstermen. I found two distinct camps: the staunch steamers and the passionate plungers.

“I plunge,” defiantly declared the chef at a well-known French restaurant. He plunges his lobsters into boiling water laced with white wine and lots of peeled garlic.

But according to the chef at another eminent restaurant, “Boiling extracts too much flavor from the lobsters. You can even see the water turn green from the tomalley [liver] that leaks out. We steam our lobsters over fish stock or vegetable broth.”

The chef at a renowned inn at first pledged allegiance to the “boiling-draws-out-flavor” school of thought and said he steams his lobsters over salted water. “They wind up with less water inside,” he said. But when pressed, he said that for flavor “both boiling and steaming are good. Arguing over it is splitting hairs.”

The latter sentiment was echoed by the owner of a venerable lobster pound, who has been fishing, selling and cooking lobsters for forty years. “I used to steam them for about twenty minutes,” he said. “I have customers who insist that they absolutely must be steamed over salted water. Everybody has an opinion. Now I boil them in seawater for about fifteen minutes.” A believer in the philosophy that the customer is always right, he refused to list either to port or starboard and recommend one method over another.

My conclusion?
Double, double, toil and trouble; lobster steam or lobster bubble.
It’s a draw.

The one thing that everybody seemed to agree upon, though, is that steaming takes longer. Why, I wondered? Theoretically, when water boils, the steam should be the same temperature as the water. But are they, really? To answer this question I repaired to my kitchen “laboratory.”

I put a few inches of water into a three-gallon lobster pot, brought it to a boil, covered the pot as tightly as one must when steaming foods, and then measured the temperature of the steam at several distances above the water’s surface with an accurate laboratory thermometer. (How I managed to rig the thermometer bulb inside the covered pot while I read the temperatures from outside will be explained upon receipt of a self-addressed, stamped envelope and a check or money order for $19.95 to help defray my medical expenses.)

Results? With the burner set high enough to maintain the water at a rolling boil, the temperatures at all distances above the water were exactly the same as that of the boiling water: 210ºF. (No, not 212. My kitchen, along with the rest of my house, is one thousand feet above sea level, and water boils at lower temperatures at higher altitudes.)

But when I turned the burner down to a slow boil, the steam temperature dropped substantially. My explanation is that some of the steam’s heat is always being lost through the side of the pot (which in this case was rather thin), and the water has to be boiling fast enough to keep replenishing that heat with fresh, hot steam.

Conclusion: Steam your lobsters on a rack over vigorously boiling water in a tightly covered, heavy pot and they will be exposed to exactly the same temperature as if they were being boiled.

The mystery, then, is why all the cooks tell me they steam lobsters for a somewhat longer time than when they boil them. In his comprehensive book
Lobster at Home
(Scribner, 1998), for example, Jasper White recommends boiling a 1½-pound lobster for 11 to 12 minutes or steaming it for 14 minutes. (These times are shorter than the Maine chefs reported because they cook several lobsters in a batch and it’s a simple case of more meat, more heat.)

The answer, I believe, lies in the fact that liquid water can hold more heat (Techspeak: it has a higher heat capacity) than steam does at the same temperature, so it has more heat to donate to the lobsters. Moreover, liquid water is a much better conductor of heat than steam is, so it can deliver those calories more efficiently into the lobsters and they will cook in a shorter time.

Now, I’m not a chef. But on the other hand, chefs are not scientists. So the chefs I interviewed can be excused for making some scientifically erroneous statements. Here are a few of them and why they’re wrong.

“Steaming makes a higher cooking temperature than boiling.” As my experiments showed, the temperatures are the same.

“Salted water makes higher-temperature steam.” Well, perhaps a trifle, because the boiling temperature is higher, but by a few hundredths of a degree at most.

“Sea salt in the steaming water gives a better flavor to the steam.” Salt does not leave the water and enter the steam, so the type of salt—or no salt at all—can have no effect. I even doubt that the essences of wine or stock in the steaming water could penetrate the lobster’s shell enough to have any effect on the flavor of the meat. Lobsters are well-armored beasts.

Here’s how Chip Gray, a native Down-Easter, told me he cooks lobsters at the shore: First, procure a 4-to 6-foot length of stovepipe at a hardware store. At the shore, build a campfire. Now plug one end of the pipe with seaweed and throw in a couple of lobsters and a handful of clams. Stuff in a second plug of seaweed and top it with more lobsters and clams. Continue alternating seaweed and shellfish until you run out of either lobsters or stovepipe. Top it all off with a final plug of seaweed and lay the pipe across the campfire. As the food cooks, baste it continually with a cup or two of seawater poured into the higher end of the pipe; it’ll turn to steam as it rolls down to the bottom. After about 20 minutes, dump the contents of the stovepipe out onto a sheet on the ground.

“It’s wicked good,” says Chip.

L
OOK AROUND THE KITCHEN
at all your modern conveniences: your toaster, your blender, your food processor, your coffee grinder, your mixer, your coffeemaker—all devices that you use only now and then for specialized purposes.

Now look at the only two appliances in your kitchen that you use daily and couldn’t do without: one that makes heat and one that makes cold. Compared with your food processor, you might not think of your stove and refrigerator as modern appliances, but they are surprisingly recent additions to the human arsenal of cooking and food-preserving equipment.

The first kitchen range, an enclosure containing a burning fuel (initially, coal) that heats a flat surface for cooking, was patented less than 375 years ago, heralding the end of more than a million years of cooking over open fires. And the electric refrigerator replaced ice for cooling only within the memories of some of the readers of this book.

When you bring fresh food home from the market, you may put it in the refrigerator, whose low temperatures will keep it from spoiling. Then you may use the stove’s high temperatures to convert some of that food into a form that is more palatable and digestible. After you’ve cooked and served the food, you may put some of the leftovers back into the refrigerator or freezer to keep. And some time later, you may take them out of the refrigerator and heat them up again. The manipulation of foods in our kitchens seems to involve a continual round of heating and cooling, of using figurative fire and ice. Only today, we do those jobs with gas and electricity.

What do heat and cold do to our foods? How can we control them to produce the best results? We can burn our food with too much heat, but on the other hand the freezer can “burn” it with…well, what
is
freezer burn, anyway? And just what is going on when we perform that most elementary of all cooking operations, the boiling of water? There’s more to it than you may think.

HOT STUFF

C IS FOR CALORIE

I know that a calorie is a unit of heat, but why does eating heat make me fat? What if I ate only cold foods?

A
calorie is a much broader concept than just heat; it’s an amount of any kind of energy. We could measure the energy of a speeding Mack truck in calories, if we wanted to.

Energy is whatever makes things happen; call it “oomph” if you wish. It comes in many forms: physical motion (think Mack truck), chemical energy (think dynamite), nuclear energy (think reactor), electrical energy (think battery), gravitational energy (think waterfall), and yes, the most common form of all, heat.

It’s not heat that’s your enemy; it’s energy—the amount of energy-for-living that your body gets by metabolizing food. And if metabolizing that cheesecake produces more energy than you use up in walking from the refrigerator to the TV, your body will store the excess energy as fat. Fat is a concentrated storehouse of energy, because it has the potential of giving off lots of heat when burned. But don’t jump to any conclusions. When an advertisement promises to “burn off fat,” it’s only a metaphor; a blowtorch is not a feasible weight-loss device.

How much energy is a calorie, and why do different foods “contain” (that is, produce) various numbers of calories when metabolized?

Since heat is the most common and familiar form of energy, the calorie is defined in terms of heat—how much heat it takes to raise the temperature of water by a certain amount. Specifically, as the term is used in nutrition, a calorie is the amount of heat it takes to raise the temperature of one kilogram of water by 1 degree Celsius.

(Chemists, as opposed to nutritionists and dieticians, use a much smaller “calorie,” only one-thousandth as big. In their world, the nutritional calorie is called a
kilocalorie
. But in this book I use the word
calorie
to mean the common one that food books, food labels, and diets talk about.)

Here’s an idea of how much heat a calorie is: A nutritional calorie is the amount of heat it would take to raise the temperature of a pint of water by 3.8°F.

Different foods, as everyone knows, provide us with different amounts of food energy. Originally, the calorie contents of foods were measured by actually burning them in an oxygen-filled container immersed in water and measuring how much the water’s temperature went up. (The apparatus is called a calorimeter.) You could do the same thing with a serving of apple pie to find out how many calories it releases.

But is the amount of energy released when a slice of pie is burned in oxygen the same as the amount of energy released when it is metabolized in the body? Remarkably, it is, even though the mechanisms are quite different. Metabolism releases its energy much more slowly than combustion does, and mercifully without flames. (Heartburn doesn’t count.) The overall chemical reaction is exactly the same, however: Food plus oxygen produces energy plus various reaction products. And it’s a basic principle of chemistry that if the initial and final substances are the same, then the amount of energy given off is the same, regardless of how the reaction took place. The only practical difference is that foods aren’t digested or “burned” completely in the body, so we actually get out of them somewhat less than the total amount of energy they would release by being burned in oxygen.

On the average, we wind up getting about 9 calories of energy from each gram of fat and 4 calories from each gram of protein or carbohydrate. So instead of running into the lab and setting fire to every food in sight, nutritionists these days just add up the numbers of grams of fat, protein and carbohydrate in a serving and multiply by either 9 or 4.

Your normal basal metabolism rate—the minimum amount of energy you use up just by breathing, pumping your blood around, digesting your food, repairing your tissues, keeping your body temperature normal, and keeping your liver and kidneys, etc., doing their jobs—is about 1 calorie per hour for every kilogram (2.2 pounds) that you weigh. That’s about 1,600 calories per day for a 150-pound male. But that can vary quite a bit depending on sex (women require about 10 percent less), age, health, body size, shape, and so on.

Among other things, weight gain depends on how much your intake of food energy above and beyond your basal metabolism rate exceeds your expenditure of energy by exercise, not counting fork-lifting. For an average healthy adult the National Academy of Sciences recommends a daily intake of 2,700 calories for men and 2,000 for women—more for jocks and fewer for couch potatoes.

The hopeful theory about eating cold, calorie-deprived food has been bandied about in various forms for some time, but unfortunately, it won’t work. One variation that I’ve heard is that drinking ice water will help you lose weight because you must expend calories in warming the water up to your body temperature. That’s true in principle, but trivial. Warming an 8-ounce glass of ice water up to body temperature uses less then 9 calories, the equivalent of a single gram (one 454th of a pound) of fat. If dieting were that simple, “fat-farm” spas would have ice-water swimming pools. (Shivering also uses up energy.) And unfortunately, while most substances shrink when their temperatures are lowered, people don’t. Not for long, anyway.

THE EFFECTS OF FUDGE ON DIETING

If there are nine calories in a gram of fat, that means that there are more than 4,000 calories in a pound (454 grams) of fat. But I’ve read that in order to lose a pound of fat I must cut my intake by only 3,500 calories. Why the discrepancy?

N
ot being a nutritionist, I asked Marion Nestle, professor and chair of the Department of Nutrition and Food Studies at New York University.

“Fudge factors,” she said.

First of all, the actual energy content of a gram of fat is closer to 9.5 calories. But that would only make the discrepancy bigger. The fact is that the number of calories of energy we get from eating a gram of fat is quite a bit less than that because of incomplete digestion, absorption, and metabolism. That’s one fudge factor.

“Another fudge factor,” Nestle continued, “is applied to the number of calories in a pound of body fat. The idea is that body fat is only about 85 percent actual fat.” The rest consists of connective tissue, blood vessels, and other stuff that you’d probably rather not know about.

Thus, in order to lose a pound of real-life blubber, your bottom line, so to speak, is that you must deprive yourself of only about 3,500 calories.

And stay away from the fudge.

REALLY
HAUTE CUISINE

T
he elevation at La Paz runs from 10,650 to 13,250 feet above sea level, depending on which part of town you’re in. And as you are aware, water boils at lower temperatures at higher elevations. That’s because in order to escape from the liquid and boil off into the air, water molecules have to fight against the downward pressure of the atmosphere. When the atmospheric pressure is lower, as it is at higher altitudes, the water molecules can boil off without having to get as hot.

The boiling temperature of water decreases about 1.9°F for every 1,000 feet above sea level. So at 13,000 feet, water will boil at 187ºF. Temperatures above 165ºF are generally thought to be high enough to kill most germs, so you should be okay on that score.

It’s hard to generalize about cooking times, because different foods behave differently. I’d suggest asking the locals how long they cook their rice, beans, and the like. Of course, you can always schlep a pressure cooker onto the airplane and manufacture your own high-pressure atmosphere at will.

Baking is a whole different ball game. For one thing, water evaporates more readily at high altitudes, so you will need to add more water to doughs and batters. And because there is less pressure to hold down the carbon dioxide gas released by baking powder, the gas can rise clear out the top of your cake, leaving it flat. So you must use less baking powder. All this can be very tricky. My advice is to leave the baking to the local
pastelerías
.

PROJECT HEAD-START

My husband claims that warm water takes longer to boil than cold water, because it is in the process of cooling as you place it on the stove. I think that’s ridiculous. But he took physics in college and I didn’t.

W
hat grade did he get in physics? Apparently, your intuition is paying off better than his tuition, because you’re right and he’s wrong.

I can guess what he’s thinking, though. Something about momentum, I’ll bet, because if an object is already falling—in temperature, presumably—it should require extra time and effort to turn it around and make it rise. You first have to kill its downward momentum.

That’s all very well and true for physical objects, but temperature isn’t a physical object. When the weather report says that the temperature is falling, we hardly expect to hear a crash.

Temperature is just our artificial human way of expressing the average speed of the molecules in a substance, because their speed is what makes a substance hot; the faster its molecules are moving, the hotter it is. We can’t get in there and clock the speed of every single molecule, so we invented the concept of temperature. It’s really little more than a handy number.

In a pot of warm water, the zillions of molecules are flitting about at a higher average speed than in a pot of cold water. Our job in heating the pot is to give more energy to those molecules and make them move even faster—eventually fast enough to boil off. Obviously, then, warm molecules will require less added energy than cold ones, because they’re already partway to the finish line: the boiling point. So the warm water will boil first.

And you can tell him I said so.

Using hot tap water for cooking may be unwise for another reason. Older houses may have copper water pipes that are joined with lead-containing solder. Hot water can leach out tiny amounts of lead, which is a cumulative poison. So it’s a good idea always to use cold water to cook with. Yes, it’ll take longer to boil, but since you may live longer you can spare the time.

PUT A LID ON IT!

My wife and I disagree on whether a pot of water will boil sooner if you keep the lid on. She says it will, because without the lid a lot of heat would be lost. I say that it will take longer to boil, because the lid increases the pressure and raises the point at which water will boil, as in a pressure cooker. Who’s right?

Y
our wife wins, although you do have a point.

As a pot of water is heated and its temperature goes up, more and more water vapor is produced above the surface. That’s because more and more of the surface molecules gain enough energy to leap off into the air. The increasing amount of water vapor carries off an increasing amount of energy that could otherwise go into raising the water’s temperature. Moreover, the closer the water gets to its boiling temperature, the more energy each water vapor molecule carries off, so the more important it becomes not to lose them. A pot lid partially blocks the loss of all those molecules. The tighter the lid, the more hot molecules are retained in the pot and the sooner the water will boil.

Your point, that a lid increases the pressure inside the pot as in a pressure cooker, thereby raising the boiling point and delaying the actual boiling, is correct in theory but insignificant in reality. Even a tightly fitting, hefty one-pound lid on a ten-inch pot would raise the pressure inside by less than a tenth of a percent, which would in turn raise the boiling point by only four hundredths of a degree Fahrenheit. You could probably delay the boiling longer by watching the pot.