Marlene Parrish - What Einstein Told His Cook 2

IN COOKING,we are continually mixing and blending ingredients. But there are several distinct kinds of mixtures. Emulsions are only one of them.

A combination of solid particles, such as salted and peppered flour or a blend of dried spices, is a simple physical mixture. But when liquids are involved, a mixture can take on any of several forms.

• Solution:The most homogeneous mixture of all is a solution , in which the individual molecules or ions (electrically charged atoms or groups of atoms) of one substance are dispersed intimately, molecule beside molecule, among those of the other. Examples are alcohol or sugar dissolved in water, where the alcohol or sugar molecules are intimately mixed in among the water molecules cheek by jowl—if they had cheeks and jowls. Another example is the tomato’s red coloring compound, lycopene, when dissolved in an oil. (Notice how the fat in your tomato-containing recipes always turns red? The color is dissolved lycopene.)

• Colloidal suspension:Many other food mixtures are colloids , or colloidal suspensions , in which invisibly small but generally bigger-than-a-molecule particles of one substance (millionths to thousandths of an inch in size) are suspended throughout the other substance, which is most often a liquid. The particles are held in suspension against the pull of gravity because they are continually being bombarded from all sides by the molecules of the substance in which they are dispersed. The liquids within plant and animal cells are colloidal protein particles suspended in water-based solutions.

• Emulsion:An emulsion is similar to a colloidal suspension. In an emulsion, formed by the action of an emulsifying agent, slightly-larger-than-colloid-sized globules of one liquid are suspended in another liquid with which it wouldn’t ordinarily mix. Mayonnaise and hollandaise sauce are the best-known examples in the kitchen.

Smoky Garlic Mayonnaise

Smoked Spanish paprika, pimentón , adds a subtle hint of wood fire to this garlic mayonnaise. It is a classic accompaniment to paella (chapter 6), and is also good with Hot-Wok Mussels (chapter 6). You can use it as a dip for raw vegetables, or serve it with steamed fish, especially with fresh cod. If the flavor is too intense, half olive oil and half peanut oil makes a delicious dressing.

For herb mayonnaise, add ½ cup minced fresh herbs (parsley, chives, chervil, tarragon) in place of the garlic in step 2. A blender does the best job of blending the herbs into the emulsion.

1 large egg

1 teaspoon smoked Spanish paprika ( pimentón )

½ teaspoon dry mustard

½ teaspoon salt

2 tablespoons cider, sherry, or wine vinegar

1 cup mild extra-virgin olive oil

1 large clove garlic, coarsely chopped

1.Break the egg into the blender container. Add the pimentón , mustard, salt, and vinegar. Add ¼ cup of the oil. Cover the container and turn the motor on to low speed.

2.Immediately uncover and pour in the remaining oil in a fine, steady stream. Do not hurry. When all the oil has been incorporated, add the garlic (or the herbs, if using). Continue to blend for 1 minute, or until smooth.

3.Allow the mayonnaise to rest in the refrigerator for at least 1 hour before using, so the flavors will mellow and soften. Refrigerate for up to 4 days. Don’t serve it cold, because chilling dulls the olive oil flavor.

MAKES ABOUT 1¼ CUPS

HOME ON THE RANGE

Oven temperatures are pretty easy to control; the dials have actual temperature numbers on them. But what about stovetops? I have a gas cooktop, and the controls are marked “hi,” “med,” and “lo.” Two of them burn at higher Btu’s than the other two; “med” on them is hotter than “hi” on the other two. I used to have an electric cooktop with the same markings, but their cooking speeds were completely different from my gas range. Are there any industry standards for burner temperatures?

Unfortunately not. The only standard that I know of seems to be that high is spelled “hi” and low is spelled “lo.” In between “hi” and “lo,” my gas range has the digits 2 through 9, but the numbers indicate nothing whatsoever about temperature. The labels “hi” and “lo” and the numbers 2 to 9 refer not to the temperature but the rate at which the burner is generating heat.

There is a lot of confusion about the words heat and temperature in the food world, so maybe it’s “hi time” for me to give you the “lodown.”

First of all, heat and temperature are two different things. Heat is a form of energy, distinct from gravitational energy, electrical energy, energy of motion ( kinetic energy), or nuclear energy. It is, in fact, the ultimate form of energy into which all other forms eventually degenerate. (See “The energy tax,” chapter 9.)

Cooking employs heat to cause physical and chemical changes that we hope will improve the food’s tenderness, digestibility, and flavor. It should come as no surprise that when a food (or anything else) absorbs heat, it gets “hotter,” meaning that its temperature rises. But what is temperature? It’s nothing more than a convenient number invented by humans (Mssrs. Fahrenheit and Celsius; see “Untangling F & C,” chapter 9) to indicate how much heat energy a substance contains. In cooking, specific changes take place when a food reaches specific temperatures, that is, when the food acquires enough heat relative to its size. You might say that temperature measures the concentration of heat in a substance.

So it’s the temperature of the food, not the temperature of the gas flame or electric burner beneath the pot or pan, that matters to the cook. The burner is there only to pump heat into the food, no matter what its own temperature may be while doing it. We could place a white-hot poker beneath a frying pan, but it would be a terribly inefficient way to heat the food in the pan.

Then why do we say that one burner at a given setting is “hotter” than another? It’s just loose talk; we don’t really mean to imply that its temperature is higher. We mean only that that burner pumps out heat at a faster rate than the other one, thereby raising the food’s temperature—and cooking it—faster. Instead of “hi” and “lo,” then, we should really label the burner settings “fast” and “slow” (or, inevitably, “slo”).

Different burners, whether gas or electric, do indeed pump out heat at different rates. We measure those rates in Btu’s per hour. A Btu , or British thermal unit , is an amount of heat energy, just as a calorie is. (A nutritional calorie happens to be almost exactly equal to four Btu’s.) But what’s important about a cooktop burner is how many Btu’s or calories it can pump out per minute or per hour . The number of Btu’s pumped out per hour is a good indication of how fast a burner will heat and cook our food. A candle, for example, gives off a total of about 5,000 Btu’s of heat over a period of a few hours, but that’s hardly fast enough to cook with, because its Btu-per-hour rate is pathetic.

Most people, including appliance salesmen and cookbook authors, either are too lazy to say “Btu’s per hour” or don’t know the difference, so they (as you did in your question) speak simply of “Btu’s” as if they were a measure of heating speed. But as Tony Soprano would say, wha’y’gon’do?