What Einstein Kept Under His Hat: Secrets of Science in the Kitchen (11 page)
Read What Einstein Kept Under His Hat: Secrets of Science in the Kitchen Online
Authors: Robert L. Wolke
How, then, does butter homogenize and thicken a pan sauce? In two ways. First, butter’s fat content can absorb the fat in the pan while its water content can absorb the wine or stock, thus bringing them into a sort of matrimonial harmony. But the marriage wouldn’t last very long if the butter didn’t contain a small amount (about 0.24 percent) of lecithin, an emulsifier. An emulsifier’s molecules stabilize an emulsion by latching onto both fat molecules and water molecules at the same time, effectively keeping them together. (See p. 380.) When the entire contents of the pan have thus become a fat-and-water emulsion, the contents will obviously be thicker, glossier, and more unctuous than the watery wine or stock alone. French chefs ever since Escoffier have been finishing their pan sauces with
une noisette
of butter.
THE FOODIE’S FICTIONARY:
Acidophilus—the Escoffier of Greek cuisine
| | GOOD EGGS GET GOOD GRADES | |
There are so many kinds of eggs in my supermarket, I don’t know which to buy. They all seem to be Grade A, which I suppose is good, but what about size and freshness?
....
T
he USDA grades eggs according to quality—not according to freshness—as AA, A, or B. To earn a grade of AA, an egg must have an air cell within the wide end that is less than an eighth of an inch (3 millimeters) deep; a shell that is well shaped and clean, with very few ridges or rough spots; and when the egg is broken onto a flat surface, a yolk that stands up high and domelike in the center of a clear, thick, and firm white.
Grades A and B fit these criteria slightly less rigorously. They may not look as pretty when fried or poached, because the yolks may be a bit flat and the whites a bit more runny, but they are perfectly fine for uses in which they won’t be served whole.
Submitting eggs for federal grading, however, is optional for the producers (the human ones, that is, not the hens). Eggs sold in cartons without the USDA shield will have been graded according to state laws, which vary all over the lot.
If you find some eggs in a carton that don’t appear to be the same size, curb your suspicions. The USDA determines their average size by the weight of a whole dozen. The standard egg sizes are jumbo, extra-large, large, medium, small, and peewee. By the dozen, they weigh 30, 27, 24, 21, 18, and 15 ounces, respectively.
Unless they state otherwise, you can assume that all recipes, including those in this book, have been tested using large eggs. But if you have only mediums, here’s how to substitute: If the recipe calls for one, two, or three large eggs, use the same number of mediums. For four, five, or six large eggs, add one medium. Have only extra-large eggs? For one, two, three, or four large eggs, use the same number of extra-large. For five or six large eggs, use one fewer extra-large. Or, just forget the whole thing and use
1
/
4
cup of beaten egg for every egg specified in the recipe.
But are they fresh? Like so many other things we’d rather not think about, an egg’s yolk tends to sag with age. Its white thins (like our hair) and grows cloudy (like our eyes), while its air cell increases in size (like . . . well, you know). But we don’t know that until we’ve bought and broken the eggs.
Cartons of eggs from USDA-inspected plants and from most state-regulated plants must display the date on which the eggs were packed, which is almost always the same day they were laid. Although not required to by law, the packer or the supermarket chain may also choose to specify a “sell by” date, not to exceed thirty days from packing.
Eggs should be stored on an inside shelf of your refrigerator, not in those cute little depressions in the door rack. Refrigerator engineers apparently consider the rack an efficient use of space, but it’s a poor preserver of eggs because of its higher and varying temperature. Refrigerated eggs will keep, with slightly deteriorating flavor and texture, for four to five weeks beyond the packing date. Keep them in their cartons to protect them from refrigerator odors; eggshells are porous and can absorb unpleasant smells. Most commercial eggs, however, have been coated with a thin film of oil to seal the pores and extend their shelf life by reducing moisture loss and preventing bacteria from invading the shell.
Simplified diagram of a hen’s egg. (1) shell, (2) membrane, (3) air chamber, (4) thin albumen, (5) thick albumen, (6) yolk, (7) chalazae. (Redrawn by permission from Zdzislaw E. Sikorski, ed., “Chemical and Functional Properties of Food Components,” CRC Press, 2002.)
| | Fresh Orange Sponge Cake | |
O
ne great thing about eggs is that you can separate the yolks from the whites and take advantage of their unique characteristics separately. In this cake, the yolks act as a binder and contribute fat, color, and rich flavor, while the whipped whites produce a light, foamy structure.
Delicate in texture and magnificent to behold, this cake is classic company fare. Sponge-type, also known as foam, cakes are springy and light. They include chiffon, angel food, and sponge cakes. All have one thing in common: stiffly beaten egg whites, on which their fluffiness depends.
Important: Never grease the cake pan for any foam-type cake. If it has been used before to bake a cake with shortening, scour it and dry it thoroughly before using. The batter needs a clean, dry wall to cling to.
The texture and flavor of sponge cakes are so delightful that the cakes are usually eaten without frosting, which can weigh them down. But a little lily-gilding—a shower of confectioners’ sugar—does no harm.
This cake can be made in advance and stored at room temperature for 2 days, in the refrigerator for 5 days, or in the freezer for 2 months. But bring it back to room temperature for serving. Leftover cake? (You should be so lucky.) Serve slices, lightly toasted, for breakfast.
6 large egg whites
1
3
/
4
cups all-purpose flour
1
/
2
teaspoon salt
1
1
/
2
cups sugar
6 large egg yolks
Orange oil, optional*
6 tablespoons freshly squeezed orange juice
1 tablespoon freshly grated orange zest
Confectioners’ sugar, for dusting, optional
1.
In a medium bowl, allow the egg whites to warm to room temperature, about 1 hour.
2.
Meanwhile, place a rack in the lower level of the oven. Preheat the oven to 350°F. Have ready a 10-inch tube pan.
3.
Using a fine-mesh strainer or a sifter, sift together the flour and salt in a medium bowl. Set aside.
4.
With an electric mixer on medium speed, beat the egg whites until foamy. Gradually add
1
/
2
cup of the sugar, beating after each addition. Continue beating until soft peaks form when the beater is slowly raised. Set aside.
5.
In a large bowl, using the electric mixer with the same beaters on high speed, beat the egg yolks while gradually adding the remaining 1 cup of sugar until the mixture is thick and lemon colored. This will take 5 to 8 minutes in all. Add 1 or 2 drops orange oil, if using—a little goes a long way—and beat until combined.
6.
Remove the beaters from the bowl, shake to free any adhering yolk, and continue with the recipe using a whisk and rubber spatula.
7.
Add the orange juice and orange zest to the egg yolk mixture and whisk to combine. Add the flour mixture and whisk just until no white patches are visible.
8.
With the whisk or spatula, and using an under-and-over motion, stir one-third of the egg whites into the yolk mixture to lighten it. Then fold in another half of the remaining egg whites. Finally, fold in the remaining egg whites just until blended.
9.
Gently pour the fluffy batter into the tube pan. Bake for 35 to 40 minutes, or until the cake has risen to the top of the pan, the top is browned, and a cake tester inserted into the center of the cake comes out clean.
10.
If your pan has feet, invert the pan over a wire rack. Alternatively, invert the pan over the neck of a bottle. Don’t worry, it won’t fall out. Let the cake hang for about 1 hour to cool completely.
11.
Place the pan on a work surface. With a metal spatula, carefully loosen the cake from the pan and transfer to a platter. Serve plain or sift a dusting of confectioners’ sugar over the top. Use a serrated knife to cut the cake.
MAKES 12 SERVINGS
*Orange oil is available in the baking areas of some supermarkets or at Williams-Sonoma or other cookware stores.
| | HOW NOW, BROWN EGG? | |
A well-known organic restaurant says it uses fertilized brown eggs, claiming that they are the “most nutritious eggs available.” Are there any scientific facts to back this up?
....
U
nfortunately, no.
I hereby join forces with every other printed dissertation on eggs to assure you that no differences in flavor or nutrition have been found between brown eggs and white eggs. Just as brown-skinned people produce brown-skinned children, brown-feathered chickens lay brown-shelled eggs. Among the brown-egg layers are the Barred Plymouth Rock and the Red Rock Cross, while the white-feathered White Leghorn lays white eggs. The Columbian Rock, which sports both black and white feathers, is one of several exceptions. It must have flipped a genetic coin at some time in the past and decided to lay brown eggs.
The color of the yolk, incidentally, depends on the hen’s diet; wheat-based diets produce lemon-yellow yolks, while alfalfa-based diets produce orange-yellow yolks.
Then why do brown eggs cost more? They are generally produced by species of larger hens that consume more feed and lay bigger eggs. One might also speculate that people who think brown eggs are superior are willing to pay more for them.
Some people believe that fertilized eggs are more healthful to eat because they contain a “life force” not present in “dead” foods. I shall not express my opinion of that idea because I am a very tolerant, open-minded, and nonjudgmental person who believes that people have the right to think whatever they choose.
No matter how absurd.
THE FOODIE’S FICTIONARY:
Egg roll—a Chinese Easter festival
| | VIRGIN HENS | |
While making breakfast the other day, I broke an egg and found a red spot, looking like blood, on the yolk. I threw it away, but was it okay to eat? And what caused it?
....
I
t doesn’t mean that the egg was fertilized, and it will not hatch no matter how long you sit on it. Hens that lay eggs for commercial distribution have never even seen, much less “dated,” a rooster. Layers just aren’t breeders.
The red spots are indeed blood, from the rupture of a blood vessel on the yolk’s surface that occurred during formation of the egg, or by a similar mishap in the wall of the oviduct. Less than one percent of all eggs laid have blood spots.
The routine inspection process of candling—turning the eggs on rollers in front of high-intensity lights (originally they were held up to a candle) to reveal their interior qualities—catches most eggs with blood spots, and they are removed. But a few inevitably sneak though and reach the market. They are perfectly fit to eat, although Jewish dietary law rejects them as not kosher.
| | Instant Vanilla Custard Sauce (Crème Anglaise) | |
H
ere’s a trick I learned from Seattle chef Jerry Traunfeld of the Herbfarm. Early in his career, when he was a pastry chef at Stars, Jeremiah Towers’ restaurant in San Francisco, Traunfeld had to make gallons and gallons of crème anglaise every day. It took way too much time, he said, when he’d rather be creating pastries. So he developed a reverse-cooking method for the sauce that is risk-free and speedy.
Instead of adding egg yolks to boiling milk, he adds boiling hot milk directly and quickly to slightly warmed egg yolks. The milk cooks them instantly with no risk of curdling. The custard immediately coats a spoon, which is the standard test for the finished sauce. It thickens further as it cools in the refrigerator. Hard to believe, until you try it.
Called by either its English or its French name, this sauce is wonderful warm or cold, served over apple dumplings or pie, strudel, chocolate cake, gingerbread, bread pudding, or even baked fruit. To dress it up for company, substitute 1 tablespoon Grand Marnier or Cointreau for the vanilla. And in season, transform it into eggnog by adding freshly grated nutmeg and rum.
6 large egg yolks, at room temperature
1
/
2
cup sugar
1
/
8
teaspoon salt
2 cups whole milk
3
/
4
teaspoon vanilla extract
FOR EGGNOG:
1
/
4
teaspoon freshly grated nutmeg
1 tablespoon rum, or more to taste
1.
Warm a medium bowl by rinsing it under hot tap water; dry. Place the egg yolks in the warmed bowl and place the bowl over barely warm water in a larger bowl. (You just want to take the chill off the yolks.)
2.
Before proceeding to the next step, pick up the yolk bowl from the warming bowl and place it on a damp, flat washcloth. This will prevent the bowl from skidding on the counter when you start to whisk.
3.
In a medium saucepan, combine the sugar, salt, and milk. Place over medium heat and stir constantly until the sugar has dissolved and the milk is coming to a boil.
4.
As soon as the milk boils and as it rises in the pan, immediately remove the pan from the heat and quickly whisk the milk into the egg yolks, whisking briskly for the first 3 to 5 seconds and then switching to a slow stirring motion until all the milk is in (takes about 15 seconds). Continue to stir slowly and blend without any aeration for another 10 seconds. The yolks will cook without further heating.
5.
Stir in the vanilla.
6.
Pour the mixture through a fine-mesh strainer into a container to remove those thick, cordlike strands of egg white (chalazae) that anchor the yolk in the center of the egg. Refrigerate until ready to serve. The mixture will thicken as it cools.
MAKES 3 CUPS SAUCE, OR FOUR
3
/
4
CUP SERVINGS OF EGGNOG.
