Pie and Pastry Bible (157 page)

If you heat a citrus fruit (about 10 seconds in a microwave oven on high power) and roll it around on the counter while pressing on it lightly, it will release a significantly greater quantity of juice.

When reducing juices in a microwave, be sure to grease the cup to keep the juices from bubbling over. Use no more than 1¼ cups of juice in a 4-cup heatproof liquid measuring cup. It will take 10 to 15 minutes to reduce it by one half to three quarters in the microwave. Watch carefully toward the end so that it does not overconcentrate and start to caramelize.

To prevent curdling, be sure to mix the sugar with the yolks before adding the fruit juice. Use a heavy nonreactive pan that conducts heat evenly or a double boiler. Also to prevent curdling, do not allow the mixture to boil. Remove the curd immediately from the heat when thickened and strain it at once, as the residual heat in the pan will continue to raise the temperature. (If you are working with an accurate thermometer,
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you can refer to the specified finished temperature.)

UNDERSTANDING

An (unlined) aluminum pan should not be used, because it reacts with the egg yolks, turning them chartreuse.

Sugar raises the coagulation point of the egg yolks. It also protects them from premature coagulation during the addition of the acidic fruit juice. If the juice were added directly to the unprotected yolks, the yolks would partially coagulate and, when strained, a large percentage of them would be left behind in the strainer.

Straining the curd after cooking produces the silkiest texture because it removes any coagulated bits of egg. The zest is therefore added after straining, except for the juice orange curd. In order to maximize the elusive orange flavor, the zest must be heated with the yolk mixture and left in after cooking.

Except for bitter Seville oranges, oranges require concentration of their juices for adequate flavor impact. Reducing fruit juices in a microwave results in the purest fruit flavor without any of the slight browning, or caramelization, of the fruit sugars that often takes place using the cooktop.

CURD CREAM FILLING AND TOPPING

F
ruit curd combined with lightly stabilized whipped cream makes a wonderful filling for fresh fruit tarts. In this recipe, just enough gelatin is added to firm the filling enough to slice well. For a topping or a garnish for pies or tarts, omit the gelatin and double, or as much as quadruple, the heavy cream. The more cream in proportion to the curd, the lighter and airier the texture and the more subtle the fruit flavor.

Chill a medium bowl for the cream.

In a small heatproof measuring cup, place the gelatin and water and allow it to sit for 5 minutes. Set the cup in a pan of simmering water for a few minutes, stirring occasionally until the gelatin is dissolved (or microwave on high power for a few seconds, stirring once or twice). Set it aside briefly. (The mixture must still be warm when added to the cold cream, or it will lump.)

In the chilled mixing bowl, beat the cream and sugar until it begins to thicken. Gradually beat in the warm gelatin mixture and beat just until stiff peaks form when the beater is raised. With a large wire whisk, fold the whipped cream into the fruit curd until uniform in color. Pour it immediately into the prebaked pastry crust and chill for at least 1 hour.

STORE

Refrigerated, up to 2 days.

POINTERS FOR SUCCESS

The thickness of the curd will vary depending on the acidity of the fruit juice. If it is very thick, whisk a small amount (about 1 tablespoon) of the whipped cream into it to soften it before folding in the rest.

MERINGUE FILLINGS AND TOPPINGS

M
eringue, in its many forms, always contains two ingredients: egg whites and sugar. Since the finished texture is dependent on the proper beating of egg whites, it is important to understand a few basic facts about egg whites. First let’s try to settle the age-old controversy: Which beat better, fresh egg whites or older ones? The answer is six of one, half a dozen of the other. When beaten, egg whites will increase six to eight times in volume. Fresh whites are thicker, so they take longer to beat. The resulting foam has less volume but more stability and loses less volume when folded into other ingredients. Older whites are thinner, so they beat more quickly and yield greater but less stable volume. When folded into other ingredients, they lose the extra volume.

The flavor of fresh egg whites is slightly superior to that of older whites, so I tend to prefer them for recipes like mousses, where the egg white does not get cooked.

The following is a simple demystification from research biochemist and cookbook author Shirley Corriher:

Egg white is made up of water and protein. When exposed to air, heat, or acid, the proteins in the egg whites change (denature) from their original form. For
the perfect egg white foam, the egg whites should be beaten so that the egg white proteins denature (change) just the right amount. They must remain moist and flexible and not dry out and become rigid. When the beaten egg white, filled with air bubbles, goes into a hot oven or is subjected to hot syrup, it should be soft, moist, flexible, and able to expand until it reaches the temperature that coagulates (sets) it. Overheating produces dried-out, rigid egg white foam that will not expand properly in the oven. The cook has several secret weapons to produce the perfect degree of egg white denaturization to result in beaten egg whites with the greatest volume and stability. These are the copper bowl, cream of tartar, and sugar. The copper bowl produces stable egg whites by combining with conalbumin, the protein in the egg white that lines each air bubble, to form a totally new protein, copper conalbumin. This copper conalbumin remains moist and flexible even when slightly overbeaten and provides a more stable foam.

Cream of tartar, an acid salt (by-product of the wine industry), provides an even more stable foam in another way. The acid serves to denature the protein just enough to produce a moist stable foam. I have performed several experiments with cream of tartar and find that when the correct amount (1 teaspoon cream of tartar per cup of egg whites—
teaspoon per large egg white) is used, there is no danger at all of overbearing. Because of this, I recommend always using cream of tartar for egg whites that will be cooked. If the egg whites will remain uncooked, I prefer using the copper bowl because it offers the least possibility of extraneous flavor.

Sugar is effective, with either the copper bowl or cream of tartar, to keep the proteins moist and flexible, because sugar itself holds moisture. Superfine sugar is preferable because it dissolves faster. (Undissolved sugar will appear as teardrops on the surface of the meringue.) Sugar can be added at any time while beating the egg whites; however, if it is added early, the whites will require much longer beating and may not reach as great a volume. If sugar is added very late in the beating process, drying may already have started to occur. Most recipes specify to start adding the sugar after the soft peak stage but before the stiff peak stage.

Salt not only increases beating time, it decreases the egg white foam’s stability by drawing out water from the egg whites. I prefer adding salt to the other ingredients in the recipe.

Any fat substance or egg yolk is a foam inhibitor and even one drop will keep the egg whites from becoming stiff.

For the most stable foam, start beating the egg whites slowly, gradually increasing speed. Never decrease speed or the volume will permanently decrease. When it is necessary to stop the beater to check consistency, turn it off only very briefly and then bring up the speed quickly to prevent deflation.

Because sugar is hygroscopic (readily absorbs water), avoid making royal icing, meringue, or dacquoise on humid days, as they will be soft and sticky and will not set well.

The recipes in this chapter appear as components throughout the book in many interesting and varied ways. The crisp meringue shell is juxtaposed against creamy lemon chiffon in the Lemon Angel Chiffon Pie (page 157) and the crisp cocoa version becomes boulders atop the Grand Canyon Pie (page 190). Soft meringue topping and extra-light Italian meringue lend their incomparable sweet airiness to Lemon Meringue and Key Lime pies. Italian meringue adds its billowy texture to mixtures such as chiffon pies. And, of course, the various meringues, from chocolate to speckled, are great to eat by themselves when baked until crisp.