Baking Class - Cakes.

Lewisburg.

Well, the baking classes are finished for the semester. Definitely fun while they lasted, though it'll be nice to have Wednesdays back again. Until next semester, anyhow; I've already been offered the chance to do another class then. This time, I think I'll focus on basic cooking techniques.

Which definitely includes a session on how to read a recipe. And another on knife skills. Boy, won't those be interesting.

CAKES
Baking 101 – Spring 2008

ABOUT SPONGE CAKES

The sponge cake, with its variations and eventual reduction to boxed mixes, is the quintessential birthday cake. Though the specific variations are many, they tend to fall into two distinct categories: American and European. The former, which is by far the most common in the United States, has relatively high proportions of eggs and sugar, and rarely contains butter. The texture is moist and tender, and they’re quite good eaten plain, lightly frosted, or with fresh fruit. The European versions, biscuit and genoise, are drier and less tender than the American sponge cake, and are generally components of elaborate desserts. They are often soaked with liquor syrups and layered with rich buttercreams and sliced fruits.

THE INCREDIBLE, EDIBLE EGG

In a traditional, unleavened sponge cake, eggs are primarily responsible for the light, airy texture. This is due to some of the unique characteristics of egg whites and egg yolks, especially when separated. Eggs, perhaps more than any other ingredient, are responsible for some of the most spectacular tricks in the kitchen.

Although it’s possible to find duck, turkey, quail, ostrich and all sorts of other eggs if you know where to look, American cooking depends on the everyday chicken egg. Generally, unless otherwise specified, this means “large” eggs, but it’s possible to adjust quantities if you only have medium or jumbo. Most general purpose cookbooks have conversion charts for just that purpose.

The Yolk. About a third of the contents of the egg, the yolk contains a variety of useful chemical components: water, for the most part; fats; proteins; some cholesterols; and lecithin, a phospholipid that’s remarkably handy for making emulsions like mayonnaise. In most baking recipes, egg yolks provide a rich, eggy flavor; though it’s not apples to apples, think of a sponge cake (with yolks) compared to an angel food cake (whites only). There are exceptions, such as zabaglione and sabayons, which use heated, whisked yolks to create a silky foam, but egg yolks are primarily a source of flavor and a texture enhancer.

The White. The other two thirds of the egg, the white contains: lots of water, around 90%; trace amounts of vitamins, minerals, fatty materials, and glucose; and several different proteins that help produce, set, and stabilize foams, among other culinary tasks. Whole eggs can be used in custards, where the proteins, when carefully cooked, will set into a smooth gel; they can even be used to create an airy foam when heated properly, as for a genoise cake. But egg whites alone are capable of producing foams unlike anything else in the kitchen.

It’s a simple experiment to create foam from egg whites. Just whisk vigorously in a bowl, and they will first start to foam with large bubbles that soon multiply into smaller and smaller bubbles. Eventually, the bubbles themselves become too small to see, and the foam expands and expands, reaching eight or more times its original volume. Like any foam, from soap bubbles to whipped cream, this will settle and separate over time, and so needs to be consumed quickly or set, either with the addition of starches or gelatin, or by the application of heat. Heat, in particular, is a permanent change, as the proteins unfold and coagulate, reinforcing the bubbles walls into a solid, airy form.

Aside from the difficulty of whipping an egg white foam by hand, there are several basic chemical components that can help or hinder the creation of the foam. The basics are:

• Egg yolk. The fats within the egg yolk will prevent the formation of a foam by competing with the egg white proteins in the spaces where they want to connect, without offering any structural support. When heated, the yolk’s proteins can overcome some of this problem, but as a rule it’s best to whip an egg foam in a clean bowl, free of traces of yolk. Yolk doesn’t pose a problem once the foam has formed, but only at the outset.
  
  
• Oils and fats. These have the same effect as egg yolk, so it’s best to be careful. They won’t absolutely prevent foaming, but they’ll make it much, much more difficult.
  
  
• Detergents. Chemically similar to fats, which is one reason they’re so great at removing grease, detergents cause the same problems with foam formation, so be sure to rinse and dry bowls well. Plus, they taste truly awful.
  
  
• Salt. Salt weakens the overall foam structure by competing with proteins for bonding sites, making it harder to whip and less stable. Salt should be added to the other components of a dish, rather than the foam.
  
  
• Water. Though very few recipes call for water, it can be used to create a lighter, airier foam by diluting the egg white proteins. These foams are less stable, however, and too much will keep them from forming.
  
  
• Sugar. Sugar can both help and hinder. If added at the start, it will delay foaming and reduce the overall lightness; some recipes call for this, in order to create a firm, dense foam, but it doubles the work. If added once the foam has started to form, often at the soft peaks stage, sugar can help to stabilize a foam. It does this by holding on to water, preventing it from draining away.
  
  
• Acids. Although proteins are responsible for foam formation, they can also cause its downfall by swapping out the existing sulfur-hydrogen bonds in the egg proteins for sulfur-sulfur bonds with adjacent proteins, squeezing out the air. Adding more available hydrogen, in the form of a little acid, greatly minimizes that process. Per egg white, use ½ teaspoon of lemon juice or 1/8 teaspoon or cream of tartar, a salt made from tartaric acid, a winemaking byproduct.
  
  
• Copper. Cooking tradition sometimes calls for whipping egg whites in a copper bowl, which produces a more stable foam. This works because the copper binds to sulfur, doing the same work as a little added acid. Silver works, too – but since bowls made from either are inordinately expensive, you’re best off with a pinch of cream of tartar.

One last note on eggs: the proteins in both the yolk and white are temperature-sensitive. Too much heat will cause them to curdle, which is undesirable in just about every instance except scrambled eggs. When recipes call for mixing a hot liquid with eggs, they need to be tempered first. To do this, add a small amount of the hot liquid to the eggs, whisking thoroughly. This will help raise the eggs’ temperature without overcooking them, so that they can be added to the hot liquid without curdling.

CAKE FLOUR

Cake flour is an innovation from the early 20th century, made from very finely milled, low-protein wheat flour. It’s strongly bleached with chlorine dioxide or chlorine gas, which enables the starch to absorb water much more readily in the presence of large amounts of sugar, and allows fats to bind more readily. It isn’t directly interchangeable with pastry or other low-protein flours, although it is possible to use all-purpose or pastry flour mixed with corn, potato, or arrowroot starch. Some cakes are even made with no flour at all, but use only pure starch or similar ingredients, such as chestnut flour.

ICINGS

Icings originally began as a means to keep the food underneath from drying out. The first were simple syrup glazes, though they’ve now evolved into a more elaborate variety of choices. Typical icings are made from powdered sugar, a little water, and sometimes some added fat, often butter or cream. Some may include corn syrup, which helps prevent the sugar from forming coarse crystals, creating a glossy surface; the added fats will also help reduce sugar crystallization.

Some simple icings may simply take a fat (solid at room temperature) such as butter, cream cheese, or vegetable shortening, and whip in air and sugar to create a sweet, light, spreadable mass. In this case, the sugar crystals must be ground fine to keep them from feeling grainy on the tongue; the finer grades of powdered sugar are the common choice. Other frostings require cooking, and typically use egg proteins or flour starches to create body. In these kinds, sugar crystal size is unimportant, because the sugar is dissolved in liquid during the cooking process.

Some of the common types of cake icings and frostings include:

• Fondant. A version of fondant candy, which is often used as a filling or a coating for other candies. It produces a translucent, satin glaze typical of petits fours and some European cakes. The icing differs from the candy filling in that it is warmed and thinned with a simple syrup to a pourable consistency. Given the clarity of the finished glaze, it cannot be used to hide imperfections; it is sometimes applied over a layer of buttercream or other frosting that gives a smooth, even appearance.
  
  
• Buttercream. One of the classic frostings for decorative cakes, buttercreams require mixing a cooked sugar syrup into beaten eggs (or egg yolks), then working in a large quantity of butter to produce a smooth, spreadable frosting. Due to the large proportion of butter, the consistency of buttercreams varies with temperature.
  
  
• Ganache. The same as the center of a chocolate truffle, a ganache is a mixture of chocolate and heavy cream. Butter can be included in addition to or in place of the cream, with similar results. Typically, the chocolate is chopped into fine pieces, and hot cream is poured over, melting the chocolate; different proportions of chocolate and cream will give different consistencies. Most versions are pourable when warm and spreadable when cooled to room temperature.
  
  
• Quick. “Quick” icings rely on the thickening ability of the cornstarch in powdered sugar. The typical ratio is approximately a quarter pound of butter to a pound of powdered sugar, with just enough added liquid to thin the consistency to the desired point. These icings may be cooked or not; cooking is done in a double boiler to avoid melting the sugar, which would make the texture grainy.
  
  
• Cream cheese. Cream cheese frostings are essentially sweetened, butter-enriched cream cheese, beaten to a smooth texture. Quick and easy, they are prone to overmixing, which can break down the cream cheese and make the frosting too soft to hold its shape. Cream cheese frostings, since they don’t depend on the chemical properties of sugar to form their structure, can be made anywhere from barely to very sweet.
  
  
• Royal icing. Unlike most other icings, royal icing is primarily for decoration, rather than for eating. A mixture of egg whites and sugar, it is extremely stiff and traditionally used to create ornate detailing for wedding cakes. It dries hard and pure white, which looks elegant, but it tastes like hard, chalky sugar.
  
  
• Sugar glaze. Sugar glazes are basically simple sugar syrups, which can be used to create a thin, translucent glaze over the surface of a cake. These are typically used for plain, rich cakes that need little extra adornment, such as pound cake, to provide a shiny crust and a hint of additional sweetness.

TYPES OF CAKES

The term “cake” may describe any of a wide variety of baked goods, ranging from quickbreads – such as coffee cake – to unleavened, egg-foam mixtures like a true sponge cake. Even dense confections, such as flourless chocolate cakes and fruit cakes fall into the general category. Cheesecakes, despite the name, are cheese and egg custards, not cakes; only the general shape and typical wedge servings are cake-like.

Just some of the possible examples of cakes include:

• Quick cakes. Quick cakes are, as the name suggests, quick and simple to prepare. Though considered cakes, they are prepared in much the same manner as quickbreads. Sometimes baking in a cake pan or the addition of a layer of icing is all that separates the two groups. Some examples include apple cake, carrot cake, and virtually all vegan cake recipes, which cannot include any dairy or eggs.
  
  
• Gingerbread. Gingerbreads are some of the oldest varieties of baked goods, with the exception of breads. Like quick cakes, they are easy and fast to prepare, and there are a wealth of different ways to make it. What all have in common is the use of spices, including ginger – sometimes dried, sometimes fresh – and molasses, which provides much of the characteristic color and flavor. Gingerbread batters also tend to be thinner than many other cake batters, which can make them more prone to overmixing and toughness, so it’s best to use a light hand when mixing.
  
  
• Pound cakes and butter cakes. Pound cakes, known as quatres-quarts in French (four quarters), are so called because the original recipe called for four ingredients: a pound each of flour, sugar, butter and eggs. Since the invention of baking powder in the mid-nineteenth century, recipes for pound cakes and the related butter cakes have become much more varied, including a wide range of ingredients in the lighter, much easier to prepare, versions. Due to the high proportion of butter in these cakes, the taste and quality genuinely suffers when replaced with shortening or margarine.
  
  
• Foam cakes and sponge cakes. Foam cakes, of which sponge cakes are a subset, are based on a high proportion of eggs. Beating eggs (or just whites) into a stable foam provides the delicate structure and most, if not all of the leavening; some recipes call for additional baking powder for added lift. American sponge cakes are light, delicate and moist; European sponge cakes, such as genoise and biscuit, are drier and less tender, though no less flavorful.
  
  
• Chiffon cakes. Chiffon cakes are a variation on foam cakes invented in 1927 by Hollywood insurance salesman Harry Baker, who catered cakes for private parties on the side. The key difference is that the fat used is oil, rather than butter or shortening, which can’t hold onto bubbles like solid fats can. The egg foam, bolstered with baking powder, gives a chiffon cake its lift and lightness; oil lends it moistness, even when refrigerated.
  
  
• Angel food cakes. Angel food cakes are essentially sponge cakes without the egg yolks or butter. This makes for an exceptionally delicate and airy cake, and fat-free to boot. Angel food cakes are cooked in a specific pan just for the purpose, a tube pan with a removable bottom.
  
  
• Cupcakes. True cupcakes can be made from any cake recipe, baked in muffin pans; most have a top layer of icing, though this isn’t strictly necessary. As cakes will go stale more quickly than muffins of the same size and shape, paper liners do a good job of keeping them moist and fresh longer.
  
  
• Fruitcakes. Fruitcakes are essentially butter cakes liberally studded with fruit, either dried or candied, and nuts, then often soaked and preserved by soaking in spirits. When made from good ingredients, a fruitcake can be a rich, intense dessert for a holiday or other special occasion. Some recipes are even intended to mature over a period of a year or more; they’re often recipes surviving through generations, originally intended as a way to preserve a bountiful fruit harvest throughout the year.
  
  
• Flourless chocolate cakes. Like sponge cakes, flourless chocolate cakes or tortes rely on egg foams to provide leavening. Without the structural backbone of flour’s starch, however, these cakes are much denser and moister. They also tend to be extremely rich, with large amounts of eggs, butter, cream and chocolate, though often not overly sweet.

AMERICAN SPONGE CAKE
Adapted from The Joy of Cooking
Serves 8 to 10

INGREDIENTS

• 1 cup sifted cake flour
  
• ¼ teaspoon salt
  
• 1 cup sugar
  
• 7 large egg yolks
  
• 1 teaspoon vanilla
  
• 1 teaspoon lemon zest
  
• 1 teaspoon orange zest
  
• 3 tablespoons water
  
• 7 large egg whites
  
• ½ teaspoon cream of tartar

DIRECTIONS

1. Have all ingredients at room temperature. Preheat the oven to 325° F. Have ready an ungreased 9-inch springform pan. Sift together the flour and salt three times, then return to the sifter.
   
   
2. In a bowl, whisk together the egg yolks, 2/3 cup sugar, and the vanilla until thick and pale yellow. Beat in the lemon and orange zest and water. Sift the flour mixture over the top, but do not mix in.
   
   
3. In a large bowl, whisk together the egg whites and cream of tartar until soft peaks form. The add the remaining 1/3 cup sugar and beat until the peaks are stiff, but not dry. Using a rubber spatula, fold one quarter of the egg whites into the yolk mixture. Then fold in the remaining whites.
   
   
4. Scrape into the pan and spread evenly. Bake until the top springs back when lightly pressed and a toothpick comes out clean, about 40 to 45 minutes. Allow to cool upside down for at least an hour and a half. Unmold by sliding a thin knife around the edge to detach the cake from the pan; remove the pan side and bottom and allow to finish cooling right side up on a rack.

NOTES

• This cake must cool upside-down for at least ninety minutes to retain its delicate texture. Until the protein/starch network has cooled, it cannot even support its own weight and will deflate. Likewise, the cake pan must remain ungreased, lest the warm cake simply fall out while cooling upside-down.
  
  
• Store this cake covered, at room temperature. A layer of icing will help prevent the cake from drying out.

QUICK ICING
Adapted from The Joy of Cooking
Makes about 1 cup

INGREDIENTS

• 2 cups powdered sugar, sifted if lumpy
  
• 4 Tablespoons unsalted butter, softened
  
• 3 to 4 Tablespoons milk
  
• 1 teaspoon vanilla
  
• 1/8 teaspoon salt

DIRECTIONS

1. Beat together the sugar and butter until smooth. Add the milk, vanilla, and salt and beat until smooth. Adjust the texture with additional powdered sugar or milk if necessary.
   
   
2. To store, cover the surface directly with plastic wrap. This will keep for three days at room temperature or three weeks refrigerated. Before using, soften and stir until smooth.

NOTES

• The icing will thicken as it stands, so it’s best to work quickly when icing cakes, especially those with a delicate texture. Thorough stirring will help loosen it up, as will the addition of a little extra liquid to thin it out.