During Passover, any bread products eaten by people of the Jewish faith must be unleavened. This rule, as stipulated in the Bible, serves as a reminder of the swiftness of the Israelites’ redemption from bondage in Egypt—there was no time to let their bread rise. Also, ingredients that cause foods to rise are seen as representing ego, or “puffing up,” and thus are avoided in an effort to remain humble.
Whether or not you follow the rules of Passover, making an unleavened bread product is a science lesson in itself. Not only must the recipe’s leavening agent (yeast, baking powder) be omitted, but so must the flour, as there is a chance it could become moist and then rise. But, how can one make a cake without flour and baking soda, or a bread without yeast?
Looked at scientifically, there are two keys to the answer. The baker must replace the flour with another protein for structure, and replace the yeast or baking soda with another source of fluffiness. Moisture, heat and air are important to the process as well.
In the angel food cake recipe shown here, egg whites are a source of protein. The globular proteins found in egg whites are long chains of amino acids that are wrapped in tiny bundles. They behave much like magnets, repelling each other due to their like charges. When we whip the egg whites, however, the charges break up into likes and opposites. The chains unfold, and lose their shape and bond with each other. This produces a net-like structure, which traps water molecules and air inside, creating a meringue. Adding sugar produces a sponge-like effect to keep the meringue from draining.
Next we must come up with a way to keep our cake light and airy while eliminating yeast or baking soda. Leavening agents cause cakes and doughs to rise by producing carbon dioxide gas. In an unleavened cake, we don’t add ingredients to produce a gas, we just use the batter’s existing gases. When we heat our batter in the oven, the air that we have whipped into the meringue expands, as does the water from the egg whites. The resulting steam expands the cake and makes it light and fluffy.
Lynn Parrucci is the coordinator of the Science Center’s Kitchen Theater.
More Passover Cooking Ideas
Chef Chaim Reisner visits the Kitchen Theater at Carnegie Science Center Sunday, April 6 and 13, for a cooking demonstration entitled “Traditional and Non-Traditional Recipes for Passover.” Demonstrations are at 3:00 p.m. For information call 237-3400
Visit the Kitchen Theater at Carnegie Science Center to learn more about the science of cooking, and get a taste of what we’re cooking and a recipe to take home. For a schedule of daily cooking shows, check the schedule board in the Science Center lobby on the day of your visit, or call 237-3400. Be sure to ask if there is a guest chef appearing. The Kitchen Theater at Carnegie Science Center is sponsored by the Jewish Healthcare Foundation. n
1 1/4 cup egg whites
1 teaspoon cream of tartar
1 1/2 cup sugar, divided
1 envelope (.43 ounces) vanilla sugar
1/2 teaspoon lemon juice
1 cup potato starch
1/2 teaspoon salt
In a large bowl of an electric mixer, beat the egg whites until frothy. Add the cream of tartar and beat until stiff peaks form. Gradually add 1 cup of the sugar, 1 tablespoon at a time, beating well after each addition. Add the vanilla sugar and lemon juice.
Sift together the potato starch, salt, and the remaining 1_2 cup of sugar. Slowly fold the dry mixture into the beaten egg white mixture. Pour the batter into an ungreased 9-inch tube pan and bake in a preheated 350 F oven for 45 minutes. Remove from the oven and invert immediately onto a cake rack to cool. Cake may fall out of the baking pan when it is inverted. Serves 10 or more.
2/3 cup sugar
1/3 cup water
2 cups frozen raspberries
Combine water and sugar in a medium sauce pan. Stir over medium heat until sugar dissolves. Add raspberries. Stirring constantly, continue to heat until syrup has boiled for approximately 5 minutes. Remove from heat and chill. Drizzle sauce over Angel Food Cake or swirl sauce onto serving dishes and place pieces of cake in center.
From The Complete Passover Cookbook by Frances R. AvRutick. This book is available at the Carnegie Library, as are other books illustrating Passover traditions and recipes. You may also visit Passover on the Web at http://www.holidays.net/passover/