The Science of Cooking

Barbara J. Avery

Through the centuries, there has been much debate as to whether cooking is art or science.  It is easy to argue that it is both.  Knowing the scientific principals behind what happens to food as it is transformed from raw ingredients to fabulous food can help the food artist, the cook, create masterpieces.   

Let’s start our laboratory view of cooking with the simple egg.  It’s a wonder, really, in that its white can be whipped into stiff peaks for meringue, or its yolk can cause sauces to thicken.  Egg whites won’t hold air on their own, so by whipping them their normally coiled protein strands are lengthened, and voila! The air is held, and you are on your way to meringue or a soufflé.   

Proteins in egg yolks are emulsifiers for sauces such as mayonnaise and hollandaise.  Emulsifiers are ingredients used to bind together substances that normally wouldn’t combine well, such as oil and water. The protein lecithin found in eggs yolks is a natural emulsifier and thickens and binds sauces.   

As an aside, have you ever hard-boiled an egg and found that greenish-gray color around the yolk? According to On Food and Cooking author Harold McGee, this only happens when an egg is heated and is less-than-fresh.  The yolk contains iron and the white has albumin.  When those are heated, the iron and albumin interact and cause the unsavory color.  You can minimize this interaction by cooking the eggs only as long as necessary and running under cold water immediately when they are done cooking.  

Next, we move on to flour. There is a large variety of flour available, not just wheat flour.  There are so many types on the market today that a whole article could be devoted to them.  However, for the sake of printed space, we’ll need to content ourselves discussing the attributes of widely used wheat flour.  Whether it is bleached or unbleached, flour has proteins that when mixed with water become gluten.  Wheat is especially good at forming strong glutens which are good for making bread rise.  As you knead bread dough, you are toughening the glutens, yet if you knead too long, you break them down.  The gluten is what helps hold the gas bubbles in bread, created by the use of yeast, which makes the loaf rise.  

What is sugar’s role in all this cooking chemistry?  Sugar, or as we know it, sucrose, is actually two sugars stuck together: fructose and glucose.  So, what happens when you heat sugar?  When baking bread, the sugar can affect the development of gluten creating a moist, dense loaf.  Sugar also helps baked goods brown.  Acid, such as lemon juice, added to boiling sugar water helps prevent sugar crystals from reforming when the solution cools.  That’s because the acid breaks apart the fructose and glucose.  This is handy to know when making candy. When used in cookie dough, sugar helps create a treat that is tender and crumbly.   

Flour, eggs, and sugar are all important ingredients in baking; as is bicarbonate of soda, also know as good old baking powder.  It is an alkali and is used as a leavener in baked goods such as quick breads.  Yeast as a leavener can generally be used only in elastic dough such as many types of bread dough.  The Food Lovers Companion by Sharon Tyler Herbst states that, “When combined with an acid ingredient such as buttermilk, yogurt, or molasses, baking soda produces carbon dioxide gas bubbles, thereby causing a dough or batter to rise.”  Keep this in mind as you prepare your recipes calling for baking soda.  It should be added first to your dry ingredients, then to your liquid, then right to the oven.  

Many baking recipes call for baking powder rather than baking soda.  Baking powder is also a leavener and contains a combination of baking soda, an acid such as cream of tartar, and something to absorb moisture, such as corn starch.  Double-acting baking powder produces an initial set of gas bubbles once added to the batter and a second set during the baking process.  Add it to your recipes in the same steps as for baking soda.  

This chemistry of cooking overview has been exceedingly brief considering the vast array of available foods and their actions and interactions with other foods.  So that you may continue to learn and become an even more enlightened cook and artist, you may wish to read further.  Here are a couple of suggestions:  

On Food and Cooking:  The Science and Lore of the Kitchen by Harold McGee

The Accidental Scientist by Peter Barham

The Inquisitive Cook by Anne Gardiner

Spring is here, so walk on past those year ‘round fruits like pineapples and oranges.  Instead, treat yourself so some fresh strawberry shortcake.

Easy Yogurt Shortcake

 Adapted from Better Homes and Gardens Old Fashioned Baking

Serves 6  

1 ½ cups all-purpose flour

1 ½ teaspoons baking powder

¾ teaspoon salt

¼ teaspoon baking soda

2 tablespoons brown sugar or Splenda ® brown sugar substitute

¼ cup butter

1 large egg, beaten

1 8-ounce carton vanilla or strawberry-flavored yogurt

2 tablespoons milk

4 cups sliced strawberries

1 cup whipping cream

1 tablespoon sugar or Splenda®  

Preheat oven to 450 degrees.

Grease an 8 x 1 ½-inch round baking pan.  Set pan aside.  In a medium mixing bowl stir together the flour, baking powder, salt, baking soda, and brown sugar.  Using a pastry blender, cut in the butter or margarine until mixture resembles coarse crumbs.  Make a well in the center of the dry mixture.  In a small mixing bowl stir together egg, yogurt, and milk.  Add wet ingredients to the dry mixture.  Stir with a fork just until moistened.  

Spread dough evenly in the prepared pan.  Bake for 18-20 minutes or until done.  Cool in the pan on a wire rack for 10 minutes.  Remove shortcake from the pan and continue to let cool on the wire rack.  

In a small bowl, combine whipping cream and sugar.  Beat with an electric mixer on medium speed until soft peaks form.  

To serve, cut the shortcake into 6 wedges.  Place wedges on small plates and top each with an equal amount of fruit and whipped cream.

Sour Cream Hollandaise

From the Good Housekeeping Cookbook

Great on tender fresh asparagus  

¼ cup butter

1 cup sour cream

2 tablespoons lemon juice

4 egg yolks  

In a small saucepan over medium-low heat, melt butter.  With wire whisk beat in sour cream and lemon juice.  Beat in egg yolks and heat, beating constantly for about 5 minutes or until slightly thickened. Use warm or refrigerate and reheat over low heat.  Keeps in the refrigerator for up to 2 weeks.