Starring Roles

• To bake without a recipe, it's important to understand the role of each ingredient. Eggs seem like they add moisture, but in fact, they add structure to baked goods. Eggs, and in particular, the whites, contain protein. Like the gluten in flour, this protein forms a network that allows bubbles to form and expand. Without eggs, baked goods would be a soggy mess. Egg yolks contain fat, so they do add some moisture and help coat flour proteins. Eggs also add color and flavor to baked goods. Oil -- or any other fat -- adds moisture, flavor and tenderness, just as sugar does. When baking, you must balance the drying characteristics of eggs with the moistening ability of oil.

General Guidelines

• Bakers follow general guidelines for ratios when making cakes, cookies and breads. These ratios have some flexibility, but if you veer off by more than 20 percent, you'll probably be unhappy with the results. For soft, sweet cakes, the oil should weigh the same or slightly less than the eggs. For a pound cake, which has less sugar, use equal amounts of flour, sugar, oil and eggs. Yeast breads, and especially sweet breakfast doughs, occasionally call for small amounts of oil and eggs. In general, use equal amounts of oil and eggs, although these quantities will be far smaller than the flour and water. Few cookie recipes call for oil, but rely on butter or shortening creamed with sugar.

Weigh In

• To bake by ratios, it's best to use a kitchen scale and a glass measuring cup for liquids. Baking ratios are generally measured by weight, rather than volume because ingredients measured by volume don't necessarily weigh the same. A cup of sugar, for example, weighs 7 ounces, while a cup of flour weighs 4 1/2 ounces. A scale isn't as necessary for wet ingredients, such as eggs, but it's important for measuring dry ingredients.

Choosing Ingredients

• Although the ratios don't change, the type of oil or fat you use depends on the baked good. Oils are made from seeds and plants and unlike butter, which contains 80 percent fat, they contain 100 percent fat. Oil produces baked goods that are moister, denser and softer than those made with butter. You can't cream oil with sugar or eggs, so butter is a better choice for light, airy cakes. When choosing eggs, you can use eggs with white or brown shells, cage-free, conventional or organic eggs interchangeably. Most baking recipes call for large eggs, which is what you should use whenever possible. Large eggs weigh 1 3/4 ounce, shelled. The yolks weigh 2/3 to 3/4 ounce and the whites weigh about 1 ounce. Knowing these basic weights can help you accurately determine the number of eggs, as well as the oil, you need to get the ratio right.