The Long and Short of Shortening

• Shortening has come in a few different varieties over the years. Animal shortening -- which is also known as lard or suet, and which grandmothers once sprinkled into dishes like pixie dust -- is no longer as prominent in the kitchen as it once was. Vegetable shortening is a solid-fat form of vegetable oil that comes from many different types of vegetables and fruits, such as palm, soybean or coconut. After reports about the dangers of trans fats, makers of vegetable shortenings introduced both low and no trans fat versions.

The Law of Recipe Averages

• Shortening, though its consistency is more like the actual frosting than the cake, is important in helping the cake remain tender and moist. Most recipes do not call for more than 1/2 cup of it. In addition to the shortening, most recipes list either margarine or butter as additional ingredients. Margarine is closer to shortening in that it also comes from vegetable oils, though it doesn't have as high of a fat content. Usually the butter or margarine amount is equal to the needed amount of shortening.

The Butter Difference

• Butter is different from shortening in a few ways. First, butter has less fat content than shortening and it also contains water. Also, shortening typically comes from vegetable oils, whereas butter is a dairy product. Substituting butter for shortening in baked goods means that the finished product won't be as light and airy. Also, since butter comes from milk, adding more butter could aggravate mild dairy allergies. With Italian cream cakes that already call for butter as an ingredient, doubling up on the ingredient will make the cake taste more buttery -- though the taste won't overpower the other flavors.

Proper Substitutions

• A simple rule for substituting butter for shortening in recipes is to keep the amounts equal; for example, if the recipe calls for 1/2 cup butter and 1/2 cup shortening, then just make the butter amount equal to 1 cup. Due to butter not having as much fat as shortening, adding an extra tablespoon of butter on top of what is already needed will give you a slightly lighter texture -- though the equal substitution will produce the correct flavors. Also, butter may substitute any shortening needed to grease the cake pan.