What Are the Functions of Oil in Cakes?

by Alicia Rudnick, The Nest 

Cake contains fat, which contains an abundance of calories. However, you may eat your cake and feel joyful too knowing you can bake healthier cakes by using oils instead of solid fats, such as butter and shortening. Each kind of fat affects cakes in different ways. Effects also vary when baking with different kinds of oil.

Tenderness and Moisture

Oil-based cakes are more tender and moist than ones made with butter, because oil coats wheat flour proteins better than butter does. If the proteins aren't adequately coated, they bond with water and create stretchy gluten, a form of protein that holds ingredients together and makes bread chewy. Aside from being one of the most healthy oils due to its monounsaturated fatty acids, olive oil is one of the best for making cakes. It not only moisturizes and tenderizes better than butter and shortening, but it also enhances flavor better than other oils.

Flavor Enhancement

Butter is the fat of choice in many cakes due, in part, to the flavor it imparts. Also, both butter and shortening provide a lighter texture than oils. Most vegetable oils can't compete in the area of lightness and flavor. However, "Fine Cooking" magazine reports that olive oil -- the less expensive kind simply labeled "olive oil" rather than "extra-virgin" -- adds a "deeper character" to cake drawing out and marrying the flavors of the other ingredients. Best of all, it won't make the cake taste like olives.

Mouthfeel

Although you are likely to find that cakes made with oil are moist and tender, some may create feelings of mealiness, heaviness or oiliness in your mouth. Even though butter and sugar can pose risks to your health, they create a lighter mouthfeel in cakes because they trap air in the batter when creamed with sugar. Fortunately, you can easily lighten an oil-based cake by whipping egg whites together with oil to incorporate more air in the batter.

Adaptability for Fat Reduction

All fats, including oil, technically are shortenings. This is because they interfere with and shorten the strands of proteins that join together to form gluten in wheat, barley, rye, triticale, spelled and other flours. If you want to reduce the oil in a cake recipe, it is possible to substitute an equal amount of sugar or applesauce for the portion of oil removed. However, applesauce may create a denser product. Sugar absorbs water, thus preventing the proteins in grains from bonding and forming gluten. This trait causes sugar to lighten and tenderize cake. In contrast, although the water in applesauce contributes to the moistness of a cake, it also activates the gluten in flour and may create a noticeably tougher product.