Excellent cake baking requires proper moisture know-how. Along with sugar, bakers achieve this moisture through the use of fats. Butter and vegetable oil are often the baker's ingredients of choice for gourmet baking.
It is tempting to swap one fat out for the other when supplies are short, but the lack of consideration for the fat's composition and using the improper method of mixing can make or break the cake's quality and texture.
The Water Factor
The most significant composition difference between oil and butter is its water content. Solid butter is mostly composed of fat, but it is also twenty-percent water. This water evaporates away during baking and, in some cases, can risk a drier cake.
Oil is one-hundred percent fat and aids the cake's tenderness by coating the proteins in the flour. This prevents gluten strand development, forming a softer, more moist crumb. Oil is a flavorless fat, and it does work well for cakes and baked goods with a strong inherent flavor, such as high-cocoa desserts. However, if you wish to add richness to your desserts, other options should be considered.
It's All In the Mixing
In spite of its water content, butter does have a flavor advantage over oil, and softened butter can contribute to a moist cake when using the right method.
In scratch-made cakes, bakers use a mixing method called the “creaming method”: the baker blends together sugar with room-temperature, solid butter to aerate and add volume to the fat before adding the other ingredients. This method is popular because it aids the leavening process. The air bubbles in the fat expand as the cake bakes. This method is only usable while the sugar is separated from the other dry ingredients — it won't work for cake mixes.
The Melted Option
For cake mixes with a gentle flavor profile, such as white and yellow cakes, butter can also be melted and used to act as an oil while adding flavor. The heating and melting of the butter reduces the water content, leaving mostly the fat. Using melted butter in place of oil also adds a richer, bakery-style flavor in cocoa desserts like brownies and devil's food cake. Clarified butter would make an ideal butter fat for tender cakes since the process removes nearly all the water, though this is not strictly necessary.
At Sweet Day Gourmet, our mixes recommend a liquid fat, oil or melted butter, to simplify the work of making moist, delicious, and flavorful cakes and desserts at home. Contact us to learn about our full line of gourmet cake and dessert mixes that deliver straight to your door.