Oil cake vs. butter cake
Butter is about 80 percent fat and goes solid in the fridge. Vegetable oil stays liquid even when cold. So a chilled oil cake keeps a soft crumb, while a chilled butter cake firms up.
Butter adds air and flavor
Creaming drives air into solid butter, and baking powder and steam expand those pockets in the oven. Butter also brings dairy flavor. Oil can't hold air that way, so oil cakes lean on their leavener and taste more neutral.
Test yourself
Questions from the interactive lesson, with the answer and the why.
Why does an oil cake stay soft straight from the fridge?
Oil stays liquid when cold, so the crumb stays soft. Butter solidifies and stiffens the crumb. Oil doesn't.
True or false: Beating soft butter with sugar traps tiny air pockets that help a cake rise.
True. Sugar crystals cut tiny air pockets into solid butter, and those pockets expand in the oven.
What went wrong? You cream butter straight from the fridge with sugar. The mixture stays lumpy and the cake bakes up dense.
The butter was too cold to trap air with the sugar. Rock-hard butter won't hold air pockets. Softened butter will.
Fill the blank: Oil is liquid even in the fridge, so an oil cake crumb stays ___ when cold.
Oil is liquid even in the fridge, so an oil cake crumb stays soft when cold. Liquid fat keeps the crumb tender even when chilled.
You want a rich, buttery taste and a fine, light crumb. Which fat and method?
Softened butter, creamed with the sugar. Creaming adds air and the butter adds flavor.