America's Test Kitchen LogoCook's Country LogoCook's Illustrated Logo

Cake That Holds Up—and Cake That Doesn't

The structure of a genoise cake comes from abundant egg proteins that unwind and link with each other when the eggs are whipped and form a strong mesh once baked. When this mesh encounters liquid, it isn’t affected—the water just fills in any gaps in the network. The upshot? The cake holds its shape.

Faced with having to guess which type of cake—a relatively dense yellow butter cake or an airy sponge cake—was the stronger of the two, some might guess butter cake. We did, and we were unhappy with our decision when we tried using one as a base for our Refined Strawberry Shortcake recipe (see related content). It practically dissolved once it soaked up the strawberry juice. Conversely, the sponge cake (we chose a style known as genoise) held up perfectly in our subsequent rounds of testing. Here’s why: A combination of gluten proteins and gelatinized starch provides the structure in a butter cake, but the ample amount of butter it contains and the gentle mixing method it undergoes help minimize gluten development to allow for a more-tender texture. When this sparse network encounters the liquid from the strawberries, the starch softens, causing the delicate network to collapse, and the cake crumbles.

The structure of a genoise cake comes from abundant egg proteins that unwind and link with each other when the eggs are whipped and form a strong mesh once baked. When this mesh encounters liquid, it isn’t affected—the water just fills in any gaps in the network. The upshot? The cake holds its shape.

Super Soaker: Genoise absorbs juice and holds together.

Crumbles Under Pressure: Butter cake doesn’t have the ­structure to hold up.

This is a members' feature.