They are leavened primarily by the air that is beaten into the egg whites that they contain.

[1] They differ from butter cakes, which contain shortening, and baking powder or baking soda for leavening purposes.

Foam cakes are typically airy, light and spongy.

[1] After it is cooked, the cake and the pan are flipped down on a sheet pan with parchment paper in order for them to cool down at the same rate.

Foam, sponge or unshortened cakes are distinguished by their large proportion of foamed eggs and/or egg whites to a small proportion of sugar and wheat flour.