Shortening

Shortening is 100% fat, while butter is about 80% fat with water and milk solids. Because it stays solid over a wider range of temperatures, it is easier to work into pastry dough without melting, and it helps cookies hold their shape and spread less. The name comes from the way fat shortens gluten strands, which makes baked goods tender.

Many bakers mix shortening with butter for pie crust, to combine flakiness with butter's flavor. When replacing butter with shortening, the dough may need a little more liquid. It is also used for greasing pans and for deep-frying.