Shortening is any type of solid fat used to prevent the formation of a gluten matrix in baked goods. Lard, hydrogenated (solidified) oils, and even butter can be used as shortening, although in the mainstream market shortening often refers solely to hydrogenated oils.
Vegetable shortenings, or hydrogenated vegetable oils, are extremely shelf stable and require no refrigeration. They have a higher smoke point than butter and are less expensive than both butter and lard. For these reasons, vegetable shortening gained popularity quickly after its invention in the early 20th century.
How Does Shortening Work?
"Shortening" refers to the process of a fat interfering with the formation of a gluten matrix in dough. This process is important for many baked goods, such as pie crusts, because gluten creates a gummy or chewy end product. When fat is worked into dry flour, the fat creates a barrier between gluten molecules, thus preventing them from cross-linking once a liquid is added.
Shortening is also used in baked goods to keep them soft after baking. Unlike butter, which separates into oil and milk solids upon melting, shortening remains intact and reverts back to its soft, semi-solid state upon cooling. For this reason, cookies and other baked goods made with shortening tend to be soft, while those made with butter have a crispier texture.
How is Shortening Used?
To create a shortening effect, a solid fat is “cut” into flour or a dry flour mixture. This can be accomplished with a pastry cutter, two knives, food processor, or even your hands. The fat is repeatedly cut into smaller pieces, which then become coated with flour. The final size of the fat pieces will determine the final texture of the baked good. Pea sized fat pieces tend to create a flakey product, such as a pie crust or croissant, while a texture that resembles coarse sand will create crumbly mixtures like streusel.
Vegetable shorting is commonly used for deep fat frying due to its high smoke point, low moisture level, and stability. The high smoke point allows food to be cooked quickly at high temperatures without burning the oil, which causes foul flavors. The low moisture level reduces splatter, delays rancidity, and increases the stability of the fat, allowing it to be used repeatedly with less degradation.
Vegetable shortening has a neutral flavor, unlike butter or lard, and can be used for applications where strong fat flavors are not desired. Some vegetable shortenings have artifical butter flavor added to them and are used as an inexpensive replacement for butter.