thumb|right|upright|Strutto, clarified pork fat or [[lard, a type of shortening common in Italy and Corsica (where it is named sdruttu)]]
Shortening is any fat that is a solid at room temperature and is used to make crumbly pastry and other food products.
The idea of shortening dates back to at least the 18th century, well before the invention of modern, shelf-stable vegetable shortening. In earlier centuries, lard was the primary ingredient used to shorten dough. The reason it is called shortening is that it makes the resulting food crumbly, or to behave as if it had short fibers. Solid fat prevents cross-linking between gluten molecules. This cross-linking would give dough elasticity, so it could be stretched into longer pieces. In 1907, a German chemist, Edwin Cuno Kayser, moved to Cincinnati, Ohio, the home town of soap manufacturer Procter & Gamble. He had worked for British soap manufacturer Joseph Crosfield and Sons and was well acquainted with Normann's process, as Crosfield and Sons owned the British rights to Normann's patent. Later in 1909, Procter & Gamble hired McCaw and purchased his patents along with the patents of other scientists working on partial hydrogenation which later helped in the development of "shortening". Since the product looked like lard, Procter & Gamble instead began selling it as a vegetable fat for cooking purposes in June 1911, calling it "Crisco", a modification of the phrase "crystallized cottonseed oil". With these advantages, plus an intensive advertisement campaign by Procter & Gamble, Crisco quickly gained popularity in American households. Procter & Gamble also advertised how economical it was to use shortening, often advertising cheap recipes incorporating shortening to appeal to frugal mothers. As food production became increasingly industrialized and manufacturers sought low-cost raw materials, the use of vegetable shortening also became common in the food industry. In addition, in the US, government-financed surpluses of cottonseed oil, corn oil, and soybeans also helped lower the cost of vegetable shortening.
In the late 1990s, vegetable shortening became the subject of some health concerns due to partially hydrogenated vegetable oils containing trans fats, a type found only in small amounts in milk and some other natural foods. Trans fats have been linked to coronary artery disease and other adverse health effects. Beginning in 2004, the US shortening brand Crisco was first reformulated to contain less than one gram of trans fat per serving, and then, after the US FDA issued a 2018 ban on partially hydrogenated oils, to a trans-fat-free vegetable shortening made from fully hydrogenated palm oil and some soybean oils to improve the texture. Use of palm oil is controversial due to the environmental impact of commercial palm oil production, which is increased by clearing rainforests. In 2006, UK brand Cookeen was also reformulated to remove trans fats. In the UK, Trex (Rapeseed oil and palm oil) is the main one, while in Australia, Copha is popular, made primarily from coconut oil.
Shortened dough
thumb|A "short" dough is crumbly, and will crack or crumble if stretched too far.
thumb|A "long" dough can be stretched easily.
A short dough is one that is crumbly Not everything that can shorten dough is necessarily called by the name of shortening. For example, butter and margarine can be used to shorten dough; however, these are not usually called shortening. Similarly, liquid shortening is a pourable liquid that most home cooks would not recognize as shortening. A high-ratio shortening is used in cake recipes whose ratio of flour to sugar (by weight) has a higher amount of sugar.