The peanut — aka goober or groundnut — is a plant in the pea family and was originally native to South America. It is now widely grown throughout the tropic and subtropic areas of the world.
The peanut plant is a green, oval-leafed legume about 12 to 20 inches tall with yellow flowers. The plant flowers above ground, but fruits below the ground. After the flowers of a plant are fertilized, the pods formed grow downward and force their way into the soil. This allows the peanut, which is the plant's seed, to ripen underground. This feature protects the seed from predators and enables it to more efficiently soak up the water it needs to germinate.
The peanuts harvested today are very popular for both eating and baking. A very popular peanut product around the world is peanut butter. It is a food paste, or spread, made from ground, dry-roasted peanuts. It often contains additional ingredients such as salt, sweeteners or emulsifiers that modify the taste or texture. It is thought that the Inca of ancient Peru were the first to grind peanuts into a paste for consumption.
In 1895, John Harvey Kellogg filed a patent in the U.S. for a proto-peanut butter. He endorsed a plant-based diet and promoted peanut butter as a healthy alternative to meat.
Meat shortages and rationing made it very popular during the periods of World Wars I and II. It is a good source of protein and is rich in a variety of nutrients, but it's also rich in calories and fat.
Early types of peanut butter had the problem of the oils separating from the solids which made vigorous and difficult stirring a problem faced when wanting to use it. However, this problem was solved in 1921 when a patent was filed applying a chemical process called partial hydrogenation This procedure made it possible for the oil and solids to remain blended at room temperature. The practice had been used to make substitutes for butter and lard (e.g. Crisco). Although eaten all over the world, peanut butter is still an American icon.