Prune
Prune, a dried plum. The term also may mean any plum suitable for drying. Such plums are called fresh prunes when they are used, like other types of plums, in the undried state. Prune juice is the juice of fresh prunes.
Commercial prunes are prepared from the purplish fruits of several varieties of the European plum tree. In this species the fruit has a high sugar content, which prevents spoilage as the fruit dries. Only tree-ripened fruits are used. They are gathered after they have fallen to the ground. The fruits may be dried artificially or in the sun.
In artificial drying—the process commonly used in the United States—the fruits are clipped in hot water, placed on trays, and moved through a dehydrator. This is a large machine that dries the prunes in a day or so by means of fan-circulated hot air.
In sun-drying, the fruits first are dipped in a hot lye solution. This process perforates the skins and makes them thinner. The fruits then are spread on trays in direct sunlight. After a week or two the trays are stacked so that the prunes are exposed to the air but not to the sun. Lastly, the prunes are heaped together in bins for several weeks until they all contain the same amount of moisture.
For table use, prunes are stewed until they are soft. Stewed prunes (and prune juice) have laxative value, but usually are less rich in vitamins than the fresh fruit.
Next to raisins, prunes are the most popular dried fruit in the United States. Most of the crop comes from California.
The European plum tree is Prunus domestica of the rose family, Rosaceae.