raisin, dried fruit of certain varieties of grapevines bearing grapes with a high content of sugar and solid flesh. Although the fruit is sometimes artificially dehydrated, it is usually sun-dried. The culture of grapes for the production of raisins is limited to regions with a long, hot growing season because the grape must remain on the vine until fully mature in order to attain a high percentage of sugar and because enough time must elapse between harvesting and fall rains to permit sun-drying. Raisins are produced from grapes of the European type ( Vitis vinifera ). Most seedless raisins, especially in California, are produced from the Sultanina, or Thompson, variety of seedless grape, known in international trade as the Sultana. A different variety, produced in California, is known there as the Sultana. The Muscat, a very ancient variety, is noted for its flavor and meatiness, but it has seeds and is somewhat sticky; it is commonly marketed in clusters for table use. Raisins of sharp flavor and firm texture are often called currants (although unrelated to the true currant) and are preferred for certain bakery products. Grapes have been dried for out-of-season consumption from ancient times and were important in early Mediterranean trade. Spain, Asia Minor, and Greece were long the centers of cultivation, but in the 20th cent. Australia is an important producer and California is the leading producer. Raisin production was introduced in California by Spanish missionaries in the late 18th cent. and began to assume importance after 1875. Today most seed grapes are seeded, and many grapes are bleached and dipped in oil to improve their appearance. About 31/2 lb (1.6 kg) of grapes yield 1 lb (.45 kg) of raisins. Raisins are valuable nutritionally because of their sugar, mineral (especially iron), and vitamin (B and A) content.