Raisin (Fr., a grape), the dried fruit of the European grape vine (vitis vinifera). None of our native grapes (see Grape) has yet afforded raisins suitable for commerce, though one or two varieties encourage the hope that some may yet be produced which will make good raisins. The European grape succeeds perfectly in California, and the production there is already sufficient to supply the home demand. The raisins of commerce are produced in the countries around the Mediterranean. The varieties recognized in trade arise not merely from the original differences in the grapes, but also from the methods of drying. Among the best sorts are those known as the Malaga, muscatel, or "sun raisins;" these are dried upon the vines, as, unlike most fruits, the grape does not drop when ripe; the stem to each bunch when ripe is twisted or partly severed, and the grapes soon shrivel by the evaporation of the water they contain, and become sweeter by the consequent concentration of the pulp; when dried the bunches are taken off and carefully placed in boxes with sheets of paper separating the layers. These raisins, better than any other sort, retain the freshness and bloom of the fruit, and when fresh have less of the saccharine exudation which is found upon most of the other varieties.
The common kinds of raisins are prepared by drying the ripe grapes after they are picked, either in the sun or in heated rooms, and while they are drying dipping them in a lye of wood ashes and barilla, of specific gravity 1.110, to every four gallons of which is added a pint of oil and a handful of salt; the effect of this is to cause a saccharine exudation to take place, which forms concretions upon the raisins and coats them with a thin varnish. The best raisins of this kind are hung on lines to dry in the sun, and as they begin to shrivel they are dipped in the lye once or twice and hung up again to complete the drying. The raisins known as sultana come from Smyrna; they are from a small grape without seeds, and come packed in drums. The black Smyrna raisins are also small, but have very large seeds, and are generally free from sugary concretions. - A very important variety of raisins are called currants, or Zante currants, and are popularly supposed to be common currants preserved in some manner; they are, however, produced by a very small-sized grape, largely cultivated at Patras, in Zante, Ithaca, and Cephalonia, and in the Grecian archipelago. The grapes are no larger than peas, and the bunches are only about 3 in. long.
After drying in the sun, they are stored in large masses, which become so compact from the sugar which exudes from them, that they have to be forcibly dug apart for packing. For shipment they are placed in casks, and made into a solid mass by treading. They were formerly called corinths, and are mentioned in old books as currans. The demand for them is very large in the United States. - Raisins are sometimes employed instead of grapes in making wine, and among the ancient Greeks and Romans some of the best wines were of this character.