This section is from the book "A Text Book Of Materia Medica, Being An Account Of The More Important Crude Drugs Of Vegetable And Animal Origin", by Henry G. Greenish. Also available from Amazon: A Text Book of Materia Medica : Being an Account of the More Important Crude Drugs of Vegetable and Animal Origin.
The grape vine, Vitis vinifera, Linne (N.O. Ampelideoe) is cultivated in numerous varieties in most of the warmer temperate regions, particularly in central and southern Europe, California, and Australia.
When the grapes are ripe most of the leaves are stripped from the vine, and the stalk of the bunch is cut half through or twisted; the grapes are then allowed to dry by the heat of the sun. This process, which occupies two or three weeks, is often hastened by cutting the bunch off when partially dried, sterilising the fruits by dipping them into a boiling alkaline solution and drying on wicker trays in the sun.
The ovary of the grape vine is superior and two-celled, each cell containing two ovules. As the fruit reaches maturity the interior becomes pulpy, the dissepiment disappears, and the ripe fruit may be regarded as a superior berry. It is usually ovoid or nearly globular in shape, and varies in colour according to the variety. The dried fruits are of a purplish black or brownish colour, and more or less shrivelled.
Raisins contain in the pulp dextrose (grape sugar) and acid potassium tartrate, both of which may be found crystallised in small granular masses in old raisins. The skin and the seeds contain tannin, and the latter a fixed oil in addition.
Varieties - Muscatels: these are considered the best and are exported from Malaga and Valencia; the clusters of purplish black fruits are usually packed in boxes in layers.
Valencias: these are also exported from Valencia, but are generally picked from their stalks; they are of a rather dark golden brown colour.
Turkish: a light brown, elongated raisin.
Sultanas: a seedless variety grown in Turkey, Greece, and Persia; exported chiefly from Smyrna.
Currants: a small seedless variety grown on the Ionian Islands and in the Grecian archipelago.
Raisins possess demulcent, refreshing, and nutrient properties, and are also slightly laxative.