_Passulæ majores_; _Raisins_; F. _Raisins_; G. _Rosinen_.
=Botanical Origin=—_Vitis vinifera_ L., the Common Grape-vine. It
appears to be indigenous to the Caucasian provinces of Russia, that is
to say, to the country lying between the eastern end of the Black Sea
and the south-western shores of the Caspian; extending thence southward
into Armenia. Under innumerable varieties, it is cultivated in most of
the warmer and drier countries of the temperate regions of both the
northern and southern hemispheres. Humboldt defines the area of the
profitable culture of the vine as a zone lying between 36° and 40° of
north latitude.
=History=—The vine is among the oldest of cultivated plants, and
is mentioned in the earliest Mosaic writings. _Dried_ grapes as
distinguished from _fresh_ were used by the ancient Hebrews, and in
the Vulgate are translated _Uvæ passæ_.[647] During the middle ages,
raisins were an article of luxury imported into England from Spain.
[647] Numbers vi. 3; 1 Sam. xxv. 18, xxx. 12; 2 Sam. xvi. 1; 1 Chron.
xii. 40.
=Description=—The ovary of _Vitis vinifera_ is 2-celled with 2 ovules
in each cell; it develops into a succulent, pedicellate berry of
spherical or ovoid form, in which the cells are obliterated and some of
the seeds generally abortive. As the fruit is not articulated with the
rachis or the rachis with the branch, it does not drop at maturity but
remains attached to the plant, on which, provided there is sufficient
solar heat, it gradually withers and dries: such fruits are called
_Raisins of the sun_. Various methods are adopted to facilitate the
drying of the fruit, such as dipping the bunches in boiling water or in
a lye of wood ashes, or twisting or partially severing the stalk,—the
effect of each operation being to arrest or destroy the vitality of
the tissues. The drying is performed by exposure to the sun, sometimes
supplemented by artificial heat.
The raisins commonly found in the shops are the produce of Spain and
Asia Minor, and are sold either in entire bunches or removed from the
stalk. The former kind, known as _Muscatel Raisins_ and imported from
Malaga, are dried and packed with great care for use as a dessert
fruit. The latter kind, which includes the _Valencia Raisins_ of Spain,
and the _Eleme_, _Chesme_ and stoneless _Sultana Raisins_ of Smyrna,
are used for culinary purposes. For pharmacy, Valencia raisins are
generally employed.
=Microscopic Structure=—The outer layer or skin of the berry is made
up of small tabular cells loaded with a reddish granular matter, which
on addition of an alcoholic solution of perchloride of iron assumes a
dingy green hue. The interior parenchyme exhibits large, thin-walled,
loose cells containing an abundance of crystals (bitartrate of
potassium and sugar). There are also some fibro-vascular bundles
traversing the tissue in no regular order.
=Chemical Composition=—The pulp abounds in grape sugar and cream
of tartar, each of which in old raisins may be found crystallized
in nodular masses; it also contains gum and malic acid. The seeds
afford 15 to 18 per cent. of a bland fixed oil, which is occasionally
extracted. Fitz[648] has shown that it consists of the glycerides
of _Erucic Acid_, C₂₂H₄₂O₂, stearic acid, and palmitic acid, the
first-named acid largely prevailing. The crystals of erucic acid melt
at 34° C.; by means of fused potash they may be resolved into arachic
acid, C₂₀H₄₀O₂, and acetic acid, C₂H₄O₂.
The seeds further contain 5 to 6 per cent. of tannic acid, which also
exists in the skin of the fruit. The latter is likewise the seat of
chlorophyll and other colouring matter.
=Commerce=—The consumption of raisins in Great Britain is very large
and is increasing. The imports into the United Kingdom have been as
follows:—
1870. 1871. 1872. 1876.
365,418 427,056 617,418 583,860 cwt.
val. £593,527. val. £707,344. val. £1,149,337. val. £1,058,406.
Of the quantity mentioned for 1872 there were 400,570 cwt. shipped
from Spain, 176,500 cwt. from Asiatic Turkey, and the remainder from
other countries.[649] It is stated that Greece, in 1874, exported about
1⅓ millions of cwt., value £28,000,000; much of this was shipped to
England.
[648] _Berichte der deutsch. chem. Gesellsch. zu Berlin_, iv. (1871)
442.
[649] _Annual Statement of the Trade of the United Kingdom._
=Uses=—Raisins are an ingredient of Compound Tincture of Cardamoms and
of Tincture of Senna. They have no medicinal properties, and are only
used for the sake of the saccharine matter they impart.[650]