PRUNE, dried plums of certain varieties and the varieties used for drying. They are extensively cultivated in the Danubian princi palities, France, Italy, and in recent years in California, Oregon and Washington, from which States the American market is now chiefly supplied. The product is of great com mercial importance and nutritious qualities. Any variety of plum having the requisite per centage of sugar, plenty of solids and which, when cured, will keep for a long time without deterioration, is suitable for making prunes.
Prune growing was introduced into Califor nia in 1856, from scions imported from France, and in 1863 prunes were for the first time pub licly exhibited as a California product. The first large orchard was planted in 1870, yet in 1915 nearly 100,000 acres of bearing and 30,000 of young trees were recorded. Attempts have been made to cultivate the prune in eastern parts of the United States, but without success, owing to the absence of requisite conditions for curing. Cultivation has been successfully ex tended to Australia and South America, and these countries will ultimately prove formid able competitors in the trade. In California where the wet and dry seasons are well defined, and from May until October rains are infrequent, never exceeding a fraction of an inch in volume, exist the best natural conditions for perfect curing of the prune. The fruit is not picked until perfectly ripe, then it is gathered from the ground whence it has fallen naturally from the trees when ripe. It is then passed through a sizer which separates the various sizes in order to secure uniformity in drying, as small fruit will dry in a shorter time than will a larger size. Next it is dipped into a weak solution of boil ing lye to take off the bloom and facilitate cur ing. Sometimes the outer skin is punctured by needles to allow the surplus moisture in the fruit to escape readily. In large establishments endless-chain machines are employed in dipping, but where it is done by hand a wire dipper is used. The fruit is washed in fresh water after the process to clean off the lye. After spread ing upon wire-netting trays, the fruit is taken to the field and exposed to the sun's heat until properly cured. The summer days in California are invariably hot and the raw fruit, after ex posure to the sun's rays for 6 to 10 days, de pending upon size, is thoroughly dried. (In eastern Europe it is customary to cook the fruit partly before exposing it to the sun). In coun
tries where penods of dry weather are liable to be interrupted, evaporators are used in ex tracting the moisture of the fruit, the trays be ing introduced into a chamber in which the temperature is raised to 140° to 180°, and where they remain from 12 to 48 hours. To under stand the exact amount of time necessary per fectly to cure the fruit is essential, as if this matter is ill-judged an inferior quality of prod uct results. When sufficiently cured, the fruit is taken from the trays to bins, where it is al lowed to °sweat') for two or three weeks, after which it is ready to be graded and packed for market. Grades are indicated by the number of prunes to the pound, according to the size; 30 to 40 to the pound represents the highest grade, 120 or 130, the smallest. Before final packing the prunes are °processed') by dipping into a hot solution of water with glycerine or fruit syrup, which not only adds to the beauty and polish of the fruit, but extirpates insect germs that may be present. Producers seldom introduce a substance in the process mixture for increasing weight. In shipping, sacks are employed when a buyer intends to pack for his own trade, byt the larger quantity is packed into boxes or stated dimensions at the place of shipment. French methods are also practised in packing high grades in fancy boxes with attractive linings. In quantity the States of California, Oregon and Washington produce a larger amount than all foreign count 'es put together, the annual output of the thre States aggregating about 210,000,000 pounds 1912.
Large quantities of the better sort of erican fruit are exported to Europe, where they rank equally with the finest brands of Franie.
Orchards of large size are found in various parts of California. They require the same careful cultivation as plums and frequent prun ing, besides occasional irrigation. The nomen clature of the prune-making plum is large and abounds in synonyms. The following varieties are most favored in America: Petite or Prune d'Agen, the most important in California; Italian (Fellenberg) in Oregon, with Tragedy perhaps second and Hungarian third. Other varieties grown commercially are Pacific, Wil lamette, Clairac, Mammoth, Columbia, Tennant, Silver and Sugar. Consult Bailey,