TOBACCO

common name of the plant Nicotiana tabacum and, to a limited extent, N. rustica and the cured leaf that is used, usually after aging and processing in various ways, for smoking, chewing, snuffing, and extraction of nicotine. This article deals with the farming of tobacco from cultivation to curing and grading. any of numerous species of Nicotiana or the cured leaves of several of the species that are used after processing in various ways for smoking, snuffing, chewing, and extracting of nicotine. Common tobacco is Nicotiana tabacum, native to South America, Mexico, and the West Indies. Wild tobacco is Nicotiana rustica, the species cultivated by the Indians of eastern North America and presently cultivated in Turkey, India, and several European countries. These two species were described by Carolus Linnaeus in 1753. Other species, such as N. attenuata, N. trigonophylla, and N. quadrivalvis, have been used for smoking by the Indians of western North America. Ornamental, flowering tobaccos are N. sylvestris and N. alata grandiflora. All species of Nicotiana are probably native to the Western Hemisphere except several species native to Australia. When Christopher Columbus discovered the Americas, he found the natives using tobacco in much the same manner as it is used today. The American Indians believed it to possess medicinal properties, which was the main reason for its introduction into Europe. Tobacco was important in Indian ceremonies, such as the smoking of the pipe of peace. Evidently the natives of North and South America had developed crude methods of tobacco culture. Tobacco-growing's extension to practically all parts of the world began with its introduction into Europe: France, 1556; Portugal, 1558; Spain, 1559; and England, 1565. Jean Nicot, the French ambassador to Lisbon in whose honour the genus Nicotiana was named, is said to have sent the seed of N. tabacum to Catherine de Mdicis, the queen consort and regent of France. Portuguese and Spanish sailors took tobacco from Europe to all parts of the world. There are no available records as to early tobacco culture outside Europe, but the beginnings of tobacco culture by European settlers in America took place in the following areas on the dates indicated: Santo Domingo, 1531; Cuba, 1580; Brazil, 1600; Jamestown, Virginia, 1612; Maryland, 1631. Tobacco soon became the chief commodity exchanged by the colonists for European manufactured articles. Overproduction was an economic problem from the beginning. After the American Revolution tobacco culture expanded from the colonial areas in Virginia and Maryland into Kentucky, Tennessee, North Carolina, Ohio, and Missouri. Tobacco leaves were originally air-curedleft to dry in a barn or shed for several weeks. Later, smoke from a wood fire was used (fire curing), thereby enabling the leaf to withstand long ocean voyages by sailing ship. About 1825 the fire-curing method was modified in parts of Virginia and North Carolina by the use of charcoal, which eliminated the effect of smoke on the taste and aroma of the leaf. The method was further modified after the American Civil War by the introduction of a furnace with metal flues. A light, air-cured leaf known as White Burley appeared about 1864, after a farmer in Brown County, Ohio, found individual tobacco plants that were deficient in green colouring. These plants, when cured, manifested a light yellowish-red colour, and the cured leaf was porous, extremely absorptive, and highly suitable for use in manufacturing mixtures for chewing and smoking. It has also been suitable for use in manufacturing the popular American blended cigarette. Common tobacco may grow to a height of 4 to 6 feet (1 to 2 m) when not topped. The flowers, which are borne in a panicle and are normally self-fertilizing, are usually pink but may be carmine or white. The leaves of some of the large varieties may reach a length of 2 to 3 feet, with a width of about half the length; but some of the Turkish, or Oriental, kinds, as grown commercially, may be less than 3 inches (7.6 cm) long. N. rustica varies from 2 to 4 feet in height and usually develops suckers, or axillary shoots. The leaves are thick and broadly oval; the flowers are pale yellow to greenish. Both common tobacco and N. rustica have an epidermal covering of hairs, some of which are glandular and secrete a viscid liquid. Both species may have a high alkaloid content; that of N. rustica tends to be higher. Nicotine (q.v.) occurs in tobacco along with related alkaloids and organic acids such as malic and citric. Nicotine content is determined by the species, variety, and strain of tobacco; the growing conditions, particularly soil and climate; the methods of culture and cure; and the position on the plant from which the leaves are taken (lower leaves usually have less nicotine). There is considerable variation in commercial tobacco, but on average the dark, air-cured and fire-cured types contain 4 to 4.5 percent nicotine; cigar filler and Burley contain 3.5 to 4 percent; flue-cured, 2.5 to 3 percent; Maryland, 2 percent; and Turkish, less than 2 percent. N. rustica has been grown with up to 10 percent nicotine in the leaf. During the fermentation or aging process, there is a loss in nicotine. In cigar tobaccos, which are subjected to a heavy fermentation, one-half or more of the nicotine may disappear. Tobacco is high in ash content, which ranges from 15 to 25 percent of the leaf on a water-free basis. Flue-cured tobacco is rich in sugar, the cigarette grades having 15 to 20 percent or more. Cigar tobaccos are high in nitrogenous compounds but are almost free of starch and sugars. If leaf tobacco is not bought in ready-stemmed form, the first step in turning it into a product that the consumer can smoke, chew, or take as snuff is to remove midribs (central veins). For most products, manufacturers blend leaf of various types, origins, grades, and crop years to obtain the qualities that they require and to assure uniformity over the years. Cigarette manufacturers usually add sweetening preparations and flavourings and process the tobacco in a variety of secret ways before it is fed, as finely shredded rag, into the cigarette-making machines. Preparation of tobaccos for pipe smoking and chewing is as varied as the assortment of these products. Their manufacture may involve the incorporation of additives and the application of pressure and heat. Snuff is usually made by fermenting fire-cured leaf and stem, and grinding it; salts and flavourings may be added. Cigars are made by wrapping a binder leaf around a bunch of cut filler leaf and overwrapping with a fine wrapper leaf; on all but the finest cigars the work is largely mechanized. In the United States and increasingly elsewhere, stems and scrap are used for nicotine extractions or are ground down and made into reconstituted sheet in a process akin to papermaking. The sheet may be used as a substitute cigar binder or, more rarely, as wrapper, or it may be finely cut and used to supplement natural tobacco in cigarettes. See also chewing tobacco; cigar; cigarette; smoking; snuff. Additional reading B.C. Akehurst, Tobacco, 2nd ed. (1981). James Edward McMurtrey, Jr. The Editors of the Encyclopdia Britannica