Barley

Barley, common name for any of a genus of cereal grass, native to Asia and Ethiopia, and one of the most ancient of cultivated plants (see Grasses). Its cultivation is mentioned in the Bible, and it was grown by the ancient Egyptians, Greeks, Romans, and Chinese. It is now the fourth largest grain crop, after wheat, rice, and corn. In the United States and Canada, as well as in the greater portion of Europe, barley is sown in the spring. Along the Mediterranean Sea and in parts of California and Arizona, it is sown in the fall. It is also grown as a winter annual in the southern United States. Drought resistant and hardy, barley can be grown on marginal cropland; salt-resistant strains are being developed to increase its usefulness in coastal regions. Barley germinates at about the same temperature as wheat. The different cultivated varieties of barley belong to three distinct types: two-rowed barley, six-rowed barley, and irregular barley. The varieties grown in the United States are generally of the six-rowed type, in Europe the two-rowed type predominates, and the irregular type is found in Ethiopia. The finest malting varieties are the six-rowed and the two-rowed types.

Barley grain, hay, straw, and several by-products are used for feed. The grain is used for malt beverages and in cooking. Like other cereals, barley contains a large proportion of carbohydrate (67 percent) and protein (12.8 percent).

Scientific classification: Barley belongs to the genus Hordeum, of the family Poaceae (formerly Gramineae). Two-rowed barley is classified as Hordeum distichon, six-rowed barley as Hordeum vulgare, and irregular barley as Hordeum irregulare.

Coffee

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Coffee, common name for any of a genus of trees of the madder family, and also for their seeds (beans) and for the beverage brewed from them. Of the 30 or more species of the genus, only three are important: Arabian, robusta, and Liberian. The shrub or small tree, 4.6 to 6 m (15 to 20 ft) high at maturity, bears shiny green, ovate leaves that persist for three to five years and white, fragrant flowers that bloom for only a few days. During the six or seven months after appearance of the flower, the fruit develops, changing from light green to red and, ultimately, when fully ripe and ready for picking, to deep crimson. The mature fruit, which resembles a cherry, grows in clusters attached to the limb by very short stems, and it usually contains two seeds, or beans, surrounded by a sweet pulp.

CHARACTERISTICS

Coffee contains a complex mixture of chemical components of the bean, some of which are not affected by roasting. Other compounds, particularly those related to the aroma, are produced by partial destruction of the green bean during roasting. Chemicals extracted by hot water are classified as nonvolatile taste components and volatile aroma components. Important nonvolatiles are caffeine, trigonelline, chlorogenic acid, phenolic acids, amino acids, carbohydrates, and minerals. Important volatiles are organic acids, aldehydes, ketones, esters, amines, and mercaptans. The principal physiological effects of coffee are due to caffeine, an alkaloid that acts as a mild stimulant. In recent years controversy arose over the possibly harmful effects of coffee beyond those recognized for people who should take few or no stimulants, and the dangers of caffeine for the fetuses of pregnant women. These debated studies were not substantiated, however.

A. Soluble Coffee

Soluble or instant coffee is an important production of the United States coffee industry. In its manufacture an extract is prepared by mixing coarsely ground and roasted coffee with hot water. The water is evaporated from the extract by various methods, including the use of spray driers or high-vacuum equipment. In freeze-dried coffee the coffee extract is frozen, and the water is removed by sublimation. The product is packed in vacuumized, sealed jars or in cans.

B. Decaffeinated Coffee

Caffeine can be removed from coffee by treating the green beans with chlorinated hydrocarbon solvents. The beans are roasted by ordinary procedures after removal of the solvents. Decaffeinated coffee is used by people hypersensitive to the caffeine present in regular coffee. In the 1980s nonchemical methods of decaffeination became more common.

Vegetable

Vegetable, the edible product of a herbaceous plant—that is, a plant with a soft stem, as distinguished from the edible nuts and fruits produced by plants with woody stems such as shrubs and trees.

Vegetables can be grouped according to the edible part of each plant: leaves (lettuce), stalks (celery), roots (carrot), tubers (potato), bulbs (onion), and flowers (broccoli). In addition, fruits such as the tomato and seeds such as the pea are commonly considered vegetables.

Most vegetables are valuable sources of vitamins, minerals, and fiber and are low in fat and calories. With cereals and legumes, they are important to a healthy diet (see Human Nutrition).

See also Cereals; Fruit; Legume; Nut.

Bark

Bark, hard covering or rind of the stem, branches, and roots of a tree or other plant, as distinguished from the wood. The bark consists of an inner and outer layer. Bark is used commercially in the tanning of leather, in boatbuilding, and in basket making and in the manufacture of clothing and shoes, food flavoring, medicine, and cork and cork products.

Barks rich in tannin are usually used for tanning, although other properties also determine the value of a bark for preparing leather. Bark from several species of oak in the genus Quercus and from the Eastern hemlock (Tsuga canadensis) used to supply much of the tannin in the northern United States. In recent years, however, use of the wood or fruit of many other trees and the development of synthetic tannins have replaced earlier sources.

Autumn Crocus

Autumn Crocus, common name for a bulbous herb (see Lily). Native to Europe and not a true crocus, this garden plant, which is also called meadow saffron, takes its name from its unusual pattern of flowering. In spring, several large, straplike leaves grow from the bulb, more or less erect, to a height of 60 cm (24 in) or more. When the leaves fall off in the autumn, clusters of purple or white crocuslike flowers appear. Autumn crocus contains poisonous alkaloids, the principal one being colchicine.

Scientific classification: The autumn crocus belongs to the family Liliaceae. It is classified as Colchicum autumnale.

Bulb

Bulb, mass of overlapping, usually fleshy leaves on a short stem, enclosing, protecting, and serving as a source of food for at least one bud that may develop into a new plant. The bulb, usually developed underground, has roots growing down from the stem. The truncated bulb, as in the onion, has tightly overlapping leaves; the scaly bulb, as in garlic, is looser. In common usage the term bulb also refers to bulblike stems, such as the corm of the crocus or the tuber of the dahlia, and even to rhizomes, masses of roots, and some underground stems. See also Rhizome; Tuber.

Archaea

Archaea or Archaebacteria, common name for a group of one-celled organisms, many of which do not require oxygen or sunlight to live. Before the discovery of archaebacteria, scientists divided all living organisms into prokaryotes (organisms without a cellular nucleus), which consisted primarily of bacteria, and eukaryotes (organisms with a cellular nucleus), which consisted of fungi, plants, and animals. Archaebacteria were initially grouped with bacteria because like bacteria, they lack a well-defined nucleus. Recent evidence, however, has demonstrated that archaebacteria have a genetic makeup that more closely resembles the eukaryotes, organisms that have a well-defined nucleus. This unique structure means that archaebacteria cannot be accurately grouped with either the prokaryotes or the eukaryotes. Instead, scientists have proposed that these microorganisms be classified in a new branch of life, or domain, called archaea.

Archaebacteria often live in extreme conditions that were once considered inhospitable to life. Some archaebacteria live in deep-sea hydrothermal vents in the Pacific Ocean. Located at depths of 3 km (2 mi), the hot vents provide a dark environment with extremely high temperature and pressure where few creatures can survive. Instead of deriving energy from the sun, these microorganisms obtain energy by oxidizing inorganic chemicals that spew from the hot vents. In a process known as chemosynthesis, archaebacteria harvest energy from chemical reactions involving hydrogen sulfide and other inorganic compounds. These deep-sea archaebacteria make up the bottom of the food chain for clams, tube worms, mussels, and other animals that live near the vents.

Scientists initially found archaebacteria only in harsh environments, but recently these microorganisms have been found in the guts of animals, compost piles, saturated marshes, and other common places. Knowledge gleaned from studying a third branch of life could provide insight on the common ancestry of all living organisms.

Scientific classification: Archaebacteria are members of the domain archaea. The archaebacterium found near deep-sea hydrothermal vents is classified as Methanococcus jannaschii.