SUGAR

any of numerous sweet, colourless, water-soluble compounds present in the sap of seed plants and the milk of mammals and making up the simplest group of carbohydrates. (See also carbohydrate.) The most common sugar is sucrose, a crystalline tabletop and industrial sweetener used in foods and beverages. As a chemical term, sugar usually refers to all carbohydrates of the general formula Cn(H2O)n. Sucrose is a disaccharide, or double sugar, being composed of one molecule of glucose linked to one molecule of fructose. Because one molecule of water (H2O) is lost in the condensation reaction linking glucose to fructose, sucrose is represented by the formula C12H22O11 (following the general formula Cnn - 1). Figure 1: Structures of the sugarcane (left) and sugar beet (right). Sucrose is found in almost all plants, but it occurs at concentrations high enough for economic recovery only in sugarcane (Saccharum officinarum) and sugar beets (Beta vulgaris). The former is a giant grass growing in tropical and subtropical areas; the latter is a root crop growing in temperate zones (see Figure 1). Sugarcane ranges from 7 to 18 percent sugar by weight, while sugar beets are from 8 to 22 percent sugar by weight. Sucrose from either source (or from two relatively minor sources, the sugar maple tree and the date palm) is the same molecule, yielding 3.94 calories per gram as do all carbohydrates. Differences in sugar products come from other components isolated with sucrose. The first cultivated sugar crop was sugarcane, developed from wild varieties in the East Indiesprobably New Guinea. The sugar beet was developed as a crop in Europe in the 19th century during the Napoleonic Wars, when France sought an alternate homegrown source of sugar in order to save its ships from running blockades to sugarcane sources in the Caribbean. Sugarcane, once harvested, cannot be stored because of sucrose decomposition. For this reason, cane sugar is generally produced in two stages, manufacture of raw sugar taking place in the cane-growing areas and refining into food products occurring in the sugar-consuming countries. Sugar beets, on the other hand, can be stored and are therefore generally processed in one stage into white sugar. any of numerous sweet, colourless, water-soluble compounds present in the sap of seed plants and the milk of mammals and making up the simplest group of carbohydrates. (See also carbohydrate.) The most common sugar is sucrose, or table sugar, which is commercially produced in large amountsmore than 100 million metric tons per yearand is almost entirely used as food. Its chemical formula is C12H22O11. Almost all sucrose is extracted from sugarcane and sugar beets by a milling process (shredding the plants, pressing out the juice, and extracting the residues with water) or by a diffusion process (separating the sugar from the finely cut plants by dissolving it in hot water or juice). The combined liquids are clarified, concentrated through evaporation, and then seeded to induce crystallization of the sugar. Refined granulated sugar, an unusually pure commercial product, is 99.9 percent sucrose. Confectioner's (powdered, or icing) sugar is pulverized sucrose, ordinarily mixed with 3 percent starch or approximately 1 percent calcium phosphate to prevent caking. Other sources of sucrose include the sugar maple tree, the date palm, and honey. Chemists have identified numerous other sugars; only a few are commercially produced, including glucose (also called dextrose) and fructose (or levulose), which occur in fruits and honey; invert sugar, a combination of glucose and fructose that is formed synthetically from sucrose; maltose (or malt sugar), produced in the malting of barley; and lactose (or milk sugar), the only common sugar of animal origin.