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sugar,compound of carbon, hydrogen, and oxygen belonging to a class of substances called carbohydratescarbohydrate,
any member of a large class of chemical compounds that includes sugars, starches, cellulose, and related compounds. These compounds are produced naturally by green plants from carbon dioxide and water (see photosynthesis).
..... Click the link for more information. . Sugars fall into three groups: the monosaccharides, disaccharides, and trisaccharides. The monosaccharides are the simple sugars; they include fructosefructose
, or fruit sugar,
simple sugar found in honey and in the fruit and other parts of plants. It is much sweeter than sucrose (cane sugar).
..... Click the link for more information. and glucoseglucose,
or grape sugar,
monosaccharide sugar with the empirical formula C6H12O6 . This carbohydrate occurs in the sap of most plants and in the juice of grapes and other fruits.
..... Click the link for more information. . The disaccharides are formed by the union of two monosaccharides with the loss of one molecule of water. Disaccharides include lactoselactose
or milk sugar,
white crystalline disaccharide (see carbohydrate). It has the same empirical formula (C12H22O11) as sucrose (cane sugar) and maltose but differs from both in structure (see isomer).
..... Click the link for more information. , maltosemaltose
or malt sugar,
crystalline disaccharide (see carbohydrate). It has the same empirical formula (C12H22O11) as sucrose and lactose but differs from both in structure (see isomer).
..... Click the link for more information. , and sucrosesucrose
, commonest of the sugars, a white, crystalline solid disaccharide (see carbohydrate) with a sweet taste, melting and decomposing at 186°C; to form caramel. It is known commonly as cane sugar, beet sugar, or maple sugar, depending upon its natural source.
..... Click the link for more information. . Less well known are the trisaccharides; raffinose is a trisaccharide present in cottonseed and in sugar beets. Sugars belong to two families denoted by the letter d- or l- written before the name of a sugar. The families are related to glyceraldehyde CH2OHCHOHCHO, which can exist in two three-dimensional forms that are mirror images of each other. The isomer of glyceraldehyde that rotates plane polarized light clockwise is labeled d-glyceraldehyde; all natural sugars can be derived from this substance and thus belong the the d family. Although l-sugars can be prepared in the laboratory, they cannot be utilized by animals.
a member of a class of carbohydrates with low molecular weight; the class comprises monosaccharides and oligosaccharides, including disaccharides and trisaccharides. Sugars exhibit a relatively high solubility in water and the ability to crystallize. Some have a sweet taste. Many monosaccharides and disaccharides fairly commonly found in nature bear names reflecting the source from which they were first isolated. For example, glucose is also known as grape sugar, lactose as milk sugar, maltose as malt sugar, and sucrose as cane sugar, beet sugar, or, in everyday usage, simply sugar.
The term “sugar” also occurs in the names of unusual natural and synthetic monosaccharides, which may in several ways differ from common sugars. The molecules of uncommon sugars may contain groups other than the hydroxyl group (OH); for example, deoxy-sugars contain a hydrogen atom, amino sugars contain the amino group NH2, and thio sugars contain the mer-capto group SH. Uncommon sugars may also have a branched carbon skeleton (branched sugars), a carbon chain consisting of seven or more atoms (higher sugars), an extra oxygen cycle (anhydrous sugars), or a double carbon-carbon bond (unsaturated sugars). Microorganisms are a rich source of various uncommon sugars.
The structure of most natural sugars has been confirmed by their chemical synthesis.
L. V. BAKINOVSKM
a sweet-tasting food product. The caloric value of 100 g of sugar is 1.68 megajoules (approximately 400 kilocalories). [For the chemical composition and properties of sugar see.] Sugar is manufactured as white crystalline granulated sugar or as refined sugar, which includes powdered, lump, and refined granulated sugar. Besides being directly consumed, sugar is also used as an ingredient in the production of bread and pastry and in canning and wine-making.
In the USSR, sugar is obtained from sugar beets, which have an average sugar content of 17.5 percent. All stages in sugar production have been mechanized and are executed continuously during the beet-processing season, which is usually from late September to February. Beets enter the processing plant on hydraulic conveyors, which are equipped with devices for the removal of impurities from the beet and water mixture produced by the system. They then pass through beet washers, where any remaining impurities are eliminated. A slicer cuts the roots into fine shavings, which drop into a diffusion apparatus. Almost all the sugar is extracted from the shavings into the dif-fuser’s hot water. The desugared shavings, which are called pulp, are used as livestock feed.
In addition to sugar, the dark-colored diffusion juice also contains various organic and mineral substances called non-sugars, which must be purified by purification, saturation, or sulphitation. Initially, the juice, which is heated to 88°C, is mixed with milk of lime. Under the action of the lime, proteins and colored substances coagulate and the insoluble calcium salts of oxalic, phosphoric, and other acids precipitate. The juice is then acted upon by CO2 (first saturation), and the excess lime, which did not react with the juice’s nonsugars, is converted into an insoluble fine crystalline deposit of CaCO3. Various nonsugars, usually those that are colored, are adsorbed onto the surface of the deposit. After heating the juice to 90°C, the deposit from the first saturation is filtered off. The filtrate used for removing calcium salt deposits from the juice is heated to 102°C, and the juice is again treated with a small amount of lime (0.25 percent CaO) and CO2 (second saturation). The deposited CaCO3 is filtered off, after which SO2 is used to bleach the juice (sulphitation). The residue, which contains calcium carbonate and deposited nonsugars, is used as fertilizer.
Purification removes 35 to 40 percent of the nonsugars found in the juice. The purified juice is light yellow in color and contains approximately 14 percent solids (including 13 percent sugar). After being heated to 126°C, the juice is run through an evaporator. The resulting syrup, which contains 65 percent solids (including 60 percent sugar), is bleached by sulphitization. After filtration, the syrup is passed to vacuum pans, where a sequence of two or three crystallizations is carried out.
During double crystallization, the syrup is evaporated in the vacuum pans until a concentration containing 92.5 percent solid matter, including approximately 85 percent sugar, is produced. This concentration, which is called the white fillmass of the first crystallization, consists of approximately 55 percent sugar crystals and an intercrystalline mother syrup containing uncrystallized sugar and nonsugars. When centrifuged, the fillmass separates into the high green syrup and a low syrup, obtained by washing the sugar crystals with water. After removal from the centrifuge, the crystals are dried and cooled and are ready for distribution as white granulated sugar.
Sugar constitutes approximately 85 percent of the total solid matter contained in the low syrup. The low syrup is used in the boiling of the fillmass of the first crystallization. The mother syrup, which contains approximately 78 percent sugar, is evaporated to produce the fillmass of the second crystallization (95 percent dry matter). In order to obtain a higher yield of sugar from the intercrystalline solution the fillmass of the second crystallization is cooled in agitators at a temperature of 40°C for a period of 24 hours. When centrifuged, the fillmass yields a yellow sugar and molasses. The yellow sugar is dissolved by purified juice to a 60–65 percent solid content and mixed with syrup, and the molasses is used as feed.
With triple crystallization, which is customary in the USSR, three fillmasses are evaporated: the first fillmass yields white granulated sugar; the second yields yellow sugar, which is dissolved and again added to the syrup; and the third is evaporated from the fillmass solution of the second crystallization, yielding a yellow sugar that is returned to the syrup after an additional purification procedure called affination.
White granulated sugar contains a minimum of 99.75 percent sucrose in solid content, a maximum of 0.14 percent moisture, and 0.03 percent ash. Each 100 kg of sugar contained in beets yields 80–82 kg of pure sugar. The remaining sugar either is in the form of molasses (10–14 kg) or is lost during production (5–6 kg).
Sugar is similarly produced from sugarcane. The special features of cane-sugar production is that the juice is most commonly squeezed out of the crushed stalk by rolling presses and only a small quantity (approximately 0.1 percent) of lime is used to purify the juice. Cane-sugar mills usually do not manufacture white sugar but an intermediate product—unpurified raw sugar. During the off-season, sugar mills in the USSR process raw sugar imported primarily from Cuba. Purified granulated cane sugar is indistinguishable from beet sugar.
Refined sugar is processed by sugar refineries or by beet-sugar plants. It differs from ordinary granulated sugar in its higher purity; 100 g of dry matter contains a minimum of 99.9 g of sucrose. Ordinary granulated sugar or raw cane sugar serve as raw materials. The sugar raw material is dissolved, further bleached by adsorbents or ion-exchangers, and carefully filtered, and the purified syrup is then evaporated into a fillmass. The centrifugation of the fillmass produces sugar with a moisture content of approximately 2 percent. The sugar is then pressed and dried.
REFERENCESSilin, P. M. Tekhnologiia sakhara, 2nd ed. [Moscow, 1967.]
Demchinskii, F. A. Proizvodstvo sakhara-rafinada, 2nd ed. Moscow, 1974.
P. IA. IVANOV
What does it mean when you dream about sugar?
Dreaming about sugar could reflect a sense that life is sweet or a wish that life could be sweeter. Sugar is also a symbol of love, as when some refers to their love interest as “Sugar.” Sugar can also be slang for everything from a kiss to cocaine.
OLPC(One Laptop per Child, Cambridge, MA, www.laptop.org) A research initiative of MIT Media Labs devoted to the creation of a USD $100 PC for educating children in developing countries around the world. Founded in 2005 by Nicholas Negroponte, OLPC laptops are geared to the educational ministries of governments that can purchase thousands of units at a time.
Taiwan-based Quanta Computer was selected as the original design manufacturer (ODM), and manufacturing began in late 2007. Although USD $100 was the target, a manufacturing cost of about $190 was announced for the first run of 300,000 units, a smaller order than anticipated.
Although orders for millions of OLPCs were expected by 2007, Intel persuaded several countries to use its own low-cost PC (see Classmate). Negroponte admonished Intel for interfering with his non-profit venture to help the poor. Soon after, Intel joined OLPC's board to help design future products but withdrew in 2008. For details about OLPC models, see XO computer.
|The OLPC Laptop|
|The laptop was designed to help stimulate and educate millions of kids in countries that would not otherwise have access to computers. (Image courtesy of the One Laptop Per Child Association, www.laptop.org)|
|An XO Machine Running Sugar|
|Since the OLPC's logo is an abstract person (X for the body; O for the head), the OLPC is called the "XO" computer. Its graphical interface is "Sugar," which boots up with icons of friends and activities. See XO computer. (Image courtesy of One Laptop Per Child Association, www.laptop.org)|