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For the common table sugar, see sucrose.

Magnification of grains of sugar, showing their monoclinic hemihedral crystalline structure.

Magnified crystals of refined sugar.

Sugar is a class of edible crystalline substances, mainly sucrose, lactose, and fructose. Human taste buds interpret its flavor as sweet. Sugar as a basic food carbohydrate primarily comes from sugar cane and from sugar beet, but also appears in fruit, honey, sorghum, sugar maple (in maple syrup), and in many other sources. It forms the main ingredient in candy. Excessive consumption of sugar has been associated with increased incidences of type 2 diabetes, obesity and tooth decay.^[1] Sugar consumption varies by country depending on the cultural traditions. Brazil has the highest per capita consumption and India has the highest per-country consumption.^[2]

Terminology

Popular

In non-scientific use, the term sugar refers to sucrose (also called "table sugar" or "saccharose") — a white crystalline solid disaccharide. In this informal sense, the word "sugar" principally refers to crystalline sugars.

Humans most commonly use sucrose as their sugar of choice for altering the flavor and properties (such as mouthfeel, preservation, and texture) of beverages and food. Commercially produced table sugar comes either from sugar cane or from sugar beet. Manufacturing and preparing food may involve other sugars, including palm sugar and fructose, generally obtained from corn (maize) or from fruit.

Sugar may dissolve in water to form a syrup. A great many foods exist which principally contain dissolved sugar. Generically known as "syrups", they may also have other more specific names such as "honey", molasses or treacle.

Scientific

Scientifically, sugar refers to any monosaccharide or disaccharide. Monosaccharides (also called "simple sugars"), such as glucose, store chemical energy which biological cells convert to other types of energy.

In a list of ingredients, any word that ends with "-ose" (such as "glucose", "dextrose", "fructose", etc.) will likely denote a sugar. Sometimes such words may also refer to any types of carbohydrates soluble in water.

Glucose (a type of sugar found in human blood plasma) has the molecular formula C₆ H₁₂ O₆.

Culinary/nutritional

In culinary terms, the foodstuff known as sugar delivers a primary taste sensation of sweetness. Apart from the many forms of sugar and of sugar-containing foodstuffs, alternative non-sugar-based sweeteners exist, and these particularly attract interest from people who have problems with their blood sugar level (such as diabetics) and people who wish to limit their calorie-intake while still enjoying sweet foods. Both natural and synthetic substitutes exist with no significant carbohydrate (and thus low-calorie) content: for instance stevia (a herb), and saccharin (produced from naturally occurring but not necessarily naturally edible substances by inducing appropriate chemical reactions).

ant feeding on sugar crystals

Etymology

In the case of sugar, the etymology reflects the spread of the commodity. The English word "sugar" originates from the Arabic and Persian word shakar,^[3] itself derived from Sanskrit Sharkara.^[4] It came to English by way of French, Spanish and/or Italian, which derived their word for sugar from the Arabic and Persian shakar (whence the Portuguese word açúcar, the Spanish word azúcar, the Italian word zucchero, the Old French word zuchre and the contemporary French word sucre). (Compare the OED.) The Greek word for "sugar", zahari, means "pebble". Note that the English word jaggery (meaning "coarse brown Indian sugar") has similar ultimate etymological origins (presumably in Sanskrit).

Culinary sugars

Grainier, raw sugar.

The World Health Organisation and the Food and Agriculture Organization of the United Nations expert report (WHO Technical Report Series 916 Diet, Nutrition and the Prevention of Chronic Diseases)^{[citation needed]} defines free sugars as all monosaccharides and disaccharides added to foods by the manufacturer, cook or consumer, plus sugars naturally present in honey, syrups and fruit juices. This includes all the sugars referred to above. The term distinguishes these forms from all other culinary sugars added in their natural form with no refining at all.

Natural sugars comprise all completely unrefined sugars: effectively all sugars not defined as free sugars. The WHO Technical Report Series 916 Diet, Nutrition and the Prevention of Chronic Diseases^{[citation needed]} approves only natural sugars as carbohydrates for unrestricted consumption. Natural sugars come in fruit, grains and vegetables in their natural or cooked form.

Chemistry

Sucrose: a disaccharide of glucose (left) and fructose (right), important molecules in the body.

Biochemists regard sugars as relatively simple carbohydrates. Sugars include monosaccharides, disaccharides, trisaccharides and the oligosaccharides - containing 1, 2, 3, and 4 or more monosaccharide units respectively. Sugars contain either aldehyde groups (-CHO) or ketone groups (C=O), where there are carbon-oxygen double bonds, making the sugars reactive. Most simple sugars (monosaccharides) conform to (CH₂O)_n where n is between 3 and 7. A notable exception, deoxyribose, as its name suggests, has a "missing" oxygen atom. All saccharides with more than one ring in their structure result from two or more monosaccharides joined by glycosidic bonds with the resultant loss of a molecule of water (H₂O) per bond. Sugars can also be used as monomers to create biopolymers such as cellulose, which is made of glucose, or DNA, which uses deoxyribose as a backbone.

As well as using classifications based on their reactive group, chemists may also subdivide sugars according to the number of carbons they contain. Derivatives of trioses (C₃H₆O₃) are intermediates in glycolysis. Pentoses (5-carbon sugars) include ribose and deoxyribose, which form part of nucleic acids. Ribose also forms a component of several chemicals that have importance in the metabolic process, including NADH and ATP. Hexoses (6-carbon sugars) include glucose, a universal substrate for the production of energy in the form of ATP. Through photosynthesis plants produce glucose, which has the formula C₆H₁₂O₆, and convert it for storage as an energy reserve in the form of other carbohydrates such as starch, or (as in cane and beet) as sucrose (table sugar). Sucrose has the chemical formula C₁₂H₂₂O₁₁.

Many pentoses and hexoses can form ring structures. In these closed-chain forms, the aldehyde or ketone group remains unfree, so many of the reactions typical of these groups cannot occur. Glucose in solution exists mostly in the ring form at equilibrium, with less than 0.1% of the molecules in the open-chain form.

Monosaccharides in a closed-chain form can form glycosidic bonds with other monosaccharides, creating disaccharides (such as sucrose) and polysaccharides (such as starch). Enzymes must hydrolyse or otherwise break these glycosidic bonds before such compounds become metabolised. After digestion and absorption. the principal monosaccharides present in the blood and internal tissues include glucose, fructose, and galactose.

The prefix "glyco-" indicates the presence of a sugar in an otherwise non-carbohydrate substance. Note for example glycoproteins, proteins connected to one or more sugars.

Monosaccharides include fructose, glucose, galactose and mannose. Disaccharides occur most commonly as sucrose (cane or beet sugar - made from one glucose and one fructose), lactose (milk sugar - made from one glucose and one galactose) and maltose (made of two glucoses). These disaccharides have the formula C₁₂H₂₂O₁₁.

Hydrolysis can convert sucrose into a syrup of fructose and glucose, producing invert sugar. This resulting syrup, sweeter than the original sucrose,^[5] has uses in making confections because it does not crystallize as easily and thus produces a smoother finished product.

If combined with fine ash, sugar will burn with a blue flame.

Measuring sugar

See also International Commission for Uniform Methods of Sugar Analysis The purity (sucrose content) of table sugar by polarimetry — the measurement of the rotation of plane-polarized light by a solution of sugar.

Baking weight/mass volume relationship

Different culinary sugars have different densities due to differences in particle size and inclusion of moisture.

The Domino Sugar Company has established the following volume to weight conversions:

• Brown sugar 1 cup = 48 teaspoons ~ 195 g = 6.88 oz
• Granular sugar 1 cup = 48 teaspoons ~ 200 g = 7.06 oz
• Powdered sugar 1 cup = 48 teaspoons ~ 120 g = 4.23 oz

Bulk Density^[6]

• Dextrose Sugar 0.62 g/ml
• Granulated Sugar 0.70 g/ml
• Powdered Sugar 0.56 g/ml
• Beet Sugar 0.80 g/ml

See also

Wikimedia Commons has media related to: Sugars

Notes

References

• Adas, Michael (January 2001). Agricultural and Pastoral Societies in Ancient and Classical History. Temple University Press. ISBN 1566398320. OCLC 44493265. 
• James, Glyn (2004). Sugarcane. Blackwell Publishing. ISBN 063205476X. OCLC 51837990 84251137. 
• A C Hannah, The International Sugar Trade, Cambridge: Woodhead, 1996. ISBN 1-85573-069-3
• William Dufty, Sugar Blues, ISBN 0-446-34312-9

External links

• Cook's Thesaurus: Sugar
• sugar at the Open Directory Project
• Density of Sugar Factory Products