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.
[Wuebben, Joseph and Mike Carlson. "Sugar: What Kinds to Eat and When." http://men.webmd.com/features/sugar-what-kinds-eat-when] 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.
[International sugar statistics http://www.illovosugar.com/World_of_sugar/Sugar_Statistics/International.aspx]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 formulaC
6 H
12 O
6.
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).
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,
itself derived from
Sanskrit Sharkara.
[Ahmad Y Hassan, , History of Science and Technology in Islam.] 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) 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 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 (CH
2O)
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 (H
2O) 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 (C
3H
6O
3) 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 C
6H
12O
6, 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 C
12H
22O
11.
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 C
12H
22O
11.
Hydrolysis can convert sucrose into a syrup of fructose and glucose, producing
invert sugar. This resulting syrup, sweeter than the original sucrose, 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
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
- Granulated Sugar 0.70 g/ml
See also