Sucrose is common table sugar. It is a disaccharide, a molecule composed of two monosaccharides: glucose and fructose. Sucrose is produced naturally in plants, from which table sugar is refined. It has the formulaC12H22O11.
For human consumption, sucrose is extracted, and refined, from either sugar cane or sugar beet. Sugar mills are located where sugar cane is grown to crush the cane and produce raw sugar which is shipped around the world for refining into pure sucrose. Some sugar mills also process the raw sugar into pure sucrose. Sugar beet factories are located in colder climates where the beet is grown and process the beets directly into refined sugar. The sugar refining process involves washing the raw sugar crystals before dissolving them into a sugar syrup which is filtered and then passed over carbon to remove any residual colour. The by-now clear sugar syrup is then concentrated by boiling under a vacuum and crystallized as the final purification process to produce crystals of pure sucrose. These crystals are clear, odourless, and have a sweet taste. En masse, the crystals appear white.
Sugar is often an added ingredient in food production and food recipes. About 175 million tonnes of sugar were produced worldwide in 2013.
The word "sucrose" was coined in 1857 by the English chemist William Miller from the French sucre ("sugar") and the generic chemical suffix for sugars -ose. The abbreviated term Suc is often used for sucrose in scientific literature.
Saccharose is an obsolete name for sugars in general, especially sucrose. The name "saccharose" was coined in 1860 by the French chemist Marcellin Berthelot.
Physical and chemical properties
In sucrose, the components glucose and fructose are linked via an ether bond between C1 on the glucosyl subunit and C2 on the fructosyl unit. The bond is called a glycosidic linkage. Glucose exists predominantly as two isomeric "pyranoses" (? and ?), but only one of these forms links to the fructose. Fructose itself exists as a mixture of "furanoses", each of which having ? and ? isomers, but only one particular isomer links to the glucosyl unit. What is notable about sucrose is that, unlike most disaccharides, the glycosidic bond is formed between the reducing ends of both glucose and fructose, and not between the reducing end of one and the nonreducing end of the other. This linkage inhibits further bonding to other saccharide units. Since it contains no anomeric hydroxyl groups, it is classified as a non-reducing sugar.
Sucrose crystallizes in the monoclinic space group P21 with room-temperature lattice parameters a = 1.08631 nm, b = 0.87044 nm, c = 0.77624 nm, ? = 102.938°.
The purity of sucrose is measured by polarimetry, through the rotation of plane-polarized light by a solution of sugar. The specific rotation at 20 °C using yellow "sodium-D" light (589 nm) is +66.47°. Commercial samples of sugar are assayed using this parameter. Sucrose does not deteriorate at ambient conditions.
Thermal and oxidative degradation
Solubility of sucrose in water vs. temperature
Sucrose does not melt at high temperatures. Instead, it decomposes at 186 °C (367 °F) to form caramel. Like other carbohydrates, it combusts to carbon dioxide and water. Mixing sucrose with the oxidizer potassium nitrateproduces the fuel known as rocket candy that is used to propel amateur rocket motors.
- C12H22O11 + 6 KNO3 ? 9 CO + 3 N2 + 11 H2O + 3 K2CO3
This reaction is somewhat simplified though. Some of the carbon does get fully oxidized to carbon dioxide, and other reactions, such as the water-gas shift reaction also take place. A more accurate theoretical equation is:
- C12H22O11 + 6.288 KNO3 ? 3.796 CO2 + 5.205 CO + 7.794 H2O + 3.065 H2 + 3.143 N2 + 2.998 K2CO3 + 0.274 KOH 
Sucrose burns with chloric acid, formed by the reaction of hydrochloric acid and potassium chlorate:
- 8 HClO3 + C12H22O11 ? 11 H2O + 12 CO2 + 8 HCl
Sucrose can be dehydrated with sulfuric acid to form a black, carbon-rich solid, as indicated in the following idealized equation:
- H2SO4(catalyst) + C12H22O11 ? 12 C + 11 H2O + Heat (and some H2O + SO3 as a result of the heat).
The formula for sucrose's decomposition can be represented as 2 step reaction, first simplified reaction is dehydration of sucrose to pure Carbon and water then carbon oxidises to CO2 with O2 from air.
- C12H22O11 + heat ? 12 C + 11 H2O
- 12 C + 12 O2 ? 12 CO2
Hydrolysis breaks the glycosidic bond converting sucrose into glucose and fructose. Hydrolysis is, however, so slow that solutions of sucrose can sit for years with negligible change. If the enzyme sucrase is added, however, the reaction will proceed rapidly. Hydrolysis can also be accelerated with acids, such as cream of tartar or lemon juice, both weak acids. Likewise, gastric acidity converts sucrose to glucose and fructose during digestion, the bond between them being an acetal bond which can be broken by an acid.
Given (higher) heats of combustion of 1349.6 kcal/mol for sucrose, 673.0 for glucose, and 675.6 for fructose, hydrolysis releases about 1.0 kcal (4.2 kJ) per mole of sucrose, or about 3 small calories per gram of product.
Synthesis and biosynthesis of sucrose
The biosynthesis of sucrose proceeds via the precursors UDP-glucose and fructose 6-phosphate, catalyzed by the enzyme sucrose-6-phosphate synthase. The energy for the reaction is gained by the cleavage of uridine diphosphate (UDP). Sucrose is formed by plants and cyanobacteria but not by other organisms. Sucrose is found naturally in many food plants along with the monosaccharide fructose. In many fruits, such as pineapple and apricot, sucrose is the main sugar. In others, such as grapesand pears, fructose is the main sugar.
Model of sucrose molecule
Although sucrose is almost invariably isolated from natural sources, its chemical synthesis was first achieved in 1953 by Raymond Lemieux.
In nature, sucrose is present in many plants, and in particular their roots, fruits and nectars, because it serves as a way to store energy, primarily from photosynthesis. Many mammals, birds, insects and bacteria accumulate and feed on the sucrose in plants and for some it is their main food source. Seen from a human consumption perspective, honeybees are especially important because they accumulate sucrose and produce honey, an important foodstuff all over the world. The carbohydrates in honey itself primarily consists of fructose and glucose with trace amounts of sucrose only.
As fruits ripen, their sucrose content usually rise sharply, but some fruits contain almost no sucrose at all. This includes grapes, cherries, blueberries, blackberries, figs, pomegranates, tomatoes, avocados, lemons and limes.
Sucrose is a naturally occurring sugar, but with the advent of industrialization, it has been increasingly refined and consumed in all kinds of processed foods.
History of sucrose refinement
Table sugar production in the 19th century. Sugar cane
plantations (upper image) employed slave or indentured laborers. The picture shows workers harvesting cane, loading it on a boat for transport to the plant, while a European overseer watches in the lower right. The lower image shows a sugar plant with two furnace chimneys. Sugar plants and plantations were harsh, inhumane work.
was a traditional form for sugar from the 17th to 19th centuries. Sugar nips
were required to break off pieces.
The production of table sugar has a long history. Some scholars claim Indians discovered how to crystallize sugar during the Gupta dynasty, around AD 350.
Other scholars point to the ancient manuscripts of China, dated to the 8th century BC, where one of the earliest historical mentions of sugar cane is included along with the fact that their knowledge of sugar cane was derived from India. Further, it appears that by about 500 BC, residents of present-day India began making sugar syrup and cooling it in large flat bowls to make raw table sugar crystals that were easier to store and transport. In the local Indian language, these crystals were called khanda (????), which is the source of the word candy.
The army of Alexander the Great was halted on the banks of river Indus by the refusal of his troops to go further east. They saw people in the Indian subcontinent growing sugarcane and making granulated, salt-like sweet powder, locally called s?khar (????), pronounced as sakcharon (????????) in Greek (Modern Greek, zachari ??????). On their return journey, the Greek soldiers carried back some of the "honey-bearing reeds". Sugarcane remained a limited crop for over a millennium. Sugar was a rare commodity and traders of sugar became wealthy. Venice, at the height of its financial power, was the chief sugar-distributing center of Europe. Arabs started producing it in Sicily and Spain. Only after the Crusades did it begin to rival honey as a sweetener in Europe. The Spanish began cultivating sugarcane in the West Indies in 1506 (Cuba in 1523). The Portuguese first cultivated sugarcane in Brazil in 1532.
Sugar remained a luxury in much of the world until the 18th century. Only the wealthy could afford it. In the 18th century, the demand for table sugar boomed in Europe and by the 19th century it had become regarded as a human necessity. The use of sugar grew from use in tea, to cakes, confectionery and chocolates. Suppliers marketed sugar in novel forms, such as solid cones, which required consumers to use a sugar nip, a pliers-like tool, in order to break off pieces.
The demand for cheaper table sugar drove, in part, colonization of tropical islands and nations where labor-intensive sugarcane plantations and table sugar manufacturing could thrive. Growing sugar cane crop in hot humid climates, and producing table sugar in high temperature sugar mills was harsh, inhumane work. The demand for cheap and docile labor for this work, in part, first drove slave trade from Africa (in particular West Africa), followed by indentured labor trade from South Asia (in particular India). Millions of slaves, followed by millions of indentured laborers were brought into the Caribbean, Indian Ocean, Pacific Islands, East Africa, Natal, north and eastern parts of South America, and southeast Asia. The modern ethnic mix of many nations, settled in the last two centuries, has been influenced by table sugar.
Beginning in the late 18th century, the production of sugar became increasingly mechanized. The steam engine first powered a sugar mill in Jamaica in 1768, and, soon after, steam replaced direct firing as the source of process heat. During the same century, Europeans began experimenting with sugar production from other crops. Andreas Marggraf identified sucrose in beet root and his student Franz Achard built a sugar beet processing factory in Silesia (Prussia). However, the beet-sugar industry really took off during the Napoleonic Wars, when France and the continent were cut off from Caribbean sugar. In 2010, about 20 percent of the world's sugar was produced from beets.
Today, a large beet refinery producing around 1,500 tonnes