Sucrose

Sucrose, adisaccharide, is asugarcomposed ofglucoseandfructosesubunits. It is produced naturally in plants and is the main constituent ofwhite sugar. It has themolecular formulaC12H22O11.
For human consumption, sucrose is extracted and refined from eithersugarcaneorsugar beet.Sugar mills– typically located intropical regionsnear where sugarcane is grown – crush the cane and produce raw sugar which is shipped to other factories for refining into pure sucrose. Sugar beet factories are located intemperate climateswhere the beet is grown, and process the beets directly into refined sugar. Thesugar-refiningprocess 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 sugar syrup is then concentrated by boiling under a vacuum and crystallized as the final purification process to produce crystals of pure sucrose that are clear, odorless, and sweet.
Sugar is often anaddedingredient in food production and recipes. About 185 milliontonnesof sugar were produced worldwide in 2017.
Sucrose is particularly dangerous as a risk factor fortooth decaybecauseStreptococcus mutansbacteria convert it into a sticky, extracellular,dextran-basedpolysaccharidethat allows them to cohere, formingplaque. Sucrose is the only sugar that bacteria can use to form this sticky polysaccharide.
The wordsucrosewas coined in 1857, by the English chemistWilliam Millerfrom theFrenchsucre("sugar") and the generic chemical suffix for sugars-ose. The abbreviated termSucis often used forsucrosein scientific literature.
The namesaccharosewas coined in 1860 by the French chemistMarcellin Berthelot.Saccharose is an obsolete name for sugars in general, especially sucrose.
In sucrose, themonomersglucose and fructose are linked via an ether bond between C1 on theglucosylsubunit and C2 on thefructosylunit. The bond is called aglycosidic linkage. Glucose exists predominantly as a mixture of α and β "pyranose"anomers, but sucrose has only the α form. Fructose exists as a mixture of fivetautomersbut sucrose has only the β-D-fructofuranose form. Unlike mostdisaccharides, the glycosidic bond in sucrose is formed between the reducing ends of both glucose and fructose, and not between the reducing end of one and the non-reducing end of the other. This linkage inhibits further bonding to other saccharide units, and prevents sucrose from spontaneously reacting with cellular and circulatory macromolecules in the manner that glucose and other reducing sugars do. Since sucrose contains no anomeric hydroxyl groups, it is classified as a non-reducing sugar.
Sucrose crystallizes in themonoclinicspace groupP21with room-temperature lattice parametersa= 1.08631 nm,b= 0.87044 nm,c= 0.77624 nm, β = 102.938°.
The purity of sucrose is measured bypolarimetry, through the rotation ofplane-polarized lightby a sugar solution. Thespecific rotationat 20 °C (68 °F) 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.
Sucrose does not melt at high temperatures. Instead, it decomposes at 186 °C (367 °F) to formcaramel. Like othercarbohydrates, it combusts tocarbon dioxideand water by the simplified equation:
C12H22O11+ 12 O2→ 12 CO2+ 11 H2O
Mixing sucrose with the oxidizerpotassium nitrateproduces the fuel known asrocket candythat 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 thewater-gas shift reactionalso 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+ 2.988 K2CO3+ 0.274 KOH
Sucrose burns withchloric acid, formed by the reaction ofhydrochloric acidandpotassium chlorate:
8 HClO3+ C12H22O11→  11 H2O + 12 CO2+ 8 HCl
Sucrose can be dehydrated withsulfuric acidto form a black,carbon-rich solid, as indicated in the following idealized equation:
H2SO4(catalyst) + C12H22O11→  12 C + 11 H2O + heat (and some H2O + SO3as a result of the heat).
The formula for sucrose's decomposition can be represented as a two-step reaction: the first simplified reaction is dehydration of sucrose to pure carbon and water, and then carbon is oxidised toCO2byO2from air.
C12H22O11+ heat  →  12 C + 11 H2O
12 C + 12 O2→  12 CO2
Hydrolysisbreaks the glycosidic bond converting sucrose intoglucoseandfructose. Hydrolysis is, however, so slow that solutions of sucrose can sit for years with negligible change. If theenzymesucraseis added, however, the reaction will proceed rapidly.Hydrolysis can also be accelerated with acids, such ascream of tartaror 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 combustionof 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 3small caloriesper gram of product.
Thebiosynthesisof sucrose proceeds via the precursorsUDP-glucoseandfructose 6-phosphate, catalyzed by the enzymesucrose-6-phosphate synthase. The energy for the reaction is gained by the cleavage ofuridine diphosphate(UDP).
Sucrose is formed by plants,algaeandcyanobacteriabut not by otherorganisms. Sucrose is the end product ofphotosynthesisand is found naturally in many food plants along with themonosaccharidefructose. In many fruits, such aspineappleandapricot, sucrose is the main sugar. In others, such asgrapesandpears, fructose is the main sugar.
After numerous unsuccessful attempts by others,Raymond Lemieuxand George Huber succeeded in synthesizing sucrose fromacetylatedglucose and fructose in 1953.
In nature, sucrose is present in many plants, and in particular their roots, fruits andnectars, because it serves as a way to store energy, primarily fromphotosynthesis.Many mammals, birds, insects and bacteria accumulate and feed on the sucrose in plants and for some it is their main food source. Althoughhoneybeesconsume sucrose, thehoneythey produce consists primarily of fructose and glucose, with only trace amounts of sucrose.
As fruits ripen, their sucrose content usually rises 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 ofindustrialization, it has been increasingly refined and consumed in all kinds of processed foods.
The production of table sugar has a long history. Some scholars claim Indians discovered how to crystallize sugar during theGupta dynasty, around CE 350.
Other scholars point to the ancient manuscripts of China, dated to the 8th century BCE, where one of the earliest historical mentions ofsugar caneis included along with the fact that their knowledge of sugar cane was derived fromIndia.By about 500 BCE, residents of modern-day India began making sugar syrup, cooling it in large flat bowls to produce raw sugar crystals that were easier to store and transport. In the local Indian language, these crystals were calledkhanda(खण्ड), which is the source of the wordcandy.
The army ofAlexander the Greatwas halted on the banks of riverIndusby 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 calledsākhar(साखर), (شکر), pronounced assakcharon(ζακχαρον) in Greek (Modern Greek,zachari,ζάχαρη). 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 ofEurope.Moors started producing it inSicilyandSpain. Only after theCrusadesdid it begin to rival honey as a sweetener in Europe. The Spanish began cultivating sugarcane in theWest Indiesin 1506 (Cubain 1523). ThePortuguesefirst cultivated sugarcane inBrazilin 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, tocakes,confectioneryandchocolates. Suppliers marketed sugar in novel forms, such as solid cones, which required consumers to use asugar 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 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. Thesteam enginefirst powered a sugar mill inJamaicain 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 Marggrafidentified sucrose inbeet rootand his studentFranz Achardbuilt a sugar beet processing factory in Silesia (Prussia). The beet-sugar industry took off during theNapoleonic Wars, when France and the continent were cut off from Caribbean sugar. In 2009, about 20 percent of the world's sugar was produced from beets.
Today, a large beet refinery producing around 1,500 tonnes of sugar a day needs a permanent workforce of about 150 for 24-hour production.
Table sugar (sucrose) comes from plant sources. Two important sugar crops predominate:sugarcane(Saccharum spp.) andsugar beets(Beta vulgaris), in which sugar can account for 12% to 20% of the plant's dry weight. Minor commercial sugar crops include thedate palm(Phoenix dactylifera),sorghum(Sorghum vulgare), and thesugar maple(Acer saccharum). Sucrose is obtained by extraction of these crops with hot water; concentration of the extract gives syrups, from which solid sucrose can be crystallized. In 2017, worldwide production of table sugar amounted to 185 million tonnes.
Most cane sugar comes from countries with warm climates, because sugarcane does not tolerate frost. Sugar beets, on the other hand, grow only in cooler temperate regions and do not tolerateextreme heat. About 80 percent of sucrose is derived from sugarcane, the rest almost all from sugar beets.
In mid-2018, India and Brazil had about the same production of sugar – 34 million tonnes – followed by theEuropean Union,Thailand, and China as the major producers.India, the European Union, and China were the leading domestic consumers of sugar in 2018.
Beet sugar comes from regions with cooler climates: northwest and eastern Europe, northern Japan, plus some areas in the United States (including California). In the northern hemisphere, the beet-growing season ends with the start of harvesting around September. Harvesting and processing continues until March in some cases. The availability of processing plant capacity and the weather both influence the duration of harvesting and processing – the industry can store harvested beets until processed, but a frost-damaged beet becomes effectively unprocessable.
The United States sets high sugar prices to support its producers, with the effect that many former purchasers of sugar have switched tocorn syrup(beverage manufacturers) or moved out of the country (candy manufacturers).
The low prices ofglucose syrupsproduced fromwheatand corn (maize) threaten the traditional sugar market. Used in combination withartificial sweeteners, they can allow drink manufacturers to produce very low-cost goods.
Since the 6th century BCE, cane sugar producers have crushed the harvested vegetable material from sugarcane in order to collect and filter the juice. They then treat the liquid, often with lime (calcium oxide), to remove impurities and then neutralize it. Boiling the juice then allows the sediment to settle to the bottom for dredging out, while the scum rises to the surface for skimming off. In cooling, the liquid crystallizes, usually in the process of stirring, to produce sugar crystals.Centrifugesusually remove the uncrystallized syrup. The producers can then either sell the sugar product for use as is, or process it further to produce lighter grades. The later processing may take place in another factory in another country.
Sugarcane is a major component of Brazilian agriculture; the country is the world's largest producer of sugarcane and its derivative products, such as crystallized sugar andethanol(ethanol fuel).
Beet sugar producers slice the washed beets, then extract the sugar with hot water in a "diffuser". An alkaline solution ("milk of lime" andcarbon dioxidefrom the lime kiln) then serves toprecipitateimpurities (seecarbonatation). After filtration,evaporation concentrates the juice to a content of about 70% solids, and controlled crystallisation extracts the sugar. A centrifuge removes the sugar crystals from the liquid, which gets recycled in the crystalliser stages. When economic constraints prevent the removal of more sugar, the manufacturer discards the remaining liquid, now known asmolasses, or sells it on to producers of animal feed.
Sieving the resultant white sugar produces different grades for selling.
It is difficult to distinguish between fully refined sugar produced from beet and cane. One way is byisotope analysisof carbon. Cane usesC4 carbon fixation, and beet usesC3 carbon fixation, resulting in a different ratio ofCandCisotopes in the sucrose. Tests are used to detect fraudulent abuse ofEuropean Unionsubsidies or to aid in the detection of adulteratedfruit juice.
Sugar cane tolerates hot climates better, but the production of sugar cane needs approximately four times as much water as the production of sugar beet. As a result, some countries that traditionally produced cane sugar (such asEgypt) have built new beet sugar factories since about 2008. Some sugar factories process both sugar cane and sugar beets and extend their processing period in that way.
The production of sugar leaves residues that differ substantially depending on the raw materials used and on the place of production. While cane molasses is often used in food preparation, humans find molasses from sugar beets unpalatable, and it consequently ends up mostly asindustrial fermentationfeedstock (for example inalcoholdistilleries), or asanimal feed. Once dried, either type of molasses can serve as fuel for burning.
Pure beet sugar is difficult to find, so labelled, in the marketplace. Although some makers label their product clearly as "pure cane sugar", beet sugar is almost always labeled simply as sugar or pure sugar. Interviews with the five major beet sugar-producing companies revealed that many store brands or "private label" sugar products are pure beet sugar. The lot code can be used to identify the company and the plant from which the sugar came, enabling beet sugar to be identified if the codes are known.
Mill white, also called plantation white, crystal sugar or superior sugar is produced from raw sugar. It is exposed tosulfur dioxideduring the production to reduce the concentration of color compounds and helps prevent further color development during the crystallization process. Although common to sugarcane-growing areas, this product does not store or ship well. After a few weeks, its impurities tend to promote discoloration and clumping; therefore this type of sugar is generally limited to local consumption.
Blanco directo, a white sugar common in India and other south Asian countries, is produced by precipitating many impurities out of cane juice usingphosphoric acidandcalcium hydroxide, similar to thecarbonatationtechnique used in beet sugar refining. Blanco directo is more pure than mill white sugar, but less pure than white refined.
White refined is the most common form of sugar in North America and Europe. Refined sugar is made by dissolving and purifying raw sugar usingphosphoric acidsimilar to the method used for blanco directo, acarbonatationprocess involving calcium hydroxide and carbon dioxide, or by various filtration strategies. It is then further purified by filtration through a bed ofactivated carbonorbone char. Beet sugar refineries produce refined white sugar directly without an intermediate raw stage.
White refined sugar is typically sold asgranulated sugar, which has been dried to prevent clumping and comes in various crystal sizes for home and industrial use:
Brown sugarcomes either from the late stages of cane sugar refining, when sugar forms fine crystals with significant molasses content, or from coating white refined sugar with a cane molasses syrup (blackstrap molasses). Brown sugar's color and taste become stronger with increasing molasses content, as do its moisture-retaining properties. Brown sugars also tend to harden if exposed to the atmosphere, although proper handling can reverse this.
Scientists and thesugar industryuse degreesBrix(symbol °Bx), introduced byAdolf Brix, as units of measurement of the mass ratio of dissolved substance to water in a liquid. A 25 °Bx sucrose solution has 25 grams of sucrose per 100 grams of liquid; or, to put it another way, 25 grams of sucrose sugar and 75 grams of water exist in the 100 grams of solution.
The Brix degrees are measured using an infrared sensor. This measurement does not equate to Brix degrees from a density or refractive index measurement, because it will specifically measure dissolved sugar concentration instead of all dissolved solids. When using a refractometer, one should report the result as "refractometric dried substance" (RDS). One might speak of a liquid as having 20 °Bx RDS. This refers to a measure of percent by weight oftotaldried solids and, although not technically the same as Brix degrees determined through an infrared method, renders an accurate measurement of sucrose content, since sucrose in fact forms the majority of dried solids. The advent of in-line infrared Brix measurement sensors has made measuring the amount of dissolved sugar in products economical using a direct measurement.
Refined sugar was a luxury before the 18th century. It became widely popular in the 18th century, then graduated to becoming a necessary food in the 19th century. This evolution of taste and demand for sugar as an essential food ingredient unleashed major economic and social changes.Eventually, table sugar became sufficiently cheap and common enough to influence standard cuisine and flavored drinks.
Sucrose forms a major element inconfectioneryanddesserts. Cooks use it for sweetening. It can also act as afood preservativewhen used in sufficient concentrations, and thus is an important ingredient in the production offruit preserves. Sucrose is important to the structure of many foods, including biscuits and cookies, cakes and pies, candy, and ice cream and sorbets. It is a common ingredient in many processed and so-called "junk foods".
Fully refined sugar is 99.9% sucrose, thus providing only carbohydrate as dietarynutrientand 390kilocaloriesper 100 g serving (table).There are nomicronutrientsof significance in fully refined sugar (table).
In humans and other mammals, sucrose is broken down into its constituent monosaccharides, glucose and fructose, bysucraseorisomaltaseglycoside hydrolases, which are located in themembraneof themicrovillilining theduodenum.The resulting glucose and fructose molecules are then rapidly absorbed into the bloodstream. Inbacteriaand some animals, sucrose is digested by the enzymeinvertase. Sucrose is an easily assimilatedmacronutrientthat provides a quick source of energy, provoking a rapid rise inblood glucoseupon ingestion. Sucrose, as a pure carbohydrate, has an energy content of 3.94kilocaloriesper gram (or 17kilojoulesper gram).
If consumed excessively, sucrose may contribute to the development ofmetabolic syndrome, including increased risk fortype 2 diabetes, insulin resistance, weight gain andobesityin adults and children.
Tooth decay(dental caries) has become a pronounced health hazard associated with the consumption of sugars, especially sucrose. Oral bacteria such asStreptococcus mutanslive indental plaqueand metabolizeanyfree sugars (not just sucrose, but also glucose,lactose, fructose, and cookedstarches)intolactic acid. The resultant lactic acid lowers the pH of the tooth's surface, stripping it of minerals in the process known as tooth decay.
All 6-carbon sugars and disaccharides based on 6-carbon sugars can be converted by dental plaque bacteria into acid that demineralizes teeth, but sucrose may be uniquely useful toStreptococcus sanguinis(formerlyStreptococcus sanguis) andStreptococcus mutans.Sucrose is the only dietary sugar that can be converted to sticky glucans (dextran-like polysaccharides) by extracellular enzymes.These glucans allow the bacteria to adhere to the tooth surface and to build up thick layers of plaque. The anaerobic conditions deep in the plaque encourage the formation of acids, which leads to carious lesions. Thus, sucrose could enableS. mutans,S. sanguinisand many other species of bacteria to adhere strongly and resist natural removal, e.g. by flow of saliva, although they are easily removed by brushing. The glucans and levans (fructose polysaccharides) produced by the plaque bacteria also act as a reserve food supply for the bacteria.
Such a special role of sucrose in the formation of tooth decay is much more significant in light of the almost universal use of sucrose as the most desirable sweetening agent. Widespread replacement of sucrose by high-fructose corn syrup (HFCS) has not diminished the danger from sucrose. If smaller amounts of sucrose are present in the diet, they will still be sufficient for the development of thick, anaerobic plaque and plaque bacteria will metabolise other sugars in the diet,such as the glucose and fructose in HFCS.
Sucrose is a disaccharide made up of 50% glucose and 50% fructose and has aglycemic indexof 65.Sucrose is digested rapidly,but has a relatively low glycemic index due to its content of fructose, which has a minimal effect on blood glucose.
As with other sugars, sucrose is digested into its components via the enzymesucraseto glucose (blood sugar). The glucose component is transported into the blood where it serves immediate metabolic demands, or is converted and reserved in theliverasglycogen.
The occurrence ofgoutis connected with an excess production of uric acid. A diet rich in sucrose may lead to gout as it raises the level of insulin, which prevents excretion of uric acid from the body. As the concentration of uric acid in the body increases, so does the concentration of uric acid in the joint liquid and beyond a critical concentration, the uric acid begins to precipitate into crystals. Researchers have implicated sugary drinks high in fructose in a surge in cases of gout.
In 2015, theWorld Health Organizationpublished a new guideline on sugars intake for adults and children, as a result of an extensive review of the available scientific evidence by a multidisciplinary group of experts. The guideline recommends that both adults and children ensure their intake of free sugars (monosaccharides and disaccharides added to foods and beverages by the manufacturer, cook or consumer, and sugars naturally present in honey, syrups, fruit juices and fruit juice concentrates) is less than 10% of total energy intake. A level below 5% of total energy intake brings additional health benefits, especially with regards to dental caries.
The sugar refining industry often uses bone char (calcinatedanimal bones) for decolorizing.About 25% of sugar produced in the U.S. is processed using bone char as a filter, the remainder being processed withactivated carbon. As bone char does not seem to remain in finished sugar, Jewish religious leaders consider sugar filtered through it to bepareve, meaning that it is neither meat nor dairy and may be used with either type of food. However, the bone char must source to a kosher animal (e.g. cow, sheep) for the sugar to bekosher.
One of the most widely traded commodities in the world throughout history, sugar accounts for around 2% of the global dry cargo market.International sugar prices show great volatility, ranging from around 3 cents to over 60 centsper pound in the past50 years. About 100 of the world's 180 countries produce sugar from beet or cane, a few more refine raw sugar to produce white sugar, and all countries consume sugar. Consumption of sugar ranges from around 3 kilograms (6.6 pounds) per person per annum in Ethiopia to around 40 kg (88 lb) in Belgium.Consumption per capita rises with income per capita until it reaches a plateau of around 35 kg (77 lb) per person per year in middle income countries.
Many countries subsidize sugar production heavily. The European Union, the United States, Japan, and manydeveloping countriessubsidize domestic production and maintain high tariffs on imports. Sugar prices in these countries have often up to triple the prices on the international market; today, with world market sugar futures prices currentlystrong, such prices were typically double world prices.
Within international trade bodies, especially in theWorld Trade Organization(WTO), the "G20" countries led by Brazil have long argued that, because these sugar markets in essence exclude cane sugar imports, the G20 sugar producers receive lower prices than they would underfree trade. While both theEuropean Unionand United States maintain trade agreements whereby certain developing andleast developed countries(LDCs) can sell certain quantities of sugar into their markets, free of the usual import tariffs, countries outside these preferred trade régimes have complained that these arrangements violate the "most favoured nation" principle of international trade. This has led to numerous tariffs and levies in the past.
In 2004, the WTO sided with a group of cane sugar exporting nations (led by Brazil and Australia) and ruled illegal the EU sugar-régime and the accompanyingACP-EU Sugar Protocol, that granted a group of African, Caribbean, and Pacific countries receive preferential access to the European sugar market.In response to this and to other rulings of the WTO, and owing to internal pressures against the EU sugar-régime, the European Commission proposed on 22 June 2005 a radical reform of the EU sugar-régime that cut prices by 39% and eliminated all EU sugar exports.
In 2007, it seemedthat theU.S. Sugar Programcould become the next target for reform. However, some commentators expected heavy lobbying from the U.S. sugar industry, which donated $2.7 million to U.S. House and Senate incumbents in the 2006 U.S. election, more than any other group of U.S. food-growers.Especially prominent among sugar lobbyists werethe Fanjul Brothers, so-called "sugar barons" who made the single largestindividual contributions ofsoft moneyto both the Democratic and Republican parties in the U.S. political system.
Small quantities of sugar, especially specialty grades of sugar, reach the market as 'fair trade' commodities; the fair trade system produces and sells these products with the understanding that a larger-than-usual fraction of the revenue will support small farmers in the developing world. However, whilst theFairtrade Foundationoffers a premium of $60.00 per tonne to small farmers for sugar branded as "Fairtrade",government schemes such as the U.S. Sugar Program and the ACP-EU Sugar Protocol offer premiums of around $400.00 per tonne above world market prices. However, the EU announced on 14 September 2007 that it had offered "to eliminate all duties and quotas on the import of sugar into the EU".