EtymologyThe word ''sucrose'' was coined in 1857, by the English chemist William Miller from the ("sugar") and the generic chemical suffix for sugars '' -ose''. The abbreviated term ''Suc'' is often used for ''sucrose'' in scientific literature. The name ''saccharose'' was coined in 1860 by the French chemist . Saccharose is an obsolete name for sugars in general, especially sucrose.
Physical and chemical properties
Structural O-α-D-glucopyranosyl-(1→2)-β-D-fructofuranosideIn sucrose, the s glucose and fructose are linked via an ether bond between C1 on the subunit and C2 on the fructosyl unit. The bond is called a . Glucose exists predominantly as a mixture of α and β "pyranose" s, but sucrose has only the α form. Fructose exists as a mixture of five s but sucrose has only the β-D-fructofuranose form. Unlike most disaccharides, 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- . Sucrose crystallizes in the P21 with room-temperature lattice parameters ''a'' = 1.08631 nm, ''b'' = 0.87044 nm, ''c'' = 0.77624 nm, β = 102.938°. The purity of sucrose is measured by , through the rotation of by a sugar solution. The at 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
Hydrolysisbreaks the converting sucrose into and . is, however, so slow that solutions of sucrose can sit for years with negligible change. If the is added, however, the reaction will proceed rapidly. Hydrolysis can also be accelerated with acids, such as 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 per mole of sucrose, or about 3 small calories per gram of product.
Synthesis and biosynthesis of sucroseThe of sucrose proceeds via the precursors and , catalyzed by the enzyme sucrose-6-phosphate synthase. The energy for the reaction is gained by the cleavage of (UDP). Sucrose is formed by plants, and cyanobacteria but not by other s. Sucrose is the end product of and is found naturally in many food plants along with the . In many fruits, such as and , sucrose is the main sugar. In others, such as and s, fructose is the main sugar.
Chemical synthesisAfter numerous unsuccessful attempts by others, Raymond Lemieux and George Huber succeeded in synthesizing sucrose from glucose and fructose in 1953.
SourcesIn nature, sucrose is present in many plants, and in particular their roots, fruits and s, because it serves as a way to store energy, primarily from . Many mammals, birds, insects and bacteria accumulate and feed on the sucrose in plants and for some it is their main food source. Although s consume sucrose, the they produce consists primarily of and , 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 of , it has been increasingly refined and consumed in all kinds of processed foods.
History of sucrose refinementThe production of table sugar has a long history. Some scholars claim Indians discovered how to crystallize sugar during the , around AD 350. Adas, Michael (2001)
TrendsTable sugar (sucrose) comes from plant sources. Two important sugar crops predominate: (''Saccharum spp.'') and s (''Beta vulgaris''), in which sugar can account for 12% to 20% of the plant's dry weight. Minor commercial sugar crops include the (''Phoenix dactylifera''), (''Sorghum vulgare''), and the (''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 tolerate 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 to
High-fructose corn syrupHigh-fructose corn syrup (HFCS) is significantly cheaper as a sweetener for food and beverage manufacturing than refined sucrose. This has led to sucrose being partially displaced in U.S. industrial food production by HFCS and other non-sucrose natural sweeteners. Reports in public media have regarded HFCS as less safe than sucrose. However, the most common forms of HFCS contain either 42 percent fructose, mainly used in processed foods, or 55 percent fructose, mainly used in soft drinks, as compared to sucrose, which is 50 percent fructose. Given approximately equal glucose and fructose content, there does not appear to be a significant difference in safety. That said, clinical s, medical professionals, and the United States (FDA) agree that dietary sugars are a source of s associated with certain health problems, and recommend limiting the overall consumption of sugar-based sweeteners.
CaneSince the 6th century BC, 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 ) 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. s usually 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 and ( ).
BeetBeet sugar producers slice the washed beets, then extract the sugar with hot water in a " ". An alkaline solution (" " and from the lime kiln) then serves to impurities (see ). 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 as , or sells it on to producers of animal feed. Sieving the resultant white sugar produces different grades for selling.
=Cane versus beet= It is difficult to distinguish between fully refined sugar produced from beet and cane. One way is by of carbon. Cane uses , and beet uses , resulting in a different ratio of 13C and 12C isotopes in the sucrose. Tests are used to detect fraudulent abuse of subsidies or to aid in the detection of adulterated fruit 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 as Egypt) 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 is often used in food preparation, humans find molasses from sugar beets unpalatable, and it consequently ends up mostly as industrial fermentation (food), fermentation feedstock (for example in ethanol, alcohol distilleries), or as compound feed, animal 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 5 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= Mill white, also called plantation white, crystal sugar or superior sugar is produced from raw sugar. It is exposed to sulfur dioxide during 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= Blanco directo, a white sugar common in India and other south Asian countries, is produced by precipitating many impurities out of cane juice using phosphoric acid and calcium hydroxide, similar to the technique used in beet sugar refining. Blanco directo is more pure than mill white sugar, but less pure than white refined.
=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 using phosphoric acid similar to the method used for blanco directo, a process involving calcium hydroxide and carbon dioxide, or by various filtration strategies. It is then further purified by filtration through a bed of activated carbon or bone char. Beet sugar refineries produce refined white sugar directly without an intermediate raw stage. White refined sugar is typically sold as ''granulated sugar,'' which has been dried to prevent clumping and comes in various crystal sizes for home and industrial use: * Coarse-grain, such as ''sanding sugar'' (also called "pearl sugar", "decorating sugar", ''nibbed sugar'' or ''sugar nibs'') is a coarse grain sugar used to add sparkle and flavor atop baked goods and candies. Its large reflective crystals will not dissolve when subjected to heat. * Granulated, familiar as table sugar, with a grain size about 0.5 mm across.Sugar Crystal Challenge
Dissolved sugar contentScientists and the sugar industry use degrees Brix (symbol °Bx), introduced by Adolf Ferdinand Wenceslaus Brix, Adolf 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 of ''total'' dried 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.
ConsumptionRefined 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 in confectionery and desserts. Cooks use it for sweetening. It can also act as a Sugaring, food preservative when used in sufficient concentrations. 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".
Nutritional informationFully refined sugar is 99.9% sucrose, thus providing only as dietary nutrient and 390 kilocalories per 100 g serving (USDA data, right table). There are no micronutrients of significance in fully refined sugar (right table).
Metabolism of sucroseIn humans and other mammals, sucrose is broken down into its constituent , and , by or isomaltase glycoside hydrolases, which are located in the cell membrane, membrane of the microvilli lining the duodenum. The resulting glucose and fructose molecules are then rapidly absorbed into the bloodstream. In bacteria and some animals, sucrose is digested by the enzyme invertase. Sucrose is an easily assimilated nutrient, macronutrient that provides a quick source of energy, provoking a rapid rise in blood glucose upon ingestion. Sucrose, as a pure , has an energy content of 3.94 kilocalories per gram (or 17 kilojoules per gram). If consumed excessively, sucrose may contribute to the development of metabolic syndrome, including increased risk for Diabetes mellitus type 2, type 2 diabetes, weight gain and obesity in adults and children.
Tooth decayDental caries, Tooth decay (dental caries) has become a pronounced health hazard associated with the consumption of sugars, especially sucrose. Oral bacteria such as '' '' live in dental plaque and metabolize ''any'' free sugars (not just sucrose, but also , lactose, , and cooked starches) into lactic 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 to ''Streptococcus sanguinis'' (formerly ''Streptococcus sanguis'') and ''Streptococcus 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 enable ''S. mutans'', ''S. sanguinis'' and 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.
Glycemic indexSucrose is a made up of 50% and 50% and has a glycemic index of 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 enzyme to glucose (blood sugar). The glucose component is transported into the blood where it serves immediate metabolic demands, or is converted and reserved in the liver as glycogen.
GoutThe occurrence of gout is 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.
UN dietary recommendationIn 2015, the World Health Organization (WHO) published 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.
Religious concernsThe sugar refining industry often uses bone char (calcinated animal bones) for decolorizing. About 25% of sugar produced in the U.S. is processed using bone char as a filter, the remainder being processed with activated carbon. As bone char does not seem to remain in finished sugar, Jewish religious leaders consider sugar filtered through it to be pareve, 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 be kosher.
Trade and economicsOne 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 to over 60 cents per pound in the 50 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 per person per annum in Ethiopia to around 40 kg/person/yr in Belgium. Consumption per capita rises with income per capita until it reaches a plateau of around 35 kg per person per year in middle income countries. Many countries subsidize sugar production heavily. The European Union, the United States, Japan, and many developing countries subsidize domestic production and maintain high tariffs on imports. Sugar prices in these countries have often exceeded prices on the international market by up to three times; , with world market sugar futures prices strong, such prices typically exceed world prices by two times. Within international trade bodies, especially in the World Trade Organization, the "G20 developing nations, 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 under free trade. While both the and United States maintain trade agreements whereby certain developing and less developed country, less 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 World Trade Organization, WTO sided with a group of cane sugar exporting nations (led by Brazil and Australia) and ruled the EU sugar-régime and the accompanying ACP-EU Sugar Protocol (whereby a group of African, Caribbean, and Pacific countries receive preferential access to the European sugar market) illegal. In response to this and to other rulings of the WTO, and owing to internal pressures on the EU sugar-régime, the European Commission proposed on 22 June 2005 a radical reform of the EU sugar-régime, cutting prices by 39% and eliminating all EU sugar exports. The African, Caribbean, Pacific and least developed country sugar exporters reacted with dismay to the EU sugar proposals. On 25 November 2005, the Council of the EU agreed to cut EU sugar prices by 36% as from 2009. In 2007, it seemed that the U.S. Sugar Program could become the next target for reform. However, some commentators expected heavy lobbying from the U.S. sugar industry, which donated $2.7 million to US House and US Senate incumbents in the 2006 US election, more than any other group of US food-growers. Especially prominent lobbyists include The Fanjul Brothers, so-called "sugar barons" who made the single individual contributions of soft money to both the Democratic and Republican parties in the political system of the United States of America. 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 the Fairtrade Foundation offers 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 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". The US Sugar Association has launched a campaign to promote sugar over artificial substitutes. The Association aggressively challenges many common beliefs regarding negative side-effects of sugar consumption. The campaign aired a high-profile television commercial during the 2007 Primetime Emmy Awards on FOX Television. The Sugar Association uses the trademark tagline "Sugar: sweet by nature".