When we consume food or drink containing carbohydrates, most of this will be either simple glucose (a monosaccharide); sucrose (a disaccharide which contains equal amounts of glucose and fructose); or starch (which is a polysaccharide — a polymer of glucose). Thus, most of the carbohydrate we consume is available to the body as glucose, and so eating or drinking it will lead, after digestion and absorption, to a rise in blood glucose. The magnitude of this rise is controlled by the release of insulin from the pancreas. Insulin acts to stimulate the uptake of glucose from the blood into cells such as those of muscle and adipose tissue, its storage as glycogen (in muscle and liver), and its part in the synthesis of triglycerides, the stored form of fat (mainly in adipose tissue). The relatively slow rate of absorption of dietary carbohydrate (it can take 2–3 hours to absorb the carbohydrate from a normal breakfast), and the effects of insulin, ensure that blood glucose does not usually rise above 8 mmol/litre after meals in non-diabetic people. The figure shows a typical 24-hour profile of blood glucose concentration. The concentration can increase rapidly after consumption of simple sugars, especially glucose itself, either in a drink or in tablet form. This will provide a more rapidly available source of energy than would occur with starchy food.
When we consume food or drink containing carbohydrates, most of this will be either simple glucose (a monosaccharide); sucrose (a disaccharide which contains equal amounts of glucose and fructose); or starch (which is a polysaccharide — a polymer of glucose). Thus, most of the carbohydrate we consume is available to the body as glucose, and so eating or drinking it will lead, after digestion and absorption, to a rise in blood glucose. The magnitude of this rise is controlled by the release of insulin from the pancreas. Insulin acts to stimulate the uptake of glucose from the blood into cells such as those of muscle and adipose tissue, its storage as glycogen (in muscle and liver), and its part in the synthesis of triglycerides, the stored form of fat (mainly in adipose tissue). The relatively slow rate of absorption of dietary carbohydrate (it can take 2–3 hours to absorb the carbohydrate from a normal breakfast), and the effects of insulin, ensure that blood glucose does not usually rise above 8 mmol/litre after meals in non-diabetic people. The figure shows a typical 24-hour profile of blood glucose concentration. The concentration can increase rapidly after consumption of simple sugars, especially glucose itself, either in a drink or in tablet form. This will provide a more rapidly available source of energy than would occur with starchy food.
When blood glucose concentration is normal, the glucose which is filtered from the blood in the kidneysis reabsorbed back into the bloodstream by the kidney tubules, and so none is lost in the urine. But if blood glucose exceeds about 12 mmol/litre, this causes more glucose to be filtered by the kidneys than they can reabsorb. Glucose is therefore lost in the urine, and, because glucose is a powerful osmotic agent, it draws water with it, causing large volumes of sweet urine to be excreted (characteristic of diabetes mellitus). The other undesirable consequence of a persistently elevated blood glucose is that a chemical reaction (glycation or glycosylation) can occur between glucose and proteins, including the important structural proteins in cell membranes, and this can damage the membranes, producing harmful effects. Thus the action of insulin to control blood glucose prevents these undesirable effects of hyperglycaemia, and also ensures that glucose is available for use by the body's tissues.
The brain and the rest of the nervous system, and also the red blood cells, must receive a constant supply of glucose to function normally. In prolonged starvation it is possible for the brain to satisfy some of its energy requirements by using ketone bodies, which are products of fat breakdown, but under normal circumstances the adult human brain needs approximately 6 g per hour of glucose to function normally. After meals containing carbohydrate this is not a problem, as the absorbed carbohydrate provides a ready supply of glucose. However, if we have a high fat meal, or have an extended period between meals (e.g. fasting overnight), we have to provide glucose from within the body. This is done either by the breakdown of the glycogen stored in the liver, which releases glucose into the blood, or by making glucose from amino acids released from the body protein stores. This synthesis of glucose (known as gluconeogenesis) occurs mainly in the liver, and to a lesser extent in the kidneys. The stimulation of the liver to break down its glycogen store and make glucose from amino acids occurs as a result of the fall in plasma insulin which occurs in fasting, together with an increase in glucagon, which is another hormone released from the pancreas.
In some circumstances the rate of use of blood glucose exceeds the rate at which it is released from the liver, and blood glucose concentration falls. When blood glucose falls below 3.5 mmol/litre, the condition of hypoglycaemia is beginning to develop. This condition occurs quite commonly in people with diabetes who are treated with insulin injections, but much less so in non-diabetics. However, hypoglycaemia can occur in healthy people if they undertake prolonged periods of quite high intensity exercise, such as ultra-distance running or cycling, without consuming carbohydrate. Another cause of hypoglycaemia in non-diabetic people is the consumption of about 50 g or more of alcohol (about 5–6 units) after either 24–36 hours of starvation or 2–3 hours of exercise to exhaustion. Starvation or exhaustive exercise will have caused liver glycogen to be depleted, so the liver needs to synthesize glucose to maintain the supply to the brain; but alcohol prevents the liver from performing this synthesis, causing blood glucose to fall and hypoglycaemia to develop.
When blood glucose is at hypoglycaemic levels, there are a number of characteristic effects on the brain. Reactions are slowed, the person has difficulty in concentrating and can feel light-headed, vision may be disturbed, and hunger is common. The autonomic nervous system reaction to hypoglycaemia causes sweating and trembling, and the person often becomes aware that their heart is beating more rapidly (they describe having palpitations). With mild degrees of hypoglycaemia (blood glucose between 3.5 and 3.0 mmol/litre) most people would be unaware of anything untoward occurring, although sensitive measurements of brain function would detect a slowing of reactions. As blood glucose falls further, the effects become more noticeable, but provided the symptoms are used to prompt the consumption of carbohydrate, these effects are rapidly reversed. If blood glucose falls to very low levels, unconsciousness can occur, but this is extremely rare, except for people with insulin-treated diabetes.
When blood glucose concentration is normal, the glucose which is filtered from the blood in the kidneysis reabsorbed back into the bloodstream by the kidney tubules, and so none is lost in the urine. But if blood glucose exceeds about 12 mmol/litre, this causes more glucose to be filtered by the kidneys than they can reabsorb. Glucose is therefore lost in the urine, and, because glucose is a powerful osmotic agent, it draws water with it, causing large volumes of sweet urine to be excreted (characteristic of diabetes mellitus). The other undesirable consequence of a persistently elevated blood glucose is that a chemical reaction (glycation or glycosylation) can occur between glucose and proteins, including the important structural proteins in cell membranes, and this can damage the membranes, producing harmful effects. Thus the action of insulin to control blood glucose prevents these undesirable effects of hyperglycaemia, and also ensures that glucose is available for use by the body's tissues.
The brain and the rest of the nervous system, and also the red blood cells, must receive a constant supply of glucose to function normally. In prolonged starvation it is possible for the brain to satisfy some of its energy requirements by using ketone bodies, which are products of fat breakdown, but under normal circumstances the adult human brain needs approximately 6 g per hour of glucose to function normally. After meals containing carbohydrate this is not a problem, as the absorbed carbohydrate provides a ready supply of glucose. However, if we have a high fat meal, or have an extended period between meals (e.g. fasting overnight), we have to provide glucose from within the body. This is done either by the breakdown of the glycogen stored in the liver, which releases glucose into the blood, or by making glucose from amino acids released from the body protein stores. This synthesis of glucose (known as gluconeogenesis) occurs mainly in the liver, and to a lesser extent in the kidneys. The stimulation of the liver to break down its glycogen store and make glucose from amino acids occurs as a result of the fall in plasma insulin which occurs in fasting, together with an increase in glucagon, which is another hormone released from the pancreas.
In some circumstances the rate of use of blood glucose exceeds the rate at which it is released from the liver, and blood glucose concentration falls. When blood glucose falls below 3.5 mmol/litre, the condition of hypoglycaemia is beginning to develop. This condition occurs quite commonly in people with diabetes who are treated with insulin injections, but much less so in non-diabetics. However, hypoglycaemia can occur in healthy people if they undertake prolonged periods of quite high intensity exercise, such as ultra-distance running or cycling, without consuming carbohydrate. Another cause of hypoglycaemia in non-diabetic people is the consumption of about 50 g or more of alcohol (about 5–6 units) after either 24–36 hours of starvation or 2–3 hours of exercise to exhaustion. Starvation or exhaustive exercise will have caused liver glycogen to be depleted, so the liver needs to synthesize glucose to maintain the supply to the brain; but alcohol prevents the liver from performing this synthesis, causing blood glucose to fall and hypoglycaemia to develop.
When blood glucose is at hypoglycaemic levels, there are a number of characteristic effects on the brain. Reactions are slowed, the person has difficulty in concentrating and can feel light-headed, vision may be disturbed, and hunger is common. The autonomic nervous system reaction to hypoglycaemia causes sweating and trembling, and the person often becomes aware that their heart is beating more rapidly (they describe having palpitations). With mild degrees of hypoglycaemia (blood glucose between 3.5 and 3.0 mmol/litre) most people would be unaware of anything untoward occurring, although sensitive measurements of brain function would detect a slowing of reactions. As blood glucose falls further, the effects become more noticeable, but provided the symptoms are used to prompt the consumption of carbohydrate, these effects are rapidly reversed. If blood glucose falls to very low levels, unconsciousness can occur, but this is extremely rare, except for people with insulin-treated diabetes.
Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. There are various types of sugar derived from different sources. Simple sugars are called monosaccharides and include glucose (also known as dextrose), fructose, and galactose. The "table sugar" or "granulated sugar" most customarily used as food is sucrose, a disaccharide of glucose and fructose. Sugar is used in prepared foods (e.g., cookies and cakes) and it is added to some foods and beverages (e.g., coffee and tea). In the body, sucrose is hydrolysed into the simple sugars fructose and glucose. Other disaccharides include maltose from malted grain, and lactose from milk. Longer chains of sugars are called oligosaccharides or polysaccharides. Some other chemical substances, such as glycerol and sugar alcohols may also have a sweet taste, but are not classified as sugars. Diet food substitutes for sugar include aspartame and sucralose, a chlorinated derivative of sucrose.
Sugars are found in the tissues of most plants and are present in sugarcane and sugar beet in sufficient concentrations for efficient commercial extraction. The world production of sugar in 2011 was about 168 million tonnes. The average person consumes about 24 kilograms (53 lb) of sugar each year (33.1 kg in developed countries), equivalent to over 260 food calories per person, per day. Since the latter part of the twentieth century, it has been questioned whether a diet high in sugars, especially refined sugars, is good for human health. Over-consumption of sugar has been implicated in the occurrence of obesity, diabetes, cardiovascular disease, dementia, and tooth decay. Numerous studies have been undertaken to try to clarify the position, but with varying results, mainly because of the difficulty of finding populations for use as controls that do not consume or are largely free of any sugar consumption.
Etymology[edit]
The etymology reflects the spread of the commodity. The English word "sugar" ultimately originates from the Sanskrit शर्करा (śarkarā), via Arabic سكر (sukkar) as granular or candied sugar, which is cognate with the Greek word, kroke, or "pebble".[1] The contemporary Italian word is zucchero, whereas the Spanish and Portuguese words, azúcar and açúcar, respectively, have kept a trace of the Arabic definite article. The Old French word is zuchre and the contemporary French, sucre. The earliest Greek word attested is σάκχαρις(sákkʰaris).
The English word jaggery, a coarse brown sugar made from date palm sap or sugarcane juice, has a similar etymological origin – Portuguese jagara from the Sanskrit शर्करा(śarkarā).[2]
History[edit]
Ancient times and Middle Ages[edit]
Sugar has been produced in the Indian subcontinent[3] since ancient times. It was not plentiful or cheap in early times and honey was more often used for sweetening in most parts of the world. Originally, people chewed raw sugarcane to extract its sweetness. Sugarcane was a native of tropical South Asia and Southeast Asia.[4] Different species seem to have originated from different locations with Saccharum barberioriginating in India and S. edule and S. officinarum coming from New Guinea.[4][5] One of the earliest historical references to sugarcane is in Chinese manuscripts dating back to 8th century BC that state that the use of sugarcane originated in India.[6]
In the tradition of Indian medicine (āyurveda), the sugarcane is known by the name Ikṣu and the sugarcane juice is known as Phāṇita. Its varieties, synonyms and characterics are defined in nighaṇṭus such as the Bhāvaprakāśa (1.6.23, group of sugarcanes).[7]
Sugar was found in Europe by the 1st century CE, but only as an imported medicine, and not as a food.[8][9] The Greek physician Pedanius Dioscorides in the 1st century CE described sugar in his medical treatise De Materia Medica,[10] and Pliny the Elder, a 1st-century CE Roman, described sugar in his Natural History: "Sugar is made in Arabia as well, but Indian sugar is better. It is a kind of honey found in cane, white as gum, and it crunches between the teeth. It comes in lumps the size of a hazelnut. Sugar is used only for medical purposes."[9]
Sugar remained relatively unimportant until the Indians discovered methods of turning sugarcane juice into granulated crystals that were easier to store and to transport.[11]Crystallized sugar was discovered by the time of the Imperial Guptas, around the 5th century CE.[11] In the local Indian language, these crystals were called khanda (Devanagari: खण्ड, Khaṇḍa), which is the source of the word candy.[12] Indian sailors, who carried clarified butter and sugar as supplies, introduced knowledge of sugar on the various trade routesthey travelled.[11] Buddhist monks, as they travelled around, brought sugar crystallization methods to China.[13] During the reign of Harsha (r. 606–647) in North India, Indian envoys in Tang China taught methods of cultivating sugarcane after Emperor Taizong of Tang (r. 626–649) made known his interest in sugar. China then established its first sugarcane plantations in the seventh century.[14] Chinese documents confirm at least two missions to India, initiated in 647 CE, to obtain technology for sugar refining.[15] In South Asia, the Middle East and China, sugar became a staple of cooking and desserts.
Crusaders brought sugar home with them to Europe after their campaigns in the Holy Land, where they encountered caravans carrying "sweet salt". Early in the 12th century, Venice acquired some villages near Tyre and set up estates to produce sugar for export to Europe, where it supplemented honey, which had previously been the only available sweetener.[16] Crusade chronicler William of Tyre, writing in the late 12th century, described sugar as "very necessary for the use and health of mankind".[17] In the 15th century, Venice was the chief sugar refining and distribution centre in Europe.[6]
Modern history[edit]
In August 1492, Christopher Columbus stopped at La Gomera in the Canary Islands, for wine and water, intending to stay only four days. He became romantically involved with the governor of the island, Beatriz de Bobadilla y Ossorio, and stayed a month. When he finally sailed, she gave him cuttings of sugarcane, which became the first to reach the New World.[18] The first sugar cane harvest was conducted in Hispaniola in 1501, and many sugar mills had been constructed in Cuba and Jamaica by the 1520s.[19] The Portuguese took sugar cane to Brazil. By 1540, there were 800 cane sugar mills in Santa Catarina Island and another 2,000 on the north coast of Brazil, Demarara, and Surinam.
Sugar was a luxury in Europe until the 18th century, when it became more widely available. It then became popular and by the 19th century, sugar came to be considered a necessity. This evolution of taste and demand for sugar as an essential food ingredient unleashed major economic and social changes.[20] It drove, in part, colonization of tropical islands and nations where labor-intensive sugarcane plantations and sugar manufacturing could thrive. The demand for cheap labor to perform the hard work involved in its cultivation and processing increased the demand for the slave trade from Africa (in particular West Africa). After slavery was abolished, there was high demand for indentured laborers from South Asia (in particular India).[21][22][23] Millions of slave and indentured laborers were brought into the Caribbean and the Americas, Indian Ocean colonies, southeast Asia, Pacific Islands, and East Africa and Natal. The modern ethnic mix of many nations that have been settled in the last two centuries has been influenced by the demand for sugar.[24][25][26]
Sugar also led to some industrialization of areas where sugar cane was grown. For example, Lieutenant J. Paterson, of the Bengal establishment, persuaded the British Government that sugar cane could be cultivated in British India with many advantages and at less expense than in the West Indies; as a result, sugar factories were established in Bihar in eastern India.[27] During the Napoleonic Wars, sugar beet production increased in continental Europe because of the difficulty of importing sugar when shipping was subject to blockade. By 1880, the sugar beet was the main source of sugar in Europe. It was cultivated in Lincolnshire and other parts of England, although the United Kingdom continued to import the main part of its sugar from its colonies.[28]
Until the late nineteenth century, sugar was purchased in loaves, which had to be cut using implements called sugar nips.[29] In later years, granulated sugar was more usually sold in bags. Sugar cubes were produced in the nineteenth century. The first inventor of a process to make sugar in cube form was the Moravian Jakub Kryštof Rad, director of a sugar company in Dačice. He began sugar cube production after being granted a five-year patent for the process on January 23, 1843. Henry Tate of Tate & Lyle was another early manufacturer of sugar cubes at his refineries in Liverpool and London. Tate purchased a patent for sugar cube manufacture from German Eugen Langen, who in 1872 had invented a different method of processing of sugar cubes.[30]
Chemistry[edit]
Scientifically, sugar loosely refers to a number of carbohydrates, such as monosaccharides, disaccharides, or oligosaccharides. Monosaccharides are also called "simple sugars," the most important being glucose. Most monosaccharides have a formula that conforms to C
nH
2nO
n with n between 3 and 7 (deoxyribose being an exception). Glucose has the molecular formula C
6H
12O
6. The names of typical sugars end with -ose, as in "glucose" and "fructose". Sometimes such words may also refer to any types of carbohydrates soluble in water. The acyclic mono- and disaccharides contain either aldehyde groups or ketone groups. These carbon-oxygen double bonds (C=O) are the reactive centers. All saccharides with more than one ring in their structure result from two or more monosaccharides joined by glycosidic bondswith the resultant loss of a molecule of water (H
2O) per bond.[31]
nH
2nO
n with n between 3 and 7 (deoxyribose being an exception). Glucose has the molecular formula C
6H
12O
6. The names of typical sugars end with -ose, as in "glucose" and "fructose". Sometimes such words may also refer to any types of carbohydrates soluble in water. The acyclic mono- and disaccharides contain either aldehyde groups or ketone groups. These carbon-oxygen double bonds (C=O) are the reactive centers. All saccharides with more than one ring in their structure result from two or more monosaccharides joined by glycosidic bondswith the resultant loss of a molecule of water (H
2O) per bond.[31]
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 hydrolyze or otherwise break these glycosidic bonds before such compounds become metabolized. After digestion and absorption the principal monosaccharides present in the blood and internal tissues include glucose, fructose, and galactose. Many pentoses and hexoses can form ring structures. In these closed-chain forms, the aldehyde or ketone group remains non-free, 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.[31]
Natural polymers[edit]
Biopolymers of sugars are common in nature. Through photosynthesis, plants produce glyceraldehyde-3-phosphate (G3P), a phosphated 3-carbon sugar that is used by the cell to make monosaccharides such as glucose (C
6H
12O
6) or (as in cane and beet) sucrose (C
12H
22O
11). Monosaccharides may be further converted into structural polysaccharides such as cellulose and pectin for cell wall construction or into energy reserves in the form of storage polysaccharides such as starch or inulin. Starch, consisting of two different polymers of glucose, is a readily degradable form of chemical energy stored by cells, and can be converted to other types of energy.[31] Another polymer of glucose is cellulose, which is a linear chain composed of several hundred or thousand glucose units. It is used by plants as a structural component in their cell walls. Humans can digest cellulose only to a very limited extent, though ruminants can do so with the help of symbiotic bacteria in their gut.[32] DNA and RNA are built up of the monosaccharides deoxyribose and ribose, respectively. Deoxyribose has the formula C
5H
10O
4 and ribose the formula C
5H
10O
5.[33]
6H
12O
6) or (as in cane and beet) sucrose (C
12H
22O
11). Monosaccharides may be further converted into structural polysaccharides such as cellulose and pectin for cell wall construction or into energy reserves in the form of storage polysaccharides such as starch or inulin. Starch, consisting of two different polymers of glucose, is a readily degradable form of chemical energy stored by cells, and can be converted to other types of energy.[31] Another polymer of glucose is cellulose, which is a linear chain composed of several hundred or thousand glucose units. It is used by plants as a structural component in their cell walls. Humans can digest cellulose only to a very limited extent, though ruminants can do so with the help of symbiotic bacteria in their gut.[32] DNA and RNA are built up of the monosaccharides deoxyribose and ribose, respectively. Deoxyribose has the formula C
5H
10O
4 and ribose the formula C
5H
10O
5.[33]
Flammability and response to heating[edit]
Because sugars burn easily when exposed to flame, the handling of sugars risks dust explosion. The 2008 Georgia sugar refinery explosion, which killed 14 people and injured 40, and destroyed most of the refinery, was caused by the ignition of sugar dust. In its culinary use, sugar that is exposed to a heat source causes caramelization to take place. As the process occurs, volatile chemicals such as diacetyl are released, producing the characteristic caramel flavor.
Types[edit]
Monosaccharides[edit]
Fructose, galactose, and glucose are all simple sugars, monosaccharides, with the general formula C6H12O6. They have five hydroxyl groups (−OH) and a carbonyl group (C=O) and are cyclic when dissolved in water. They each exist as several isomers with dextro- and laevo-rotatory forms that cause polarized light to diverge to the right or the left.[34]
- Fructose, or fruit sugar, occurs naturally in fruits, some root vegetables, cane sugar and honey and is the sweetest of the sugars. It is one of the components of sucrose or table sugar. It is used as a high-fructose syrup, which is manufactured from hydrolyzed corn starch that has been processed to yield corn syrup, with enzymes then added to convert part of the glucose into fructose.[35]
- In general, galactose does not occur in the free state but is a constituent with glucose of the disaccharide lactose or milk sugar. It is less sweet than glucose. It is a component of the antigens found on the surface of red blood cells that determine blood groups.[36]
- Glucose, dextrose or grape sugar, occurs naturally in fruits and plant juices and is the primary product of photosynthesis. Most ingested carbohydrates are converted into glucose during digestion and it is the form of sugar that is transported around the bodies of animals in the bloodstream. It can be manufactured from starch by the addition of enzymes or in the presence of acids. Glucose syrup is a liquid form of glucose that is widely used in the manufacture of foodstuffs. It can be manufactured from starch by enzymatic hydrolysis.[37]
Disaccharides[edit]
Lactose, maltose, and sucrose are all compound sugars, disaccharides, with the general formula C12H22O11. They are formed by the combination of two monosaccharide molecules with the exclusion of a molecule of water.[34]
- Lactose is the naturally occurring sugar found in milk. A molecule of lactose is formed by the combination of a molecule of galactose with a molecule of glucose. It is broken down when consumed into its constituent parts by the enzyme lactase during digestion. Children have this enzyme but some adults no longer form it and they are unable to digest lactose.[38]
- Maltose is formed during the germination of certain grains, the most notable being barley, which is converted into malt, the source of the sugar's name. A molecule of maltose is formed by the combination of two molecules of glucose. It is less sweet than glucose, fructose or sucrose.[34] It is formed in the body during the digestion of starch by the enzyme amylase and is itself broken down during digestion by the enzyme maltase.[39]
- Sucrose is found in the stems of sugarcane and roots of sugar beet. It also occurs naturally alongside fructose and glucose in other plants, in particular fruits and some roots such as carrots. The different proportions of sugars found in these foods determines the range of sweetness experienced when eating them.[34] A molecule of sucrose is formed by the combination of a molecule of glucose with a molecule of fructose. After being eaten, sucrose is split into its constituent parts during digestion by a number of enzymes known as sucrases.[40]
Sources[edit]
The sugar contents of common fruits and vegetables are presented in Table 1. All data with a unit of g (gram) are based on 100 g of a food item. The fructose/glucose ratio is calculated by dividing the sum of free fructose plus half sucrose by the sum of free glucose plus half sucrose.
| Food item | Total carbohydrateA including dietary fiber | Total sugars | Free fructose | Free glucose | Sucrose | Fructose/ Glucose ratio | Sucrose as a % of total sugars |
|---|---|---|---|---|---|---|---|
| Fruits | |||||||
| Apple | 13.8 | 10.4 | 5.9 | 2.4 | 2.1 | 2.0 | 19.9 |
| Apricot | 11.1 | 9.2 | 0.9 | 2.4 | 5.9 | 0.7 | 63.5 |
| Banana | 22.8 | 12.2 | 4.9 | 5.0 | 2.4 | 1.0 | 20.0 |
| Fig, dried | 63.9 | 47.9 | 22.9 | 24.8 | 0.9 | 0.9 | 0.15 |
| Grapes | 18.1 | 15.5 | 8.1 | 7.2 | 0.2 | 1.1 | 1 |
| Navel orange | 12.5 | 8.5 | 2.25 | 2.0 | 4.3 | 1.1 | 50.4 |
| Peach | 9.5 | 8.4 | 1.5 | 2.0 | 4.8 | 0.9 | 56.7 |
| Pear | 15.5 | 9.8 | 6.2 | 2.8 | 0.8 | 2.1 | 8.0 |
| Pineapple | 13.1 | 9.9 | 2.1 | 1.7 | 6.0 | 1.1 | 60.8 |
| Plum | 11.4 | 9.9 | 3.1 | 5.1 | 1.6 | 0.7 | 16.2 |
| Vegetables | |||||||
| Beet, red | 9.6 | 6.8 | 0.1 | 0.1 | 6.5 | 1.0 | 96.2 |
| Carrot | 9.6 | 4.7 | 0.6 | 0.6 | 3.6 | 1.0 | 77 |
| Corn, sweet | 19.0 | 6.2 | 1.9 | 3.4 | 0.9 | 0.6 | 15.0 |
| Red pepper, sweet | 6.0 | 4.2 | 2.3 | 1.9 | 0.0 | 1.2 | 0.0 |
| Onion, sweet | 7.6 | 5.0 | 2.0 | 2.3 | 0.7 | 0.9 | 14.3 |
| Sweet potato | 20.1 | 4.2 | 0.7 | 1.0 | 2.5 | 0.9 | 60.3 |
| Yam | 27.9 | 0.5 | tr | tr | tr | na | tr |
| Sugar cane | 13–18 | 0.2–1.0 | 0.2–1.0 | 11–16 | 1.0 | high | |
| Sugar beet | 17–18 | 0.1–0.5 | 0.1–0.5 | 16–17 | 1.0 | high |
- ^A The carbohydrate figure is calculated in the USDA database and does not always correspond to the sum of the sugars, the starch, and the dietary fiber.
Production[edit]
Sugar beet[edit]
Sugar beet became a major source of sugar in the 19th century when methods for extracting the sugar became available. It is a biennial plant,[42] a cultivated variety of Beta vulgaris in the family Amaranthaceae, the tuberous root of which contains a high proportion of sucrose. It is cultivated as a root crop in temperate regions with adequate rainfall and requires a fertile soil. The crop is harvested mechanically in the autumn and the crown of leaves and excess soil removed. The roots do not deteriorate rapidly and may be left in a clamp in the field for some weeks before being transported to the processing plant. Here the crop is washed and sliced and the sugar extracted by diffusion. Milk of lime is added to the raw juice and carbonatated in a number of stages in order to purify it. Water is evaporated by boiling the syrup under a vacuum. The syrup is then cooled and seeded with sugar crystals. The white sugar that crystallizes out can be separated in a centrifuge and dried. It requires no further refining.[43]
Sugarcane[edit]
Sugarcane refers to any of several species, or their hybrids, of giant grasses in the genus Saccharum in the family Poaceae. They have been cultivated in tropical climates in South Asia and Southeast Asia since ancient times for the sucrose that is found in their stems. A great expansion in sugarcane production took place in the 18th century with the establishment of slave plantations in the Americas. The use of slavery meant that this was the first time that sugar became cheap enough for most people, who previously had to rely on honey to sweeten foods. It requires a frost-free climate with sufficient rainfall during the growing season to make full use of the plant's great growth potential. The crop is harvested mechanically or by hand, chopped into lengths and conveyed rapidly to the processing plant (commonly known as a sugar mill). Here, it is either milled and the juice extracted with water or extracted by diffusion. The juice is then clarified with lime and heated to destroy enzymes. The resulting thin syrup is concentrated in a series of evaporators, after which further water is removed by evaporation in vacuum containers. The resulting supersaturated solution is seeded with sugar crystals and the sugar crystallizes out and is separated from the fluid and dried. Molasses is a by-product of the process and the fiber from the stems, known as bagasse, is burned to provide energy for the sugar extraction process. The crystals of raw sugar have a sticky brown coating and either can be used as they are or can be bleached by sulfur dioxide or can be treated in a carbonatation process to produce a whiter product.[44] About 2,500 litres (660 US gal) of irrigation water is needed for every one kilogram (2.2 pounds) of sugar produced.[45]
Refining[edit]
Refined sugar is made from raw sugar that has undergone a refining process to remove the molasses.[46][47] Raw sugar is sucrose which is extracted from sugarcane or sugar beet. While raw sugar can be consumed, the refining process removes unwanted tastes and results in refined sugar or white sugar.[48][49]
The sugar may be transported in bulk to the country where it will be used and the refining process often takes place there. The first stage is known as affination and involves immersing the sugar crystals in a concentrated syrup that softens and removes the sticky brown coating without dissolving them. The crystals are then separated from the liquor and dissolved in water. The resulting syrup is treated either by a carbonatation or by a phosphatation process. Both involve the precipitation of a fine solid in the syrup and when this is filtered out, many of the impurities are removed at the same time. Removal of color is achieved by using either a granular activated carbon or an ion-exchange resin. The sugar syrup is concentrated by boiling and then cooled and seeded with sugar crystals, causing the sugar to crystallize out. The liquor is spun off in a centrifuge and the white crystals are dried in hot air and ready to be packaged or used. The surplus liquor is made into refiners' molasses.[50] The International Commission for Uniform Methods of Sugar Analysis sets standards for the measurement of the purity of refined sugar, known as ICUMSA numbers; lower numbers indicate a higher level of purity in the refined sugar.[51]
Refined sugar is widely used for industrial needs for higher quality. Refined sugar is purer (ICUMSA below 300) than raw sugar (ICUMSA over 1,500).[52] The level of purity associated with the colors of sugar, expressed by standard number ICUMSA, the smaller ICUMSA numbers indicate the higher purity of sugar.[52]
Producing countries[edit]
The five largest producers of sugar in 2011 were Brazil, India, the European Union, China and Thailand. In the same year, the largest exporter of sugar was Brazil, distantly followed by Thailand, Australia and India. The largest importers were the European Union, United States and Indonesia. At present, Brazil has the highest per capita consumption of sugar, followed by Australia, Thailand, and the European Union.[53][54]
World sugar production (1000 metric tons)[53]
World sugar production (1000 metric tons)[53]
50,000
100,000
150,000
200,000
2007/08
2008/09
2009/10
2010/11
2011/12
- Brazil
- India
- European Union
- China
- Thailand
- United States
- Mexico
- Russia
- Pakistan
- Australia
- Other
Forms and uses[edit]
- Brown sugars are granulated sugars, either containing residual molasses, or with the grains deliberately coated with molasses to produce a light- or dark-colored sugar. They are used in baked goods, confectionery, and toffees.[55]
- Granulated sugars are used at the table, to sprinkle on foods and to sweeten hot drinks (coffee and tea), and in home baking to add sweetness and texture to baked products (cookies and cakes) and desserts (pudding and ice cream). They are also used as a preservative to prevent micro-organisms from growing and perishable food from spoiling, as in candied fruits, jams, and marmalades.[56]
- Invert sugars and syrups are blended to manufacturers specifications and are used in breads, cakes, and beverages for adjusting sweetness, aiding moisture retention and avoiding crystallization of sugars.[55]
- Liquid sugars are strong syrups consisting of 67% granulated sugar dissolved in water. They are used in the food processing of a wide range of products including beverages, hard candy, ice cream, and jams.[55]
- Low-calorie sugars and artificial sweeteners are often made of maltodextrin with added sweeteners. Maltodextrin is an easily digestible synthetic polysaccharide consisting of short chains of glucose molecules and is made by the partial hydrolysis of starch. The added sweeteners are often aspartame, saccharin, stevia, or sucralose.[57]
- Milled sugars (known as confectioner's sugar and powdered sugar) are ground to a fine powder. They are used as powdered sugar (also known as icing sugar or confectionary sugar), for dusting foods and in baking and confectionery.[55]
- Molasses is commonly used to make rum, and sugar byproducts are used to make ethanol for fuel.
- Polyols are sugar alcohols and are used in chewing gums where a sweet flavor is required that lasts for a prolonged time in the mouth.[58]
- Screened sugars are crystalline products separated according to the size of the grains. They are used for decorative table sugars, for blending in dry mixes and in baking and confectionery.[55]
- Sugar cubes (sometimes called sugar lumps) are white or brown granulated sugars lightly steamed and pressed together in block shape. They are used to sweeten drinks.[55]
- Sugarloaf was the usual cone-form in which refined sugar was produced and sold until the late 19th century. This shape is still in use in Germany (for preparation of Feuerzangenbowle), in Iran and Morocco.
- Syrups and treacles are dissolved invert sugars heated to develop the characteristic flavors. (Treacles have added molasses.) They are used in a range of baked goods and confectionery including toffees and licorice.[55]
- In winemaking, fruit sugars are converted into alcohol by a fermentation process. If the must formed by pressing the fruit has a low sugar content, additional sugar may be added to raise the alcohol content of the wine in a process called chaptalization. In the production of sweet wines, fermentation may be halted before it has run its full course, leaving behind some residual sugar that gives the wine its sweet taste.[59]
Consumption[edit]
In most parts of the world, sugar is an important part of the human diet, making food more palatable and providing food energy. After cereals and vegetable oils, sugar derived from sugarcane and beet provided more kilocalories per capita per day on average than other food groups.[60] According to the FAO, an average of 24 kilograms (53 lb) of sugar, equivalent to over 260 food calories per day, was consumed annually per person of all ages in the world in 1999. Even with rising human populations, sugar consumption is expected to increase to 25.1 kilograms (55 lb) per person per year by 2015.[61]
Data collected in multiple U.S. surveys between 1999 and 2008 show that the intake of added sugars has declined by 24 percent with declines occurring in all age, ethnic and income groups.[62]
| Country | 2007/08 | 2008/09 | 2009/10 | 2010/11 | 2011/12 | 2012/13 |
|---|---|---|---|---|---|---|
 India | 22,021 | 23,500 | 22,500 | 23,500 | 25,500 | 26,500 |
 European Union | 16,496 | 16,760 | 17,400 | 17,800 | 17,800 | 17,800 |
 China | 14,250 | 14,500 | 14,300 | 14,000 | 14,400 | 14,900 |
 Brazil | 11,400 | 11,650 | 11,800 | 12,000 | 11,500 | 11,700 |
 United States | 9,590 | 9,473 | 9,861 | 10,086 | 10,251 | 10,364 |
| Other | 77,098 | 76,604 | 77,915 | 78,717 | 80,751 | 81,750 |
| Total | 150,855 | 152,487 | 153,776 | 156,103 | 160,202 | 163,014 |
The per capita consumption of refined sugar in the United States has varied between 27 and 46 kilograms (60 and 101 lb) in the last 40 years. In 2008, American per capita total consumption of sugar and sweeteners, exclusive of artificial sweeteners, equalled 61.9 kg (136 lb) per year. This consisted of 29.65 kg (65.4 lb) pounds of refined sugar and 31 kg (68.3 lb) pounds of corn-derived sweeteners per person.[64][65]
Nutrition and flavor[edit]
| Nutritional value per 100 g (3.5 oz) | |
|---|---|
| Energy | 1,576 kJ (377 kcal) |
97.33 g
| |
| Sugars | 96.21 g |
| Dietary fiber | 0 g |
0 g
| |
0 g
| |
| Vitamins | |
| Thiamine (B1) |
(1%)
0.008 mg |
| Riboflavin (B2) |
(1%)
0.007 mg |
| Niacin (B3) |
(1%)
0.082 mg |
| Vitamin B6 |
(2%)
0.026 mg |
| Folate (B9) |
(0%)
1 μg |
| Minerals | |
| Calcium |
(9%)
85 mg |
| Iron |
(15%)
1.91 mg |
| Magnesium |
(8%)
29 mg |
| Phosphorus |
(3%)
22 mg |
| Potassium |
(3%)
133 mg |
| Sodium |
(3%)
39 mg |
| Zinc |
(2%)
0.18 mg |
| Other constituents | |
| Water | 1.77 g |
| |
| Percentages are roughly approximated using US recommendations for adults. | |
| Nutritional value per 100 g (3.5 oz) | |
|---|---|
| Energy | 1,619 kJ (387 kcal) |
99.98 g
| |
| Sugars | 99.91 g |
| Dietary fiber | 0 g |
0 g
| |
0 g
| |
| Vitamins | |
| Riboflavin (B2) |
(2%)
0.019 mg |
| Minerals | |
| Calcium |
(0%)
1 mg |
| Iron |
(0%)
0.01 mg |
| Potassium |
(0%)
2 mg |
| Other constituents | |
| Water | 0.03 g |
| |
| Percentages are roughly approximated using US recommendations for adults. | |
Brown and white granulated sugar are 97% to nearly 100% carbohydrates, respectively, with less than 2% water, and no dietary fiber, protein or fat (table). Brown sugar contains a moderate amount of iron (15% of the Reference Daily Intake in a 100 gram amount, see table), but a typical serving of 4 grams (one teaspoon), would provide 15 calories and a negligible amount of iron or any other nutrient.[66] Because brown sugar contains 5–10% molasses reintroduced during processing, its value to some consumers is a richer flavor than white sugar.[67]
Health effects[edit]
A 2003 WHO technical report provided evidence that high intake of sugary drinks (including fruit juice) increased the risk of obesity by adding to overall energy intake.[68] The 'empty calories' argument states that a diet high in added sugar will reduce consumption of foods that contain essential nutrients.[69]
Obesity and metabolic syndrome[edit]
By itself, sugar is not a factor causing obesity and metabolic syndrome, but rather – when over-consumed – is a component of unhealthy dietary behavior.[68][70] Controlled trials showed that overconsumption of sugar-sweetened beverages increases body weight and body fat,[70][71] and that replacement of sugar by artificial sweeteners reduces weight.[72] Other studies showed correlation between refined sugar ("free sugar") consumption and the onset of diabetes, and negative correlation with the consumption of fiber.[73]
Cardiovascular disease[edit]
From systematic reviews published in 2016, there is no evidence that sugar intake at normal levels increases the risk of cardiovascular diseases.[70][74] Sugar, particularly fructose, does not have unique effects causing injury to the cardiovascular system, but rather excess total energy intake increases risk of cardiovascular and metabolic diseases.[70]
Addiction[edit]
Hyperactivity[edit]
Some studies report evidence of causality between refined sugar and hyperactivity.[77] The 2003 WHO report suggests that inconclusive evidence for sugar as a cause of hyperactivity is expected when studies do not control for intake of free sugars versus unrefined sugars.[68]
Tooth decay[edit]
The 2003 WHO report stated that "Sugars are undoubtedly the most important dietary factor in the development of dental caries".[68]For tooth decay, there is "convincing evidence from human intervention studies, epidemiological studies, animal studies and experimental studies, for an association between the amount and frequency of free sugars intake and dental caries" while other sugars (complex carbohydrate) consumption is normally associated with a lower rate of dental caries.[78] Also, studies have shown that the consumption of sugar and starch have different impacts on oral health, with the ingestion of starchy foods and fresh fruit being associated with lower incidence of dental caries.[78]
Alzheimer's disease[edit]
Claims have been made of a sugar–Alzheimer's disease connection, but there is inconclusive evidence that cognitive decline is related to dietary fructose or overall energy intake.[79][80]
Recommended dietary intake[edit]
The World Health Organization recommends[81] that both adults and children reduce the intake of free sugars to less than 10% of total energy intake. A reduction to below 5% of total energy intake brings additional health benefits, especially in what regards dental caries(cavities in the teeth). These recommendations were based on the totality of available evidence reviewed regarding the relationship between free sugars intake and body weight and dental caries. Free sugars include 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.[81]
On May 20, 2016 the U.S. Food and Drug Administration announced changes to the Nutrition Facts panel displayed on all foods, to be effective by July 2018. New to the panel is a requirement to list "Added sugars" by weight and as a percent of Daily Value (DV). For vitamins and minerals the intent of DVs is to indicate how much should be consumed. For added sugars, the guidance is that 100% DV should not be exceeded. 100% DV is defined as 50 grams. For a person consuming 2000 calories a day, 50 grams, the amount to not exceed, is the same as 200 calories, and thus 10% of total calories – same guidance as the World Health Organization.[82] To put this into context, most 12 ounce (335 mL) cans of soda contain 39 grams of sugar. In the United States, a recently published government survey on food consumption reported that for men and women ages 20 and older the average total sugar intakes – naturally occurring in foods and added – were, respectively, 125 and 99 g/day.[83]
Measurements[edit]
Various culinary sugars have different densities due to differences in particle size and inclusion of moisture.
Domino Sugar gives the following weight to volume conversions (in United States customary units):[84]
- Firmly packed brown sugar 1 lb = 2.5 cups (or 1.3 L per kg, 0.77 kg/L)
- Granulated sugar 1 lb = 2.25 cups (or 1.17 L per kg, 0.85 kg/L)
- Unsifted confectioner's sugar 1 lb = 3.75 cups (or 2.0 L per kg, 0.5 kg/L)
The "Engineering Resources – Bulk Density Chart" published in Powder and Bulk gives different values for the bulk densities:[85]
- Beet sugar 0.80 g/mL
- Dextrose sugar 0.62 g/mL ( = 620 kg/m^3)
- Granulated sugar 0.70 g/mL
- Powdered sugar 0.56 g/mL
Society and culture[edit]
Manufacturers of sugary products, such as soft drinks and candy, and the Sugar Research Foundation have been accused of trying to influence consumers and medical associations in the 1960s and 1970s by creating doubt about the potential health hazards of sucrose overconsumption, while promoting saturated fat as the main dietary risk factor in cardiovascular diseases.[86] In 2016, the criticism led to recommendations that diet policymakers emphasize the need for high-quality research that accounts for multiple biomarkerson development of cardiovascular diseases.[86]
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