Sugar

From Wikipedia, the free encyclopedia

Sugars (clockwise from top-left): white refined, unrefined, unprocessed cane, brown

 

Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. The various types of sugar are derived from different sources. Simple sugars are called monosaccharides and include glucose (also known as dextrose), fructose, and galactose. "Table sugar" or "granulated sugar" refers to sucrose, a disaccharide of glucose and fructose. In the body, sucrose is hydrolysed into fructose and glucose. 

Sugars are found in the tissues of most plants, but sucrose is especially concentrated in sugarcane and sugar beet, making them ideal for efficient commercial extraction to make refined sugar. Sugarcane originated in tropical Indian subcontinent and Southeast Asia, and is known of from before 6,000 BP, sugar beet was first described in writing (1575) by Olivier de Serres and originated in southwestern, northern and Southeast Europe along the Atlantic coasts and the Mediterranean Sea, in North Africa, Macaronesia, to Western Asia. In 2016, the combined world production of those two crops was about two billion tonnes. Other disaccharides include maltose (from malted grain) and lactose (from milk). Longer chains of sugar molecules are called oligosaccharides or polysaccharides. Some other chemical substances, such as glycerol and sugar alcohols, may have a sweet taste, but are not classified as sugar. 

Sucrose is used in prepared foods (e.g. cookies and cakes), is sometimes added to commercially available beverages, and may be used by people as a sweetener for foods (e.g. toast and cereal) and beverages (e.g. coffee and tea). The average person consumes about 24 kilograms (53 lb) of sugar each year, or 33.1 kilograms (73 lb) in developed countries, equivalent to over 260 food calories per day. As sugar consumption grew in the latter part of the 20th century, researchers began to examine whether a diet high in sugar, especially refined sugar, was damaging to human health. Excessive consumption of sugar has been implicated in the onset of obesity, diabetes, cardiovascular disease, dementia, and tooth decay. Numerous studies have tried to clarify those implications, but with varying results, mainly because of the difficulty of finding populations for use as controls that consume little or no sugar. In 2015, the World Health Organization recommended that adults and children reduce their intake of free sugars to less than 10%, and encouraged a reduction to below 5%, of their total energy intake.

Etymology

The etymology reflects the spread of the commodity. From Sanskrit शर्करा (śarkarā), meaning "ground or candied sugar," originally "grit, gravel", came Persian shakar, whence Arabic سكر (sukkar), whence Medieval Latin succarum, whence 12th-century French sucre, whence the English word sugar. Italian zucchero, Spanish azúcar, and Portuguese açúcar came directly from Arabic, the Spanish and Portuguese words retaining the Arabic definite article. 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 jágara from the Malayalam ചക്കരാ (cakkarā), which is itself from the Sanskrit शर्करा (śarkarā).

History

Ancient times and Middle Ages

Sugar cane plantation

Asia

Sugar has been produced in the Indian subcontinent since ancient times and its cultivation spread from there into modern-day Afghanistan through the Khyber Pass. It was not plentiful or cheap in early times, and in most parts of the world, honey was more often used for sweetening. Originally, people chewed raw sugarcane to extract its sweetness. Sugarcane was a native of tropical Indian subcontinent and Southeast Asia.

Different species seem to have originated from different locations with Saccharum barberi originating in India and S. edule and S. officinarum coming from New Guinea. One of the earliest historical references to sugarcane is in Chinese manuscripts dating to 8th century BCE, which state that the use of sugarcane originated in India.

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). Sugar remained relatively unimportant until the Indians discovered methods of turning sugarcane juice into granulated crystals that were easier to store and to transport. Crystallized sugar was discovered by the time of the Imperial Guptas, around the 5th century CE. In the local Indian language, these crystals were called khanda (Devanagari: खण्ड, Khaṇḍa), which is the source of the word candy. Indian sailors, who carried clarified butter and sugar as supplies, introduced knowledge of sugar along the various trade routes they travelled. Traveling Buddhist monks took sugar crystallization methods to China. 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 established its first sugarcane plantations in the seventh century. Chinese documents confirm at least two missions to India, initiated in 647 CE, to obtain technology for sugar refining. In the Indian subcontinent, the Middle East and China, sugar became a staple of cooking and desserts.

Mediterranean

Nearchus, admiral of Alexander of Macedonia, knew of sugar during the year 325 B.C., because of his participation in the campaign of India led by Alexander (Arrian, Anabasis). The Greek physician Pedanius Dioscorides in the 1st century CE described sugar in his medical treatise De Materia Medica, 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." Crusaders brought sugar back 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. It supplemented the use of honey, which had previously been the only available sweetener.^[19] Crusade chronicler William of Tyre, writing in the late 12th century, described sugar as "very necessary for the use and health of mankind". In the 15th century, Venice was the chief sugar refining and distribution center in Europe.

Modern history

Still-Life with Bread and Confectionery, by George Flegel, first half of 17th century

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 he carried to the New World. This was the introduction of this plant. The cuttings were planted and the first sugar-cane harvest in Hispaniola took place in 1501. Many sugar mills had been constructed in Cuba and Jamaica by the 1520s. 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. 

Hacienda La Fortuna. A sugar mill complex in Puerto Rico, painted by Francisco Oller in 1885. Brooklyn Museum

 

Sugar was a luxury in Europe until the 18th century, when it became more widely available. It became highly 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 resulted in major economic and social changes. Demand drove, in part, the colonization of tropical islands and areas where labor-intensive sugarcane plantations and sugar manufacturing could be successful. The demand for cheap labor to perform the labor-intensive cultivation and processing increased the demand for the slave trade from Africa (in particular West Africa).

After slavery was abolished, the demand for workers in the British Caribbean colonies was filled by indentured laborers from Indian subcontinent (in particular India). 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. Thus the modern ethnic mix of many nations that have been settled in the last two centuries has been influenced by the demand for sugar.

This is a close-up image of sugar cane. Demand for sugar helped create the colonial system in areas where cultivation of sugar cane was profitable.

 

Sugar also led to some industrialization of areas where sugar cane was grown. For example, in the 1790s Lieutenant J. Paterson, of the Bengal establishment, promoted to the British Government the idea that sugar cane could grow in British India, where it had started, with many advantages and at less expense than in the West Indies. As a result, sugar factories were established in Bihar in eastern India. 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 also cultivated in Lincolnshire and other parts of England, although the United Kingdom continued to import the main part of its sugar from its colonies.

Until the late nineteenth century, sugar was purchased in loaves, which had to be cut using implements called sugar nips. 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 produce sugar in cube form was 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.

Sugar was rationed during World War I and more sharply during World War II. This led to the development and use of various artificial sweeteners.

Chemistry

Sucrose: a disaccharide of glucose (left) and fructose (right), important molecules in the body.

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 bonds with the resultant loss of a molecule of water (H
₂O) per bond.

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.

Natural polymers

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. 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. 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.

Flammability and heat response

Magnification of grains of refined sucrose, the most common free sugar.

 

Because sugars burn easily when exposed to flame, the handling of sugars risks dust explosion. The risk of explosion is higher when the sugar has been milled to superfine texture, such as for use in chewing gum. 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, exposing sugar to heat causes caramelization. As the process occurs, volatile chemicals such as diacetyl are released, producing the characteristic caramel flavor.

Types

Monosaccharides

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.

• 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.
• Galactose generally 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.
• 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. 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.

Disaccharides

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.

• 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.
• 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. 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.
• 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. 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.

Sources

The sugar contents of common fruits and vegetables are presented in Table 1. The fructose to fructose plus glucose ratio is calculated by including the fructose and glucose coming from the sucrose. 

Table 1. Sugar content of selected common plant foods (g/100g)

Food item	Total carbohydrate including dietary fiber	Total sugars	Free fructose	Free glucose	Sucrose	Fructose/ (Fructose+Glucose) ratio	Sucrose as a % of total sugars
Fruits
Apple	13.8	10.4	5.9	2.4	2.1	0.67	20
Apricot	11.1	9.2	0.9	2.4	5.9	0.42	64
Banana	22.8	12.2	4.9	5.0	2.4	0.5	20
Fig, dried	63.9	47.9	22.9	24.8	0.48	0.9	2
Grapes	18.1	15.5	8.1	7.2	0.2	0.53	1
Navel orange	12.5	8.5	2.25	2.0	4.3	0.51	51
Peach	9.5	8.4	1.5	2.0	4.8	0.47	57
Pear	15.5	9.8	6.2	2.8	0.8	0.67	8
Pineapple	13.1	9.9	2.1	1.7	6.0	0.52	61
Plum	11.4	9.9	3.1	5.1	1.6	0.40	16
Strawberry	7.68	4.89	2.441	1.99	0.47	0.55	10
Vegetables
Beet, red	9.6	6.8	0.1	0.1	6.5	0.50	96
Carrot	9.6	4.7	0.6	0.6	3.6	0.50	77
Corn, sweet	19.0	6.2	1.9	3.4	0.9	0.38	15
Red pepper, sweet	6.0	4.2	2.3	1.9	0.0	0.55	0
Onion, sweet	7.6	5.0	2.0	2.3	0.7	0.47	14
Sweet potato	20.1	4.2	0.7	1.0	2.5	0.47	60
Yam	27.9	0.5	tr	tr	tr	na	tr
Sugar cane		13–18	0.2–1.0	0.2–1.0	11–16	0.50	high
Sugar beet		17–18	0.1–0.5	0.1–0.5	16–17	0.50	high

Production

Sugar beet production – 2016
Country	(millions of tonnes)
Russia	51.4
France	33.8
United States	33.5
Germany	25.5
Turkey	19.5
World	277.2
Source: FAOSTAT, United Nations

Due to rising demand, sugar production in general increased some 14% over the period 2009 to 2018. The largest importers were China, Indonesia, and the United States.

Sugar beet

In 2016, global production of sugar beets was 277 million tonnes, led by Russia with 19% of the world total (table). 

The 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, 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 the field for some weeks before being transported to the processing plant where the crop is washed and sliced, and the sugar extracted by diffusion. Milk of lime is added to the raw juice with calcium carbonate. After water is evaporated by boiling the syrup under a vacuum, the syrup is cooled and seeded with sugar crystals. The white sugar that crystallizes can be separated in a centrifuge and dried, requiring no further refining.

Sugarcane

Sugarcane production – 2016
Country	(millions of tonnes)
Brazil	768.7
India	348.4
China	122.7
Thailand	87.5
World	1890.7
Source: FAOSTAT, United Nations

Global production of sugarcane in 2016 was 1.9 billion tonnes, with Brazil producing 41% of the world total and India 18% (table).

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 the Indian subcontinent and Southeast Asia over centuries for the sucrose 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 for the labor-intensive process resulted in sugar production, enabling prices cheap enough for most people to buy. Mechanization reduced some labor needs, but in the 21st century, cultivation and production relied on low-wage laborers. 

Sugar cane requires a frost-free climate with sufficient rainfall during the growing season to make full use of the plant's substantial 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) where it is either milled and the juice extracted with water or extracted by diffusion. The juice is 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. The resulting supersaturated solution is seeded with sugar crystals, facilitating crystal formation and drying. 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, can be bleached by sulfur dioxide, or can be treated in a carbonatation process to produce a whiter product. About 2,500 litres (660 US gal) of irrigation water is needed for every one kilogram (2.2 pounds) of sugar produced.

Refining

A pack of sugar made from sugar beet

 

Refined sugar is made from raw sugar that has undergone a refining process to remove the molasses. 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.

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.

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.

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). 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.

Forms and uses

Rock candy crystallized out of a supersaturated sugar solution that contains green dye.

• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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) as well as 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.
• 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.

Consumption

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. According to one source, per capita consumption of sugar in 2016 was highest in the United States, followed by Germany and the Netherlands.

Nutrition and flavor

Sugar (sucrose), brown (with molasses)

Nutritional value per 100 g (3.5 oz)
Energy	1,576 kJ (377 kcal)
Carbohydrates	97.33 g
Sugars	96.21 g
Dietary fiber	0 g
Fat	0 g
Protein	0 g
Vitamins	Quantity %DV†
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	Quantity %DV†
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	Quantity
Water	1.77 g

Sugar (sucrose), granulated

Nutritional value per 100 g (3.5 oz)
Energy	1,619 kJ (387 kcal)
Carbohydrates	99.98 g
Sugars	99.91 g
Dietary fiber	0 g
Fat	0 g
Protein	0 g
Vitamins	Quantity %DV†
Riboflavin (B2)	2% 0.019 mg
Minerals	Quantity %DV†
Calcium	0% 1 mg
Iron	0% 0.01 mg
Potassium	0% 2 mg
Other constituents	Quantity
Water	0.03 g

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. Because brown sugar contains 5–10% molasses reintroduced during processing, its value to some consumers is a richer flavor than white sugar.

Health effects

Sugar industry funding and health information

Sugar refiners and manufacturers of sugary foods and drinks have sought to influence medical research and public health recommendations, with substantial and largely clandestine spending documented from the 1960s to 2016. The results of research on the health effects of sugary food and drink differ significantly, depending on whether the researcher has financial ties to the food and drink industry. A 2013 medical review concluded that "unhealthy commodity industries should have no role in the formation of national or international NCD [non-communicable disease] policy".

There have been similar efforts to steer coverage of sugar-related health information in popular media, including news media and social media.

Obesity and metabolic syndrome

A 2003 World Health Organization technical report provided evidence that high intake of sugary drinks (including fruit juice) increased the risk of obesity by adding to overall energy intake. By itself, sugar is not a factor causing obesity and metabolic syndrome, but rather – when over-consumed – is a component of unhealthy dietary behavior. Meta-analyses showed that excessive consumption of sugar-sweetened beverages increased the risk of developing type 2 diabetes and metabolic syndrome – including weight gain and obesity – in adults and children.

Addiction

A 2018 systematic review concluded that the potential for sugar addiction was greater when in combination with dietary fats.

Hyperactivity

Some studies report evidence of causality between high consumption of refined sugar and hyperactivity. One review of low-quality studies of children consuming high amounts of energy drinks showed association with higher rates of unhealthy behaviors, including smoking and alcohol abuse, and with hyperactivity and insomnia.

Tooth decay

The 2003 WHO report stated that "Sugars are undoubtedly the most important dietary factor in the development of dental caries". A review of human studies showed that the incidence of caries is lower when sugar intake is less than 10% of total energy consumed.

Nutritional displacement

The "empty calories" argument states that a diet high in added sugar will reduce consumption of foods that contain essential nutrients. This nutrient displacement occurs if sugar makes up more than 25% of daily energy intake, a proportion associated with poor diet quality and risk of obesity. Displacement may occur at lower levels of consumption.

Alzheimer's disease

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.

Recommended dietary intake

The World Health Organization recommends that both adults and children reduce the intake of free sugars to less than 10% of total energy intake, and suggests a reduction to below 5%. "Free sugars" include monosaccharides and disaccharides added to foods, and sugars found in fruit juice and concentrates, as well as in honey and syrups. According to the WHO, "[t]hese recommendations were based on the totality of available evidence reviewed regarding the relationship between free sugars intake and body weight (low and moderate quality evidence) and dental caries (very low and moderate quality evidence)."

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 is equal to 200 calories and thus 10% of total calories—the same guidance as the World Health Organization. To put this in context, most 12 ounce (335 mL) cans of soda contain 39 grams of sugar. In the United States, a government survey on food consumption in 2013–2014 reported that, for men and women aged 20 and older, the average total sugar intakes—naturally occurring in foods and added—were, respectively, 125 and 99 g/day.

Measurements

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):

• 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:

• 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

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. In 2016, the criticism led to recommendations that diet policymakers emphasize the need for high-quality research that accounts for multiple biomarkers on development of cardiovascular diseases.

Bread

From Wikipedia, the free encyclopedia

Bread

Various leavened breads
Main ingredients	Flour, water
Cookbook: Bread   Media: Bread

Bread is a staple food prepared from a dough of flour and water, usually by baking. Throughout recorded history it has been a prominent food in large parts of the world and is one of the oldest man-made foods, having been of significant importance since the dawn of agriculture.

Bread may be leavened by processes such as reliance on naturally occurring sourdough microbes, chemicals, industrially produced yeast, or high-pressure aeration. Commercial bread commonly contains additives to improve flavor, texture, color, shelf life, nutrition, and ease of manufacturing.
Bread plays essential roles in religious rituals and secular culture.

Etymology

The Old English word for bread was hlaf (hlaifs in Gothic: modern English loaf), which appears to be the oldest Teutonic name. Old High German hleib and modern German Laib derive from this Proto-Germanic word, which was borrowed into Slavic (Polish chleb, Russian khleb) and Finnic (Finnish leipä, Estonian leib) languages as well. The Middle and Modern English word bread appears in Germanic languages, such as West Frisian brea, Dutch brood, German Brot, Swedish bröd, and Norwegian and Danish brød; it may be related to brew or perhaps to break, originally meaning "broken piece", "morsel".

History

Bread shop, Tacuinum Sanitatis from Northern Italy, beginning of the 15th century

 

Bread is one of the oldest prepared foods. Evidence from 30,000 years ago in Europe revealed starch residue on rocks used for pounding plants. It is possible that during this time, starch extract from the roots of plants, such as cattails and ferns, was spread on a flat rock, placed over a fire and cooked into a primitive form of flatbread. The world's oldest evidence of bread-making has been found in a 14,500 year old Natufian site in Jordan's northeastern desert. Around 10,000 BC, with the dawn of the Neolithic age and the spread of agriculture, grains became the mainstay of making bread. Yeast spores are ubiquitous, including on the surface of cereal grains, so any dough left to rest leavens naturally.

There were multiple sources of leavening available for early bread. Airborne yeasts could be harnessed by leaving uncooked dough exposed to air for some time before cooking. Pliny the Elder reported that the Gauls and Iberians used the foam skimmed from beer called barm to produce "a lighter kind of bread than other peoples" such as barm cake. Parts of the ancient world that drank wine instead of beer used a paste composed of grape juice and flour that was allowed to begin fermenting, or wheat bran steeped in wine, as a source for yeast. The most common source of leavening was to retain a piece of dough from the previous day to use as a form of sourdough starter, as Pliny also reported.

The Chorleywood bread process was developed in 1961; it uses the intense mechanical working of dough to dramatically reduce the fermentation period and the time taken to produce a loaf. The process, whose high-energy mixing allows for the use of lower protein grain, is now widely used around the world in large factories. As a result, bread can be produced very quickly and at low costs to the manufacturer and the consumer. However, there has been some criticism of the effect on nutritional value.

Types

Brown bread (left) and whole grain bread

 

Dark sprouted bread

 

Bread is the staple food of the Middle East, Central Asia, North Africa, Europe, and in European-derived cultures such as those in the Americas, Australia, and Southern Africa, in contrast to parts of South and East Asia where rice or noodle is the staple. Bread is usually made from a wheat-flour dough that is cultured with yeast, allowed to rise, and finally baked in an oven. The addition of yeast to the bread explains the air pockets commonly found in bread. Owing to its high levels of gluten (which give the dough sponginess and elasticity), common or bread wheat is the most common grain used for the preparation of bread, which makes the largest single contribution to the world's food supply of any food.

Strucia — a type of European sweet bread

 

Bread is also made from the flour of other wheat species (including spelt, emmer, einkorn and kamut). Non-wheat cereals including rye, barley, maize (corn), oats, sorghum, millet and rice have been used to make bread, but, with the exception of rye, usually in combination with wheat flour as they have less gluten.

Gluten-free breads have been created for people affected by gluten-related disorders such as coeliac disease and non-coeliac gluten sensitivity, who may benefit from a gluten-free diet. Gluten-free bread is made with ground flours from a variety of materials such as almonds, rice, sorghum, corn, or legumes such as beans, and tubers such as cassava, but since these flours lack gluten they may not hold their shape as they rise and their crumb may be dense with little aeration. Additives such as xanthan gum, guar gum, hydroxypropyl methylcellulose (HPMC), corn starch, or eggs are used to compensate for the lack of gluten.

Properties

Physical-chemical composition

In wheat, phenolic compounds are mainly found in hulls in the form of insoluble bound ferulic acid, where it is relevant to wheat resistance to fungal diseases.

Rye bread contains phenolic acids and ferulic acid dehydrodimers.

Three natural phenolic glucosides, secoisolariciresinol diglucoside, p-coumaric acid glucoside and ferulic acid glucoside, can be found in commercial breads containing flaxseed.

Glutenin and gliadin are functional proteins found in wheat bread that contribute to the structure of bread. Glutenin forms interconnected gluten networks within bread through interchain disulfide bonds. Gliadin binds weakly to the gluten network established by glutenin via intrachain disulfide bonds. Structurally, bread can be defined as an elastic-plastic foam (same as styrofoam). The glutenin protein contributes to its elastic nature, as it is able to regain its initial shape after deformation. The gliadin protein contributes to its plastic nature, because it demonstrates non-reversible structural change after a certain amount of applied force. Because air pockets within this gluten network result from carbon dioxide production during leavening, bread can be defined as a foam, or a gas-in-solid solution.

Culinary uses

Bread pudding

 

Bread can be served at many temperatures; once baked, it can subsequently be toasted. It is most commonly eaten with the hands, either by itself or as a carrier for other foods. Bread can be dipped into liquids such as gravy, olive oil, or soup; it can be topped with various sweet and savory spreads, or used to make sandwiches containing meats, cheeses, vegetables, and condiments.

Bread is used as an ingredient in other culinary preparations, such as the use of breadcrumbs to provide crunchy crusts or thicken sauces, sweet or savoury bread puddings, or as a binding agent in sausages and other ground meat products.

Nutritional significance

Nutritionally, bread is categorized as a source of grains in the food pyramid and is a good source of carbohydrates and nutrients such as magnesium, iron, selenium, B vitamins, and dietary fiber.

Crust

Bread crust is formed from surface dough during the cooking process. It is hardened and browned through the Maillard reaction using the sugars and amino acids and the intense heat at the bread surface. The crust of most breads is harder, and more complexly and intensely flavored, than the rest. Old wives tales suggest that eating the bread crust makes a person's hair curlier. Additionally, the crust is rumored to be healthier than the remainder of the bread. Some studies have shown that this is true as the crust has more dietary fiber and antioxidants such as pronyl-lysine, which is being researched for its potential colorectal cancer inhibitory properties.

Preparation

Steps in bread making, here for an unleavened Chilean tortilla

 

Doughs are usually baked, but in some cuisines breads are steamed (e.g., mantou), fried (e.g., puri), or baked on an unoiled frying pan (e.g., tortillas). It may be leavened or unleavened (e.g. matzo). Salt, fat and leavening agents such as yeast and baking soda are common ingredients, though bread may contain other ingredients, such as milk, egg, sugar, spice, fruit such as raisins, vegetables such as onion, nuts such as walnut or seeds such as poppy.

Methods of processing dough into bread include the straight dough process, the sourdough process, the Chorleywood bread process and the sponge and dough process. 

Baking bread in East Timor

Formulation

Professional bread recipes are stated using the baker's percentage notation. The amount of flour is denoted to be 100%, and the other ingredients are expressed as a percentage of that amount by weight. Measurement by weight is more accurate and consistent than measurement by volume, particularly for dry ingredients. The proportion of water to flour is the most important measurement in a bread recipe, as it affects texture and crumb the most. Hard wheat flours absorb about 62% water, while softer wheat flours absorb about 56%. Common table breads made from these doughs result in a finely textured, light bread. Most artisan bread formulas contain anywhere from 60 to 75% water. In yeast breads, the higher water percentages result in more CO₂ bubbles and a coarser bread crumb. One pound (450 g) of flour yields a standard loaf of bread or two French loaves.

Calcium propionate is commonly added by commercial bakeries to retard the growth of molds.

Flour

Flour is grain ground to a powdery consistency. Flour provides the primary structure, starch and protein to the final baked bread. The protein content of the flour is the best indicator of the quality of the bread dough and the finished bread. While bread can be made from all-purpose wheat flour, a specialty bread flour, containing more protein (12–14%), is recommended for high-quality bread. If one uses a flour with a lower protein content (9–11%) to produce bread, a shorter mixing time is required to develop gluten strength properly. An extended mixing time leads to oxidization of the dough, which gives the finished product a whiter crumb, instead of the cream color preferred by most artisan bakers.

Wheat flour, in addition to its starch, contains three water-soluble protein groups (albumin, globulin, and proteoses) and two water-insoluble protein groups (glutenin and gliadin). When flour is mixed with water, the water-soluble proteins dissolve, leaving the glutenin and gliadin to form the structure of the resulting bread. When relatively dry dough is worked by kneading, or wet dough is allowed to rise for a long time, the glutenin forms strands of long, thin, chainlike molecules, while the shorter gliadin forms bridges between the strands of glutenin. The resulting networks of strands produced by these two proteins are known as gluten. Gluten development improves if the dough is allowed to autolyse.

Liquids

Water, or some other liquid, is used to form the flour into a paste or dough. The weight of liquid required varies between recipes, but a ratio of 3 parts liquid to 5 parts flour is common for yeast breads. Recipes that use steam as the primary leavening method may have a liquid content in excess of 1 part liquid to 1 part flour. Instead of water, recipes may use liquids such as milk or other dairy products (including buttermilk or yoghurt), fruit juice, or eggs. These contribute additional sweeteners, fats, or leavening components, as well as water.

Fats or shortenings

Fats, such as butter, vegetable oils, lard, or that contained in eggs, affect the development of gluten in breads by coating and lubricating the individual strands of protein. They also help to hold the structure together. If too much fat is included in a bread dough, the lubrication effect causes the protein structures to divide. A fat content of approximately 3% by weight is the concentration that produces the greatest leavening action. In addition to their effects on leavening, fats also serve to tenderize breads and preserve freshness.

Bread improvers

Bread improvers and dough conditioners are often used in producing commercial breads to reduce the time needed for rising and to improve texture and volume. The substances used may be oxidising agents to strengthen the dough or reducing agents to develop gluten and reduce mixing time, emulsifiers to strengthen the dough or to provide other properties such as making slicing easier, or enzymes to increase gas production.

Salt is often added to enhance flavor and restrict yeast activity. It also affects the crumb and the overall texture by stabilizing and strengthening the gluten. Some artisan bakers forego early addition of salt to the dough, whether wholemeal or refined, and wait until after a 20-minute rest to allow the dough to autolyse.

Leavening

A dough trough, located in Aberdour Castle, once used for leavening bread.

 

Leavening is the process of adding gas to a dough before or during baking to produce a lighter, more easily chewed bread. Most bread eaten in the West is leavened.

Chemicals

A simple technique for leavening bread is the use of gas-producing chemicals. There are two common methods. The first is to use baking powder or a self-raising flour that includes baking powder. The second is to include an acidic ingredient such as buttermilk and add baking soda; the reaction of the acid with the soda produces gas. Chemically leavened breads are called quick breads and soda breads. This method is commonly used to make muffins, pancakes, American-style biscuits, and quick breads such as banana bread.

Yeast

Compressed fresh yeast

 

Many breads are leavened by yeast. The yeast most commonly used for leavening bread is Saccharomyces cerevisiae, the same species used for brewing alcoholic beverages. This yeast ferments some of the carbohydrates in the flour, including any sugar, producing carbon dioxide. Commercial bakers often leaven their dough with commercially produced baker's yeast. Baker's yeast has the advantage of producing uniform, quick, and reliable results, because it is obtained from a pure culture. Many artisan bakers produce their own yeast with a growth culture. If kept in the right conditions, it provides leavening for many years.

The baker's yeast and sourdough methods follow the same pattern. Water is mixed with flour, salt and the leavening agent. Other additions (spices, herbs, fats, seeds, fruit, etc.) are not needed to bake bread, but are often used. The mixed dough is then allowed to rise one or more times (a longer rising time results in more flavor, so bakers often "punch down" the dough and let it rise again), then loaves are formed, and (after an optional final rising time) the bread is baked in an oven.

Many breads are made from a "straight dough", which means that all of the ingredients are combined in one step, and the dough is baked after the rising time; others are made from a "pre-ferment" in which the leavening agent is combined with some of the flour and water a day or so ahead of baking and allowed to ferment overnight. On the day of baking, the rest of the ingredients are added, and the process continues as with straight dough. This produces a more flavorful bread with better texture. Many bakers see the starter method as a compromise between the reliable results of baker's yeast and the flavor and complexity of a longer fermentation. It also allows the baker to use only a minimal amount of baker's yeast, which was scarce and expensive when it first became available. Most yeasted pre-ferments fall into one of three categories: "poolish" or "pouliche", a loose-textured mixture composed of roughly equal amounts of flour and water (by weight); "biga", a stiff mixture with a higher proportion of flour; and "pâte fermentée", which is simply a portion of dough reserved from a previous batch.

Before first rising	After first rising	After proofing, ready to bake

Sourdough

Sourdough loaves

 

Sourdough is a type of bread produced by a long fermentation of dough using naturally occurring yeasts and lactobacilli. It usually has a mildly sour taste because of the lactic acid produced during anaerobic fermentation by the lactobacilli.

Sourdough breads are made with a sourdough starter. The starter cultivates yeast and lactobacilli in a mixture of flour and water, making use of the microorganisms already present on flour; it does not need any added yeast. A starter may be maintained indefinitely by regular additions of flour and water. Some bakers have starters many generations old, which are said to have a special taste or texture. At one time, all yeast-leavened breads were sourdoughs. Recently there has been a revival of sourdough bread in artisan bakeries.

Traditionally, peasant families throughout Europe baked on a fixed schedule, perhaps once a week. The starter was saved from the previous week's dough. The starter was mixed with the new ingredients, the dough was left to rise, and then a piece of it was saved (to be the starter for next week's bread).

Steam

The rapid expansion of steam produced during baking leavens the bread, which is as simple as it is unpredictable. Steam-leavening is unpredictable since the steam is not produced until the bread is baked. Steam leavening happens regardless of the raising agents (baking soda, yeast, baking powder, sour dough, beaten egg white) included in the mix. The leavening agent either contains air bubbles or generates carbon dioxide. The heat vaporises the water from the inner surface of the bubbles within the dough. The steam expands and makes the bread rise. This is the main factor in the rising of bread once it has been put in the oven. CO₂ generation, on its own, is too small to account for the rise. Heat kills bacteria or yeast at an early stage, so the CO₂ generation is stopped.

Bacteria

Salt-rising bread employs a form of bacterial leavening that does not require yeast. Although the leavening action is inconsistent, and requires close attention to the incubating conditions, this bread is making a comeback for its cheese-like flavor and fine texture.

Aeration

Aerated bread was leavened by carbon dioxide being forced into dough under pressure. From the mid 19th to mid 20th centuries bread made this way was somewhat popular in the United Kingdom, made by the Aerated Bread Company and sold in its high-street tearooms. The company was founded in 1862, and ceased independent operations in 1955.

The Pressure-Vacuum mixer was later developed by the Flour Milling and Baking Research Association for the Chorleywood bread process. It manipulates the gas bubble size and optionally the composition of gases in the dough via the gas applied to the headspace. The organic baker Andrew Whitely, writing in The Independent, called the process "the covert corruption of our daily food".

Cultural significance

A Ukrainian woman in national dress welcoming with bread and salt

Bread has a significance beyond mere nutrition in many cultures because of its history and contemporary importance. Bread is also significant in Christianity as one of the elements (alongside wine) of the Eucharist, and in other religions including Paganism.

In many cultures, bread is a metaphor for basic necessities and living conditions in general. For example, a "bread-winner" is a household's main economic contributor and has little to do with actual bread-provision. This is also seen in the phrase "putting bread on the table". The Roman poet Juvenal satirized superficial politicians and the public as caring only for "panem et circenses" (bread and circuses). In Russia in 1917, the Bolsheviks promised "peace, land, and bread." The term "breadbasket" denotes an agriculturally productive region. In Slavic cultures bread and salt is offered as a welcome to guests. In India, life's basic necessities are often referred to as "roti, kapra aur makan" (bread, cloth, and house).

Words for bread, including "dough" and "bread" itself, are used in English-speaking countries as synonyms for money. A remarkable or revolutionary innovation may be called the best thing since "sliced bread". The expression "to break bread with someone" means "to share a meal with someone". The English word "lord" comes from the Anglo-Saxon hlāfweard, meaning "bread keeper."

Bread is sometimes referred to as "the staff of life", although this term can refer to other staple foods in different cultures: the Oxford English Dictionary defines it as "bread (or similar staple food)". This is sometimes thought to be a biblical reference, but the nearest wording is in Leviticus 26 "when I have broken the staff of your bread". The term has been adopted in the names of bakery firms.

Golden rice

From Wikipedia, the free encyclopedia

Golden rice (right) compared to white rice (left)

 

Golden rice is a variety of rice (Oryza sativa) produced through genetic engineering to biosynthesize beta-carotene, a precursor of vitamin A, in the edible parts of rice. It is intended to produce a fortified food to be grown and consumed in areas with a shortage of dietary vitamin A, a deficiency which each year is estimated to kill 670,000 children under the age of 5 and cause an additional 500,000 cases of irreversible childhood blindness. Rice is a staple food crop for over half of the world's population, making up 30–72% of the energy intake for people in Asian countries, making it an excellent crop for targeting vitamin deficiencies.

Golden rice differs from its parental strain by the addition of three beta-carotene biosynthesis genes. The parental strain can naturally produce beta-carotene in its leaves, where it is involved in photosynthesis. However, the plant does not normally produce the pigment in the endosperm, where photosynthesis does not occur. Golden rice has met significant opposition from environmental and anti-globalization activists that claim that there are sustainable, long-lasting and more efficient ways to solve vitamin A deficiency that do not compromise food, nutrition and financial security, as they claim golden rice does. A study in the Philippines is aimed to evaluate the performance of golden rice, if it can be planted, grown and harvested like other rice varieties, and whether golden rice poses risk to human health. There has been little research on how well the beta-carotene will hold up when stored for long periods between harvest seasons, or when cooked using traditional methods.

In 2005, Golden Rice 2 was announced, which produces up to 23 times more beta-carotene than the original golden rice. To receive the USDA's Recommended Dietary Allowance (RDA), it is estimated that 144 g/day of the high-yielding strain would have to be eaten. Bioavailability of the carotene from golden rice has been confirmed and found to be an effective source of vitamin A for humans. Golden Rice was one of the seven winners of the 2015 Patents for Humanity Awards by the United States Patent and Trademark Office. In 2018 came the first approvals as food in Australia, New Zealand, Canada and the USA.

History

The search for a golden rice started off as a Rockefeller Foundation initiative in 1982.

A simplified overview of the carotenoid biosynthesis pathway in golden rice. The enzymes expressed in the endosperm of golden rice, shown in red, catalyze the biosyntheis of beta-carotene from geranylgeranyl diphosphate. Beta-carotene is assumed to be converted to retinal and subsequently retinol (vitamin A) in the animal gut

 

Peter Bramley discovered in the 1990s that a single phytoene desaturase gene (bacterial CrtI) can be used to produce lycopene from phytoene in GM tomato, rather than having to introduce multiple carotene desaturases that are normally used by higher plants. Lycopene is then cyclized to beta-carotene by the endogenous cyclase in golden rice.

The scientific details of the rice were first published in Science in 2000, the product of an eight-year project by Ingo Potrykus of the Swiss Federal Institute of Technology and Peter Beyer of the University of Freiburg. At the time of publication, golden rice was considered a significant breakthrough in biotechnology, as the researchers had engineered an entire biosynthetic pathway. 

The first field trials of golden rice cultivars were conducted by Louisiana State University Agricultural Center in 2004. Additional trials have been conducted in the Philippines and Taiwan, and in Bangladesh (2015). Field testing provides an accurate measurement of nutritional value and enables feeding tests to be performed. Preliminary results from field tests have shown field-grown golden rice produces 4 to 5 times more beta-carotene than golden rice grown under greenhouse conditions.

Crossbreeding

In several countries, golden rice has been bred with local rice cultivars. or crossbred with the American rice cultivar 'Cocodrie'. As of March 2016, golden rice has not yet been grown commercially, and backcrossing is still ongoing in current varieties to reduce yield drag .

Golden Rice 2

In 2005, a team of researchers at Syngenta produced Golden Rice 2. They combined the phytoene synthase gene from maize with crt1 from the original golden rice. Golden rice 2 produces 23 times more carotenoids than golden rice (up to 37 µg/g), and preferentially accumulates beta-carotene (up to 31 µg/g of the 37 µg/g of carotenoids).

Approvals

In 2018, Canada, Australia, New Zealand, and the United States approved Golden Rice for cultivation while the Philippines and Bangladesh were considering applications for cultivation.

Bangladeshi Agriculture Minister Abdur Razzak announced in February 2019 that cultivation of Golden Rice may start in Bangladesh within three months.

As of 2018, no Golden Rice or Golden Rice 2 has been grown for human consumption other than in supervised clinical trials.

Genetics

Golden rice was created by transforming rice with two beta-carotene biosynthesis genes:

1. psy (phytoene synthase) from daffodil ('Narcissus pseudonarcissus')
2. crtI (phytoene desaturase) from the soil bacterium Erwinia uredovora

(The insertion of a lcy (lycopene cyclase) gene was thought to be needed, but further research showed it is already produced in wild-type rice endosperm.) 

The psy and crtI genes were transferred into the rice nuclear genome and placed under the control of an endosperm-specific promoter, so that they are only expressed in the endosperm. The exogenous lcy gene has a transit peptide sequence attached, so it is targeted to the plastid, where geranylgeranyl diphosphate is formed. The bacterial crtI gene was an important inclusion to complete the pathway, since it can catalyze multiple steps in the synthesis of carotenoids up to lycopene, while these steps require more than one enzyme in plants. The end product of the engineered pathway is lycopene, but if the plant accumulated lycopene, the rice would be red. Recent analysis has shown the plant's endogenous enzymes process the lycopene to beta-carotene in the endosperm, giving the rice the distinctive yellow color for which it is named. The original golden rice was called SGR1, and under greenhouse conditions it produced 1.6 µg/g of carotenoids.

Vitamin A deficiency

Prevalence of vitamin A deficiency. Red is most severe (clinical), green least severe. Countries not reporting data are coded blue. Data collected for a 1995 report.

 

The research that led to golden rice was conducted with the goal of helping children who suffer from vitamin A deficiency (VAD). In 2005, 190 million children and 19 million pregnant women, in 122 countries, were estimated to be affected by VAD. VAD is responsible for 1–2 million deaths, 500,000 cases of irreversible blindness and millions of cases of xerophthalmia annually. Children and pregnant women are at highest risk. Vitamin A is supplemented orally and by injection in areas where the diet is deficient in vitamin A. 

As of 1999, 43 countries had vitamin A supplementation programs for children under 5; in 10 of these countries, two high dose supplements are available per year, which, according to UNICEF, could effectively eliminate VAD. However, UNICEF and a number of NGOs involved in supplementation note more frequent low-dose supplementation is preferable.

Because many children in VAD-affected countries rely on rice as a staple food, genetic modification to make rice produce the vitamin A precursor beta-carotene was seen as a simple and less expensive alternative to ongoing vitamin supplements or an increase in the consumption of green vegetables or animal products. Initial analyses of the potential nutritional benefits of golden rice suggested consumption of golden rice would not eliminate the problems of vitamin A deficiency, but could complement other supplementation. Golden Rice 2 contains sufficient provitamin A to provide the entire dietary requirement via daily consumption of some 75g per day.

Since carotenes are hydrophobic, sufficient fat must be present in the diet for golden rice (or most other vitamin A supplements) to alleviate vitamin A deficiency. Vitamin A deficiency is usually coupled to an unbalanced diet (see also Vandana Shiva's arguments below). Moreover, this claim referred to an early cultivar of golden rice; one bowl of the latest version provides 60% of RDA for healthy children. The RDA levels advocated in developed countries are far in excess of the amounts needed to prevent blindness.

Research

Clinical trials/food safety and nutrition research

In 2009, results of a clinical trial of golden rice with adult volunteers from the US were published in the American Journal of Clinical Nutrition. The trial concluded that "beta-carotene derived from golden rice is effectively converted to vitamin A in humans". A summary for the American Society for Nutrition suggested that "Golden Rice could probably supply 50% of the Recommended Dietary Allowance (RDA) of vitamin A from a very modest amount — perhaps a cup — of rice, if consumed daily. This amount is well within the consumption habits of most young children and their mothers".

It is well known that beta-carotene is found and consumed in many nutritious foods eaten around the world, including fruits and vegetables. Beta-carotene in food is a safe source of vitamin A. In August 2012, Tufts University and others published research on golden rice in the American Journal of Clinical Nutrition showing that the beta-carotene produced by golden rice is as effective as beta-carotene in oil at providing vitamin A to children. The study stated that "recruitment processes and protocol were approved". In 2015 the journal retracted the study, claiming that the researchers had acted unethically when providing Chinese children golden rice without their parents' consent.

The Food Allergy Resource and Research Program of the University of Nebraska undertook research in 2006 that showed the proteins from the new genes in Golden Rice 2 showed no allergenic properties.

Controversy

Critics of genetically engineered crops have raised various concerns. An early issue was that golden rice originally did not have sufficient vitamin A. This problem was solved by the development of new strains of rice. The speed at which vitamin A degrades once the rice is harvested, and how much remains after cooking are contested. However, a 2009 study concluded that beta-carotene from golden rice is effectively converted into vitamin A in humans and a 2012 study that fed 68 children ages 6 to 8 concluded that golden rice was as good as vitamin A supplements and better than the natural beta-carotene in spinach.

Greenpeace opposes the use of any patented genetically modified organisms in agriculture and opposes the cultivation of golden rice, claiming it will open the door to more widespread use of GMOs. The International Rice Research Institute (IRRI) has emphasised the non-commercial nature of their project, stating that "None of the companies listed ... are involved in carrying out the research and development activities of IRRI or its partners in Golden Rice, and none of them will receive any royalty or payment from the marketing or selling of golden rice varieties developed by IRRI."

Vandana Shiva, an Indian anti-GMO activist, argued the problem was not the plant per se, but potential problems with poverty and loss of biodiversity. Shiva claimed these problems could be amplified by the corporate control of agriculture. By focusing on a narrow problem (vitamin A deficiency), Shiva argued, golden rice proponents were obscuring the limited availability of diverse and nutritionally adequate food. Other groups argued that a varied diet containing foods rich in beta-carotene such as sweet potato, leaf vegetables and fruit would provide children with sufficient vitamin A. Keith West of Johns Hopkins Bloomberg School of Public Health has stated that foodstuffs containing vitamin A are often unavailable, only available at certain seasons, or too expensive for poor families in underdeveloped countries.

In 2008, WHO malnutrition expert Francesco Branca cited the lack of real-world studies and uncertainty about how many people will use golden rice, concluding "giving out supplements, fortifying existing foods with vitamin A, and teaching people to grow carrots or certain leafy vegetables are, for now, more promising ways to fight the problem". In 2013, author Michael Pollan, who had critiqued the product in 2001, unimpressed by the benefits, expressed support for the continuation of the research.

Support

The Bill and Melinda Gates Foundation supports the use of genetically modified organisms in agricultural development and supports the International Rice Research Institute in developing golden rice. In June 2016, 107 Nobel laureates signed a letter urging Greenpeace and its supporters to abandon their campaign against GMOs, and against golden rice in particular.

In May 2018, the U.S. Food and Drug Administration approved the use of golden rice for human consumption, stating: "Based on the information IRRI has presented to FDA, we have no further questions concerning human or animal food derived from GR2E rice at this time." This marks the fourth national health organisation to approve the use of golden rice in 2018, joining Australia, Canada and New Zealand who issued their assessments earlier in the year.

Protests

On August 8, 2013, an experimental plot of golden rice being developed at IRRI in the Philippines was uprooted by protesters. British author Mark Lynas reported in Slate that the vandalism was carried out by a group of activists led by the extreme left-inclined Kilusang Magbubukid ng Pilipinas (KMP) (unofficial translation: Farmers' Movement of the Philippines), to the dismay of other protesters. No local farmers participated in the uprooting; only the small number of activists damaged the golden rice crops because the farmers believe local customs which imply that killing a living rice plant is unlucky.

Distribution

A recommendation was made that golden rice to be distributed free to subsistence farmers. Free licenses for developing countries were granted quickly due to the positive publicity that golden rice received, particularly in Time magazine in July 2000. Monsanto Company was one of the companies to grant free licences for related patents owned by the company. The cutoff between humanitarian and commercial use was set at US$10,000. Therefore, as long as a farmer or subsequent user of golden rice genetics would not make more than $10,000 per year, no royalties would need to be paid. In addition, farmers would be permitted to keep and replant seed.