gluten

(glūt'n)

1. The mixture of proteins, including gliadins and glutelins, found in wheat grains, which are not soluble in water and which give wheat dough its elastic texture.
2. Any of the prolamins found in cereal grains, especially the prolamins in wheat, rye, barley, and possibly oats, that cause digestive disorders such as celiac disease.

[French, from Latin glūten, glue.]

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The protein complex in wheat, and to a lesser extent barley and rye, which gives dough the viscid property that holds gas when it rises. It is a mixture of two proteins, gliadin and glutelin. Allergy to, or intolerance of, the gliadin fraction of gluten is coeliac disease.

In the undamaged state with extensible properties it is termed vital gluten; when overheated, these properties are lost and the product, devitalized gluten, is used for protein enrichment of foods. See also food, gluten-free.

A mixture of two proteins, gliadin and glutenin, gluten is a major component of rye, wheat flower and barley, imparting springiness into wheat products. Gluten is not present in oats or maize. See also coeliac disease.

[GLOO-tihn] Wheat and other cereals that are made into flour contain proteins, one of which is glutenin, commonly known as gluten. Viewed alone, gluten is a tough, elastic, grayish substance resembling chewing gum. It's the gluten in flour that, when a dough is kneaded, helps hold in the gas bubbles formed by the leavening agent (see leavener). Gas contained within a dough or batter helps a bread or other baked good rise, creating a light structure. Most (but not all) flours contain gluten in varying amounts. Bread (or hard wheat) flour has a high gluten content and is therefore good for yeast breads, which require an elastic framework. On the other hand, low-protein (and therefore low-gluten) cake flour has a softer, less elastic quality and is better suited for cakes. See also bread; flour; seitan.

The term ‘gluten’ comes from the Latin word for glue. The use of the word gluten to describe a sticky proteinatious component of dough was established by the middle of the nineteenth century. Mrs Beeton in her famous Book of household management observed that when flour and water were mixed and kneaded, an elastic dough was produced which was best using wheat flour, less satisfactory with rye flour, and inadequate with barley, maize (corn), oats, or rice. This sticky elastic substance, or gluten, is essential for making satisfactory leavened bread. Bubbles of carbon dioxide released from fermenting yeast are trapped by the visco-elastic protein, ensuring a light honeycombed texture for the dough. The elastic nature of gluten also holds particles of the dough together, preventing crumbling during rolling and shaping.

Wheat gluten can be extracted from wheat flour by adding sufficient water to make a kneadable dough which is then washed with a stream of cold water. The water-soluble protein and starch granules are thus flushed away, leaving a sticky mass high in structural plant protein. About 70% of the mass is water and 30% is protein. With drying, a pale, yellow-grey powder is produced. Gluten is poorly soluble in water, but the fraction known as ‘gliadin’ is soluble in aqueous alcohol. Two thirds of gluten protein is in the form of glutenins, which are insoluble in ethyl alcohol but soluble in a mixture of ethanoic acid, urea, and cetrimide. There are more than 40 different gliadin proteins, which traditionally have been separated by starch gel electrophoresis. The fraction with the fastest mobility is known as alpha gliadin, with progressively slower mobility groups classified as beta, gamma, and omega. These proteins have molecular weights between 30 000 and 40 000. The glutenin proteins are much larger units, mostly around 2 000 000 molecular weight. The glutenin protein chains form a three-dimensional net when hydrated (mixed with water) and this gives the elastic properties to gluten.

Not all sticky plant cereals in our diet contain gluten. A type of rice grown in the Far East known as glutinous or sticky rice contains no proteinatious gluten and owes its sticky nature to a waxy carbohydrate.

The sticky nature of gluten has been utilized as a paper and fabric glue, as in making papier-mâché and wallpaper paste. Wheat gluten has also been used as a cattle feed and as a starting point for the manufacture of the food flavour enhancer, monosodium glutamate.

Although the presence of gluten in wheat flour has been utilized to create a variety of pasta shapes, such as noodles, spaghetti, and tagliatelle, gluten is not an essential human nutrient. There is however, some experimental work to suggest that dietary gluten may be protective against some toxic substances. For example, gluten in the diet of rats reduces the liver toxicity of a known toxic chemical, D-galactosamine.

Gluten and coeliac disease

The importance of gluten in the human diet however, relates to the fact that 1 in 200-300 of the European Caucasian population are intolerant to wheat, barley, and rye gluten.

The lining cells of the small intestine become damaged and the patients develop a condition known as coeliac disease or permanent gluten-induced enteropathy. The classical presentation was of a pre-school child with diarrhoea and weight loss. Possibly due to nutritional campaigns to delay the introduction of gluten to infant diets, an insidious onset later in childhood, with anaemia and poor growth in height, is now more frequently seen. Onset in adult life may occur, with anaemia, infertility, and vitamin D deficient bone disease amongst the possible presenting features, although gastrointestinal symptoms and weight loss may, as in children, be the main complaints.

Although this medical condition was described in the first century ad by Aretaeus and accurately, clinically, delineated by a London physician, Dr Samuel Gee, in the late nineteenth century, its cause and cure were not discovered until the 1940s. Dr W. K. Dicke, an astute Dutch physician, noticed that in Holland children with coeliac disease were temporarily cured and improved in health during the World War II famine created by Nazi occupation. He then observed the relapse in their condition when wheat flour was flown in by the Swedish authorities. Subsequent work by Dicke and colleagues and later investigators identified the toxic factor to be an oligopeptide in alpha gliadin.

The practice of cereal cultivation by man started first in the Middle East around 8000 years bc. There was subsequently a gradual spread north and westward. Cereal cultivation arrived late in southwest Ireland, at around 3000 years bc, and wheat was not a staple food until after the potato famine of 1847. The majority of patients suffering from gluten-induced enteropathy (coeliac disease) are of tissue type HLA B8. The incidence of coeliac disease in southwest Ireland, particularly Galway, is amongst the highest in Europe, and there is correspondingly a high prevalence of HLA B8 tissue type. It has been suggested that when populations consume large quantities of gluten from wheat cereals the susceptible HLA B8 individuals develop disease and are at a reproductive disadvantage compared with those not genetically predisposed to the disease, leading to a reduced proportion of B8 individuals in subsequent generations.

Many commercially-prepared foods in Europe contain gluten. Wheat flour is added as a bulking agent in many items of confectionery, as thickeners in sauces, to give bulk and to reduce the cost of meat products, such as sausage meat, and even in some pharmaceutical preparations. It is therefore difficult without a detailed knowledge of the constituents of manufactured foods for an individual to adhere strictly to a gluten free diet. Some food labels indicate the product is gluten free, either in words or as a symbol — an ear of wheat with a cross through it. ‘Gluten free’ flour and bread are available and usually contain starch from maize (corn) or rice, with some of the elastic properties of gluten being provided by guar gum or similar substances.

— T. J. Evans

See also alimentary system; diets.

Tutor's tip: You can be a "glutton" (a heavy eater) for breads and cereals that have a lot of "gluten" (proteins found in cereal grains) in them.

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The protein of wheat and other grains that gives dough its tough, elastic character.

• g. sensitivity — called also gluten enteropathy. See wheat-sensitive enteropathy.

An insoluble protein constituent of wheat and other grains consisting of a mixture of gliadin, glutenin, and other proteins. Gluten provides the elastic qualities of bread dough.

• flour

For the food products made from gluten, see Wheat gluten (food).

Sources of gluten.

Gluten (from Latin gluten, "glue") is a protein composite found in foods processed from wheat and related grain species, including barley and rye. It gives elasticity to dough, helping it to rise and to keep its shape, and often giving the final product a chewy texture.

Gluten is the composite of a gliadin and a glutelin, which is conjoined with starch in the endosperm of various grass-related grains. The prolamin and glutelin from wheat (gliadin, which is alcohol-soluble, and glutenin, which is only soluble in dilute acids or alkalis) compose about 80% of the protein contained in wheat seed. Being insoluble in water, they can be purified by washing away the associated starch. Worldwide, gluten is a source of protein, both in foods prepared directly from sources containing it, and as an additive to foods otherwise low in protein.

The seeds of most flowering plants have endosperms with stored protein to nourish embryonic plants during germination. True gluten, with gliadin and glutenin, is limited to certain members of the grass family. The stored proteins of maize and rice are sometimes called glutens, but their proteins differ from gluten.

Contents 1 Extraction 2 Uses 2.1 Bread products 2.1.1 Added gluten 2.2 Imitation meats 2.3 Added to other foods 2.4 Animal feed 3 Adverse reactions 4 References 5 Further reading

Extraction

Gluten is extracted from flour by kneading the flour, agglomerating the gluten into an elastic network, a dough, and then washing out the starch. Starch granules disperse in cold water, and the dispersed starch will be sedimented and dried. If a saline solution is used instead of water, a purer protein is obtained, with certain harmless impurities going into solution with the starch. Where starch is the prime product, cold water is the favored solvent because the impurities stay with the gluten.

In home or play-dough cooking, a ball of wheat flour dough is kneaded under water until the starch disperses out. In industrial production, a slurry of wheat flour is kneaded vigorously by machinery until the gluten agglomerates into a mass. This mass is collected by centrifugation, then transported through several stages integrated in a continuous process.^[1] Approximately 65% of the water in the wet gluten is removed by means of a screw press; the remainder is sprayed through an atomizer nozzle into a drying chamber, where it remains at an elevated temperature a short time to evaporate the water without denaturing the gluten. The process yields a flour-like powder with a 7% moisture content, which is air cooled and pneumatically transported to a receiving vessel. In the final step, the collected gluten is sifted and milled to produce a uniform product.^[2]

Uses

Wheat, a prime source of gluten

Fried gluten balls

Bread products

Gluten forms when glutenin molecules cross-link to form a sub-microscopic network attached to gliadin, which contributes viscosity (thickness) and extensibility to the mix.^[3] If this dough is leavened with sugar, fermentation produces carbon dioxide bubbles, which, trapped by the gluten network, cause the dough to rise. Baking coagulates the gluten, which, along with starch, stabilizes the shape of the final product. Gluten content has been implicated as a factor in the staling of bread, possibly because it binds water through hydration.^[4]

The development of gluten (i.e., enhancing its elasticity) affects the texture of the baked goods. Gluten's attainable elasticity is proportional to its content of glutenins with low molecular weights as this portion contains the preponderance of the sulfur atoms responsible for the cross-linking in the network.^[5][6] More refining (of the gluten) leads to chewier products such as pizza and bagels, while less refining yields tender baked goods such as pastry products. Generally, bread flours are high in gluten (hard wheat); pastry flours have a lower gluten content. Kneading promotes the formation of gluten strands and cross-links, creating baked product that is chewier in proportion to the length of kneading. An increased moisture content in the dough enhances gluten development,^[7] and very wet doughs left to rise for a long time require no kneading (see no-knead bread). Shortening inhibits formation of cross-links and is used, along with diminished water and less kneading, when a tender and flaky product, such as a pie crust, is desired.

The strength and elasticity of gluten in flour is measured in the baking industry using a farinograph. This gives the baker a measurement of quality for different varieties of flours in developing recipes for various baked goods.

Added gluten

Gluten, when dried and milled to a powder and added to ordinary flour dough, improves a dough's ability to rise and increases the bread's structural stability and chewiness.^[8] Gluten-added dough must be worked vigorously to induce it to rise to its full capacity; an automatic bread machine or food processor may be required for kneading.^[9] The added gluten provides supplemental protein to products with low or nonexistent protein levels.

Imitation meats

For more details on the use of gluten in cooking, see Wheat gluten (food).

Gluten, especially wheat gluten, is often the basis for imitation meats resembling chicken, duck (mock duck), fish, pork and beef. When cooked in broth, gluten absorbs some of the surrounding liquid (including the taste) and becomes firm to the bite.

Added to other foods

The "Codex Alimentarius" international standards for food labeling has a standard relating to the labeling of products as "gluten-free", but this standard does not apply to foods that "...in their normal form do not contain gluten."^[10] Gluten is used as a stabilizing agent in products like ice cream and ketchup, where it might be unexpected.^[11][12] Foods of this kind present a problem because the hidden gluten constitutes a hazard for people with coeliac disease: In the United States, at least, gluten might not be listed on the labels of such foods because the U.S. Food and Drug Administration has classified gluten as GRAS (generally recognized as safe).^[13] Requirements for proper labeling are being formulated by the USDA. In the United Kingdom, only cereals currently must be labeled, while labeling of other products is voluntary.^[14]

Animal feed

The protein content of some pet foods may also be enhanced by adding gluten.^[15]

Adverse reactions

Main articles: Gluten sensitivity and Gluten-free diet

Between 0.5 and 1.0 percent of people in the United States are sensitive to gluten due to Coeliac disease.^[16][17] Celiac disease constitutes an abnormal immune reaction to partially digested gliadin. It probably occurs with comparable frequencies among all wheat-eating populations in the world.^[18] Certain allergies and neuropathies are also caused by gluten consumption and inhalation. In some instances what is known as cross contamination can occur without the person even being aware that they are ingesting gluten. Reported examples occur when people share silverware or other eating instruments. ^[19] Wheat allergy and celiac disease are different disorders.^[20]

References

1. ^ "Wheat Starch and Wheat Gluten". GEA Westfalia Separator Group. http://www.westfalia-separator.com/applications/renewable-resources/wheat-starch-wheat-gluten.html. Retrieved 19 October 2011. 
2. ^ "Wheat". GEA Barr-Rosin. http://www.barr-rosin.com/applications/wheat.asp. Retrieved 8 September 2009. 
3. ^ Woychick, JH; et al.. "The Gluten Proteins and Deamidated Soluble Wheat Protein". http://www.friedli.com/research/PhD/gluten/chap2.html. Retrieved 8 September 2009. 
4. ^ Sahlstrom, S. & Brathen, E. (1997). "Effects of enzyme preparations for baking, mixing time and resting time on bread quality and bread staling". Food Chemistry, 58, 1, 75-80. Effects of wheat variety and processing conditions in experimental bread-baking studied by univariate and multivariate analysis.
5. ^ Edwards, N. M.; Mulvaney, S. J.; Scanlon, M. G.; Dexter, J. E. (2003). "Role of gluten and its components in determining durum semolina dough viscoelastic properties". Cereal chemistry 80 (6): 755–763. doi:10.1094/CCHEM.2003.80.6.755. http://cat.inist.fr/?aModele=afficheN&cpsidt=15273405. Retrieved 2007-08-14. 
6. ^ Tosi, Paola; Masci, Stefania; Giovangrossi, Angela2; D'Ovidio, Renato; Bekes, Frank; Larroque, Oscar; Napier, Johnathan; Shewry, Peter (September 2005). "Modification of the Low Molecular Weight (LMW) Glutenin Composition of Transgenic Durum Wheat: Effects on Glutenin Polymer Size and Gluten Functionality". Molecular Breeding 16 (2): 113–126. doi:10.1007/s11032-005-5912-1. http://www.ingentaconnect.com/content/klu/molb/2005/00000016/00000002/00005912. Retrieved 2007-08-14. 
7. ^ "Baking Technology, Bread". Bakersassist. http://www.bakersassist.nl/processing5-2.htm. Retrieved 2007-08-14. 
8. ^ Amendola, J., Rees, N., & Lundberg, D. E. (2002). Understanding Baking.
9. ^ Echkardt, LW & Butts, DC. (1997). Rustic European Breads from your Bread Machine
10. ^ "Codex Standard For "Gluten-Free Foods" CODEX STAN 118-1981" (PDF). Codex Alimentarius. February 22, 2006. http://www.codexalimentarius.net/download/standards/291/CXS_118e.pdf. 
11. ^ Pat Kendall, Ph.D., R.D. (March 31, 2003). "Gluten sensitivity more widespread than previously thought". Colorado State University Extension. http://www.ext.colostate.edu/pubs/columnnn/nn030331.html. 
12. ^ A Harvard teaching hospital. "Following a Gluten-free Diet". Beth Israel Deaconess Medical Center. http://bidmc.harvard.edu/default.asp?leaf_id=12799. 
13. ^ "Sec. 184.1322 Wheat gluten". Code of Federal Regulations Center. April 1, 2007. http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=184.1322. 
14. ^ "Guidance Notes on the Food Labelling (Amendment) (No. 2) Regulations 2004" (PDF). Food Standards Agency. November 2005. http://www.food.gov.uk/multimedia/pdfs/labelamendguid21nov05.pdf. 
15. ^ "Pet Foods". International Wheat Gluten Association. Archived from the original on 2007-10-07. http://web.archive.org/web/20071007175039/http://www.iwga.net/04_pet.htm. Retrieved 2007-08-14. 
16. ^ "Ceoliac Disease". National Digestive Diseases Information Clearing House. National Institutes of Health (NIH). 2004. http://digestive.niddk.nih.gov/ddiseases/pubs/celiac/index.htm. Retrieved 8 September 2009. 
17. ^ "Ceoliac disease". Consensus Development Panel on Celiac Disease. National Institutes of Health (NIH). 2005. http://www.guideline.gov/summary/summary.aspx?doc_id=5692&nbr=0. Retrieved 2007-08-14. 
18. ^ van Heel D, West J (2006). "Recent advances in coeliac disease". Gut 55 (7): 1037–46. doi:10.1136/gut.2005.075119. PMC 1856316. PMID 16766754. http://gut.bmjjournals.com/cgi/content/full/55/7/1037. 
19. ^ David A. Nelsen. "Gluten Sensitive Enteropathy". http://www.uams.edu/celiac/review/GSE1.htm. Retrieved 2007-08-14. ^{[dead link]}
20. ^ "Food intolerance and coeliac disease" (PDF). Food Standards Agency. September 2006. http://www.food.gov.uk/multimedia/pdfs/allergyfactsheettwo.pdf. Retrieved 8 September 2009. 

Sources

• "Gluten Intolerance Celiac disease the Truth Revealed" by Dr Vikki Petersen D.C., C.C.N. of HealthNOW Medical Center

Further reading

• Curtis, B.C.; Rajaram, S.; Macpherson, H.G.. "Bread Wheat, Improvement and production — FAO Plant Production and Protection Series No. #30.". http://www.fao.org/DOCREP/006/Y4011E/y4011e05.htm. Retrieved 2007-08-21 
• Pfluger, Laura. "Marker Assisted Selection in Wheat, Quality traits. Gluten Strength, Coordinated Agricultural Project (funded by USDACREES)". http://maswheat.ucdavis.edu/protocols/gluten/index.htm. Retrieved 2007-09-29 
• Agricultural Databases, Statistics, etc.. USDA Cereal Disease Laboratory. http://www.ars.usda.gov/Main/docs.htm?docid=11017. Retrieved 2007-9-2007 
• Wieser, H. (2007). Cereal Chemistry and Dough Properties, KL1-Gluten Chemistry. German Research Centre of Food Chemistry and Cereal Chemistry and Hans-Dieter-Belitz-Institute for Cereal Grain Research, D-85748 Garching, Germany. http://fp.cerealsandeurope.net/events/sourdough/session1.htm. Retrieved 2007-09-27 
• Wrigley, C.W; Bekes, F.; Bushuk, W (2006). The Gluten Composition of Wheat Varieties and Genotypes. AACC International. ISBN 1-891127-51-9. http://aaccnet.org/grainbin/gluten_gliadin.asp. Retrieved 2007-09-21 

• Dr Vikki and Rick Petersen (2009). The Gluten Effect. True Health Publishing. http://www.healthnowmedical.com/book-and-dvds/the-gluten-effect-book/ 

v d e Barley resources History Domestication · Neolithic Revolution · Triticeae Types of barley Genus: Hordeum · Cultivars: Bere Agronomy Barley diseases Trade Australian Barley Board · Canadian Wheat Board · Corn exchange · Production by country · Wheat pool Parts of the plant Bran · Germ · Husk · Kernel · Gluten · Straw Basic preparations Milling: Flour (types) · Groats · Meal · Middlings · Parboiling: As an ingredient Barley bread · Barley honey · Beer · Caffé d'orzo · Irish whiskey · Japanese whisky · Malta · Roasted barley tea · Scotch whisky · Talbina · see also: Category:Barley-based beverages Associated human diseases Gluten sensitivity (Coeliac disease, etc.) Related concepts Bread riot · Cattle feeding · Plant breeding · Refined grains · Staple food · Whole grain Further information

v d e Wheat resources History Domestication · Neolithic Revolution · Tell Abu Hureyra · Tell Aswad · Triticeae Types of wheat Common · Durum · Einkorn · Emmer · Kamut · Norin 10 · Red Fife · Spelt · Winter wheat Agronomy Wheat breeding · Wheat diseases (list) · Wheat mildew Trade Australian Wheat Board · Canadian Wheat Board · Corn exchange · International Wheat Council · Peak wheat · Production statistics · Protein premium · Wheat pool Parts of the plant Bran · Germ · Gluten · Husk · Kernel · Straw Basic preparations None: Wheatberry · Milling: Farina · Flour (types) · Groats · Middlings · Semolina · Parboiling: Bulgur As an ingredient Bread · Couscous · Cracker · Flatbread · Pasta · Wheat beer · Wheat germ oil · Wheat gluten Associated human diseases Exercise-induced anaphylaxis · Gluten sensitivity (Coeliac disease, Wheat allergy, etc.) Related concepts Bread riot · Plant breeding · Refined grains · Staple food · Wheatpaste · Whole grain Further information

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Dansk (Danish)
n. - gluten

Nederlands (Dutch)
gluten, kleverige stof

Français (French)
n. - gluten

Deutsch (German)
n. - (chem.) Gluten, Kleber, Leim

Ελληνική (Greek)
n. - (βιολ.) γλουτένη, γλοιίνη

Italiano (Italian)
glutine

Português (Portuguese)
n. - glúten (m)

Русский (Russian)
клейковина

Español (Spanish)
n. - gluten

Svenska (Swedish)
n. - gluten

中文（简体）(Chinese (Simplified))
麸质

中文（繁體）(Chinese (Traditional))
n. - 麩質

한국어 (Korean)
n. - (단백질의 일종) 글루텐

日本語 (Japanese)
n. - グルテン

العربيه (Arabic)
‏(الاسم) غراء, مادة بروتينيه دبقه‏

עברית (Hebrew)
n. - ‮תרכובת שני חלבונים הנמצאת בקמח חיטה, חומר דביק‬

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