Tannins are astringent, bitter-tasting plant polyphenols that bind and precipitate proteins. The term tannin refers to the source of tannins used in tanning animal hides into leather; however, the term is widely applied to any large polyphenolic compound containing sufficient hydroxyls and other suitable groups (such as carboxyls) to form strong complexes with proteins and other macromolecules. Tannins have molecular weights ranging from 500 to over 3,000^[1]. An astringent substance is a chemical substance that tends to shrink or constrict body tissues, usually locally after topical medicinal application. ... Polyphenols are a group of plant chemical substances, characterized by the presence of more than one phenol group per molecule. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Tanning is the process of conversion of putrescible skin into non putrescible leather. ... Hides are skins obtained from animals that are used for human use. ... Modern leather-working tools Leather is a material created through the tanning of hides and skins of animals, primarily cattlehide. ... // Hydroxyl group The term hydroxyl group is used to describe the functional group -OH when it is a substituent in an organic compound. ... A carboxyl or carboxylic group is a functional group consisting of a carbon atom and an oxygen atom doubly bonded to each other. ... The molecular mass of a substance (less accurately called molecular weight and abbreviated as MW) is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of carbon-12). ...

Tannins are usually divided into hydrolyzable tannins and condensed tannins (proanthocyanidins). At the center of a hydrolyzable tannin molecule, there is a polyol carbohydrate (usually D-glucose). The hydroxyl groups of the carbohydrate are partially or totally esterified with phenolic groups such as gallic acid (in gallotannins) or ellagic acid (in ellagitannins). Hydrolyzable tannins are hydrolyzed by weak acids or weak bases to produce carbohydrate and phenolic acids. Condensed tannins, also known as proanthocyanidins, are polymers of 2 to 50 (or more) flavonoid units that are joined by carbon-carbon bonds, which are not susceptible to being cleaved by hydrolysis. While hydrolyzable tannins and most condensed tannins are water soluble, some very large condensed tannins are insoluble. Hydrolysis is a chemical reaction or process in which a molecule is split into two parts by reacting with a molecule of water, which has the chemical formula H2O. One of the parts gets an OH- from the water molecule and the other part gets an H+ from the water. ... In chemistry, a molecule is an aggregate of two or more atoms in a definite arrangement held together by chemical bonds [1] [2] [3] [4] [5]. Chemical substances are not infinitely divisible into smaller fractions of the same substance: a molecule is generally considered the smallest particle of a pure... Esterification is the general name for a chemical reaction in which two chemicals (typically an alcohol and an acid) form an ester as the reaction product. ... Chemical structure of gallic acid Gallic acid is an organic acid, also known as 3,4,5-trihydroxybenzoic acid, found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and other plants. ... Ellagic acid C14 H6 O8 CAS No. ... Proanthocyanidin (also known as oligomeric proanthocyanidin (OPC), pycnogenol, leukocyanidin and leucoanthocyanin) is a class of flavonoids. ... Molecular structure of flavone The term flavonoid refers to a class of plant secondary metabolites based around a phenylbenzopyrone structure. ... Hydrolysis is a chemical reaction or process in which a molecule is split into two parts by reacting with a molecule of water, which has the chemical formula H2O. One of the parts gets an OH- from the water molecule and the other part gets an H+ from the water. ...

Tannins may be employed medicinally in antidiarrheal, hemostatic, and antihemorrhoidal compounds. Also, they produce different colors with ferric chloride (either blue, blue black, or green to greenish black) according to the type of tannin. An antidiarrhoeal drug is any medication which provides symptomatic relief for diarrhoea. ... Hemostasis refers to a process whereby bleeding is halted in most animals with a closed circulatory system. ... Hemorrhoids (also known as haemorrhoids, emerods, or piles) are varicosities or swelling and inflammation of veins in the rectum and anus. ...

Examples of gallotannins are the gallic acid esters of glucose in tannic acid (C₇₆H₅₂O₄₆), found in the leaves and bark of many plant species. Chemical structure of gallic acid Gallic acid is an organic acid, also known as 3,4,5-trihydroxybenzoic acid, found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and other plants. ... General formula of a carboxylate ester. ... Glucose (Glc), a monosaccharide (or simple sugar), is the most important carbohydrate in biology. ... This is a bottle of tannic acid. ... Leaves are an Icelandic five-piece alternative rock band who came to prominence in 2002 with their debut album, Breathe, drawing comparisons to groups such as Coldplay and Doves. ... For other meanings of bark, see Bark (disambiguation). ... Divisions Green algae Chlorophyta Charophyta Land plants (embryophytes) Non-vascular plants (bryophytes) Marchantiophyta - liverworts Anthocerotophyta - hornworts Bryophyta - mosses Vascular plants (tracheophytes) †Rhyniophyta - rhyniophytes †Zosterophyllophyta - zosterophylls Lycopodiophyta - clubmosses †Trimerophytophyta - trimerophytes Pteridophyta - ferns and horsetails Seed plants (spermatophytes) †Pteridospermatophyta - seed ferns Pinophyta - conifers Cycadophyta - cycads Ginkgophyta - ginkgo Gnetophyta - gnetae Magnoliophyta - flowering plants...

Foods with tannins

Tea

The tea plant (Camellia sinensis) is an example of a plant said to have a naturally high tannin content. When any type of tea leaf is steeped in hot water it brews a "tart" (astringent) flavor that is characteristic of tannins. This is due to the catechins and other flavonoids. Tea "tannins" are chemically distinct from other types of plant tannins such as tannic acid^[2] and tea extracts have been reported to contain no tannin^[3]. Tea leaves in a Chinese gaiwan. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Molecular structure of flavone The term flavonoid refers to a class of plant secondary metabolites based around a phenylbenzopyrone structure. ...

Wine

Tannins (mainly condensed tannins) are also found in wine, particularly red wine. Tannins in wine can come from many sources and the tactile properties differ depending on the source. Tannins in grape skins and seeds (the latter being especially harsh) tend to be more noticeable in red wines, which are fermented while in contact with the skins and seeds. Tannins extracted from grapes are condensed tannins, which are polymers of procyanidin monomers. Hydrolysable tannins are extracted from the oak wood the wine is aged in. Hydrolysable tannins are more easily oxidised than condensed tannins. A glass of red wine This article is about the alcoholic beverage. ... Species Vitis acerifolia Vitis aestivalis Vitis amurensis Vitis arizonica Vitis x bourquina Vitis californica Vitis x champinii Vitis cinerea Vitis x doaniana Vitis girdiana Vitis labrusca Vitis x labruscana Vitis lincecumii Vitis monticola Vitis mustangensis Vitis x novae-angliae Vitis palmata Vitis riparia Vitis rotundifolia Vitis rupestris Vitis shuttleworthii Vitis... Beer fermenting at a brewery. ... Proanthocyanidin (also known as oligomeric proanthocyanidin (OPC), pycnogenol, leukocyanidin and leucoanthocyanin) is a class of flavonoids. ... In chemistry, a monomer (from Greek mono one and meros part) is a small molecule that may become chemically bonded to other monomers to form a polymer. ...

Modern winemakers take great care to minimize undesirable tannins from seeds by crushing grapes gently to extract their juice. Pressing the grapes results in press wine which is more tannic and might be kept separately. Wines can also take on tannins if matured in oak or wood casks with a high tannin content. Tannins play an important role in preventing oxidation in aging wine and appear to polymerize and make up a major portion of the sediment in wine. The term vintner is applied to wine merchants as well as winemakers. ... A barrel is a hollow cylindrical container, usually made of wood staves and bound with iron bands. ... The most fundamental reactions in chemistry are the redox processes. ... A polymer is a substance composed of molecules with large molecular mass consisting of repeating structural units, or monomers, connected by covalent chemical bonds. ... Sediment is any particulate matter that can be transported by fluid flow and which eventually is deposited as a layer of solid particles on the bed or bottom of a body of water or other liquid. ...

Recently, a study in wine production and consumption has shown that tannins in the form of procyanidins, have a beneficial effect on vascular health. The study showed that tannins suppressed production of the peptide responsible for hardening arteries. To support their findings, the study also points out that wines from the regions of southwest France and Sardinia are particularly rich in procyanidins, and that these regions also produce populations with longer life spans.^[4] Proanthocyanidin (also known as oligomeric proanthocyanidin (OPC), pycnogenol, leukocyanidin and leucoanthocyanin) is a class of flavonoids. ...

Fruits

Pomegranates

Pomegranates contain a diverse array of tannins, particularly hydrolysable tannins. The most abundant of pomegranate tannins are called punicalagins. Punicalagins have a molecular weight of 1038 and are the largest molecule found intact in rat plasma after oral ingestion ^[5] and were found to show no toxic effects in rats who were given a 6% diet of punicalagins for 37 days. ^[6]. Punicalagins are also found to be the major component responsible for pomegranate juice's antioxidant and health benefits ^[7]. Binomial name Punica granatum L. The Pomegranate (Punica granatum) is a fruit-bearing deciduous shrub or small tree growing to 5–8 m tall. ... Punicalagins are tannins, large polyphenol compound which are isomers of 2,3-(S)-hexahydroxydiphenoyl-4,6-(S,S)-gallagyl-D-glucose, hydrolysable tannins with a molecular weight of 1038. ... Space-filling model of the antioxidant metabolite glutathione. ...

Several dietary supplements and nutritional ingredients are available that contain extracts of whole pomegranate and/or are standardized to punicalagins, the marker compound of pomegranate. Extracts of pomegranate are also 'Generally Recognized As Safe' (GRAS) by the United States. It has been recommended to look for pomegranate ingredients that mimic the polyphenol ratio of the fruit, as potent synergistic effects have been observed in 'natural spectrum' extracts, especially pomegranate concentrate normalized to punicalagins ^[8]. Generally Recognized as Safe (GRAS): Designation by the FDA that a chemical or substance (including certain pesticides) added to food is considered safe by experts, and so is exempted from the usual FFDCA food additive tolerance requirements. ...

Persimmons

Some persimmons are highly astringent and therefore inedible when they are not extremely ripe (specifically the Korean, American, and Hachiya or Japanese). This is due to the high level of tannins, and if eaten by humans (and many other animals), the mouth will become completely dry, yet the saliva glands will continue to secrete saliva which cannot affect the tannin-laced food. Species (kaki persimmon) (black sapote) (velvet apple) (date plum) (Texas persimmon) (American persimmon) Persimmon most commonly refers to the edible fruit borne by some species of the genus Diospyros. ...

Berries

Most berries, such as cranberries^[9] strawberries and blueberries^[10], contain both hydrolyzable and condensed tannins. Album cover for Everybody Else Is Doing It, So Why Cant We?, the Cranberries breakthrough debut album. ... Strawberries Promo Strawberries is an album by The Damned released October 1982 on Bronze Records (catalogue #BRON 542). ... For other uses, see Blueberry (disambiguation). ...

Nutrition

If ingested in excessive quantities, tannins inhibit the absorption of minerals such as iron into the body. This is because tannins are metal ion chelators, and tannin-chelated metal ions are not bioavailable. Tannins have been shown to precipitate proteins^[1], which inhibits the absorption of nutrients in some ruminant animals from high-tannin grains such as sorghum. Minerals are natural compounds formed through geological processes. ... General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Atomic mass 55. ... Chelation (from Greek χηλή, chelè, meaning claw) is the process of reversible binding (complexation) of a ligand - the chelant, chelator, chelating agent, sequestering agent, or complexing agent - to a metal ion, forming a metal complex, the chelate. ... In pharmacology, bioavailability is used to describe the fraction of an administered dose of medication that reaches the systemic circulation, one of the principal pharmacokinetic properties of drugs. ...

Uses

Tannins are an important ingredient in the process of tanning leather. Oak bark has traditionally been the primary source of tannery tannin, though synthetic tanning agents are also in use today. Species See List of Quercus species The term oak can be used as part of the common name of any of several hundred species of trees and shrubs in the genus Quercus, and some related genera, notably Cyclobalanopsis and Lithocarpus. ... Tanning is the process of conversion of putrescible skin into non putrescible leather. ...

Iron gall ink utilizes the tannin collected from galls, typically from oak trees. Oak galls and iron(II) sulfate, ingredients of iron gall ink Iron gall ink (sometimes iron gall nut ink) is a purple-black ink made from iron salts and tannin from vegetable sources. ... Kalanchoë infected with crown-gall using Agrobacterium tumefaciens. ... Species See List of Quercus species The term oak can be used as part of the common name of any of several hundred species of trees and shrubs in the genus Quercus, and some related genera, notably Cyclobalanopsis and Lithocarpus. ...

Tannin is a component in a type of industrial particleboard adhesive developed jointly by the Tanzania Industrial Research and Development Organization and Forintek Labs Canada.

References

1. ^ ^{a b} Bate-Smith and Swain, 1962, Flavonoid compounds. In : Comparative biochemistry. Florkin M. Mason H.S. Eds. Vol III. 75-809. Academic Press, New-York.
2. ^ Hamilton-Miller JM. Antimicrobial properties of tea (Camellia sinensis L.). Antimicrob Agents Chemother. 39(11): 2375-2377 (1995) PMID 8585711
3. ^ Wheeler, S.R. Tea and Tannins Science 204: 6-8 (1979) [1] as cited in Yam TS, Hamilton-Miller JM, Shah S. The effect of a component of tea (Camellia sinensis) on methicillin resistance, PBP2' synthesis, and beta-lactamase production in Staphylococcus aureus. J Antimicrob Chemother. 42(2):211-216. (1998) PMID 9738838
4. ^ R. Corder, W. Mullen, N. Q. Khan, S. C. Marks, E. G. Wood, M. J. Carrier and A. Crozier Nature 444, 566 (30 November 2006)
5. ^ Biomed. Pharmacother. 2002, 56, 276-82
6. ^ J. Agric. Food Chem. 2003, 51, 3493-3501
7. ^ J Agric Food Chem 2000 48 (10) 4581-89
8. ^ J Nutr Biochemistry 2005 (16) 360-367
9. ^ Vattem, D. A. Ghaedian, R. Shetty, K. Enhancing health benefits of berries through phenolic antioxidant enrichment: focus on cranberry Asia Pacific Journal of Clinical Nutrition (2005) 14(2) 120-130 [2]
10. ^ R. Puupponen-Pimiä, L. Nohynek, C. Meier, M. Kähkönen, M. Heinonen, A. Hopia & K.-M. Oksman-Caldentey, Antimicrobial properties of phenolic compounds from berries, Journal of Applied Microbiology 90(4) pp494 (2001) [3]

L. Calvi, G.C.J. Mwalongo, B.A. Mwingira, B. Riedl and J.A. Shields; Characterization of Wattle-Tannin-Based Adhesives for Tanzania (A paper published in Holzforchung Vol 49 No 2, 1995).

External links

• Tannin and wine making!
• Tannins: fascinating but sometimes dangerous molecules
• Tannin ChemistryPDF (1.41 MiB)
• History of the italian tannin industry from 1854 at present.