TANNIN

TANNIN = TANNIC ACID = TANNEN

CAS Number: 1401-55-4
EC-Number: 215-753-2
MDL Number: MFCD00066397
Molecular Formula : C76H52O46

Tannins produce different colors with ferric chloride (either blue, blue black, or green to greenish-black) according to the type of tannin. 
Iron gall ink is produced by treating a solution of tannins with iron(II) sulfate.
The type of tannin used may or may not have an impact on the final color of the fiber.

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.
Pinus radiata tannins has been investigated for the production of wood adhesives.
Condensed tannins, e.g., quebracho tannin, and Hydrolyzable tannins, e.g., chestnut tannin, appear to be able to substitute a high proportion of synthetic phenol in phenol-formaldehyde resins for wood particleboard.

Immobilized tannins have been tested to recover uranium from seawater.
Tannins are water-soluble high molecular weight polyphenolic compounds with an ability to bind to proteins, sugars, and starches forming strong chemical complexes stable at pH3.5 to 7.
Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids.

The term tannin (from Anglo-Norman tanner, from Medieval Latin tannāre, from tannum, oak bark) refers to the use of oak and other bark in tanning animal hides into leather. 
The term tannin is widely applied to any large polyphenolic compound containing sufficient hydroxyls and other suitable groups (such as carboxyls) to form strong complexes with various macromolecules.
The tannin compounds are widely distributed in many species of plants, where they play a role in protection from predation (including as pesticides) and might help in regulating plant growth. 

The astringency from the tannins is what causes the dry and puckery feeling in the mouth following the consumption of unripened fruit, red wine or tea.
Tannins have molecular weights ranging from 500 to over 3,000 (gallic acid esters) and up to 20,000 Daltons (proanthocyanidins).
Tannins are an important descriptor for wine tastings and it basically refers to the dryness, bitterness, and astringency of a wine. 

Tannins is most often associated with red wine and is the opposite of the sweetness found in many white wines.
Some varietals of red wines are known and loved for their high tannin levels. 
Tannins are, essentially, a wine's pucker power. 
Tannin is generally more dominant in younger red wines that haven't had the time to soften up with age. 
A wine with high tannins can be described as bitter and astringent.

Tannins are derived from the skins, stems, and seeds of the grapes used to produce the wine. 
Technically, Tannins are plant-derived polyphenols. 
Red wines are in contact with the grape for a longer period, which is why they tend to have higher tannins.
Tannins can also come from the oak barrels used for many aged wines. 
These wood tannins are absorbed into the wine and, in the case of oak, vanilla flavors become apparent in the wine.

Tannins are often described as the textural component that "dries the mouth" when drinking red wines.
Tannins are largely responsible for giving red wines a defined structure or "body." 
Tannins are often one reason why it is recommended that you allow a wine to "breathe" or aerate before drinking it. 
The air softens the tannins, particularly in young red wines.

Tannins are also found in teas, nuts like walnuts and almonds, dark chocolate, spices like cinnamon and clove, a few fruits like pomegranate and grapes, quince, and red beans.
Many styles of wine are considered to be high in tannins. 
One wine of the same varietal can be more or less tannic due to its production
Beyond the taste, high tannin wines tend to bottle age better than those that have fewer tannins. 

Tannins are a recurring term in wine descriptions and a fundamental part of wine jargon. 
Tannins are a type of bitter and astringent chemical compounds that belongs to a larger group called polyphenols. 
Tanninsoccur abundantly in nature, namely in the bark of many trees and in a variety of leaves, legumes and fruits, including grapes.
Tannin molecules are typically much larger than those found in other types of polyphenols, and they have a unique ability to easily combine with other molecules, namely proteins, causing them to precipitate. 

Tannin is the basis of leather production, in which the structure of animal hide is changed (tanned) by using various tree barks.
Because tannins bind with other proteins, including those in human saliva, they create a characteristic astringent, mouth-coating sensation in the mouth.
Tannins' primary role in nature is to make unripe fruits and seeds unpalatable, thus dissuading animals from eating them.

Tannin is a naturally occurring polyphenol found in plants, seeds, bark, wood, leaves, and fruit skins.
Tannins are macromolecules made of phenols: complex bonds of oxygen and hydrogen molecules. (Yep, wine is science!)
The term “tannin” comes from the ancient Latin word for tanner, and refers to the use of tree bark to tan hides.
You’ll find tannin in the skins, seeds and stems of grapes. 
Tannin is also found in oak barrels.

Tannin in wine adds both bitterness and astringency, as well as complexity. 
Tannin is most commonly found in red wine, although some white wines have tannin too (from aging in wooden barrels or fermenting on skins).
While wines with pronounced tannin can seem harsh and astringent on their own, Tannins can be the best of all possible partners for certain foods, and are a key ingredient toward a wine’s ability to age well.

Soluble in water, tannins form dark blue or dark green solutions with iron salts, a property utilized in the manufacture of ink.
Tannins may be classified chemically into two main groups, hydrolyzable and condensed. 
Hydrolyzable tannins (decomposable in water, with which they react to form other substances) yield various water-soluble products, such as gallic acid and protocatechuic acid and sugars. 

Gallotannin, or common tannic acid, is the best known of the hydrolyzable tannins. 
Hydrolyzable tannin is produced by extraction with water or organic solvents from the galls of certain trees, notably the Aleppo oak (Quercus infectoria) and Chinese nutgall (Rhus chinensis). 
Tara, the pod from Caesalpinia spinosa, a plant indigenous to Peru, contains a gallotannin similar to that from galls and has become an important source for refined tannin and gallic acid. 

The European chestnut tree (principally Castanea sativa) and the American chestnut oak (Q. montana) yield hydrolyzable tannins important in leather manufacture. 
Condensed tannins, the larger group, form insoluble precipitates called tanner’s reds, or phlobaphenes. 
Among the important condensed tannins are the extracts from the wood or bark of quebracho (Schinopsis), mangrove (various genera and species), and wattle (Acacia).
Tannin solutions are acidic and have an astringent taste. 

Tannins are responsible for the astringency, colour, and some of the flavour in black and green teas.
Tannin, also called tannic acid, any of a group of phenolic compounds in woody flowering plants that are important deterrents to herbivores and have a number of industrial applications. 
As secondary metabolites, tannins are sequestered in vacuoles within the plant cell, which protects the other cell components. 

Tannins occur normally in the roots, wood, bark, leaves, and fruit of many plants, particularly in the bark of oak (Quercus) species and in sumac (Rhus) and myrobalan (Terminalia chebula). 
Tannins also occur in galls, pathological growths resulting from insect attacks.
Commercial tannins typically are pale yellow to light brown amorphous substances in the form of powder, flakes, or a spongy mass. 
Tannins are complex chemical substances derived from phenolic acids (sometimes called tannic acid). 

Tannins are classified as phenolic compounds, which are found in many species of plants, from all climates and all parts of the globe. 
Tannins are large molecules that bind readily with proteins, cellulose, starches, and minerals. 
Tannins occur in many species of coniferous trees as well as a number of flowering plant families. 
Tannins can leach out of the plants. 

The water in the soil becomes rich with tannins and seeps into the ground water or drains into lakes and streams. 
These waters become brown in color and look like tea.
Tannins are found commonly in the bark of trees, wood, leaves, buds, stems, fruits, seeds, roots, and plant galls. 
In all of these plant structures, tannins help to protect the individual plant species. 
Tannins that become stored in the bark of trees protect the tree from being infected by bacteria or fungi. 

In this case, the tannins precipitate out the enzymes and other protein exudates from bacteria and fungi thus not allowing these organisms to infect the tree. 
Many bud scales on woody plants contain tannins to protect the inner leaf tissue from being consumed and in many seed plants the initial set of leaves from a germinating seed are also high in tannins.
Unripened fruits are high in tannin content. 

The high tannin content discourages fruit eating animals from consuming the fruit until the seeds are mature and ready for dispersal. 
As the fruit ripens the tannin content lessens.
Beside fruits, tannins are also contained in coffee, tea, red wine and beer. 
The initial astringent taste when you sip a red wine actually comes from tannins in the wood of the oak barrels in which the wine was aged.
Tannins are also responsible for many of the enchanting colors seen in flowers and the final beauty of autumn leaves.

Tannins also play a role in medicine and human health. 
Tannins are astringents that tighten pores and draw out liquids. 
The tannins in cranberries (Vaccinium macrocarpon) have been medically proven to help prevent urinary tract infections in women by reducing the ability of the bacteria E. coli from adhering to cells lining the urinary tract. 
Anti-adhesive property of tannins may reduce the ability of H. pylori to cause stomach ulcers. 
Recent medical research has also shown that these tannins can also reduce LDL cholesterol and improve cardiac health.

Tannin is a yellow or brown chemical that is found in plants such as tea. 
The term ‘tannin’ is an old one, and comes from the practice of using extracts from plants to cure leather (the process referred to as ‘tanning’). 
Tanning process exploits one of the key properties of tannins: they have a strong tendency to link up with a range of other chemical entities, most particularly proteins. 

Applied to animal skins, tannins cross-link the proteins, turning something rather soft and floppy into a material that’s tough and inert enough to make shoes, belts and saddles from.
Tannins are defined functionally. 
Tannins are polyphenolic compounds that bind to and precipitate proteins.

Tannins themselves are found principally in the bark, leaves and immature fruit of a wide range of plants. 
Tannins form complexes with proteins and other plant polymers such as polysaccharides. 
The role of tannins in nature is one of plant defence: they have an astringent, aversive taste that is off-putting to wannabe herbivores. 

Significantly for winemaking, the grape vine exploits tannins in a rather clever way in its fruit. 
Grapes start life small, green, mean, and extremely bitter and astringent, through a combination of searingly high acidity and green, aggressive tannins. 
Wine tannins come from grape skins, stems and seeds, and their extraction is heavily dependent on the particular winemaking process involved. 

Some tannins also come from barrels, particularly new ones, where these are used to age wine. 
Wine tannins constitute “evolved” grape tannins plus some grape tannins in the same chemical state as they were in the grape.
Wine tannins are considered more complex than grape tannins due to the various chemical reactions that occur during winemaking and storage.
There are two major classes of tannins: condensed and hydrolysable. 

Hydrolysable tannins aren’t as important in wine: if they’re present, they’ll have most likely come from the oak barrels the wine is fermented and/or aged in. 
The condensed tannins, also known as proanthocyanidins, are the main grape-derived tannins. 
The condensed tannins are formed by the polymerization of the polyphenolic flavan-3-ol monomers catechin and epicatechin. 
In wine, the bonds between tannin polymers are repeatedly breaking and reforming. 

Tannins are naturally occurring compounds that exist inside grape skins, seeds and stems. 
The scientific word for Tannins is polyphenols. 
Tannins release from the skins, seeds and stems when they soak in the grape juice just after the grapes have been pressed and are what give certain wines, such as Cabernet Sauvignon, their characteristic dryness or astringency. 
We say a wine that is high in tannins is tannic.
Tannins naturally occur in black tea and their characteristics emerge when the tea is brewed a few minutes longer than recommended. 

What makes a wine have strong or weak tannins depends on how long the juice sits with the grape skins, seeds and stems after the grapes have been pressed. 
The longer the skins, seeds and stems soak in the juice, the more tannin characteristics they will impart. 
Winemakers love tannins because tannins work as a natural antioxidant to protect the wine. 
Tannins is actually a key reason why certain red wines, including Cabernet Sauvignon, can be so age-worthy. 
And, as we know, Tannins aren’t just useful for helping us age wine; they also have great health benefits for humans! 

Tannin is a natural substance present throughout the plant kingdom: in wood, bark, rhizomes, roots and fruits. 
Tannin is part of the polyphenols family, a term that you may have already heard.  
Tannins are antioxidant substances found in fruits, vegetables and, in general, in different plants, which help to preserve tissues against cellular ageing.

Tannin is 100% natural.
Tannin's chemical structure confers them the property to counteract fungi and bacteria’s activity, and it’s so powerful to act even in water.
Unlike most animals, plants cannot move: they have developed tannin as a natural protection from the onslaught of pathogens, such as fungi, bacteria and viruses. 

Tannins, a group of bitter and astringent compounds, can be found abundantly in nature. 
Tannins are present in the wood, bark, leaves and fruit of plants as various as oak, rhubarb, tea, walnut, cranberry, cacao and grapes.
Tannins are also found in wine.
Plants have tannins to make themselves unpalatable. 

Tannins' purpose in nature is to deter animals from eating a plant’s fruit or seeds before it’s ripe.
Tannins are responsible for that astringent, mouth-coating feeling you get from biting into an unripe pear or plum. 
Tannin is any of a group of astringent vegetable principles or compounds, chiefly complex glucosides of catechol and pyrogallol, as the reddish compound that gives the tanning properties to oak bark or the whitish compound that occurs in large quantities in nutgalls

Tannin is any of these compounds occurring in wine and imparting an astringent taste, especially in red wine.
Tannins are naturally occurring plant polyphenols. 
Tannins' main characteristic is that they bind and precipitate proteins. 
Tannins can have a large influence on the nutritive value of many foods eaten by humans and feedstuff eaten by animals. 

Tannins are common in fruits (grapes, persimmon, blueberry, etc.), in tea, in chocolate, in fruit dish.legume forages (trefoil, etc.), in legume trees (Acacia spp., Sesbania spp., etc.), in grasses (sorghum, corn, etc.).
Tannins contribute to many aspects of our daily lives. 
Tannins are responsible for the astringent taste we experience when we partake of wine or unripe fruits, and for the enchanting colors seen in flowers and in autumn leaves.
The word tannin is very old and reflects a traditional technology. 

Plant parts containing tannins include bark, wood, fruit, fruitpods, leaves, roots, and plant galls.
Examples of plant species used to obtain tannins for tanning purposes are wattle (Acacia sp.), oak (Quercus sp.), eucalyptus (Eucalyptus sp.), birch (Betula sp.), willow (Salix caprea), pine (Pinus sp.), quebracho (Scinopsis balansae) .
Tannins are phenolic compounds that precipitate proteins. 
Tannins are composed of a very diverse group of oligomers and polymers. 

There is some confusion about the terminology used to identify or classify a substance as a tannin, in fact,
*not only tannins bind and precipitate proteins (other phenolics such as pyrogallol and resorcinol also have this property),
*not all polyphenols precipitate proteins or complex with polysaccharides.

Tannins are any phenolic compound of sufficiently high molecular weight containing sufficient hydroxyls and other suitable groups (i.e. carboxyls) to form effectively strong complexes with protein and other macromolecules under the particular environmental conditions being studied.
Tannins can complex with:
*Proteins
*Starch
*Cellulose
*Minerals

A type of chemical found in plants and in certain foods, such as fruits, vegetables, nuts, wine, and tea. 
Tannins have antioxidant properties and may promote good health. 
Tannins are being studied in the prevention of cancer, heart disease, and other diseases. 
Tannins are also used in certain medicines, fabrics, leather, and ink. 
A tannin is a type of polyphenol. 

Also called tannic acid.
Tannins perform many functions of great utility for the production of wine: Tannins act as antioxidant agents,  interfere on oxidases activity, improve color and protein stability,  contribute to wine sensory quality, and prevent pinking and “light-struck” defect. Since the different origins and properties of tannins can produce substantially different results, care must be taken to select the best tannin for each winemaking application. 

Tannins are a group of compounds found in tea. 
Tannins are known for their distinct flavor and interesting chemical properties and may also provide health benefits.
Tannins are a type of chemical compound that belongs to a larger group of compounds called polyphenols.
Tannins' molecules are typically much larger than those found in other types of polyphenols, and they possess a unique ability to easily combine with other molecules, such as proteins and minerals.

Tannins are naturally found in a variety of edible and inedible plants, including tree bark, leaves, spices, nuts, seeds, fruits, and legumes. 
Plants produce Tannins as a natural defense against pests. 
Tannins also contribute color and flavor to plant foods.

Some of the richest and most common dietary sources of tannins include tea, coffee, wine, and chocolate.
The astringent and bitter flavors that are characteristic of these foods and beverages are usually attributable to their abundant supply of tannins 
Tannins are a type of plant compound naturally found in foods and beverages, including tea, coffee, chocolate, and wine. 
Tannins are well known for their astringent, bitter flavors and ability to easily bind with proteins and minerals.

Tannins (tannic acids) are naturally occurring complex chemicals found in plants. 
Tannins are particularly prevalent in a variety of vascular plants, including fruits (especially grapes), teas, legumes, and grasses. 
Tannins' taste is quite sharp or caustic, providing the distinctive astringency that humans associate with red wines, teas, and unripe fruits. 

Tannins are essential products for plant defense, and they provide plants with a chemical mechanism with which to combat pathogens and herbivores. 
Because tannins are so bitter, most herbivorous predators are disinclined to consume them. 
Tannins also protect plants from ultraviolet radiation. 

In 2013, investigators pinpointed the exact location in plant cells where tannins are manufactured. 
The source for tannins is a newly discovered organelle called the tannosome. 
Tannosome arises in chloroplasts (cell plastids occurring in the green parts of plants, which contain chlorophyll pigments and function in photosynthesis and protein synthesis) and is responsible for tannin formation. 
After the tannins are created, the tannosome is encapsulated in a membrane, allowing the structure to bud off from the chloroplast and to be shuttled to a plant vacuole for safe storage. 

By determining the location and method by which tannins are produced, it should be possible in the future to bioengineer food products with modified tannins, thereby altering, for example, the tannin content and taste of teas and wines. 
Soft, silky, velvety, youthful, puckery, aggressive, harsh, bitter, astringent: these are all adjectives used in winespeak to describe the many taste sensations from tannins in red wines.
Tannins are substances widely distributed in plants where they serve as defense mechanisms against predators. 

Chemically, tannins belong to a large class of compounds known as phenolics or polyphenols, and indeed, they impart bitterness and astringency. 
Not all tannins are created equally. 
The two main sources of tannins in red wine are grapes and oak barrels, but if we dissect a grape berry and stems, we will find very different types and polymerization of tannins. 

Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids. 
The term tannin (from Anglo-Norman tanner, from Medieval Latin tannāre, from tannum, oak bark) refers to the use of oak and other bark in tanning animal hides into leather. 

The presence or amount of tannins in wine doesn’t make that wine good or bad. 
Artfully leveraging tannins can make a good wine soar, and uninspired use of tannins can make a wine flat and one-dimensional. 
Pouring wine through the best wine aerators, decanters, and wine pourers can help soften tannins if need be.
Tannins are a group of naturally-occurring, bitter-tasting compounds found in many leaves, seeds, stems, wood, bark, and fruit. 

Up to 50% of the dry weight of leaves is pure tannin. 
Tannins are substances with high molecular weight and are water soluble polyphenols able to precipitate proteins. 
Tannins were classified for the first time in 1922 by Freudemberg, depending on their chemical structures.
Tannins are absorbed by the hides and skins during the tanning process. 
Tannins bind to the protein collagen in the skins and prevent the disintegration of the fibres by turning them into leather. 

The term tannin refers to a group of polyphenols that can bind with proteins and precipitate them. 
Tannins are organic compounds that can react with amino acids and alkaloids. 
Also, these tannins are well-known as astringent compounds. 
Tannins  occur in a wide variety of plant tissues. 
Tannins play an important role in providing protection to the plants from predation and help the regulation of plant growth. 
Tannins occur in unripe fruits; astringency of tannins cause their dry and pucker felling.

Tannins can be classified into three major groups: hydrolyzable tannins, phlorotannins and condensed tannins. 
All these groups of tannins are polymeric structures with monomer units. 
The monomer of hydrolyzable tannins is gallic acid, and the monomer of phlorotannins is phloroglucinol. 
The monomer of condensed tannins is flavan-3-ol. 
These three classes of tannins have different sources as well.
There are three types of methods to determine the existence of tannins in a given sample.  

Tannin can be named as a polyphenol due to the presence of several phenyl groups. 
Tannin has a weak acidity. 
Tannin is a compound that does not give off a flavor but a tactile sensation that feels rough and dry on the tongue. 
Tannin is a natural antioxidant and a natural preservative that protects the wine as it ages. 
Tannin is naturally found in the skins, stems, and seeds of a grape, and also found in oak barrels (and green tea leaves, dark chocolate, and walnuts).

The amount of tannin in wine has a lot to do with the grape because grapes with thicker skins mean more tannin will be present in the wine. 
Over extraction of skins or stems would result in too firm of tannins that mask delicate flavors. 
Tannin is a molecule found in wine. 
Tannins are the plural form, as in, “The tannins in this wine are light and velvety.” 

Tannins are abundant in the plant world. 
Tannins are polyphenols found in nearly all plants — in bark, skin, seeds and stems. 
With antioxidant and antibacterial properties, they are one of nature’s defenses against disease. 
Early mankind figured out how to soak tannins out of plants and use them to “tan” animal hides and make leather, transforming something that would naturally rot into a strong, durable product. 
It does require removing flesh from the hide, though, and that may be what the expression means.

Their natural antioxidant properties make tannins a healthy additive to livestock feed, and they have even been touted as a natural alternative to antibiotics. 
Humans consume tannins, too, in nuts, seeds, vegetables such as spinach and drinks such as tea and, of course, wine.
Tannins give wine structure and texture. 
Just as tannins make leather supple, they add to wine’s texture and mouthfeel. 
Grapes contain tannins in their skins, seeds or pips, and stems. 
Aging in oak barrels also adds tannins from the wood. 

Powdered tannins, naturally extracted from plants, can also be added to wine, giving the winemaker greater control over the final product.
In wine-tasting parlance, tannins can be ripe, supple, velvety, soft, silky or sweet.
Tannins are tactile. 
In big red wines, good tannins — the supple, ripe type — creep up at the finish just as the fruit fades and tickle your teeth with a pleasant caress that reminds you there is more in the bottle. 

Aggressive tannins are like a sucker punch to the mouth: 
They leave the wine tasting bitter.
Some grape varieties contain more tannins than others: 
Cabernet sauvignon, syrah and nebbiolo, for instance, yield wines more tannic than those made from merlot, gamay or pinot noir. 

Fat cuts tannins. 
Tannins bind with protein, leading to the classic pairing of grilled steak and cabernet sauvignon. 
Richer, more succulent dishes benefit from pairing with tannic wines, as the tannins cut through that richness and their astringency leaves our palates refreshed and ready for the next bite.
Tannins leach into the wine during pressing, maceration and fermentation of the grape juice.
Tannins help wine age. 

Tannins’ preservative properties help give wine endurance. 
Tannins are relatively small, and as wine ages in bottle, they combine to form larger compounds that eventually fall out of solution as sediment. 
The natural wine movement favors wines with less extraction and reliance on winemaking techniques that emphasize tannins and structure. 
White wines have tannins, too. 

Tannins are natural compounds that are found in plants. 
Tannins occur in certain fruits, tree bark, roots, leaves, and of course, wine.
In terms of wine, tannins are in grape skins, pips, and stems. 
While there are tannins in wine of all varieties, red wine is often more tannic than white or rosé since grape skins are left on during the winemaking process. 

You can usually tell if a wine will be tannic even before tasting it. 
If the wine is red, chances are it’ll be higher in tannins. 
Some white wines such as chardonnay can be higher in tannins.
If your tongue and teeth feel dry, chances are your wine is a higher tannin variety.

Some winemakers purposely add tannin powder into their wines to raise the tannin level because tannins act as a natural antioxidant, which protects the wine from bacteria.
Tannins help the wine to age successfully, taking on complexity in the process. 
Tannin powders are unnecessary additives and are usually only used in large-batch, low-quality winemaking. 
When a high-tannin wine is aged it often takes on a much smoother texture, which is far less bitter than a younger wine of the same grape. 

Whether you love wine with intense character, or you prefer sticking to something lighter, tannins play a large part in your overall enjoyment of wine.
ıf you want to avoid firm tannins, choose white wines, rosés, and red wines with thin skins, such as Pinot Noir. 
Tannins are usually divided into hydrolyzable tannins and condensed tannins (proanthocyanidins).
Tannin is found in the nutgalls formed by insects on the twigs of certain oak trees. 
Tannin contains ingredients that have a protective effect on the skin.

Tannins are a natural organic material that can be the byproducts of nature’s fermentation process, be created as water passes through peaty soil and decaying vegetation. 
Tannins can cause water to have a faint yellow to tea-like color, and can cause yellow staining on fabrics, fixtures,china and laundry.
Tannins may give a tangy or tart aftertaste to water. 
Tannins may also cause water to have an earthy odor.

Tannins – also known as fulvic or humic acid – are more common in surface water supplies and shallow wells than in deep wells. 
Water in marshy, low-lying, or coastal areas is also more
susceptible to tannins.
While Tannins may make water unappealing to drink and stain laundry, Tannins present no health hazard.

Winemaking tannins come from a variety of sources. 
Though all tannins provide some degree of anti-oxidative protection, each is also quite distinctive. 
The selection, processing and blending are all critical when developing commercial tannins which you might use in your wine.
The polysaccharides linked with tannins contribute to the global impact on the palate.

The most general and useful definition of tannins is any molecule that binds with proteins. 
Binding to proteins can happen in many different ways, meaning there isn’t a specific chemical structure to tannins like there is for other families of molecules.
Tannins come from many different sources in the natural environment but are mostly found in plant matter. 
The most common relevant plant with tannins from a human perspective is tea. 

Tea leaves have some of the highest concentrations of tannins in common food and drink and provide most of the tannins consumed by humans. 
Coffee is generally considered to have about half the tannin concentration as tea.
The word tannin’s etymology involves the traditional leather industry, where compounds containing tannins were used for tanning leather skins. 
In traditional Celtic languages, oak bark is called tann, and thus tannins were named.

Tannins are the thing that make your mouth dry and pucker up when you swirl a wine around your mouth.  
A good example of tannin is strongly brewed black tea.
Tannins are a substance found in the skins, seeds and stems of grapes, but also in the oak used to age wine. 
In the plant world Tannins are used to protect against threats.

Tannins mainly occur in red wines which are fermented from whole grapes, seeds and possibly stems – and more commonly aged in oak
Tannins don’t occur as much in most white wines which take the skins, stems and seeds out, but some white wine with obvious tannins exist
Some skin contact and oak ageing means rose may have some tannins

Orange wines (white wines made like red wines) will have tannin as they include skins and seeds
A natural astringent, acidic compound that has a drying, puckering effect on the palate. 
In reference to wine making, tannins are derived from the seed, skins, and stems of grapes. 
Tannin content is imperative in the preservation/aging of wine. 
Tannin is most prominent in red wines and mellows with the aging process.

Natural tannins are sourced from different plants, present either in bark, leaves, wood, fruits or roots. 
While some tannins acts as antioxidants and can help combat inflammation, protect your heart health and reduce your risk of developing cancer, others, like tannic acid, act as anti-nutrients, interfering with the way certain minerals, like iron, are absorbed. 

Most teas contain tannins, but some types of teas have higher amounts than others.
There are lots of different phytochemicals out there, but one group that's found in high levels in tea is called tannins. 
Tannins belong to a group of phytochemicals called phenols or phenolics.
Plants produce tannins as part of their defense system.
When an animal (or human) eats the plant, the tannins give off a bitter, unpleasant taste that's an attempt to get the animal or human to stop eating. 

Tannins also have a major effect on your nutrition and overall diet because they have an ability to bind with several macronutrients and other compounds involved in digestion, including:
*Carbohydrates
*Proteins
*Bacterial cell membranes
*Enzymes involved in food digestion
Unlike some other compounds, tannins are heat-stable, meaning tannins aren't destroyed when you heat them up — like when making tea. 

Tannins from grapes are called condensed tannins or proanthocyanidins, and are oligomers or polymers of flavan-3-ols. 
Tannin exist in nature but with a much different chemical structure. 
Tannin can be found in wood or other fruit sources apart from grapes, and they are called hydrolyzable tannins. 
Hydrolyzable tannins are found in wine after their extraction from barrels or chips during wine maturation. 
Hydrolyzable tannins are important in winemaking to “protect” the wine against oxidation or to help stabilizing the red wine color.

Tannins are known for their antioxidant properties, acting as a barrier against oxidation. 
Tannins are known for their ability to interact with proteins and their involvement in wine astringency perception.
Hydrolyzable tannins, especially ellagitannins, have a greater contribution to astringency than bitterness and are therefore considered to contribute to the wine structure. 
An excess of hydrolyzable tannins in wine can lead to a high wood flavor perception.

Similar to condensed tannins from grapes, hydrolyzable tannins can improve the red wine color by their reaction with anthocyanins, and the formation of stable pigments.
Hydrolyzable tannins can also protect against oxidation due to their antioxidant properties. 
It has been observed that enological tannins from wood have a similar effect on oxygen consumption as sulfur dioxide. 
It has been suggested to develop the use of enological tannins as an alternative to sulfur dioxide addition to protect wines against oxidation.

USES and APPLICATIONS of TANNIN:
-Tannins can be used as a mordant, and is especially useful in natural dyeing of cellulose fibers such as cotton.
-Tannins can be used for production of anti-corrosive primer rust converter to transform oxidized steel into a smooth sealed surface and rust inhibitor.
-Tannins are used chiefly in tanning leather, dyeing fabric, and making ink and in various medical applications. 
-In addition to Tannins 's principal applications in leather manufacture and dyeing, tannins are used in the clarification of wine and beer, as a constituent to reduce viscosity of drilling mud for oil wells, and in boiler water to prevent scale formation. 

-Because of Tannins' styptic and astringent properties, tannin has been used to treat tonsillitis, pharyngitis, hemorrhoids, and skin eruptions; Tannin has been administered internally to check diarrhea and intestinal bleeding and as an antidote for metallic, alkaloidal, and glycosidic poisons, with which Tannins forms insoluble precipitates.
-Witch hazel (Hamamelis virginiana) is a source of tannin used in a number of skin care products. 
-Different colors, textures, and durability of leathers were achieved by using different formulations of plant tannins referred to as “tanning liqueurs”.

-In addition to tanning leather, tannins are used in photography, as mordants in dyeing, clarifying wine and beer by precipitating proteins out of them, and as astringents in medicine.
-Tannin is used in the process of making leather and in dyeing.
-Humans have used tannins from various tree barks for a long time to tan animal hides and make leather.
-Tannins are used in the dyeing of textiles and in the tanning of leather products. 
-Tannin is widely used to any large polyphenolic compound containing sufficient hydroxyls and other suitable groups (such as carboxyls) to form strong complexes with various macromolecules.

-Tannins are chemicals used by tanners to prevent the disintegration of the collagen fibres of the leather. 
-A variety of tanning agents are used for tanning but the three main types of tanning are vegetable tanning, which involves the use of plant substances, chromium III and synthetic tanning.
-We can use Tannin as a mordant in the dyeing process in the production of cellulose fibre forms such as cotton. 
-We can also apply Tannin to wood that has a low tannin content. 
-We can use Tannin on metal objects to prevent corrosion. 

-Tannin is useful in the food industry as well; for example, in wine clarification, beer clarification, colour stabilizing, etc.
-Tannin can be applied to wood that is low in tannin, which helps to react with chemical stains, and can be added as a mordent for dye production, etc.
-Tannins are an important ingredient in the process of tanning leather. 
-Oak bark has traditionally been the primary source of tannery tannin, though inorganic tanning agents are also in use today.
-Tannins may be employed medicinally in antidiarrheal, hemostatic, and antihemorrhoidal compounds.

-Tannins produce different colors with ferric chloride (either blue, blue black, or green to greenish black) according to the type of tannin. 
-Purified Tannin is sometimes used as medicine.
-People use Tannin for conditions such as cold sores, diaper rash, heat rash, and many others, but there is no good scientific evidence to support these uses.

-In foods and beverages, Tannin is used as a flavoring agent.
-In manufacturing, Tannin is used in ointments and suppositories; for tanning hides and manufacturing ink; and to kill dust mites on furniture.
-Tannin is a yellowish or brownish bitter-tasting organic substance present in some galls, barks, and other plant tissues, consisting of derivatives of gallic acid, used in leather production and ink manufacture.

BENEFITS of TANNINS:
One benefit of tannins is that they act as natural fining agents by binding to and precipitating haze-causing proteins. 
Protein stability in tannic red wines is therefore not of concern; however, wines processed very quickly (for early drinking) with little or no tannin extraction (such as whites) should still be tested for protein stability before bottling.

But the single, most important benefit of tannins is that they are natural antioxidants — a red wine’s aging potential is largely based on its tannin content. 
Tannins have an affinity for binding to oxygen to protect wine from the effects of oxidation. 
By restricting the availability of dissolved oxygen to oxidation-prone compounds, less oxygen is available, for example, to transform phenolics into browning compounds and alcohol into acetaldehyde, a common spoilage compound.

As well as providing exceptional texture and intensity, tannins are also celebrated for their health benefits. 
Studies have shown that wines higher in tannins are healthier for the heart, and countries consuming more of these wines are enjoying longer lives.
London-based scientist Roger Corder has long said he believes that traditional winemaking production methods, which are commonly used in Sardinia and Southern France, may have a strong connection to the overall well-being and longevity of residents in those regions. 

That’s because traditional winemaking methods support these beneficial compounds, known as procyanidins (aka condensed tannins).
Corder proclaimed, Wine drinkers who hope to be rewarded with the maximum protection from heart disease should start seeking out wines with firmer tannins.

Tannins can act as antioxidants. 
Certain tannins may help reduce the risk of heart disease, prevent the formation of tumors and certain cancers and help protect against allergies.
Because of its tannin content, lukewarm tea has also been used to treat burns by applying it right to the skin or by dipping a burn dressing in it. 

Tannins are anti-inflammatory and can decrease adipogenesis — a technical term for the creation of new fat cells. 
Tannins have been shown to help regulate blood sugar by improving the health of the cells in your pancreas (called the beta cells) that produce insulin (the hormone that you need to properly use the glucose, or sugar, in your blood).

CHEMICAL STRUCTURE of TANNIN:
Tannins are one of the many types of secondary compounds found in plants:
Characteristics of tannins:
*oligomeric compounds with multiple structure units with free phenolic groups,
*molecular weight ranging from 500 to >20,000,
*soluble in water, with exception of some high molecular weight structures,
*ability to bind proteins and form insoluble or soluble tannin-protein complexes.
Tannins are usually subdivided into two groups:
*Hydrolyzable tannins (HT)
*Proanthocyanidins (PA) (often called Condensed Tannins)

-Hydrolyzable tannins:
HTs are molecules with a polyol (generally D-glucose) as a central core. 
The hydroxyl groups of these carbohydrates are partially or totally esterified with phenolic groups like gallic acid (-->gallotannins) or ellagic acid (--> ellagitannins). 
HT are usually present in low amounts in plants.
Some authors define two additional classes of hydrolyzable tannins: taragallotannins(gallic acid and quinic acid as the core) and caffetannins (caffeic acid and quinic acid)

--Gallotannins:
*The phenolic groups that esterify with the core are sometimes constituted by dimers or higher oligomers of gallic acid (each single monomer is called galloyl)
*Each HT molecule is usually composed of a core of D-glucose and 6 to 9 galloyl groups
*In nature, there is abundance of mono and di-galloyl esters of glucose (MW about 900). 
They are not considered to be tannins. 
At least 3 hydroxyl groups of the glucose must be esterified to exhibit a sufficiently strong binding capacity to be classified as a tannin.
*The most famous source of gallotannins is tannic acid obtained from the twig galls of Rhus semialata. 
It has a penta galloyl-D-glucose core and five more units of galloyl linked to one of the galloyl of the core.

--Ellagitannins:
*The phenolic groups consist of hexahydroxydiphenic acid, which spontaneously dehydrates to the lactone form, ellagic acid.
*Molecular weight range: 2000-5000.
HT properties:
*hydrolyzed by mild acids or mild bases to yield carbohydrate and phenolic acids
*Under the same conditions, proanthocyanidins (condensed tannins) do not hydrolyze.
*HTs are also hydrolyzed by hot water or enzymes (i.e. tannase).

-Proanthocyanidins (condensed tannins):
PAs are more widely distributed than HTs. 
Proanthocyanidins are oligomers or polymers of flavonoid units (i.e. flavan-3-ol) linked by carbon-carbon bonds not susceptible to cleavage by hydrolysis.

*PAs are more often called condensed tannins due to their condensed chemical structure. 
However, HTs also undergo condensation reaction. 
The term, condensed tannins, is therefore potentially confusing.
*The term, proanthocyanidins, is derived from the acid catalyzed oxidation reaction that produces red anthocyanidins upon heating *PAs in acidic alcohol solutions.
*The most common anthocyanidins produced are cyanidin (flavan-3-ol, from procyanidin) and delphinidin (from prodelphinidin)

*PAs may contain from 2 to 50 or greater flavonoid units; PA polymers have complex structures because the flavonoid units can differ for some substituents and because of the variable sites for interflavan bonds.
*Anthocyanidin pigments are responsible for the wide array of pink, scarlet, red, mauve, violet, and blue colors in flowers, leaves, fruits, fruit juices, and wines. 
They are also responsible for the astringent taste of fruit and wines.
*PA carbon-carbon bonds are not cleaved by hydrolysis.
*Depending on their chemical structure and degree of polymerization, PAs may or may not be soluble in aqueous organic solvents.

There are three major classes of tannins.
Particularly in the flavone-derived tannins, the base shown must be (additionally) heavily hydroxylated and polymerized in order to give the high molecular weight polyphenol motif that characterizes tannins. 
Typically, tannin molecules require at least 12 hydroxyl groups and at least five phenyl groups to function as protein binders.
Oligostilbenoids (oligo- or polystilbenes) are oligomeric forms of stilbenoids and constitute a minor class of tannins.

-Pseudo tannins:
Pseudo tannins are low molecular weight compounds associated with other compounds. 
Pseudo tannins do not change color during the Goldbeater's skin test, unlike hydrolysable and condensed tannins, and cannot be used as tanning compounds.

TANNIN CLASSIFICATION:
-Hydrolyzable tannins:
The class of hydrolyzable tannins, so called because the compounds are attached to sugar molecules and which can be cleaved, or hydrolyzed, into their subcomponents, gallotannins and ellagitannins. 
These are relatively soft tannins found in low concentrations in grape juice; the ellagitannins castalagin and vescalagin are found abundantly in the woody Quercus (oak) and Castanea (chestnut) plant species. 

That’s why chestnut barrels were once popular only to succumb to the now more popular oak barrels or oak adjuncts, such as staves, cubes and chips, which impart additional and more favorable aromas and flavors. 
And if you want to add a more pronounced yet rounder mouthfeel, add a tannin mix specifically formulated with gallotannins and ellagitannins.

-Condensed tannins:
The class of condensed tannins, so called because of their ability to polymerize or bind with anthocyanins, and also referred to as proanthocyanins, are found in seeds and to a lesser extent in stems, and relatively little in the skin of red grapes. 
In general, you can expect that the thicker and the more colored the grape skin, the higher the concentrations of tannins and anthocyanins.
Condensed tannins are all derivatives of a flavanol (a class of compounds found in plants and certain fruits and vegetables) known as catechin. 

Catechins found in seeds and stems are very bitter and astringent, particularly because of their much smaller degree of polymerization, compared to the beneficial ones found in the skins.
Since there is no maceration of juice with grape solids in white winemaking, tannin content in unoaked whites is negligible; however, red winemaking is all about maceration. 
There are some interesting chemical properties of and interactions between catechins and anthocyanins at play during maceration and fermentation that need to be managed to produce a desired style of wine.

-Complex tannins:
Tannins continue to evolve over the course of the life of a wine, both in bulk in carboys or barrels and in bottles. 
During aging, both hydrolyzable and condensed tannins polymerize into large, high-molecular weight complex tannins that also bind to anthocyanins and precipitate as tannin-anthocyanin complexes, resulting in a lighter color and reduced bitterness over time. 

This reaction and sedimentation occurs over a long period of time depending on wine chemistry and storage conditions.
Tannin-anthocyanin complexes are too large to pass through a filter medium and can therefore be filtered out to achieve the same level of clarity as extended aging without filtration. 
But filtration naysayers argue that other critical compounds are also filtered out — which ones, we don’t know — and that is the essence of the debate regarding the quality of filtered vs. unfiltered wine.

-Hydrolysable tannins:
Hydrolysable tannins are further divided into gallic and ellagic tannins. 
The first, the gallotannins release glucose and gallic acid by hydrolysis at low ambient pH. 
They are mainly extracted from Tara (Caesalpinia spinosa), sumac (Rhus coriaria) and gallnuts (Quercus infectoria and Rhus semialata). 
The ellagitannins, made from ellagic acid glycosides, are one of the components of oak wood (Quercus robur, Quercus petraea and Quercus alba), chestnut wood (Castanea sativa) and myrobalan (Terminalia chebula).

-Condensed tannins:
Condensed tannins have a reduced astringent power when compared to hydrolysable tannins. 
They are further divided into proanthocyanidin and profisetinidin. Proanthocyanidins are naturally present in grapes (Vitis vinifera) consisting of various flavonoids which release anthocyanins and other insoluble molecules when they are treated under acid hydrolysis. 
They are mainly diffused in the skins and seeds of grapes, and therefore you can find them in red wines.
Profisetinidins are extracted from the quebracho wood (Schinopsis lorentzii).

-Recently a third class of tannins has been identified, the phlorotannins, present in many species of dark algae:
Along with many other substances of a mainly phenolic nature, the tannins enter into the class of semiochemicals, which is a generic term used for a chemical substance or mixture that carries a message. 
These chemicals act as messengers within or between species. 
The semiochemicals are divided into two classes: pheromones and allelochemicals. 
Pheromones are involved in the communication between the same species while allelochemicals interact with different species.

-Hydrolyzable Tannins:
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.
Examples of gallotannins are the gallic acid esters of glucose in tannic acid (C76H52O46), found in the leaves and bark of many plant species.

-Condensed Tannins:
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.

Hydrolyzable tannins are mainly found in wood such as oak, chestnut, and acacia and therefore in barrels or staves, chips, and powder. 
Hydrolyzable tannins are found in gallnuts, Tara in the trunks of vines and in grape stems. 
They are called hydrolyzable tannins because Hydrolyzable tannins can be hydrolyzed under acidic or hot or basic conditions. 
This means that Hydrolyzable tannins' structure can be cleaved to release smaller units, gallic or ellagic acids. 

Hydrolyzable tannins include gallotannins and ellagitannins, which are respectively characterized by gallic acid and ellagic acid units. 
As condensed tannins, Hydrolyzable tannins are able to interact with other molecules such as proteins and polysaccharides. They also have antioxidant and/or antimicrobial activities that are more or less intense depending on their structure.
Depending on the source of tannins, the chemical structure of gallotannins can vary with up to thirteen gallic acid groups as observed in Chinese sumach tannin extracts.
Ellagitannins are widespread in nature and have the same core structure as gallotannins. 

Ellagitannins are composed of ellagic acids that are the product of the oxidation of two gallic acids. 
Their size can be up to 5,000 Daltons with at least 5 ellagic acid units. 
The ellagitannin content in oak wood is highly influenced by environmental characteristics such as the soil and climate, but also by the age of the tree, and the geographical location of the wood piece in the tree. 
In oak wood, the ellagitannin content ranges from 6 to 33 mg of released ellagic acid per gram of dry wood, and up to 63 mg/g of dry wood can be found in chestnut heartwood.

INTERACTION of TANNIN with OTHER MACROMOLECULES:
Tannins have a major impact on animal nutrition because of their ability to form complexes with numerous types of molecules, including, but not limited to,
*Carbohydrates,
*Proteins,
*Polysaccharides,
*Bacterial cell membranes,
*Enzymes involved in protein and carbohydrates digestion.

-Carbohydrates:
Both starch and cellulose are complexed by tannins (especially by PAs):
*Starch-tannin interaction:
starch has the ability to form hydrophobic cavities that allow inclusion complexes with tannins and many other lipophyllic molecules. 
Only starch, among the molecules that are bound by tannins, has this embedding characteristic.
*Cellulose-tannin interaction:
cellulose has a direct surface interaction with tannins.

*Cell wall carbohydrate-tannin interaction 
this association is less understood. One explanation is that tannins associate with plant cell walls in a manner reminiscent to that of lignin. 
However, another explanation is that this association is merely an artifact of tannin isolation from non-living cells. 
Indeed, the location of tannins and cell wall carbohydrates is quite different in living cells than in plant cells after digestion by animals.

*Tannin-carbohydrate interactions are increased by carbohydrates with high molecular weight, low solubility and conformational flexibility. 
These interactions are probably based on hydrophobic and hydrogen linkages.

-Proteins:
The capacity of tannins to bind proteins has been recognized for centuries. 
Leather tanning is a very ancient practice. 
Tannin-protein interactions are specific and depend on the structure of both the protein and tannin.

Protein characteristics that favor strong bonding:
*large molecular size,
*open and flexible structures,
*richness in proline.

Tannin characteristics that favor strong bonding:
*high molecular weight,
*high conformational mobility.

-Chemical linkages:
Tannin-protein interactions are most frequently based on hydrophobic and hydrogen bonding.
Ionic and covalent bonding occur less frequently.
*The tannin's phenolic group is an excellent hydrogen donor that forms strong hydrogen bonds with the protein's carboxyl group.
For this reason, tannins have a greater affinity to proteins than to starch.

*Hydrophobic bonds are stronger at higher ionic strength (higher tannin/protein ratios) and higher temperatures.
*Covalent bonding occurs only under oxidizing conditions such as
autoxidation over time, or action of oxidative enzymes (i.e. polyphenoloxydases and peroxidases). 
Covalent bonding is far more difficult to disrupt than the previous types of bonding and is nutritionally very important because of its irreversible nature.
*Precipitation of proteins by tannins is maximum at pH values near the isoelectric point of the protein.

*In solution at high pH, phenolic hydroxyls are ionized and proteins have net negative charges. 
Under these conditions, precipitation does not occur because proteins exhibit repulsive forces.
*Strong complexes with tannins are formed by tannin-binding agents like polyvinylpyrrolidone (PVP) and polyethylen glycol (PEG), and protein denaturants like phenol.
*To have high protein affinity, tannins must be small enough to penetrate interfibrillar region of protein molecules but large enough to crosslink peptide chains at more than one point.

*HTs and PAs form tannin-protein complexes in similar manners. 
*Proteins thus bound are generally resistant to attack by proteases and hence may be unavailable for livestock nutrition. 
However, it is hypothesized that HTs may have a less damaging effect on protein digestion because these tannins may hydrolyze in the acidic gastric environment and release the bound proteins.
*When soluble tannins interact with proteins, both soluble and insoluble complexes are formed; their relative proportion depends on the concentration and size of both molecules.

*Soluble complexes are favored when protein concentration is in excess (fewer tannin attachment sites per each protein molecule). 
*Soluble complexes represent an analytical problem because they do not precipitate and, thus, are difficult to measure.
*Insoluble complexes are formed when tannins are present in excess and form an hydrophobic outer layer in the complex surface.

OCCURRENCE of TANNIN:
Tannins are distributed in species throughout the plant kingdom. 
Tannins are commonly found in both gymnosperms and angiosperms. 
Mole studied the distribution of tannin in 180 families of dicotyledons and 44 families of monocotyledons (Cronquist). 
Most families of dicot contain tannin-free species (tested by their ability to precipitate proteins). 

The best known families of which all species tested contain tannin are: Aceraceae, Actinidiaceae, Anacardiaceae, Bixaceae, Burseraceae, Combretaceae, Dipterocarpaceae, Ericaceae, Grossulariaceae, Myricaceae for dicot and Najadaceae and Typhaceae in Monocot. 
To the family of the oak, Fagaceae, 73% of the species tested contain tannin. 
For those of acacias, Mimosaceae, only 39% of the species tested contain tannin, among Solanaceae rate drops to 6% and 4% for the Asteraceae. 

Some families like the Boraginaceae, Cucurbitaceae, Papaveraceae contain no tannin-rich species.
The most abundant polyphenols are the condensed tannins, found in virtually all families of plants, and comprising up to 50% of the dry weight of leaves.
Tannins are widely distributed in the plant kingdom. 
Tannins are common both in Gymnosperms and Angiosperms. 
Within Angiosperms, tannins are more common in Dicotyledons than in Monocotyledons.

Examples of families of Dicotyledons rich in tannins are:
*Leguminosae : Acacia sp. (wattle); Sesbania sp.; Lotus sp. (trefoil); *Onobrychis sp. (sainfoin);
*Anacardiaceae: Scinopsis balansae (quebracho)
*Combretaceae: myrobalan
*Rhizophoraceae: mangrove
*Myrtaceae: Eucalyptus sp., Mirtus sp. (Myrtle)
*Polinaceae: canaigre.

*Other important tannin containing plants are Quercus sp. (oak), Acer sp. (maple), Betula sp. (birch), Salix caprea (willow), Pinus sp. (Pine), Sorghum sp.
Tannins are located mainly in the vacuoles or surface wax of the plants. 
In these sites Tannins do not interfere with plant metabolism. 
Only after cell breakdown and death can Tannins act and have metabolic effects.
Location of the tannins in various plant tissues:

*Bud tissues:
most common in the outer part of the bud, probably as protection against freezing

*Leaf tissues:
most common in the upper epidermis. 
However, in evergreen plants, tannins are evenly distributed in all leaf tissues. 
Tannins serve to reduce palatability and, thus, protect against predators.

*Root tissues:
most common in the hypodermis (just below the suberized epidermis). 
Tannins probably act as a chemical barrier to penetration and colonization of roots by plant pathogens.

*Seed tissues:
located mainly in a layer between the outer integument and the aleurone layer. 
Tannins have been associated with the maintenance of plant dormancy, and have allelopathic and bactericidal properties.

*Stem tissues:
often found in the active growth areas of the trees, such as the secondary phloem and xylem and the layer between epidermis and cortex. 
Tannins may have a role in the growth regulation of these tissues. 
Tannins are also found in the heartwood of conifers and may be a contribute to the natural durability of wood by inhibiting microbial activity.

CELLULAR LOCALIZATION of TANNIN:
In all vascular plants studied, tannins are manufactured by a chloroplast-derived organelle, the tannosome.
Tannins are mainly physically located in the vacuoles or surface wax of plants. 
These storage sites keep tannins active against plant predators, but also keep some tannins from affecting plant metabolism while the plant tissue is alive.

Tannins are classified as ergastic substances, i.e., non-protoplasm materials found in cells. 
Tannins, by definition, precipitate proteins. 
In this condition, they must be stored in organelles able to withstand the protein precipitation process. 
Idioblasts are isolated plant cells which differ from neighboring tissues and contain non-living substances. 
They have various functions such as storage of reserves, excretory materials, pigments, and minerals. 

They could contain oil, latex, gum, resin or pigments etc. 
They also can contain tannins. 
In Japanese persimmon (Diospyros kaki) fruits, tannin is accumulated in the vacuole of tannin cells, which are idioblasts of parenchyma cells in the flesh.

BIOSYNTHESIS of TANNIN:
There are three large classes of secondary metabolites in plants:
*Nitrogen containing compounds
*Terpenoids
*Phenolics

Tannins belong to the phenolics class. 
All phenolic compounds (primary and secondary) are, in one way or another, formed via the shikimic acid pathway, also known as the phenylpropanoid pathway.
The same pathway leads to the formation of other phenolics such as isoflavones, coumarins, lignins and aromatic aminoacids (tryptophan, phenylalanine and tyrosine).
The two main categories of tannins that impact animal nutrition are hydrolyzable tannins (Hts) and condensed tannins identified more correctly as proanthocyyanidins (Pas) that are resistant to hydrolytic degragation. 

An example of how several common tannins are formed is as follows:
*Gallic acid is derived from quinic acid.
*Ellagotannins are formed from hexahydroxydiphenic acid esters by the oxidative coupling of neighboring gallic acid units attached to a D-glucose core.
*Further oxidative coupling forms the hydrolyzable tannin (HT) polymers.
*Proanthocyanidin (PA) biosynthetic precursors are the leucocyanidins (flavan-3,4-diol and flavan-4-ol)
*Upon autoxidation, in the absence of heat, they form anthocyanidin and 3-deoxyanthocianidin, which, in turn, polymerize to form PAs.

PRESENCE of TANNIN:
-Presence in soils
The convergent evolution of tannin-rich plant communities has occurred on nutrient-poor acidic soils throughout the world. 
Tannins were once believed to function as anti-herbivore defenses, but more and more ecologists now recognize them as important controllers of decomposition and nitrogen cycling processes. 
As concern grows about global warming, there is great interest to better understand the role of polyphenols as regulators of carbon cycling, in particular in northern boreal forests.

Leaf litter and other decaying parts of kauri (Agathis australis), a tree species found in New Zealand, decompose much more slowly than those of most other species. 
Besides its acidity, the plant also bears substances such as waxes and phenols, most notably tannins, that are harmful to microorganisms.

-Presence in water and wood:
The leaching of highly water soluble tannins from decaying vegetation and leaves along a stream may produce what is known as a blackwater river. 
Water flowing out of bogs has a characteristic brown color from dissolved peat tannins. 
The presence of tannins (or humic acid) in well water can make it smell bad or taste bitter, but this does not make it unsafe to drink.
Tannins leaching from an unprepared driftwood decoration in an aquarium can cause pH lowering and coloring of the water to a tea-like tinge. 

A way to avoid this is to boil the wood in water several times, discarding the water each time. Using peat as an aquarium substrate can have the same effect. 
Many hours of boiling the driftwood may need to be followed by many weeks or months of constant soaking and many water changes before the water will stay clear. 
Adding baking soda to the water to raise its pH level will accelerate the process of leaching, as the more alkaline solution can draw out tannic acid from the wood faster than the pH-neutral water.

Softwoods, while in general much lower in tannins than hardwoods are usually not recommended for use in an aquarium so using a hardwood with a very light color, indicating a low tannin content, can be an easy way to avoid tannins. 
Tannic acid is brown in color, so in general white woods have a low tannin content. 
Woods with a lot of yellow, red, or brown coloration to them (like cedar, redwood, red oak, etc.) tend to contain a lot of tannin.

TESTS FOR TANNINS:
There are three groups of methods for the analysis of tannins: 
Precipitation of proteins or alkaloids, reaction with phenolic rings, and depolymerization.

-Alkaloid precipitation:
Alkaloids such as caffeine, cinchonine, quinine or strychnine, precipitates polyphenols and tannins. 
This property can be used in a quantitation method.
-Goldbeater's skin test:
When goldbeater's skin or ox skin is dipped in HCl, rinsed in water, soaked in the tannin solution for 5 minutes, washed in water, and then treated with 1% FeSO4 solution, tannin gives a blue black color if tannin was present.

-Ferric chloride test:
Use of ferric chloride (FeCl3) tests for phenolics in general. 
Powdered plant leaves of the test plant (1.0 g) are weighed into a beaker and 10 ml of distilled water are added. 
The mixture is boiled for five minutes. 
Two drops of 5% FeCl3 are then added. 
Production of a greenish precipitate is an indication of the presence of tannins.
Alternatively, a portion of the water extract is diluted with distilled water in a ratio of 1:4 and few drops of 10% ferric chloride solution is added. 
A blue or green color indicates the presence of tannins (Evans, 1989).

-Tannins create a light yellow to dark brown discoloration in the water. 
A simple test for tannins involves filling a clear glass with water and letting it sit overnight. 
If the color settles to the bottom of the glass, the discoloration is most likely caused by iron and/or manganese and not tannins. 
If the intensity of the color remains intact, it is most likely caused by tannins.
There is another reason to test for iron along with tannins; iron creates a false positive for tannins and must be subtracted from the tannin result to determine that true tannin concentration.

WHERE DO TANNINS in WINE COME FROM?
Tannins in wine come primarily from the skin, seeds and, to a lesser extent, the stems of the grapes. 
During fermentation, the juice, skins and pips (and sometimes stems if the winemaker decides to do full or partial whole cluster fermentation) macerate together. 

As sugar is processed and alcohol produced, colour and tannin are released into the wine – alcohol will dissolve more tannins than water and therefore the longer the skins and pips macerate during and after fermentation the more tannic the final wine will be.
Because white and rosé wines are fermented by excluding or minimising the contact with grape components, tannin levels will be lower than in reds. 
On the other hand, if a white wine is fermented with extended skin and pip contact (i.e. thus producing a so-called orange wine) the level of tannins can be as significant as in a red wine. 

White wines contain structures similar to the pigmented tannins of a red wine, but the absence of anthocyanins, the compounds responsible for red pigmentation, explains why they look different and do not impart the same colour.
Tannins can also come from the wood vessels in which a wine is fermented and/or aged. Wood can impart both tannins and flavour to wine.

Tannins can stem from four primary sources: the grape skins, pips (seeds) and stems, and the wood barrels used during aging. 
They provide texture and mouthfeel to wine as well as a sense of weight and structure.
While white wine is made mostly from the juice that’s pressed as soon as the grapes get to the winery, red wine is made from the entire grape. 

As red wine ferments, skins, pips, juice and sometimes stems are all macerated together. 
During that process, both color and tannin are leached into the wine. 
Tannins create the drying sensation in your mouth when you drink a red wine.

TANNINS in WINE:
Tannins in wine come from two places: the skins, stems, and seeds of grapes and the oak barrels wine is often aged in.
During winemaking, grapes are crushed. 
When grapes are crushed, all the stems, skins, seeds, and juice form what’s called the must. 
As the must is allowed to sit, it macerates. 

That means the color and tannins from the stems, seeds, and skin are leached out into the raw grape juice. 
And that eventually becomes wine through fermentation. 
Fermentation will also convert the sugar in wine into alcohol which helps build stronger tannins.
Then, during the aging process, the oak from aging barrels imparts its own level of tannins into the wine.
Red wines have more tannins than white wines, but not all red wines are equal. 

Here are some examples of high-tannin red wines:
*Tannat: 
Uruguay’s most planted grape, Tannat is known for having some of the highest polyphenols of all red wines.
*Sagrantino: 
A rare treasure of central Italy, Sagrantino stands neck and neck with Tannat with its extreme tannin content.

*Petite Sirah: 
Originally French, Petite Sirah and its powerful flavors are now largely found in California.
*Nebbiolo:
One of Italy’s most legendary grapes, Nebbiolo boasts high tannin content and bitterness while still having a delicate nose.

*Cabernet Sauvignon: 
You know this one. 
The most widely planted grape in the world is known for velvety tannins and high aging potential.
*Petit Verdot: 
Known best as one of Bordeaux’s red blending grapes, Petit Verdot offers a floral, smooth sense of tannin.

*Monastrell: 
Popular in Spain and France, Monastrell (aka Mourvèdre) has a smoky, bold sense of tannin.
It’s helpful to remember that winemaking style greatly affects how much tannin is in a wine. 
In general, high production wines are deliberately created to have rounder, softer feeling tannins.

Some grape varieties have more tannins than others. 
Examples that can make really tannic wines include Cabernet Sauvignon, Nebbiolo, Mourvèdre, Malbec, Tannat, Syrah/Shiraz, Tempranillo, Merlot and Sangiovese. 
Whether the winemaking technique encourages the extraction of the tannins is a question of style. 
Wines made from grapes like Pinot Noir, Gamay and Grenache, which have much thinner grape skins, are much less tannic.
While grape variety can provide a good idea about the concentration of tannin in a wine, ripeness also matters. 

A good example is Syrah/Shiraz. 
It has a lot of tannin, but expresses itself differently, depending on climate and vintage.
A hot climate like Barossa, Australia, produces Shiraz grapes that are superripe, making the tannins particularly smooth, lush and rounded. 
In the temperate Northern Rhône, the tannins come across as more structured, drying and angular. 
The tannin structure of Cabernet Sauvignon grapes from Bordeaux in France differ with warmer and cooler vintages. Extraction during winemaking also plays a big role.

Red wines have far more tannins than white. 
White wines and young, ready-to-drink red wines that haven’t been aged have no or very little tannins. 
The same can't be said for the calories in red wine or calories in white wine.
White wines aren’t macerated for very long, if at all, and the grape juice absorbs very little of the tannins from the must. 
Young reds that aren’t aged for long like Pinot Noir, Grenache, Gamay, and Barbera are made with grapes that naturally have less tannins. 

They also have relatively little contact with oak barrels and so absorb less tannins. 
Those tannic red wines are also the cause of deep red wine stains. 
If your prefer these wines, it might be a good idea to pick up a really good red wine stain remover and a set of wine glasses with pour lines to avoid overflow spilling.
If you love dark chocolate, black tea, and sour pomegranate, chances are you could also be a fan of wines with high tannins. 
In this case, look out for the following varieties:

-Cabernet Sauvignon: 
This wine is synonymous with tannins. 
The illegitimate love child of Cabernet Franc and Sauvignon Blanc, this beloved grape is grown internationally. 
It’s robust, heavy, highly acidic, and pairs fabulously with red meat and rich cheeses.
Shiraz or Syrah: 
No matter how you spell it, this is another high-tannin wine. 
Syrah is full-bodied, deeply dark, and feels quite heavy in the mouth. 
It has poignant flavors of berries, tobacco, and even smoky savory notes.

-Nebbiolo: 
This is a lesser-known grape hailing from Italy. 
Although as pale as its low-tannin distant cousin Pinot Noir (don’t worry, more on that one later), Nebbiolo is intensely tannic. 
It’s a bold and surprisingly affordable Italian grape, which is always a plus.
If you prefer your wine a little smoother and not so biting, then you may want to opt for one that’s low in tannins. 
Obvious choices would include unoaked white wines, such as:

Sauvignon Blanc: 
This highly aromatic wine is marked by its fresh and zingy taste. 
It often has notes of passionfruit and fresh-cut grass, and pairs nicely with fish and pasta dishes.
Riesling: 
This highly aromatic wine is marked by its fresh and zingy taste. 
It often has notes of passionfruit and fresh-cut grass, and pairs nicely with fish and pasta dishes.

Pinot Noir: 
This classic red is internationally adored for its complex flavors and light texture.
It has thin grape skins, making it naturally lower in tannins.

Grenache: 
This full-bodied wine is high in alcohol and has an array of red fruit and cherry flavors. 
It’s a medium-tannin wine, so while it’s not as low as Pinot Noir, it's a good option for those trying to avoid intense tannic flavors.

Here are some of the higher tannin wine varieties, these have thicker grape skins:
*Shiraz
*Cabernet Sauvignon
*Nebbiolo (I had a youngish Barolo once and have never forgotten how much my mouth puckered up)
*Malbec
And a couple of lower tannin red wines, these have thinner grape skins:
*Pinot Noir
*Gamay

WHAT AFFECTS the LEVEL of TANNINS in WINE?
Tannin management in the winemaking process is a useful lever winemakers have to control the flavor and character of their wines. 
There are four primary ways tannins are managed. 
They are the ripeness of grapes chosen, the type of grape, the maceration process, and the aging process.

-Ripeness of Grapes:
You’ve experienced this before when you’ve eaten fruit. 
Young fruit is typically harder and more bitter. 
Ripe fruit is softer and sweeter. 
That’s the depletion of tannins in action. 
The riper the grapes, the more tannins have broken down. 
That results in a weaker physical structure and less tannin molecules to bind to taste receptors and create a bitter flavor. 
You can really weaken the tannins if you use frozen grapes or freeze wine.

-Grape Varieties:
Some grapes are just more tannic than others. 
This has everything to do with how that particular grape evolved to ensure its survival and thrive in its environment. 
Which the presence of tannins helps it do. 
Consider the soil and climate it grows in (warmer weather produces less tannic grapes), the irrigation and water it receives (the less water the grape gets, the more tannins), and the natural predators it has (exposure to natural predators increases tannins in grapes).
All of these factors play a role in how much natural tannin a grape has. 
Some of the most tannic wine varietals out there are from Nebbiolo, Cabernet Sauvignon, Syrah, Sangiovese, and Malbec. 

-Maceration:
While a grape may be naturally tannic, its tannins can be tempered or enhanced through different types of maceration. 
Two commonly used maceration strategies to increase tannins in wine are cold-soaking and extended maceration. 
Cold-soaking is when the maceration process is done in a temperature-regulated vat to keep the raw grape juice from fermenting. 

This allows the maceration process to continue as usual, and the grape juice to keep absorbing tannins from the must.
Extended maceration is done after the wine is fermented. 
The fermented wine is returned to the must to soak in the grape skins, seeds, and stems for up to 100 days. 
This increases the tannin level in the wine, but in a different way. 
Because the fermented wine is now has a wine alcohol content, the tannins it extracts have increased molecule sizes. 
That usually makes them a bit softer and less bitter than tannins derived from cold-soaking.

-Wine Tannins and Aging :
We know wood and bark—especially oak—have tannins, and if wine is kept in constant contact with oak, it absorbs them. 
The longer a wine is aged in an oak barrel, the more tannins it will absorb from the oak barrel. 
The resulting wine can be varied combinations of tannins from different sources. 
That’s why aged red wines are considered the most complex. 
Optimal wine storage temperature, wine cellar lighting, and how long wine sits after the wine bottle is opened all have long- or short-term ramifications on tannin levels, too. 
A wine cellar app helps, too.

Hydrolyzable tannins can be found in wine either:
*during the alcoholic fermentation/maceration step where hydrolyzable tannins from grape stems are extracted if the whole cluster is used.

*during the wine maturation in barrels or after addition of staves, chips, or wood powder.
During maturation of wine in oak barrels, several phenomena occur. 
First, the wine is being absorbed by the wood, especially in new barrels, and then some water and ethanol from the wine evaporate due to the porosity of wood and depending on the relative humidity and temperature. 

Then, the wine that is a hydroalcoholic solution starts to extract ellagitannins from the wood, as they are easily extractable and highly soluble in wine. 
At the same time, oxygen diffuses through the wood to the wine, and oxidation reactions between the wine compounds occurs. 
Ellagitannins are highly reactive with other flavonoids, and through several reactions formation of flavano-ellagitannin products may occur. 

Ellagitannins can also react with anthocyanins, the red pigment from grape skins, to form new-pigmented compounds involved in the stabilization of the red wine color. 
Ellagitannins can also protect anthocyanins from oxidation by acting as a barrier against oxidation. 
Ellagitannins in wines after maturation depend on many parameters including raw material (wood) content, and wood toasting.

TANNINS and WINE TASTING:
Will tannins always be described as bitter and astringent?
There are whole wine lingo dictionaries out there. 
They have lots of words the wine community uses to describe the effect of tannins on the senses.

Here are some them:
*Aggressive: 
Wines with bold tannins and sharp flavors
*Big:
While big can refer to big fruit flavors, it can also refer to big tannins
*Brawny: Big, sharp wines with raw, woody characteristics

*Chewy: 
Wines with a thicker mouthfeel, often because of a firm tannic structure
*Coarse: 
Robust and raw tannins; like brawny but without the woody bits
*Dry: 
Another word for astringent, a tightening, puckering feeling in the mouth and tongue

*Firm: 
Solid, bold tannic structure
*Grippy:
Like dry and astringent, these speaks to the constricting feel on the tongue
*Harsh: 
Noticeable, strong tannins
*Plush: 
The firm texture of tannins can make it feel thick and smooth in the mouth

*Silky: 
Like plush, but with enhanced smoothness
Not only will these help you identify a tannic wine, but it can help you describe them, too.
People can usually identify with characteristics like “acidity” and “sweetness” as these are commonly used with everyday food. 
Once you know what to look for, tannins are actually one of the easiest things to identify in wine. 

To help you get used to tannins, try this test:
*Swirl a red wine around your mouth like a real wine taster, get it right up onto your gums
*Notice how dry your mouth becomes for a few seconds. 
That is a “high tannin” or “tannic”
*Then compare to a lower tannin red like a Pinot Noir. 
Notice that mouth-drying still occurs but it is much less prominent. 
These are finer tannins
*Then try it with something like a unoaked Sauvignon Blanc or Pinot Grigio to see that there is no real drying sensation

TANNINS in TEA:
-Tannin levels vary between different types of tea:
Although tea is generally considered a rich source of tannins, multiple variables can affect the amount that ends up in your teacup.
The four main types of tea are white, black, green, and oolong, all of which are made from the leaves of a plant called Camellia sinensis.
Each type of tea contains tannins, but the concentration is strongly affected by the way it’s produced and how long it’s steeped when you prepare it.

Some sources say black tea has the highest tannin concentration, while green tea is often credited with having the lowest.
White and oolong teas usually fall somewhere in between, but the amount in each type can vary considerably depending on how they’re produced.
Generally, lower-quality teas tend to have higher tannin levels, and the longer you steep your tea, the higher the concentration of tannins in your cup.
All types of tea contain tannins, but the exact amount can vary considerably depending on how the tea is produced and for how long it’s steeped.

-Potential health benefits:
There are many different types of tannins found in tea, and how tannins affect the human body is still not well understood.
However, early research suggests that certain tea tannins possess characteristics similar to those of other polyphenols, helping prevent disease by providing antioxidant and antimicrobial benefits.

-Epigallocatechin gallate:
One of the main tannins found in green tea is known as epigallocatechin gallate (EGCG).
EGCG belongs to a group of compounds known as catechins. 
EGCG is thought to be one of the reasons behind the many health benefits associated with green tea.
Ultimately, more research is needed to better understand how EGCG may be used to support human health.

-Theaflavins and thearubigins:
Tea also offers a plentiful supply of two groups of tannins called theaflavins and thearubigins. 
Black teas contain particularly high levels of these tannins, and these tannins are also credited with giving black teas their distinctive dark color.
At this stage, very little is known about theaflavins and thearubigins. 
However, early research indicates that they function as potent antioxidants and may offer protection against cellular damage caused by free radicals.

-Ellagitannin:
Tea also contains high levels of a tannin called ellagitannin.
Early-stage research suggests ellagitannin may promote the growth and activity of beneficial gut bacteria, but more studies in this area are needed.
Ellagitannin is also in the spotlight for Ellagitannin's potential effect on cancer treatment and prevention.
Like other types of dietary polyphenols, ellagitannin exhibits strong antioxidant and anti-inflammatory effects. 
Test-tube studies have revealed that Ellagitannin may also play a role in reducing the growth and spread of cancerous cells.
Certain tannins present in tea may help prevent disease and provide antioxidant and anti-inflammatory benefits. 

-The bottom line:
Tannins are chemical compounds found in a variety of plant-based foods and beverages, including tea.
Tannins are responsible for giving tea its dry, somewhat bitter flavor and providing color in certain types of tea.
Early research suggests that tea tannins may provide health benefits due to their antioxidant and anti-inflammatory effects. 

Black tea had the highest tannin concentration, ranging from 11.76 to 15.14 percent, while green tea had the lowest amount of tannins, with an average of 2.65 percent (and a high of 3.11 percent). 
Oolong tea fell in the middle of black and green tea, clocking in at 8.66 percent.
Because of health effects of tannin in tea, the researchers from this study concluded that green tea is the best tea option, especially if you're drinking your tea with your meals or soon before or soon after eating. 

HOW to DESCRIBE TANNINS?
Tannins can be best described through the tactile sensations they produce – think more of mouthfeel rather than aroma or flavour. 
It’s important to consider both Tannins' quantity and quality; whether more or less present, tannins can be very different in structure and cause very different sensations when you taste a wine.
There are two useful groups of descriptors to define tannins – according to texture and maturity.

Are the tannins soft, velvety, silky? 
Or coarse, grainy, chalky? 
These are examples of textural characteristics that mirror the sensations tannins can cause in your mouth.
Regarding maturity, do Tannins make you think of green, crunchy, unripe fruit? 
Or of juicy, smooth and sweet pulp? 
The nature of tannins is closely linked to the grapes’ level of ripeness and, therefore, will mirror the nature of the wine’s fruit profile.

Another important differentiation to make is astringency vs. bitterness. 
Bitterness is a taste character while astringency is, as already discussed, a textural sensation. 
Even though tannins are not flavour compounds, Tannins can produce a feeling of bitterness in addition to the mouth-coating grip. 
This is particularly true for young red and orange wines.

It’s important to distinguish between the quality and quantity of tannins.
Texture is useful to describe the quality of tannins, i.e. silky, plush or velvety. 
When a wine has a pleasant amount of tannins, noticeable but unobtrusive, it’s often described as “grippy.”
When tannins are described as “green,” they’re slightly bitter and have unpleasant astringency. 
“Polished” or “elegant” tannins will be very fine-grained in texture, noticeable but pleasant.
Another important element is the difference between bitterness and astringency. 
Bitterness refers to taste, while astringency refers to tactile sensation.

When you describe a wine, ask these questions: 
*Do tannins immediately coat the mouth, or do they appear slowly? 
*Do they dominate the wine, or are they matched by freshness and fruit? 
*Are they integrated and gentle, or assertive and harsh?

Phenolics include anthocyanins, which are responsible for color in flowers, fruits and red wine, and although odorless and nearly flavorless, tannins do impart an astringent sensation.
Although bitterness and astringency are caused by tannins binding with proteins in our saliva when drinking wine, the two should not be confused. 
Bitterness refers to one of the five basic flavors (the others being sweetness, saltiness, acidity and umami) while astringency refers to the tactile sensation of dryness and roughness in the mouth. 

Tannins' effects are a function of the degree of polymerization, i.e. how big tannin molecules become, from winemaking and aging. 
Small molecules are believed to impart bitterness while big molecules are said to impart astringency. 
Since tannins are extracted as small molecules and then polymerize into medium and big molecules during aging, the bitter taste evolves to a less bitter taste but more astringent sensation to one of mostly astringency. 
That’s because our salivary proteins cannot accommodate (i.e. bind to) those large molecules.

GRAPES with HIGHER TANNINS:
Some grapes are naturally higher in tannins than others. In general, and because tannins are predominantly in the skins and seeds of each grape, varieties with thicker skin will have the potential to produce wines with higher tannins. 
Varieties notably high in tannins include Cabernet Sauvignon, Nebbiolo, Sangiovese, Malbec, Mourvèdre/Monastrell, Syrah/Shiraz, Tannat and Tempranillo. 
Thinner skinned grapes – such as Pinot Noir, Gamay, Grenache – are therefore less tannic.
This is also true for lighter-skinned grapes. 

A thick-skinned white variety will also have a relatively high amount of tannins.
Still, growing conditions and winemaking choices have a crucial impact on the development and extraction of tannins and on the amount that actually goes into a wine from a given variety.
This accounts for the dramatic variations in a wine from a given region, produced from the same grapes in different vintages. 
Or for expressions of the same variety from very different growing regions. 
Take for example a Barossa Shiraz vs a Rhône Syrah. 
The former will likely be made with riper fruit at greater alcohol potential and the tannins will, therefore, be soft, rounded and velvety. 

The latter’s fruit, hailing from the cooler banks of the Rhône, will not be as ripe and the tannins not as developed, for a grainier and more angular mouthfeel.
In terms of winemaking, decisions such as fermentation temperature, length of maceration (how long the juice stays in contact with the grapes’ skins), number and vigour of punch-downs or even the type of yeasts used will have an impact on the amount of tannins that are extracted from the grapes and leached into the wine.

DO TANNINS HELP WINE AGING?
Tannins do play an important role in wine ageing. 
Evolution of grape tannins and the tannins imparted by wood contribute to changing aroma, flavour and textural characteristics over time. 
The nature and number of tannins change naturally: the tannin molecules will gradually polymerise (combine to form larger chains) and eventually precipitate as sediment.
Once polymerised the tannins will no longer impart any bitterness or astringency effect. 
But as key structural components, the presence of tannins will give wine more longevity – that ‘grip’ caused by tannic astringency will make wines feel ‘fresher’ as the primary fruit aromas get lost.

Despite the shocking astringency that high tannin wines have when they’re young, tannin is one of the key traits that allows red wines to age well for decades.
Over time, those big, bitter tannins will polymerize, creating long chains with each other, causing them to feel smoother and less harsh.
Tannin is one of the key reasons that a young, powerful wine like Brunello di Montalcino is often aged for as long as 10 years before it’s opened.

While often said to help a wine age, plenty of white wines reach a magnificent age without tannin. 
However, mouthfeel changes as a red wine matures. 
Initially, the tannins leached into a wine are smaller molecules. 
With time, these tannins start to combine and form larger chains—a process called polymerization.
One theory is that this aging process reduces the tannins’ reactive surface, which produces a softer mouthfeel. 

These tannin chains become so long that they fall out of suspension, which creates a deposit and leads to sediment in some bottles.
It’s not clear whether this reaction is the only thing that makes aged wine less astringent. 
In any case, mature wines are often described as having “resolved” tannins, which are smooth, soft and no longer astringent. 
However, if a red wine has harsh, bitter and unbalanced tannic structure to begin with, no amount of aging will even them out.

Aged wines, like full-bodied reds, which are quite high in tannins, typically age more gracefully than low- or non-tannic wines. 
This is because, as time passes, the tannins chemically bind into long chains of molecules. 
As this happens, the length and weight of the chains makes them fall to the bottom as sediment. 
Sediment should never be part of standard wine pour, by the way. 

Learn how to decant wine to solve that problem. 
This removes much of their harsher, bolder characteristics from the wine’s flavor profile. 
This is referred to as a wine with resolved tannins.
Light-bodied reds that don’t have extended maceration processes or oak-barrel aging, and consequently have low tannins, don’t need aging. 

That's because the amount of tannins isn’t high enough to require softening. 
That’s why they’re ready to drink young. 
These young wines can benefit from a quick decant. 
If you're wondering what does a wine aerator do, there's your answer, they can help soften some of the tannins. 
This is done my adding air to the wine aggressively giving you an intentionally oxidized wine.

FOODS and DRINKS with TANNIN:
-Pomegranates
-Strawberries contain both hydrolyzable and condensed tannins.
-Most berries, such as cranberries, and blueberries, contain both hydrolyzable and condensed tannins.

-Nuts:
Nuts vary in the amount of tannins they contain. 
Some species of acorns of oak contain large amounts. 
For example, acorns of Quercus robur and Quercus petraea in Poland were found to contain 2.4–5.2% and 2.6–4.8% tannins as a proportion of dry matter, but the tannins can be removed by leaching in water so that the acorns become edible.
Other nuts – such as hazelnuts, walnuts, pecans, and almonds – contain lower amounts. 
Tannin concentration in the crude extract of these nuts did not directly translate to the same relationships for the condensed fraction.

-Herbs and spices:
Cloves, tarragon, cumin, thyme, vanilla, and cinnamon all contain tannins.

-Legumes:
Most legumes contain tannins. 
Red-colored beans contain the most tannins, and white-colored beans have the least. 
Peanuts without shells have a very low tannin content. 
Chickpeas (garbanzo beans) have a smaller amount of tannins.

-Chocolate:
Chocolate liquor contains about 6% tannins.
Tannins are mostly associated with wine – both red and skin-macerated whites (the so-called orange wines). 
But you will also find Tannins easily in tea, coffee and dark chocolate. 
While present in many fruits (namely grapes!), nuts, spices, and legumes, they will be in much lower concentrations and therefore not as perceptible.
But taste an over-steeped black tea and you’ll have no trouble identifying the characteristic astringency of tannins.
Foods and plants high in tannins include pomegranates, grapes, most berries, nuts that can be consumed raw, most legumes, the spices clove, tarragon, cumin, thyme, vanilla, and cinnamon, beer, and, of course, red wine. 

Principal human dietary sources of tannins are tea and coffee.
Most wines aged in charred oak barrels possess tannins absorbed from the wood.
Soils high in clay also contribute to tannins in wine grapes.
This concentration gives wine its signature astringency.
Coffee pulp has been found to contain low to trace amounts of tannins.

-Fruit juices:
Although citrus fruits do not contain tannins, orange-colored juices often contain tannins from food colouring. 
Apple, grape and berry juices all contain high amounts of tannins. 
Sometimes tannins are even added to juices and ciders to create a more astringent feel to the taste.

-Beer:
In addition to the alpha acids extracted from hops to provide bitterness in beer, condensed tannins are also present. 
These originate both from malt and hops. 
Trained brewmasters, particularly those in Germany, consider the presence of tannins to be a flaw.
However, in some styles, the presence of this astringency is acceptable or even desired, as, for example, in a Flanders red ale.
In lager type beers, the tannins can form a precipitate with specific haze-forming proteins in the beer resulting in turbidity at low temperature. 
This chill haze can be prevented by removing part of the tannins or part of the haze-forming proteins. 
Tannins are removed using PVPP, haze-forming proteins by using silica or tannic acid.

High-tannin food and drink include:
*Dark chocolate
*Pomegranate
*Grape juice
*Quince
*Cinnamon
*Cloves

-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) flavour 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 and tea extracts have been reported to contain no tannic acid.

-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.
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.
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.

*Effects of tannins on the drinkability of wine
Tannins in wine have been described as having the effect of making wine difficult to drink compared to a wine with a lower level of tannins. 
The tannins can be described as leaving a dry and puckerd feeling with a "furriness" in the mouth that can be compared to a stewed tea, which is also very tannic.

-Fruits:
*Pomegranates:
Pomegranates contain a diverse array of tannins, particularly hydrolysable tannins. 
The most abundant of pomegranate tannins are called punicalagins. 
Punicalagins are also found to be the major component responsible for pomegranate juice's antioxidant and health benefits.
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 Food and Drug Administration. 
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.

*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. 
Areca Catechu also contains tannin which contributes to its antibacterial properties

*Berries:
Most berries, such as cranberries strawberries and blueberries, contain both hydrolyzable and condensed tannins.
Fruit, red wine and all types of coffee also contain significant amounts. 
Specific significant sources of tannins include:
*Grapes
*Apple juice
*Strawberries
*Raspberries
*Blackberries
*Pomegranate
*Plums
*Walnuts
*Olives
*Chickpeas
*Black-eyed peas
*Lentils
*Chocolate/cocoa

DOES COFFEE CONTAIN TANNINS?
If you’ve ever over-extracted a cup of coffee by grinding your beans too finely or leaving a French press to steep for too long, you’re familiar with the dry, astringent characteristics associated with tannins. 
It might seem like this is the end of the story, and that coffee definitely contains tannins, but not so fast.

Because tannins have such a broad definition, it is difficult to test for tannins in coffee. 
Since the only criterion is protein binding, a molecule that doesn’t bind with one protein but does bind with another can be easy to misclassify. 
This complicates the testing process and makes it technically unclear whether coffee contains tannins.

Coffee does contain a compound called chlorogenic acid that is classified as a tannin, although it only registers as a tannin on some tests, strangely. 
Another related compound, chlorogenic acid, is well-established as a tannin and is present in unripe coffee beans in significant concentrations.
While the presence of these two compounds does technically mean coffee contains tannins, the effect they have on taste in coffee is still unclear. 

Researchers aren’t sure whether either compound is present in high enough concentrations or binds strongly enough to salivary proteins to produce the astringent flavors associated with over-extracted coffee.
The bottom line is that, yes, coffee does contain tannins if you use the broadest definition of tannins. 
Whether these tannins contribute to the bitter, unpleasant flavors associated with over-extracted coffee is less clear and surprisingly difficult to study. 

WHY DO PLANTS HAVE TANNINS?
According to the U.S. Forest Service, plants developed tannins as a protection mechanism. 
The bitter taste is meant to dissuade would-be plant eaters from dining on that particular species. 
The most tannic parts of plants are usually their growth areas, like skin, stems, stalks, and seeds. 
These are the parts of the plant that are most important to survival and growth, and most in need of defense. 

It’s an evolutionary strategy that works well for grapes. 
Until they meet a winemaker.
In the case of tree bark, its purpose is twofold. 
First, to make the bark inedible. 
Second, to stop mold and fungi from infecting the tree through the bark. 
They do this by binding to the enzymes and proteins on the mold or fungi and disabling them.

NUTRITIONAL EFFECTS of TANNIN:
In ruminants, tannins can induce beneficial effects. 
For example,
*In sheep and cattle higher retention of nitrogen has been observed in sheep and cattle with low to moderate levels of tannins in forages,
*In these cases, the lower apparent and true digestibility of nitrogen was compensated for by reduced urinary loss of hydrogen,
*Moderate levels of tannins (less than 4% ) in forage legumes can have beneficial responses in ruminants, resulting in higher growth rates and milk yield,
*However, even in ruminants, levels of tannins exceeding 6% of the diet result in negatively affect growth rates and milk yield.
Several mechanisms have been suggested to explain how tannins influence protein utilization by ruminants -

-Rumen escape:
One mechanism postulated is that tannins complex proteins at the pH of the rumen (5 to 7) and protect them from microbial enzymes. 
Subsequently, these complexes dissociate in contact with gastric (pH 2.5-3.5) and pancreatic (pH 8) secretions.
*High quality dietary proteins would be protected, at least in part, from degradation in the rumen and would then be digested more effectively in the intestine. However,
*Even when released, tannins are still biologically active and can react with digestive enzymes or other proteins.
*Indeed, in nonruminants, tannins decrease intestinal absorption of amino acids (especially methionine) and reduce growth.

-Urea recycling:
Another hypothesis is that tannins may increase efficiency in nitrogen recycling to the rumen.

Some facts:
*Tannins lower the rate of protein degradation and deamination in the rumen resulting in lower rumen ammonia concentration.
*This results in lower plasma urea nitrogen (PUN).
*Lower PUN means lower urinary nitrogen excretion with less wastage of nitrogen.
*Larger amounts of nitrogen are recycled because tannins stimulate increased saliva production.

-Microbial efficiency:
In diets based on tanniniferous forages, nitrogen rumen outflow is often larger than nitrogen intake. 
Several studies have reported an increase in protein flow when moderate doses of tannins were used. 

This has been attributed to -
*Increased rumen escape of dietary proteins,
*Increase in microbial protein flow (up to 28% in sheep).
The larger microbial flow could be the result of
*Increased saliva production, increased rumen turnover rate, and hence, increased microbial outflow,
*Increased nitrogen recycling to the rumen,
*Decreased proteolysis and slower fermentation of proteins and non-protein nitrogen in the rumen (particularly important in legume silages); this results in a more even nitrogen availability to bacteria.
Microbial flow is usually measured using a microbial internal marker (diaminopimelic acid, DAPA). 

Tannins have traditionally been considered antinutritional, but Tannin is now known that their beneficial or antinutritional properties depend upon their chemical structure and dosage. 
The new technologies used to analyze molecular and chemical structures have shown that a division into condensed and hydrolyzable tannins is too simplistic.

Recent studies have demonstrated that products containing chestnut tannins included at low dosages (0.15–0.2%) in the diet of chickens may be beneficial.
Some studies suggest that chestnut tannins have positive effects on silage quality in the round bale silages, in particular reducing NPNs (non-protein nitrogen) in the lowest wilting level.
Improved fermentability of soya meal nitrogen in the rumen may occur.

Studies conducted in 2002 on in vitro ammonia release and dry matter degradation of soybean meal comparing three different types of tannins (quebracho, acacia and chestnut) demonstrated that chestnut tannins are more efficient in protecting soybean meal from in vitro degradation by rumen bacteria.
Condensed tannins inhibit herbivore digestion by binding to consumed plant proteins and making them more difficult for animals to digest, and by interfering with protein absorption and digestive enzymes.
Many tannin-consuming animals secrete a tannin-binding protein (mucin) in their saliva. 

Tannin-binding capacity of salivary mucin is directly related to its proline content. 
Salivary proline-rich proteins (PRPs) are sometimes used to inactivate tannins. 
One reason is that they inactivate tannins to a greater extent than do dietary proteins resulting in reduced fecal nitrogen losses. 
PRPs additionally contain non-specific nitrogen and non-essential amino acids making them more convenient than valuable dietary protein.

Histatins, another type of salivary proteins, also precipitate tannins from solution, thus preventing alimentary adsorption.
However, many studied showed that legume fodders containing condensed tannins are a possible option for integrated sustainable control of gastrointestinal nematodes in ruminants, which may help address the worldwide development of resistance to synthetic anthelmintics. 
These include nuts, temperate and tropical barks, carob, coffee and cocoa.

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. 
This may not be bad for someone with an infection, as iron is mopped up by the immune system to keep microorganisms from properly multiplying. 
Tannins have been shown to precipitate proteins, which inhibits in some ruminant animals the absorption of nutrients from high-tannin grains such as sorghum.

TANNIN in WOOD
Popular timber species have high levels of Tannin. 
In fact, most tree and plant species contain tannin in varying levels and strengths. 
We’re mostly concerned with Oak and Chestnut because these two timber species have high levels of tannin and we use them for just about everything.
Probably, the first thing to understand is that moisture plays a big part in the life of Tannin. 
When wood is dry the reactions we talk about below very rarely take place. 
It’s all about the moisture i.e. water. 

The water provides a solution for the soluble tannin. 
This means that kiln dried timber (low moisture content) rarely reacts, whereas fresh sawn timber (high moisture content) often reacts.
Tannin in wood is corrosive to ferrous metals (irons) or metals with a ferrous (iron) content.
The corrosion doesn’t do any damage to the wood (the same can’t be said for the metal) but it can result in a stain on the wood, a bluey-black stain. 
The wetter the wood, the more soluble the tannin, the more it will stain.

So when you’re working on wood with strong tannin content it means considering tools, fixings, blades… anything metal that touches the wood whilst you work on it and anything metal that touches it once it’s in place. 
We recommend using austenitic stainless steel fixings for external timber use.
If you’re concerned about stains then you have to think about not only fixings but blades, machine beds and storage racks, you even have to take care of the mineral content of soil in the mud on the soles of your shoes.
If you find you have stains then, in our humble opinion, you have two options:

-Option number 1: leave it:
If the stains are on external Oak or Chestnut and you intend to leave it to weather naturally to a silvery grey then, as it weathers the stain will mellow and finally disappear so leave it and in a couple of years you’ll have forgotten all about it.

-Option number 2: treatment:
The blue black stain can be treated with oxalic acid to try to reduce the discolouration. 
Tannin is soluble and leaches out of wood in water and where the water evaporates it leaves the tannin sediment behind… as a stain.
Like the corrosion, the leaching doesn’t have any detrimental effect on the mechanical properties of the wood. 
The tannin washes out of the timber in a solution and gets left behind as very fine, rust coloured particles. 
The particles are like a fine sediment, dust or powder. 
You can wipe them away from a smooth surface with your finger but on a porous surface the pores absorb the rusty coloured dust.

If you have tannin staining as a rusty coloured tea stain on the floor under your structural oak posts, on the wall under your new chestnut cladding or as watermarks on the surface of your new garden furniture then, in truth, there’s not a lot to be done.
The answer to tannin leaching is time. 
The seasoning of the timber over time means that the timber dries and hardens and becomes less penetrable by water and less likely to release tannin.

If it’s a stain underneath your timber you can rinse regularly to help the sediment dissipate.
If it’s a tannin stain on the surface of your wood then any washing or rinsing will probably create new stains as the the water dissolves the tannin and then evaporates again (leaving you a nice new pattern).
Tannin that has leached and stained will disappear over time and washes away naturally. 
If the stains are on porous material e.g. portland stone, then logic says it will take longer to dissipate. 
If the stain is on a non-porous material e.g. zinc, it will wash off very quickly.
Whilst tannin content in timber sounds like a bad thing ironically (no pun intended) the presence of tannin makes a timber species more durable. 

TAMING TANNINS:
There are a number of possible solutions if you have extracted excessive tannins, all very effective. 
The extent of tannin “removal” depends largely on timing, i.e. trying to remove small vs. large molecules, and concentration.
Tannins have a strong affinity for proteins, and so, you can fine using a protein-containing fining agent such as egg whites, gelatin, or isinglass. 

Since gelatin comes in different formulations, i.e. low vs. high molecular weight, choose the one that best fits your needs based on the manufacturer’s recommendations, and avoid overfining. 
Gelatin formulations with different molecular weights show preferential affinity for tannin size.
PVPP, short for polyvinylpolypyrrolidone, is a highly insoluble, high-molecular weight synthetic polymer that is effective in absorbing and precipitating small tannins. 
And so, PVPP is recommended for early-drinking wine or where bitterness needs to be toned down.

Another potential solution is gum arabic (gum acacia), a natural gum extracted from the sap of specific species of African Acacia trees. 
It is very effective in reducing tannin astringency and increasing the perception of body or volume, and reducing the perceptions of acidity and tannin harshness, while adding body.
And lastly, you can tame tannins by readjusting the wine balance by tweaking sugar and acidity contents. 

A wine tolerates acidity better when its alcoholic degree is higher; acid, bitter and astringent tastes reinforce each other; the hardest wines are those which are at the same time acid and also rich in tannins; a considerable amount of tannin is more acceptable if acidity is low and alcohol is high. 
The less tannic a red wine is, the more acidity it can support (necessary for its freshness); the richer a red wine is in tannins (necessary for its development and for its longevity) the lower should be its acidity; a high tannin content allied to a pronounced acidity produces the hardest and most astringent wines.

MYTHS ABOUT TANNINS in POULTRY DIETS:
Historically, tannins were considered a double-edged sword in diets.
Sometimes known for their bitter taste, tannins have traditionally been thought of as anti-nutritional factors in poultry diets. 
However, growing attention on the development of antimicrobial resistance to antibiotics among consumers has led to increased interest in evaluating alternative ingredients – including tannins – in poultry diets.
Recent research indicates that tannins may help in managing enteric diseases – like coccidiosis and necrotic enteritis – especially in antibiotic free poultry production systems.
As poultry producers consider evaluating tannin-based ingredients, understanding the facts surrounding tannins is key. 
One thing we know for sure: not all tannins are created equal.

-Myth #1: All Tannins Have Similar Structures
Fact: 
Tannins are a highly diverse group of natural, plant polyphenolic molecules with variable structures and properties. 
There are two major types of tannins: condensed tannins and hydrolysable tannins. 
Condensed tannins (CTs), also known as proanthocyanidins, have high molecular weights and are only degraded under strong oxidative or acidic conditions. 
Hydrolysable tannins (HTs), in contrast, have lower molecular weights and can be hydrolyzed by acids, bases and enzymes. 
Interestingly, the complex structure of tannins is thought to limit development of bacterial resistance to various tannin molecules.

-Myth #2 : Sorghum Tannins, Tree Tannins and Tannic Acid are the Same
Fact: 
The type of tannin and level of tannin present in a feed ingredient is dependent on the plant source. 
Condensed tannins are commonly found in forages, grains and sorghum.
Catechins – simple CT structural units – are found in wine, green tea and dark chocolate. 
Catechins offer antioxidant benefits.
Hydrolysable tannins, in contrast, are often found in tree wood and gallnuts. 
Research suggests that bacteria, like Clostridium perfringens, may be unable to develop resistance to HTs.  
Among HTs, two sub-classes exist based on the esterified phenolic acid units: gallotannins – found in tara pods and gallnuts – and ellagitannins which are commonly found in chestnut wood.
Tannic acid – a gallotannin – is a specific type of hydrolysable tannin. 
Overall, differences in tannin source will influence the type of tannin and tannin level in a feed ingredient. 
Manufacturing processes may also impact tannin efficacy in poultry diets.

-Myth #3: Tannins Reduce Nutrient Digestibility in Poultry
Fact: 
Tannin source, tannin structure and dietary tannin content can have a big impact on the nutritive or anti-nutritive properties of the tannin. 
In general, anti-nutritional effects of tannins are often linked to tannin protein binding which may lower feed intake and decrease digestibility of proteins, carbohydrates and starches.
However, many studies showing anti-nutritional effects of tannins utilized diets either with high levels of tannins or diets containing purified condensed tannins from sorghum.
Alternatively, feeding low levels of hydrolysable tannins has been shown to have beneficial effects on intestinal health and performance of poultry.
For example, the antimicrobial and anti-parasitic effects of tannins are likely related to tannin complexation with microbial enzymes and/or metal ions, like iron, that are required for normal pathogen growth and metabolism.
Thus, the negative binding characteristics of tannins can actually be beneficial when poultry experience pathogen challenges.

-Myth #4: Tannins are Unhealthy for Poultry
Fact: 
Dietary tannins – when dosed correctly – offer a wide-range of benefits that support optimal gut health and performance of poultry. 
First, tannins are potent natural antioxidants as well as anti-inflammatory molecules. 
Second, tannins are astringent, meaning they may help to tighten junctions between intestinal epithelial cells, thereby helping to prevent leaky gut syndrome. 
Third, tannins have been shown to positively modulate the intestinal microbiota composition and may help to maintain mucosal immunity.
Fourth, tannins offer antimicrobial activities by inhibiting growth of several poultry pathogens such as Campylobacter spp.2, Salmonella spp.2 and Clostridium perfringens.

SENSING TANNINS:
You experience the effect of tannins any time you drink a wine that creates a drying sensation in your mouth.
One current research direction involves attempts to work out the relationship between tannin structure and ‘mouthfeel’ of red wines. 
Tannins contribute two characteristics to red wine character, astringency (most significantly) and bitterness—these are sensations that are sometimes confused by tasters. 

Bitter perception is quite well understood, since it is one of the five primary tastes and is sensed by a specific receptor found in taste buds on the tongue and soft palate. 
Astringency perception is much less well understood: the common understanding is that it is actually mediated by the sense of touch rather than by taste. 
Tannins are thought to taste astringent because they bind with salivary proline-rich proteins and precipitate them out. 
This leads to increased friction between mouth surfaces, and a sense of dryness or roughness. 
The term ‘mouthfeel’ has been coined to describe the sensation of wine in the mouth, and it is now recognized that this is an important property of red wines.

Chemically, tannins are what’s known as polyphenols, a type of biomolecule that binds to proteins. 
That’s what causes tannins to affect our tongues the way tannin does.
Tannin binds to the proteins on our taste buds to activate a sharp, pungent taste (bitterness). 
Dark chocolate is a good example of the bitterness of higher tannins. 
Tannins also bind to the proteins in our saliva, altering their structure and making our mouths feel dry (astringency). 
Very strong black tea is a great example of astringency. 
Higher tannins do the same thing to animals’ tongues, and that’s usually enough to discourage them from eating.

HOW to EXTRACT TANNIN?
The procedure to extract tannin recalls closely that of an infusion: the vegetable source (e.g. Chestnut and Quebracho wood) is shredded and poured into gigantic autoclaves that act as “teapot”.
In contact with hot water, the wood releases tannin: 
The water is tinged with a beautiful color that varies from brown to reddish according to the wood used and its scent is very strong.
Tannin is now ready to be used in liquid form but, to make transportation and conservation easier, an evaporation of the water is carried out to obtain a fine colored powder.

The water vapor is recovered and re-processed into the vats for new infusions. 
The exhausted wood is transformed into useful pellet for heating stoves.
First, because it is worth repeating, destem grape bunches. You want to remove as much of the stems as possible, particularly very green (as opposed to brownish) stems. 
Catechins in stems are very harsh and will require years to mellow out before the wine is approachable.
Second, anthocyanins are more soluble in grape juice than in alcohol (i.e. wine), whereas catechins are more soluble in alcohol than in water. 
To extract more anthocyanins for a deeper color, perform a cold soak maceration before fermentation.

Cold soak maceration involves soaking grape solids in the juice for several days to a week at a cold temperature, down to 45 °F (7 °C) or preferably lower to ensure fermentation does not start on its own. 
Sulfite lightly at crush, up to 25 mg/L, to minimize bleaching effects of sulfite, which would go counter to your objective of extracting more color, and to minimize catechin extraction. 
And be sure to perform daily punchdowns to stimulate anthocyanin extraction and to reduce any risk of bacterial infections.
During cold soak maceration, there will be some extraction of skin catechins, but these are also precursors to browning reactions in the presence of oxygen (air), and so, their extraction should be limited until fermentation is started — fermentation provides protection against browning by deactivating the culprit enzymes. 

This is usually not a problem but, again, do not over-sulfite as that would otherwise hasten catechin extraction and increase the risk of browning during maceration.
Third, opt for a relatively hot and quick fermentation to favor extraction of catechins from the skins and to minimize contact time with seeds. 
Anthocyanin extraction will continue, albeit, at a much slower pace. 
A typical fermentation should last five to seven days until dryness. 

If you want to minimize catechin extraction because you intend to drink the wine early, rack the wine earlier, say at an SG/Brix of 1.030/7.5, and then press. 
And fermentation temperature should never exceed the mid-80s °F (below 30 °C), which could otherwise result in a stuck fermentation.
Fourth, only perform a (cold) post-ferment maceration if you intend to create a rich, bold, full-bodied style of red meant for aging. 

During this phase of winemaking, extended contact with seeds will hasten extraction of harsher catechins.
Alternatively, perform delestage during fermentation to remove as much seeds as possible if you want to do a post-ferment maceration to extract more skin catechins. 
Delestage is a two-step “rack-and-return” process whereby fermenting red wine juice is separated from the grape solids by racking and then returned to the fermenting vat to re-soak the solids, and then repeated daily.

WHERE IS TANNIN in NATURE?
Tannin is present in wood, stems, barks, leaves, roots and fruits of any plant species.
However some plants, being more rich in tannin, are the most used raw materials for industrial level extraction. We are talking about Chestnut, Quebracho, Tara and Oak Galls.
The Chestnut tree is widespread in southern Europe and in some parts of the Middle East.

Quebracho grows in the North of Argentina and in the South of Paraguay while Tara grows in Peru. 
Galls grows predominantly in Turkey and China.
If you own a vegetable tanned leather item, like a purse, a wallet, a belt; if you wear leather sole shoes or you have a car with leather seats, it is very likely that it has been treated with Chestnut tannin, Quebracho or Tara or with a combination of two or more extracts.

CAN TANNIN HELP BALANCING BACTERIAL FLORA?
Yes, tannin brings the bacterial flora back to its natural equilibrium, and at high concentrations it can be defined as a real natural antibacterial.
A recent university research has reported that tannin contained in vegetable tanned leather can eliminate more than 99% of the bacteria tannincomes into contact with.
In our daily life, this action can particularly affect the population of bacteria responsible for the bad odor inside the footwear.
Unlike the common disinfectants and deodorants for shoes, the tannins action is not temporary but long-lasting in time. 
Tannin also takes place in harmony with the natural physiological processes of the foot.

HOW DO TANNINS WORK?
While tannin is a collective term for various phenolic compounds, all tannins have one thing in common: they bind and precipitate proteins, i.e. separate them out. 
Human saliva is full of protein, which is what makes it so slippery.
A tannic red wine will bind to saliva—this is what causes the mouth to feel dry. 
This protein-binding quality is often cited as the reason why red wine and steak are such a good pairing, though this also has to do with how the wine’s astringency counteracts the fattiness of the meat.

HISTORY of TANNIN:
Maximilian Nierenstein studied natural phenols and tannins found in different plant species. 
Working with Arthur George Perkin, he prepared ellagic acid from algarobilla and certain other fruits in 1905.
He suggested its formation from galloyl-glycine by Penicillium in 1915.
Tannase is an enzyme that Nierenstein used to produce m-digallic acid from gallotannins.
He proved the presence of catechin in cocoa beans in 1931.

He showed in 1945 that luteic acid, a molecule present in the myrobalanitannin, a tannin found in the fruit of Terminalia chebula, is an intermediary compound in the synthesis of ellagic acid.
At these times, molecule formulas were determined through combustion analysis. 
The discovery in 1943 by Martin and Synge of paper chromatography provided for the first time the means of surveying the phenolic constituents of plants and for their separation and identification. 

There was an explosion of activity in this field after 1945, including prominent work by Edgar Charles Bate-Smith and Tony Swain at Cambridge University.
In 1966, Edwin Haslam proposed a first comprehensive definition of plant polyphenols based on the earlier proposals of Bate-Smith, Swain and Theodore White, which includes specific structural characteristics common to all phenolics having a tanning property. 
It is referred to as the White–Bate-Smith–Swain–Haslam (WBSSH) definition.

PHYSICAL and CHEMICAL PROPERTIES of TANNIN:
Physical Form (at 20°C): Brown powder
Melting Point: 208-216°C
Flash Point: 199°C
Density: 2.129
Refractive Index: 1.927
Appearance Form: Powder with lumps
Color: light brown
Odor: No data available
Odor Threshold: No data available
pH: No data available
Melting point/freezing point Melting point/range: 218 °C - lit.
Initial boiling point and boiling range: No data available
Flash point: 199 °C
Evaporation rate: No data available
Flammability (solid, gas): No data available
Upper/lower flammability or explosive limits: No data available
Vapor pressure: No data available

FIRST AID MEASURES of TANNIN:
-Description of first-aid measures:
*If inhaled:
After inhalation: 
fresh air.
*In case of skin contact:
In case of skin contact: 
Take off immediately all contaminated clothing. 
Rinse skin with water/ shower.
*In case of eye contact:
After eye contact: 
rinse out with plenty of water. 
Remove contact lenses.
*If swallowed
After swallowing: 
Consult doctor if feeling unwell.
-Indication of any immediate medical attention and special treatment needed:
No data available

ACCIDENTAL RELEASE MEASURES of TANNIN:
-Personal precautions, protective equipment and emergency procedures:
Advice for non-emergency personnel: 
Evacuate the danger area, observe emergency procedures, consult an expert.
-Environmental precautions:
Do not let product enter drains.
-Methods and materials for containment and cleaning up:
Cover drains. 
Collect, bind, and pump off spills. 
Observe possible material restrictions
Take up dry. 
Dispose of properly. 
Clean up affected area.

FIRE FIGHTING MEASURES of TANNIN:
-Extinguishing media:
*Suitable extinguishing media:
Water Foam Carbon dioxide (CO2) Dry powder
*Unsuitable extinguishing media:
For this substance/mixture no limitations of extinguishing agents are given.
-Advice for firefighters:
In the event of fire, wear self-contained breathing apparatus.
-Further information:
Prevent fire extinguishing water from contaminating surface water or the ground water system.

EXPOSURE CONTROLS/PERSONAL PROTECTION of TANNIN:
-Control parameters:
Ingredients with workplace control parameters:
-Exposure controls:
Personal protective equipment:
*Eye/face protection:
Safety glasses

*Control of environmental exposure:
Do not let product enter drains.

HANDLING and STORAGE of TANNIN:
Conditions for safe storage, including any incompatibilities:
Storage conditions:
Tightly closed. 
Dry.

STABILITY and REACTIVITY of TANNIN:
-Reactivity:
Forms explosive mixtures with air on intense heating.
A range from approx. 

-Chemical stability:
The product is chemically stable under standard ambient conditions (room temperature).

SYNONYMS
Tannic acid
Gallotannin
Tannen