Phenolic compounds—

natural phenol In biochemistry, naturally occurring phenols are natural products containing at least one phenol functional group. Phenolic compounds are produced by plants and microorganisms. Organisms sometimes synthesize phenolic compounds in response to ecol ...

and

polyphenol Polyphenols () are a large family of naturally occurring phenols. They are abundant in plants and structurally diverse. Polyphenols include phenolic acids, flavonoids, tannic acid, and ellagitannin, some of which have been used historically as ...

s—occur naturally in

wine Wine is an alcoholic drink made from Fermentation in winemaking, fermented fruit. Yeast in winemaking, Yeast consumes the sugar in the fruit and converts it to ethanol and carbon dioxide, releasing heat in the process. Wine is most often made f ...

. These include a large group of several hundred

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

s that affect the

taste The gustatory system or sense of taste is the sensory system that is partially responsible for the perception of taste. Taste is the perception stimulated when a substance in the mouth biochemistry, reacts chemically with taste receptor cells l ...

color Color (or colour in English in the Commonwealth of Nations, Commonwealth English; American and British English spelling differences#-our, -or, see spelling differences) is the visual perception based on the electromagnetic spectrum. Though co ...

and

mouthfeel Mouthfeel refers to the physical sensations in the mouth caused by food or drink, making it distinct from taste. It is a fundamental sensory attribute which, along with taste and smell, determines the overall flavor of a food item. Mouthfeel i ...

of wine. These compounds include

phenolic acid Phenolic acids or phenolcarboxylic acids ? are phenolic compounds and types of aromatic acid compounds. Included in that class are substances containing a phenolic ring and an organic carboxylic acid function (C6-C1 skeleton). Two important nat ...

stilbenoid Stilbenoids are hydroxylated derivatives of stilbene. They have a C6–C2–C6 structure. In biochemical terms, they belong to the family of phenylpropanoids and share most of their biosynthesis pathway with Chalconoid, chalcones. Most stilbenoids ...

flavonol Flavonols are a class of flavonoids that have the 3-hydroxyflavone backbone (IUPAC name: 3-hydroxy-2-phenylchromen-4-one). Their diversity stems from the different positions of the phenolic –OH groups. They are distinct from flavanols (with ...

dihydroflavonol The flavanonols (with two "o"s a.k.a. 3-hydroxyflavanone or 2,3-dihydroflavonol) are a class of flavonoid Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenolic second ...

anthocyanin Anthocyanins (), also called anthocyans, are solubility, water-soluble vacuole, vacuolar pigments that, depending on their pH, may appear red, purple, blue, or black. In 1835, the German pharmacist Ludwig Clamor Marquart named a chemical compou ...

flavanol Flavan-3-ols (sometimes referred to as flavanols) are a subgroup of flavonoids. They are derivatives of flavans that possess a 2-phenyl-3,4-dihydro-2''H''-chromen-3-ol skeleton. Flavan-3-ols are structurally diverse and include a range of comp ...

monomers (

catechin Catechin is a flavan-3-ol, a type of secondary metabolite providing antioxidant roles in plants. It belongs to the subgroup of polyphenols called flavonoids. The name of the catechin chemical family derives from ''catechu'', which is the tannic ...

s) and

polymers (

proanthocyanidin Proanthocyanidins are a class of polyphenols found in many plants, such as cranberry, blueberry, and grape seeds. Chemically, they are oligomeric flavonoids. Many are oligomers of catechin and epicatechin and their gallic acid esters. More complex ...

s). This large group of natural phenols can be broadly separated into two categories,

flavonoid Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans. Chemically, flavonoids ...

s and non-flavonoids. Flavonoids include the

s and

tannin Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and Precipitation (chemistry), precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' is widel ...

s which contribute to the color and mouthfeel of the wine. The non-flavonoids include the

s such as

resveratrol Resveratrol (3,5,4′-trihydroxy-''trans''-stilbene) is a stilbenoid, a type of natural phenol or polyphenol and a phytoalexin produced by several plants in response to injury or when the plant is under attack by pathogens, such as bacterium, ba ...

and

s such as benzoic, caffeic and cinnamic acids.

Origin of the phenolic compounds

The natural phenols are not evenly distributed within the grape. Phenolic acids are largely present in the pulp,

s and

s in the skin, and other phenols (

s and

s) in the skin and the seeds. During the

growth cycle of the grapevine The annual growth cycle of grapevines is the process that takes place in the vineyard each year, beginning with bud break in the spring and culminating in leaf fall in autumn followed by winter dormancy. From a winemaking perspective, each step i ...

, sunlight will increase the concentration of phenolics in the grape berries, their development being an important component of

canopy management In viticulture, the canopy of a grapevine includes the parts of the vine visible aboveground - the trunk, cordon, stems, leaves, flowers, and fruit. The canopy plays a key role in light energy capture via photosynthesis, water use as regulated ...

. The proportion of the different phenols in any one wine will therefore vary according to the type of

vinification Winemaking, wine-making, or vinification is the production of wine, starting with the selection of the fruit, its fermentation into alcohol, and the bottling of the finished liquid. The history of wine-making stretches over millennia. There is ...

Red wine Red wine is a type of wine made from dark-colored grape varieties - (red grapes.) The color of the wine can range from intense violet, typical of young wines, through to brick red for mature wines and brown for older red wines. The juice fro ...

will be richer in phenols abundant in the skin and seeds, such as

s and

s, whereas the phenols in

white wine White wine is a wine that is Fermentation in winemaking, fermented without undergoing the process of Maceration (wine), maceration, which involves prolonged contact between the juice with the grape skins, seeds, and pulp. The wine color, colou ...

will essentially originate from the pulp, and these will be the phenolic acids together with lower amounts of

s and

stilbene Stilbene may refer to one of the two stereoisomers of 1,2-diphenylethene: * (''E'')-Stilbene (''trans'' isomer) * (''Z'')-Stilbene (''cis'' isomer) See also * Stilbenoid Stilbenoids are hydroxylated derivatives of stilbene. They have a C6–C ...

s. Red wines will also have the phenols found in white wines. Wine simple phenols are further transformed during wine aging into complex molecules formed notably by the condensation of proanthocyanidins and anthocyanins, which explains the modification in the color. Anthocyanins react with catechins, proanthocyanidins and other wine components during wine aging to form new polymeric pigments resulting in a modification of the wine color and a lower

astringency An astringent (sometimes called adstringent) is a chemical that shrinks or constricts body tissues. The word derives from the Latin '' adstringere'', which means "to bind fast". Astringency, the dry, puckering or numbing mouthfeel caused by th ...

. Average total polyphenol content measured by the Folin method is 216 mg/100 ml for red wine and 32 mg/100 ml for white wine. The content of phenols in rosé wine (82 mg/100 ml) is intermediate between that in red and white wines. In

winemaking Winemaking, wine-making, or vinification is the production of wine, starting with the selection of the fruit, its Ethanol fermentation, fermentation into alcohol, and the bottling of the finished liquid. The history of wine-making stretches over ...

, the process of maceration or "skin contact" is used to increase the concentration of phenols in wine. Phenolic acids are found in the pulp or juice of the wine and can be commonly found in white wines which usually do not go through a maceration period. The process of oak aging can also introduce phenolic compounds into wine, most notably

vanillin Vanillin is an organic compound with the molecular formula . It is a phenolic aldehyde. Its functional groups include aldehyde, hydroxyl, and ether. It is the primary component of the ethanolic extract of the vanilla bean. Synthetic vanillin ...

which adds

vanilla Vanilla is a spice derived from orchids of the genus ''Vanilla (genus), Vanilla'', primarily obtained from pods of the flat-leaved vanilla (''Vanilla planifolia, V. planifolia''). ''Vanilla'' is not Autogamy, autogamous, so pollination ...

aroma An odor (American English) or odour (Commonwealth English; see spelling differences) is a smell or a scent caused by one or more volatilized chemical compounds generally found in low concentrations that humans and many animals can perceive v ...

to wines.J. Robinson (ed), ''"The Oxford Companion to Wine"''. Third Edition, pp 517-518. Oxford University Press 2006 . Most wine phenols are classified as

secondary metabolite Secondary metabolites, also called ''specialised metabolites'', ''secondary products'', or ''natural products'', are organic compounds produced by any lifeform, e.g. bacteria, archaea, fungi, animals, or plants, which are not directly involved ...

s and were not thought to be active in the primary

metabolism Metabolism (, from ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the co ...

and function of the grapevine. However, there is evidence that in some plants

s play a role as endogenous regulators of

auxin Auxins (plural of auxin ) are a class of plant hormones (or plant-growth regulators) with some morphogen-like characteristics. Auxins play a cardinal role in coordination of many growth and behavioral processes in plant life cycles and are essent ...

transport. They are

water-soluble In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution. The extent of the solub ...

and are usually secreted into the

vacuole A vacuole () is a membrane-bound organelle which is present in Plant cell, plant and Fungus, fungal Cell (biology), cells and some protist, animal, and bacterial cells. Vacuoles are essentially enclosed compartments which are filled with water ...

of the grapevine as

glycosides In chemistry, a glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. ...

Grape polyphenols

Vitis vinifera ''Vitis vinifera'', the common grape vine, is a species of flowering plant, native to the Mediterranean Basin, Mediterranean region, Central Europe, and southwestern Asia, from Morocco and Portugal north to southern Germany and east to northern ...

'', the common grape vine, from which European style wines are made the world over, produces many phenolic compounds. There is a varietal effect on the relative composition.

Flavonoids

In red wine, up to 90% of the wine's phenolic content falls under the classification of

s. These phenols, mainly derived from the stems, seeds and skins are often leached out of the grape during the maceration period of winemaking. The amount of phenols leached is known as extraction. These compounds contribute to the

, color and mouthfeel of the wine. In white wines the number of flavonoids is reduced due to the lesser contact with the skins that they receive during winemaking. There is on-going study into the health benefits of wine derived from the

antioxidant Antioxidants are Chemical compound, compounds that inhibit Redox, oxidation, a chemical reaction that can produce Radical (chemistry), free radicals. Autoxidation leads to degradation of organic compounds, including living matter. Antioxidants ...

and

chemopreventive Chemotherapy (often abbreviated chemo, sometimes CTX and CTx) is the type of cancer treatment that uses one or more anti-cancer drugs ( chemotherapeutic agents or alkylating agents) in a standard regimen. Chemotherapy may be given with a cu ...

properties of flavonoids.J. Robinson (ed), ''"The Oxford Companion to Wine"''. Third Edition, pp. 273-274. Oxford University Press 2006 .

Flavonols

Within the flavonoid category is a subcategory known as

s, which includes the yellow

pigment A pigment is a powder used to add or alter color or change visual appearance. Pigments are completely or nearly solubility, insoluble and reactivity (chemistry), chemically unreactive in water or another medium; in contrast, dyes are colored sub ...

quercetin Quercetin is a plant flavonol from the flavonoid group of polyphenols. It is found in many fruits, vegetables, leaves, seeds, and grains; capers, red onions, and kale are common foods containing appreciable amounts of it. It has a bitter flavor ...

. Like other flavonoids, the concentration of flavonols in the grape berries increases as they are exposed to sunlight. Wine grapes facing too much sun exposure can see an accelerated ripening period, leading to a lessened ability for the synthesis of flavonols. Some viticulturalists will use measurement of flavonols such as quercetin as an indication of a vineyard's sun exposure and the effectiveness of canopy management techniques.

Anthocyanins

Anthocyanins are phenolic compounds found throughout the plant kingdom, being frequently responsible for the blue to red colors found in

flower Flowers, also known as blooms and blossoms, are the reproductive structures of flowering plants ( angiosperms). Typically, they are structured in four circular levels, called whorls, around the end of a stalk. These whorls include: calyx, m ...

fruit In botany, a fruit is the seed-bearing structure in flowering plants (angiosperms) that is formed from the ovary after flowering. Fruits are the means by which angiosperms disseminate their seeds. Edible fruits in particular have long propaga ...

s and

leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...

. In wine grapes, they develop during the stage of '' veraison,'' when the skin of red wine grapes changes color from green to red to black. As the sugars in the grape increase during

ripening Ripening is a process in fruits that causes them to become more palatable. In general, fruit becomes sweeter, less green, and softer as it ripens. Even though the acidity of fruit increases as it ripens, the higher acidity level does not make t ...

so does the concentration of anthocyanins. An issue associated with climate change has been the accumulation of sugars within the grape accelerating rapidly and outpacing the accumulation of anthocyanins. This leaves viticulturists with the choice of harvesting grapes with too high sugar content or with too low anthocyanin content. In most grapes anthocyanins are found only in the outer cell layers of the skin, leaving the grape juice inside virtually colorless. Therefore, to get color pigmentation in the wine, the fermenting

must Must is freshly crushed Juice, fruit juice (usually grape juice) that contains the skins, seeds, and stems of the fruit. The solid portion of the must is called pomace and typically makes up 7–23% of the total weight of the must. Making must ...

needs to be in contact with the grape skins in order for the anthocyanins to be extracted. Hence, white wine can be made from red wine grapes in the same way that many white

sparkling wine Sparkling wine is a wine with significant levels of carbon dioxide in it, making it fizzy. While it is common to refer to this as champagne, European Union countries legally reserve that word for products exclusively produced in the Champagne ( ...

s are made from the red wine grapes of

Pinot noir Pinot noir (), also known as Pinot nero, is a red-wine grape variety of the species ''Vitis vinifera''. The name also refers to wines created predominantly from Pinot noir grapes. The name is derived from the French language, French words fo ...

and Pinot Meunier. The exception to this is the small class of grapes known as

teinturier Teinturier grapes () are grapes whose flesh and juice are red in colour due to anthocyanin pigments accumulating within the pulp of the grape berry itself. In non-teinturier red grapes, anthocyanin pigments are confined to the outer skin tissue ...

s, such as

Alicante Bouschet Alicante Bouschet or Alicante Henri Bouschet is a wine grape variety that has been widely cultivated since 1866. It is a cross of Petit Bouschet (itself a cross of the very old variety Teinturier du Cher and Aramon) and Grenache.J. Robinson (ed), ''"The Oxford Companion to Wine"''. Third Edition, p. 24. Oxford University Press 2006 . There are several types of anthocyanins (as the

glycoside In chemistry, a glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. ...

) found in wine grapes which are responsible for the vast range of coloring from ruby red through to dark black found in wine grapes. Ampelographers can use this observation to assist in the identification of different

grape varieties This list of grape varieties includes cultivated grapes, whether used for wine, or eating as a table grape, fresh or dried (raisin, currant, sultana). For a complete list of all grape species, including those unimportant to agriculture, see ''V ...

. The European vine family ''

'' is characterized by anthocyanins that are composed of only one molecule of

glucose Glucose is a sugar with the Chemical formula#Molecular formula, molecular formula , which is often abbreviated as Glc. It is overall the most abundant monosaccharide, a subcategory of carbohydrates. It is mainly made by plants and most algae d ...

while non-''vinifera'' vines such as hybrids and the American ''

Vitis labrusca ''Vitis labrusca'', the fox grape, is a species of grapevines belonging to the ''Vitis'' genus in the flowering plant family Vitaceae. The vines are native to eastern North America and are the source of many grape cultivars, including Catawba, ...

'' will have anthocyanins with two molecules. This phenomenon is due to a double mutation in the anthocyanin 5-O-glucosyltransferase gene of ''V. vinifera''. In the mid-20th century, French ampelographers used this knowledge to test the various vine varieties throughout France to identify which vineyards still contained non-''vinifera'' plantings. Red-berried Pinot grape varieties are also known to not synthesize para-coumaroylated or acetylated anthocyanins as other varieties do. Tempranillowine

The color variation in the finished red wine is partly derived from the

ionization Ionization or ionisation is the process by which an atom or a molecule acquires a negative or positive Electric charge, charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged at ...

of anthocyanin pigments caused by the

acidity An acid is a molecule or ion capable of either donating a proton (i.e. hydrogen cation, H+), known as a Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis acid. The first category of acids are the ...

of the wine. In this case, the three types of anthocyanin pigments are red, blue and colorless with the concentration of those various pigments dictating the color of the wine. A wine with low pH (and such greater acidity) will have a higher occurrence of ionized anthocyanins which will increase the amount of bright red pigments. Wines with a higher pH will have a higher concentration of blue and colorless pigments. As the wine ages, anthocyanins will react with other acids and compounds in wines such as tannins,

pyruvic acid Pyruvic acid (CH3COCOOH) is the simplest of the keto acids, alpha-keto acids, with a carboxylic acid and a ketone functional group. Pyruvate, the conjugate acid, conjugate base, CH3COCOO−, is an metabolic intermediate, intermediate in several m ...

and

acetaldehyde Acetaldehyde (IUPAC systematic name ethanal) is an organic compound, organic chemical compound with the chemical formula, formula , sometimes abbreviated as . It is a colorless liquid or gas, boiling near room temperature. It is one of the most ...

which will change the color of the wine, causing it to develop more "brick red" hues. These molecules will link up to create

polymer A polymer () is a chemical substance, substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeat unit, repeating subunits derived from one or more species of monomers. Due to their br ...

s that eventually exceed their

solubility In chemistry, solubility is the ability of a chemical substance, substance, the solute, to form a solution (chemistry), solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form su ...

and become sediment at the bottom of wine bottles.

Pyranoanthocyanins The pyranoanthocyanins are a type of pyranoflavonoids. They are chemical compounds formed in red wines by Yeast in winemaking, yeast during Fermentation (wine), fermentation processes or during Microoxygenation, controlled oxygenation processes duri ...

are chemical compounds formed in red

s by

yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom (biology), kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are est ...

during

fermentation Fermentation is a type of anaerobic metabolism which harnesses the redox potential of the reactants to make adenosine triphosphate (ATP) and organic end products. Organic molecules, such as glucose or other sugars, are catabolized and reduce ...

processes or during controlled oxygenation processes during the

aging of wine The aging of wine is potentially able to improve the quality of wine. This distinguishes wine from most other consumable goods. While wine is perishable and capable of deteriorating, complex chemical reactions involving a wine's sugars, acids ...

Tannins

Tannins refer to the diverse group of chemical compounds in wine that can affect the color, aging ability and texture of the wine. While tannins cannot be smelled or tasted, they can be perceived during

wine tasting Wine tasting is the sensory examination and evaluation of wine. While the practice of wine tasting is as ancient as its production, a more formalized methodology has slowly become established from the 14th century onward. Modern, professional w ...

by the tactile sensation of

and sense of bitterness that they can leave in the mouth. This is due to the tendency of tannins to react with

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

s, such as the ones found in

saliva Saliva (commonly referred as spit or drool) is an extracellular fluid produced and secreted by salivary glands in the mouth. In humans, saliva is around 99% water, plus electrolytes, mucus, white blood cells, epithelial cells (from which ...

. In food and wine pairing, foods that are high in proteins (such as

red meat In gastronomy, red meat is commonly red when raw (and a dark color after it is cooked), in contrast to white meat, which is pale in color before (and after) cooking. In culinary terms, only flesh from mammals or fowl (not fish) is classified ...

) are often paired with tannic wines to minimize the astringency of tannins. However, many wine drinkers find the perception of tannins to be a positive trait—especially as it relates to mouthfeel. The management of tannins in the winemaking process is a key component in the resulting quality.J. Robinson (ed), ''"The Oxford Companion to Wine"''. Third Edition, p. 680. Oxford University Press 2006 . Tannins are found in the skin, stems, and seeds of wine grapes but can also be introduced to the wine through the use of oak barrels and chips or with the addition of tannin powder. The natural tannins found in grapes are known as

s due to their ability to release red anthocyanin pigments when they are heated in an acidic solution. Grape extracts are mainly rich in monomers and small oligomers (mean degree of polymerization < 8). Grape seed extracts contain three monomers (catechin, epicatechin and epicatechin gallate) and procyanidin oligomers. Grape skin extracts contain four monomers (catechin, epicatechin, gallocatechin and epigallocatechin), as well as procyanidins and

prodelphinidin Prodelphinidin is a name for the polymeric tannins composed of gallocatechin. It yields delphinidin during depolymerisation under oxidative conditions. Natural occurrences Prodelphinidins are one of the two sorts of tannins in grape (the other ...

s oligomers. The tannins are formed by

enzymes An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as pro ...

during metabolic processes of the grapevine. The amount of tannins found naturally in grapes varies depending on the variety with

Cabernet Sauvignon Cabernet Sauvignon () is one of the world's most widely recognized red wine grape varieties. It is grown in nearly every major wine producing country among a diverse spectrum of climates from Australia and British Columbia, Canada to Lebano ...

Nebbiolo Nebbiolo (, ; ) is an Italian red wine grape variety predominantly associated with its native Piedmont region, where it makes the ''Denominazione di Origine Controllata e Garantita'' (DOCG) wines of Barolo, Barbaresco, Gattinara, Ghemme, a ...

Syrah Syrah (), also known as Shiraz, is a dark-skinned grape variety grown throughout the world and used primarily to produce red wine. In 1999, Syrah was found to be the offspring of two obscure grapes from southeastern France, Dureza and Mondeuse ...

and Tannat being 4 of the most tannic grape varieties. The reaction of tannins and anthocyanins with the phenolic compound

s creates another class of tannins known as pigmented tannins which influence the color of red wine.Compositional investigation of pigmented tannin. Kennedy James A. and Hayasaka Yoji, A.C.S. symposium series, 2004, vol. 886, pp. 247-264, Commercial preparations of tannins, known as ''enological tannins'', made from oak wood,

grape A grape is a fruit, botanically a berry, of the deciduous woody vines of the flowering plant genus ''Vitis''. Grapes are a non- climacteric type of fruit, generally occurring in clusters. The cultivation of grapes began approximately 8,0 ...

seed and skin, plant

gall Galls (from the Latin , 'oak-apple') or ''cecidia'' (from the Greek , anything gushing out) are a kind of swelling growth on the external tissues of plants. Plant galls are abnormal outgrowths of plant tissues, similar to benign tumors or war ...

chestnut The chestnuts are the deciduous trees and shrubs in the genus ''Castanea'', in the beech family Fagaceae. The name also refers to the edible nuts they produce. They are native to temperate regions of the Northern Hemisphere. Description ...

, quebracho, gambierIdentification of the origin of commercial enological tannins by the analysis of monosaccharides and polyalcohols. Luz Sanz M., Martinez-Castro Isabel and Moreno-Arribas M. Victoria, ''Food chemistry'', 2008, vol. 111, no3, pp. 778-783, and myrobalan fruits, can be added at different stages of the wine production to improve color durability. The tannins derived from oak influence are known as "hydrolysable tannins" being created from the ellagic and

gallic acid Gallic acid (also known as 3,4,5-trihydroxybenzoic acid) is a trihydroxybenzoic acid with the formula C6 H2( OH)3CO2H. It is classified as a phenolic acid. It is found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and other plant ...

found in the wood. Mthomebrew maceration

In the vineyards, there is also a growing distinction being made between "ripe" and "unripe" tannins present in the grape. This " physiological ripeness", which is roughly determined by tasting the grapes off the vines, is being used along with sugar levels as a determination of when to

harvest Harvesting is the process of collecting plants, animals, or fish (as well as fungi) as food, especially the process of gathering mature crops, and "the harvest" also refers to the collected crops. Reaping is the cutting of grain or pulses fo ...

. The idea is that "riper" tannins will taste softer but still impart some of the texture components found favorable in wine. In winemaking, the amount of the time that the must spends in contact with the grape skins, stems and seeds will influence the amount of tannins that are present in the wine with wines subjected to longer maceration period having more tannin extract. Following harvest, stems are normally picked out and discarded prior to fermentation but some winemakers may intentionally leave in a few stems for varieties low in tannins (like Pinot noir) in order to increase the tannic extract in the wine. If there is an excess in the amount of tannins in the wine, winemakers can use various fining agents like

albumin Albumin is a family of globular proteins, the most common of which are the serum albumins. All of the proteins of the albumin family are water- soluble, moderately soluble in concentrated salt solutions, and experience heat denaturation. Alb ...

casein Casein ( , from Latin ''caseus'' "cheese") is a family of related phosphoproteins (CSN1S1, αS1, aS2, CSN2, β, K-casein, κ) that are commonly found in mammalian milk, comprising about 80% of the proteins in cow's milk and between 20% and 60% of ...

and

gelatin Gelatin or gelatine () is a translucent, colorless, flavorless food ingredient, commonly derived from collagen taken from animal body parts. It is brittle when dry and rubbery when moist. It may also be referred to as hydrolyzed collagen, coll ...

that can bind to tannins molecule and

precipitate In an aqueous solution, precipitation is the "sedimentation of a solid material (a precipitate) from a liquid solution". The solid formed is called the precipitate. In case of an inorganic chemical reaction leading to precipitation, the chemic ...

them out as sediments. As a wine ages, tannins will form long polymerized chains which come across to a taster as "softer" and less tannic. This process can be accelerated by exposing the wine to

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

, which oxidize tannins to quinone-like compounds that are polymerization-prone. The winemaking technique of micro-oxygenation and decanting wine use oxygen to partially mimic the effect of aging on tannins. A study in wine production and consumption has shown that tannins, in the form of

s, 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 proanthocyanidins, and that these regions also produce populations with longer life spans. Reactions of tannins with the phenolic compound

anthocyanidin Anthocyanidins are common plant pigments, the aglycones of anthocyanins. They are based on the flavylium cation, an oxonium ion, with various groups substituent, substituted for its hydrogen atoms. They generally change color from red through p ...

s creates another class of tannins known as ''pigmented tannins'' which influences the color of red wine.

= Addition of enological tannins

= Commercial preparations of tannins, known as ''enological tannins'', made from oak wood,

seed and skin, plant

, quebracho, gambier and myrobalan fruits, can be added at different stages of the wine production to improve color durability.

= Effects of tannins on the drinkability and aging potential of wine

= Tannins are a natural preservative in wine. Un-aged wines with high tannin content can be less palatable than wines with a lower level of tannins. Tannins can be described as leaving a dry and puckered feeling with a "furriness" in the mouth that can be compared to a stewed tea, which is also very tannic. This effect is particularly profound when drinking tannic wines without the benefit of food. Many wine lovers see natural tannins (found particularly in varietals such as

and often accentuated by heavy

oak An oak is a hardwood tree or shrub in the genus ''Quercus'' of the beech family. They have spirally arranged leaves, often with lobed edges, and a nut called an acorn, borne within a cup. The genus is widely distributed in the Northern Hemisp ...

barrel aging) as a sign of potential longevity and ageability. Tannins impart a mouth-puckering astringency when the wine is young but "resolve" (through a chemical process called

polymerization In polymer chemistry, polymerization (American English), or polymerisation (British English), is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. There are many fo ...

) into delicious and complex elements of "bottle bouquet" when the wine is cellared under appropriate temperature conditions, preferably in the range of a constant . Such wines mellow and improve with age with the tannic "backbone" helping the wine survive for as long as 40 years or more. In many regions (such as in

Bordeaux Bordeaux ( ; ; Gascon language, Gascon ; ) is a city on the river Garonne in the Gironde Departments of France, department, southwestern France. A port city, it is the capital of the Nouvelle-Aquitaine region, as well as the Prefectures in F ...

), tannic grapes such as

are blended with lower-tannin grapes such as

Merlot Merlot ( ) is a dark-blue-colored wine grape variety that is used as both a blending grape and for varietal wines. The name ''Merlot'' is thought to be a diminutive of , the French name for the blackbird, probably a reference to the color ...

Cabernet Franc Cabernet Franc is one of the major black grape varieties worldwide. It is principally grown for blending with Cabernet Sauvignon and Merlot in the Bordeaux (wine), Bordeaux style, but can also be vinified alone, as in the Loire (wine), Loire's C ...

, diluting the tannic characteristics. White wines and wines that are vinified to be drunk young (for examples, see nouveau wines) typically have lower tannin levels.

Other flavonoids

Flavan-3-ol Flavan-3-ols (sometimes referred to as flavanols) are a subgroup of flavonoids. They are derivatives of flavans that possess a 2-phenyl-3,4-dihydro-2''H''-chromen-3-ol skeleton. Flavan-3-ols are structurally diverse and include a range of compo ...

s (catechins) are flavonoids that contribute to the construction of various tannins and contribute to the perception of bitterness in wine. They are found in highest concentrations in grape seeds but are also in the skin and stems. Catechins play a role in the

microbial A microorganism, or microbe, is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells. The possible existence of unseen microbial life was suspected from antiquity, with an early attestation in ...

defense of the grape berry, being produced in higher concentrations by the grape vines when it is being attacked by grape diseases such as

downy mildew Downy mildew refers to any of several types of oomycete microbes that are obligate parasites of plants. Downy mildews exclusively belong to the Peronosporaceae family. In commercial agriculture, they are a particular problem for growers of c ...

. Because of that grape vines in cool, damp climates produce catechins at high levels than vines in dry, hot climates. Together with anthocyanins and tannins they increase the stability of a wines color-meaning that a wine will be able to maintain its coloring for a longer period of time. The amount of catechins present varies among grape varieties with varietals like Pinot noir having high concentrations while

and especially Syrah have very low levels. As an antioxidant, there are some studies into the health benefits of moderate consumption of wines high in catechins.J. Robinson (ed), ''"The Oxford Companion to Wine"''. Third Edition, p. 144. Oxford University Press 2006 . In red grapes, the main flavonol is on average

, followed by

myricetin Myricetin is a member of the flavonoid class of polyphenolic compounds, with antioxidant properties. Common dietary sources include vegetables (including tomatoes), fruits (including oranges), nuts, berries, tea, and red wine. Myricetin is stru ...

kaempferol Kaempferol (3,4′,5,7-tetrahydroxyflavone) is a natural flavonol, a type of flavonoid, found in a variety of plants and plant-derived foods including kale, beans, tea, spinach, and broccoli. It is also found in propolis extracts. Kaempferol i ...

, laricitrin, isorhamnetin, and syringetin. In white grapes, the main flavonol is quercetin, followed by kaempferol and isorhamnetin. The delphinidin-like flavonols myricetin, laricitrin, and syringetin are missing in all white varieties, indicating that the enzyme flavonoid 3',5'-hydroxylase is not expressed in white grape varieties.

Myricetin Myricetin is a member of the flavonoid class of polyphenolic compounds, with antioxidant properties. Common dietary sources include vegetables (including tomatoes), fruits (including oranges), nuts, berries, tea, and red wine. Myricetin is stru ...

, laricitrin and syringetin, flavonols which are present in red grape varieties only, can be found in red wine.

Non-flavonoids

Hydroxycinnamic acids

Hydroxycinnamic acid Hydroxycinnamic acids (hydroxycinnamates) are a class of aromatic acids or phenylpropanoids having a C6–C3 skeleton. These compounds are hydroxy derivatives of cinnamic acid. In the category of List of phytochemicals in food, phytochemicals tha ...

s are the most important group of nonflavonoid phenols in wine. The four most abundant ones are the

tartaric acid Tartaric acid is a white, crystalline organic acid that occurs naturally in many fruits, most notably in grapes but also in tamarinds, bananas, avocados, and citrus. Its salt (chemistry), salt, potassium bitartrate, commonly known as cream of ta ...

esters ''trans''-caftaric, ''cis''- and ''trans''- coutaric, and ''trans''- fertaric acids. In wine they are present also in the free form (''trans''- caffeic, ''trans''- p-coumaric, and ''trans''- ferulic acids).

Stilbenoids

''V. vinifera'' also produces

Resveratrol Resveratrol (3,5,4′-trihydroxy-''trans''-stilbene) is a stilbenoid, a type of natural phenol or polyphenol and a phytoalexin produced by several plants in response to injury or when the plant is under attack by pathogens, such as bacterium, ba ...

is found in highest concentration in the skins of wine grapes. The accumulation in ripe berries of different concentrations of both bound and free resveratrols depends on the maturity level and is highly variable according to the genotype. Both red and white wine grape varieties contain resveratrol, but more frequent skin contact and maceration leads to red wines normally having ten times more resveratrol than white wines. Resveratrol produced by grape vines provides defense against microbes, and production can be further artificially stimulated by

ultraviolet radiation Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of t ...

. Grapevines in cool, damp regions with higher risk of grape diseases, such as

and

Burgundy Burgundy ( ; ; Burgundian: ''Bregogne'') is a historical territory and former administrative region and province of east-central France. The province was once home to the Dukes of Burgundy from the early 11th until the late 15th century. ...

, tend to produce grapes with higher levels of resveratrol than warmer, drier wine regions such as

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

and

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

. Different grape varieties tend to have differing levels, with

Muscadine ''Vitis rotundifolia'', or muscadine, is a grapevine species native to the southern United States, southeastern and south-central United States. The growth range extends from Florida to New Jersey coast, and west to eastern Texas and Oklahoma. I ...

s and the Pinot family having high levels while the Cabernet family has lower levels of resveratrol. In the late 20th century interest in the possible health benefits of resveratrol in wine was spurred by discussion of the French paradox involving the health of wine drinkers in France.J. Robinson (ed), ''"The Oxford Companion to Wine"''. Third Edition, p. 569. Oxford University Press 2006 .

Piceatannol Piceatannol is the organic compound with the formula . Classified as a stilbenoid and a phenol, it is a white solid, although samples often are yellow owing to impurities. Natural occurrences Piceatannol and its glucoside, astringin, are foun ...

is also present in grape from where it can be extracted and found in red wine.

Phenolic acids

Vanillin Vanillin is an organic compound with the molecular formula . It is a phenolic aldehyde. Its functional groups include aldehyde, hydroxyl, and ether. It is the primary component of the ethanolic extract of the vanilla bean. Synthetic vanillin ...

is a phenolic

aldehyde In organic chemistry, an aldehyde () (lat. ''al''cohol ''dehyd''rogenatum, dehydrogenated alcohol) is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred ...

most commonly associated with the vanilla notes in wines that have been aged in oak. Trace amounts of vanillin are found naturally in grapes, but they are most prominent in the

lignin Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidit ...

structure of oak barrels. Newer barrels will impart more vanillin, with the concentration present decreasing with each subsequent usage.J. Robinson (ed), ''"The Oxford Companion to Wine"''. Third Edition, p. 727. Oxford University Press 2006 .

Phenols from oak ageing

Oak barrel will add compounds such as

and hydrolysable tannins (

ellagitannin image:Castalagin.svg, 130px, Castalagin is a representative ellagitannin, characterized by coupled gallic acid substituents The ellagitannins are a diverse class of hydrolyzable tannins, a type of polyphenol formed primarily from the oxidative link ...

s). The

hydrolyzable tannin A hydrolysable tannin or pyrogallol-type tannin is a type of tannin that, on heating with hydrochloric or sulfuric acids, yields gallic or ellagic acids. At the center of a hydrolysable tannin molecule, there is a carbohydrate (usually D-gluc ...

s present in oak are derived from

structures in the wood. They help protect the wine from oxidation and reduction.J. Robinson (ed), ''"The Oxford Companion to Wine"''. Third Edition, p. 492, Oxford University Press 2006, . 4-Ethylphenol and 4-ethylguaiacol are produced during ageing of red wine in oak barrels that are infected by brettanomyces .

Natural phenols and polyphenols from cork stoppers

Low molecular weight polyphenols, as well as ellagitannins, are susceptible to be extracted from cork stoppers into the wine. The identified polyphenols are gallic, protocatechuic, vanillic, caffeic, ferulic, and ellagic acids; protocatechuic, vanillic, coniferyl, and sinapic aldehydes; the coumarins aesculetin and scopoletin; the ellagitannins are roburins A and E, grandinin,

vescalagin Castalagin is an ellagitannin, a type of hydrolyzable tannin, found in oak and chestnut wood and in the stem barks of ''Terminalia leiocarpa'' and ''Terminalia avicennoides''. Castalagin is the diastereomer of vescalagin in C-1 of the glycosidic c ...

and

castalagin Castalagin is an ellagitannin, a type of hydrolyzable tannin, found in oak and chestnut wood and in the stem barks of ''Terminalia leiocarpa'' and ''Terminalia avicennoides''. Castalagin is the diastereomer of vescalagin in C-1 of the glycosidic c ...

Guaiacol Guaiacol () is an organic compound with the formula C6H4(OH)(OCH3). It is a phenolic compound containing a methoxy functional group. Guaiacol appears as a viscous colorless oil, although aged or impure samples are often yellowish. It occurs wid ...

is one of the molecules responsible for the

cork taint Cork taint is a broad term referring to an off-odor and off-flavor wine fault arising from the presence of 2,4,6-trichloroanisole (TCA), a chemical compound that represents one of the strongest off-flavors, and one "generated naturally in foods/b ...

wine fault.

Phenolic content in relation with wine making techniques

Extraction levels in relation with grape pressing techniques

Flash release is a technique used in wine pressing. The technique allows for a better extraction of phenolic compounds.

Microoxygeneation

The exposure of wine to oxygen in limited quantities affects phenolic content.

Phenolic compounds found in wine

Comp LC pinot vs rose vs white wine 280 nm

Depending on the methods of production, wine type, grape varieties, ageing processes, the following phenolics can be found in wine. The list, sorted in alphabetical order of common names, is not exhaustive. *

Acutissimin A Acutissimin A is a flavono-ellagitannin, a type of tannin formed from the linking of a flavonoid with an ellagitannin. In 2003, scientists at Institut Européen de Chimie et Biologie in Pessac, France found that when the oak tannin vescalagin i ...

* aesculetin * Anthocyanidin-caftaric acid adducts * Astilbin *

Astringin Astringin is a stilbenoid, the 3-β-D-glucoside of piceatannol. It can be found in the bark of ''Picea sitchensis'' and ''Picea abies'' (Norway spruce). It is also present in ''Vitis vinifera'' cells cultures and in wine Wine is an alcoholic ...

* B type proanthocyanidin dimers * B type proanthocyanidin trimers *

Caffeic acid Caffeic acid is an organic compound with the formula . It is a polyphenol with a key role in scavenging reactive oxygen species (ROS) generated in energy metabolism. Caffeic acid is also one major polyphenol responsible for maintaining normal le ...

* Caftaric acid *

Castalagin Castalagin is an ellagitannin, a type of hydrolyzable tannin, found in oak and chestnut wood and in the stem barks of ''Terminalia leiocarpa'' and ''Terminalia avicennoides''. Castalagin is the diastereomer of vescalagin in C-1 of the glycosidic c ...

* Castavinol C1 * Castavinol C2 * Castavinol C3 * Castavinol C4 *

Catechin Catechin is a flavan-3-ol, a type of secondary metabolite providing antioxidant roles in plants. It belongs to the subgroup of polyphenols called flavonoids. The name of the catechin chemical family derives from ''catechu'', which is the tannic ...

* Catechin-(4,8)-malvidin-3-O-glucoside * Compound NJ2 * Coniferyl aldehyde *

Coumaric acid Coumaric acid is a phenolic derivative of cinnamic acid having a hydroxy group as substituent at one of the aromatic In organic chemistry, aromaticity is a chemical property describing the way in which a conjugated system, conjugated ring of un ...

Coutaric acid Coutaric acid is a hydroxycinnamoyltartaric acid found in wine, pomace and grape. It is an ester formed from coumaric acid and tartaric acid Tartaric acid is a white, crystalline organic acid that occurs naturally in many fruits, most notably ...

Cyanidin Cyanidin is a natural organic compound. It is a particular type of anthocyanidin (glycoside version called anthocyanin#Structure, anthocyanins). It is a pigment found in many red berries including grapes, bilberry, blackberry, blueberry, cherr ...

* Cyanin (Cyanidin-3,5-O-diglucoside) * Cyanidin 3O-glucoside * Cyanidin acetyl 3O glucoside * Cyanidin coumaroyl 3O glucoside * Cyanidin-3-O-glucoside-pyruvic acid * Cyanidin-3-O-acetylglucoside-pyruvic acid * Cyanidin-coumaroylglucoside-pyruvic acid *

Delphinidin Delphinidin (also delphinidine) is an anthocyanidin, a primary plant pigment, and also an antioxidant. Delphinidin gives blue hues to flowers in the genera ''Viola'' and ''Delphinium''. It also gives the blue-red color of the grape variety Cab ...

* Delphinidin 3O glucoside * Delphinidin acetyl-3O glucoside * Delphinidin coumaroyl 3O glucoside * Delphinidin-3-O-glucoside-pyruvic acid * Delphinidin-3-O-acetylglucoside-pyruvic acid * Delphinidin-3-O-coumaroylglucoside-pyruvic acid * Delphinidin-3-O-glucoside-4-vinylcatechol * Delphinidin-3-O-acetylglucoside-4-vinylcatechol * Delphinidin-3-O-coumaroylglucoside-4-vinylcatechol * Delphinidin-3-O-glucoside-4-vinylphenol * Delphinidin-3-O-acetylglucoside-4-vinylphenol * Delphinidin-3-O-coumaroylglucoside-4-vinylphenol * Delphinidin-3-O-glucoside-4-vinylguaiacol * Delphinidin-3-O-glucoside-4-vinyl(epi)catechin * Delphinidin-3-O-acetylglucoside-4-vinyl(epi)catechin * Delta-viniferin * Dihydro-resveratrol *

Ellagic acid Ellagic acid is a polyphenol found in numerous fruits and vegetables. It is the dilactone of hexahydroxydiphenic acid. Name The name comes from the French term ''acide ellagique'', from the word ''galle'' spelled backward because it can be o ...

Engeletin Engeletin is a flavanonol rhamnoside, a phenolic compound found in wine and isolated from the bark of '' Hymenaea martiana''. See also * Phenolic compounds in wine Phenolic compounds— natural phenol and polyphenols—occur naturally in wi ...

* Epicatechin gallate * Epigallocatechin * Epsilon-viniferin * Ethyl caffeate * Ethyl gallate * Ethyl protocatechuate * 4-Ethylguaiacol * 4-Ethylphenol * Fertaric acid * Ferulic acid *

Gallic acid Gallic acid (also known as 3,4,5-trihydroxybenzoic acid) is a trihydroxybenzoic acid with the formula C6 H2( OH)3CO2H. It is classified as a phenolic acid. It is found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and other plant ...

Gentisic acid Gentisic acid is a dihydroxybenzoic acid. It is a derivative of benzoic acid and a minor (1%) product of the metabolic break down of aspirin, excreted by the kidneys. It is also found in the African tree ''Alchornea cordifolia'' and in wine. Pr ...

* Grandinin * Grape reaction product (GRP) *

* Hopeaphenol *

p-Hydroxybenzoic acid 4-Hydroxybenzoic acid, also known as ''p''-hydroxybenzoic acid (PHBA), is a monohydroxybenzoic acid, a phenolic derivative of benzoic acid. It is a white crystalline solid that is slightly soluble in water and chloroform but more soluble in polar ...

* Isorhamnetol 3-glucoside *

Kaempferol Kaempferol (3,4′,5,7-tetrahydroxyflavone) is a natural flavonol, a type of flavonoid, found in a variety of plants and plant-derived foods including kale, beans, tea, spinach, and broccoli. It is also found in propolis extracts. Kaempferol i ...

* Kaempferol glucoside (astragalin) * Kaempferol glucuronide *

Malvidin Malvidin is an O-methylated anthocyanidin, the 3',5'-methoxy derivative of delphinidin. As a primary plant pigment, its glycosides are highly abundant in nature. Natural occurrences Malvidin is responsible for the blue color found in petals ...

Petunidin Petunidin (Pt), like Europinidin and Malvidin, is derived from Delphinidin and is an O-methylated anthocyanidin of the 3-hydroxy type. It is a natural organic compound, a dark-red or purple water-soluble pigment found in many red berries includi ...

* Petunidin 3O glucoside *

Petunidin acetyl-3O-glucoside Petunidin (Pt), like Europinidin and Malvidin, is derived from Delphinidin and is an O-methylated anthocyanidin of the 3-hydroxy type. It is a natural organic compound, a dark-red or purple water-soluble pigment found in many red berries including ...

Petunidin coumaroyl-3O glucoside Petunidin (Pt), like Europinidin and Malvidin, is derived from Delphinidin and is an O-methylated anthocyanidin of the 3-hydroxy type. It is a natural organic compound, a dark-red or purple water-soluble pigment found in many red berries includin ...

* Petunidin-3-O-glucoside-pyruvic acid * Petunidin-3-O-acetylglucoside-pyruvic acid * Petunidin-3-O-coumaroylglucoside-pyruvic acid * Petunidin-3-O-glucoside-4-vinylcatechol * Petunidin-3-O-acetylglucoside-4-vinylcatechol * Petunidin-3-O-coumaroylglucoside-4-vinylcatechol * Petunidin-3-O-glucoside-4-vinylphenol * Petunidin-3-O-acetylglucoside-4-vinylphenol * Petunidin-3-O-coumaroylglucoside-4-vinylphenol * Petunidin-3-O-glucoside-4-vinylguaiacol * Petunidin-3-O-glucoside-4-vinyl(epi)catechin * Petunidin-3-O-acetylglucoside-4-vinyl(epi)catechin * Phloroglucinol carboxylic acid *

* Piceids * Pinotin A * Oligomeric procyanidins : ** Procyanidin B1 ** Procyanidin B2 ** Procyanidin B3 ** Procyanidin B4 ** B1-3-O-gallate ** B2-3-O-gallate **

B2-3'-O-gallate B, or b, is the second letter of the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is '' bee'' (pronounced ), plural ''bees''. It represe ...

procyanidin C1 Procyanidin C1 (PCC1) is a B type proanthocyanidin. It is an epicatechin trimer found in grape (''Vitis vinifera''), unripe apples, and cinnamon. Natural occurrence and function Procyanidin C1 can be isolated from grape seed extract. Chemica ...

(epicatechin-(4β→8)-epicatechin-(4β→8)-epicatechin) **

Procyanidin C2 Procyanidin C2 is a B type proanthocyanidin trimer (chemistry), trimer, a type of condensed tannin. Natural occurrences Procyanidin C2 is found in grape seeds (''Vitis vinifera'') and wine, in barley (''Hordeum vulgare''), malt and beer, in ''Be ...

(catechin-(4α→8)-catechin-(4α→8)-catechin) ** procyanidin T2 (trimer) *

Protocatechuic acid Protocatechuic acid (PCA) is a dihydroxybenzoic acid, a type of phenolic acid. It is a major metabolite of antioxidant polyphenols found in green tea. It has mixed effects on normal and cancer cells in ''in vitro'' and ''in vivo'' studies. It is ...

* protocatechuic aldehyde *

Quercetin Quercetin is a plant flavonol from the flavonoid group of polyphenols. It is found in many fruits, vegetables, leaves, seeds, and grains; capers, red onions, and kale are common foods containing appreciable amounts of it. It has a bitter flavor ...

* Quercetol glucoside * Quercetol glucuronide *

Roburin A Roburin A is a tannin found in oak wood (''Quercus robur'' and ''Quercus petraea'' or ''Quercus alba'') or oak cork ('' Quercus suber''). It is a dimeric compound, composed of two vescalagin Castalagin is an ellagitannin, a type of hydrolyzable t ...

* Roburin E * Scopoletin * Sinapic aldehyde *

Sinapinic acid Sinapinic acid, or sinapic acid (Sinapine - Origin: L. Sinapi, sinapis, mustard, Gr., cf. F. Sinapine.), is a small naturally occurring hydroxycinnamic acid. It is a member of the phenylpropanoid family. It is a commonly used matrix in MALDI mas ...

Syringic acid Syringic acid is a naturally occurring phenolic compound and dimethoxybenzene that is commonly found as a plant metabolite. Natural occurrence Syringic acid can be found in several plants including '' Ardisia elliptica'' and ''Schumannianthus ...

* Tyrosol *

Vanillic acid Vanillic acid (4-hydroxy-3-methoxybenzoic acid) is a dihydroxybenzoic acid derivative used as a flavoring agent. It is an oxidized form of vanillin. It is also an intermediate in the production of vanillin from ferulic acid. Occurrence in n ...

Vescalagin Castalagin is an ellagitannin, a type of hydrolyzable tannin, found in oak and chestnut wood and in the stem barks of ''Terminalia leiocarpa'' and ''Terminalia avicennoides''. Castalagin is the diastereomer of vescalagin in C-1 of the glycosidic c ...

* 4-Vinylphenol * Vitisin A * Vitisin B * Vinylpyranomalvidin-3O-glucoside-procyanidin dimer * VinylpyranoMv-3-coumaroylglucoside-procyanidin dimer * Vinylpyranomalvidin-3O-glucoside-catechin * Vinylpyranomalvidin-3O-coumaroylglucoside-catechin * Vinylpyranomalvidin-3O-phenol * Vinylpyranopetunidin-3O-glucoside-catechin * Vinylpyranopeonidin-3O-glucoside-catechin * Vinylpyranomalvidin-3O-acetylglucoside-catechin

Effects

Polyphenol compounds may interact with

volatiles Volatility or volatile may refer to: Chemistry * Volatility (chemistry), a measuring tendency of a substance or liquid to vaporize easily ** Volatile organic compounds, organic or carbon compounds that can evaporate at normal temperature and pre ...

and contribute to the aromas in wine. Although wine polyphenols are speculated to provide

or other benefits, there is little evidence that wine polyphenols actually have any effect in humans. Limited preliminary research indicates that wine polyphenols may decrease

platelet aggregation Platelets or thrombocytes () are a part of blood whose function (along with the coagulation factors) is to react to bleeding from blood vessel injury by clumping to form a blood clot. Platelets have no cell nucleus; they are fragments of cytop ...

, enhance

fibrinolysis Fibrinolysis is a process that prevents blood clots from growing and becoming problematic. Primary fibrinolysis is a normal body process, while secondary fibrinolysis is the breakdown of clots due to a medicine, a medical disorder, or some other c ...

, and increase HDL cholesterol, but high-quality

clinical trial Clinical trials are prospective biomedical or behavioral research studies on human subject research, human participants designed to answer specific questions about biomedical or behavioral interventions, including new treatments (such as novel v ...

s have not confirmed such effects, as of 2017.

References

External links

Wine polyphenols vary with age and variety (Polyphenols on www.guideduvin.com)
{{in lang, fr
Polyphenol concentrations in red, white and rosé wines at www.phenol-explorer.eu
Natural phenols Polyphenols Wine chemistry