The phenolic content in wine refers to the 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 eco ...

and polyphenols—in wine, which include a large group of several hundred chemical compounds that affect the taste, color and mouthfeel of wine. These compounds include phenolic acids, stilbenoids, flavonols, dihydroflavonols,

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

s, flavanol monomers ( catechins) and flavanol polymers ( proanthocyanidins). 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 tannins which contribute to the color and mouthfeel of the wine. The non-flavonoids include the stilbenoids such as

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

and phenolic acids such as benzoic, caffeic and cinnamic acids.

Origin of the phenolic compounds

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

s and stilbenoids in the skin, and other phenols ( catechins, proanthocyanidins and flavonols) 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 ...

, sunlight will increase the concentration of phenolics in the grape berries, their development being an important component of canopy management. The proportion of the different phenols in any one wine will therefore vary according to the type of vinification.

Red wine Red wine is a type of wine made from dark-colored grape varieties. 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 from most purple grap ...

will be richer in phenols abundant in the skin and seeds, such as anthocyanin, proanthocyanidins and flavonols, whereas the phenols in white wine will essentially originate from the pulp, and these will be the phenolic acids together with lower amounts of catechins and stilbenes. Red wines will also have the phenols found in white wines. Wine simple phenols are further transformed during

wine aging 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 and ...

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. 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, 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 which adds vanilla aroma 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 metabolites and were not thought to be active in the primary metabolism 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 essenti ...

transport. They are water-soluble and are usually secreted into the vacuole 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'' 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 flavonoids. 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 Extraction may refer to: Science and technology Biology and medicine * Comedo extraction, a method of acne treatment * Dental extraction, the surgical removal of a tooth from the mouth Computing and information science * Data extraction, the pro ...

. These compounds contribute to the

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". Calamine lotion, witch hazel, and yerba mansa, a Californian plant ...

, 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 The health effects of wine are mainly determined by its active ingredient alcohol. Preliminary studies found that drinking small quantities of wine (up to one standard drink per day for women and one to two drinks per day for men), particular ...

derived from the

antioxidant Antioxidants are compounds that inhibit oxidation, a chemical reaction that can produce free radicals. This can lead to polymerization and other chain reactions. They are frequently added to industrial products, such as fuels and lubricant ...

and chemopreventive 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 flavonols, which includes the yellow pigment - quercetin. 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 flowers, fruits and

leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...

. 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 Sugars in wine are at the heart of what makes winemaking possible. During the process of fermentation, sugars from wine grapes are broken down and converted by yeast into alcohol ( ethanol) and carbon dioxide. Grapes accumulate sugars as they ...

increase during ripening 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 (from the Latin ''vinum mustum'', "young wine") is freshly crushed 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 t ...

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 wines are made from the red wine grapes of

Pinot noir Pinot Noir () is a red-wine grape variety of the species ''Vitis vinifera''. The name may also refer to wines created predominantly from pinot noir grapes. The name is derived from the French language, French words for ''pine'' and ''black.' ...

and Pinot Meunier. The exception to this is the small class of grapes known as teinturiers, such as Alicante Bouschet, which have a small amount of anthocyanins in the pulp that produces pigmented juice.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) 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. The European vine family '' Vitis vinifera'' is characterized by anthocyanins that are composed of only one molecule of glucose while non-''vinifera'' vines such as hybrids and the American '' Vitis labrusca'' will have anthocyanins with two molecules. This phenomenon is due to a double mutation in the

anthocyanin 5-O-glucosyltransferase Anthocyanin 5-O-glucosyltransferase is an enzyme that forms anthocyanin 3,5-O-diglucoside from anthocyanin 3-O-glucoside. There are several types of anthocyanins (as the glycoside) found in wine grapes which are responsible for the vast range of ...

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 Pinot (pronounced ) is a Burgundian grape family. Wine grape varieties in the Pinot family * Pinot blanc (Pinot bianco, Weißburgunder) * Pinot gris (Pinot grigio, Grauburgunder) * Pinot Meunier (Schwarzriesling) * Pinot noir (Spätburgunder, ...

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 of anthocyanin pigments caused by the acidity 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 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 and ...

, anthocyanins will react with other acids and compounds in wines such as tannins,

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

and

acetaldehyde Acetaldehyde (IUPAC systematic name ethanal) is an organic chemical compound with the formula CH3 CHO, sometimes abbreviated by chemists as MeCHO (Me = methyl). It is a colorless liquid or gas, boiling near room temperature. It is one of the mos ...

which will change the color of the wine, causing it to develop more "brick red" hues. These molecules will link up to create polymers that eventually exceed their solubility 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 during fermentation processes or during controlled oxygenation processes during the aging of wine. The different classes of pyranoanthoc ...

are chemical compounds formed in red wines by yeast during

fermentation Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food ...

processes or during controlled oxygenation processes during the aging of wine.

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 by the tactile drying sensation and sense of bitterness that they can leave in the mouth. This is due to the tendency of tannins to react with proteins, such as the ones found in

saliva Saliva (commonly referred to as spit) 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 DNA can be ...

. In food and wine pairing, foods that are high in proteins (such as red meat) 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 proanthocyanidins 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 prodelphinidins oligomers. The tannins are formed by

enzymes Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecule ...

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 Lebanon' ...

, Nebbiolo,

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 B ...

and Tannat being 4 of the most tannic grape varieties. The reaction of tannins and anthocyanins with the phenolic compound catechins 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 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, fungi, or animals. Plant galls are abnormal outgrowths of plant tissues, similar to be ...

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

, 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 The common name myrobalan can refer to several unrelated fruit-bearing plant species: * Myrobalan plum (''Prunus cerasifera''), also called cherry plum and myrobalan plum * Emblic myrobalan (''Phyllanthus emblica''), also called Amla and Amalaki In ...

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 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 gathering a ripe crop from the fields. Reaping is the cutting of grain or pulse for harvest, typically using a scythe, sickle, or reaper. On smaller farms with minimal mechanization, harvesting is the most labor-i ...

. 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, casein and

gelatin Gelatin or gelatine (from la, gelatus meaning "stiff" or "frozen") 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 ...

that can bind to tannins molecule and precipitate 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, which oxidize tannins to quinone-like compounds that are polymerization-prone. The winemaking technique of micro-oxygenation and

decanting wine A decanter is a vessel that is used to hold the decantation of a liquid (such as wine) which may contain sediment. Decanters, which have a varied shape and design, have been traditionally made from glass or crystal. Their volume is usually equ ...

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 proanthocyanidins, 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 anthocyanidins 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, grape seed and skin, plant

, quebracho, gambier and

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 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) 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), 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 ''merle'', the French name for the blackbird, probably a reference to the ...

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 style, but can also be vinified alone, as in the Loire's Chinon. In addition to being us ...

, 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-ols (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,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...

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

grape disease This is a list of diseases of grapes (''Vitis'' spp.). Bacterial diseases Fungal diseases Miscellaneous diseases and disorders Nematodes, parasitic Phytoplasma, virus and viruslike diseases See also *'' Ampeloglypter ater'' *'' Am ...

s such as downy mildew. 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 quercetin, followed by myricetin, kaempferol,

laricitrin Laricitrin is an ''O''-methylated flavonol, a type of flavonoid. It is found in red grape (absent in white grape) and in ''Vaccinium uliginosum'' (bog billberries). It is one of the phenolic compounds present in wine. Metabolism Laricitrin is ...

, isorhamnetin, and

syringetin Syringetin is an ''O''-methylated flavonol, a type of flavonoid. It is found in red grape (absent in white grape), in '' Lysimachia congestiflora'' and in ''Vaccinium uliginosum'' (bog billberries). It is one of the phenolic compounds present i ...

. 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,

and

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

Non-flavonoids

Hydroxycinnamic acids

Hydroxycinnamic acids are the most important group of nonflavonoid phenols in wine. The four most abundant ones are the tartaric acid esters ''trans''-caftaric, ''cis''- and ''trans''- coutaric, and ''trans''-

fertaric acid Fertaric acid is a hydroxycinnamic acid found in wine and grapes. It is an ester formed from ferulic acid bound to tartaric acid. It is a metabolite of caftaric acid Caftaric acid is a non-flavonoid phenolic compound. It is found in the juice ...

s. In wine they are present also in the free form (''trans''- caffeic, ''trans''- p-coumaric, and ''trans''- ferulic acids).

Stilbenoids

''V. vinifera'' also produces stilbenoids.

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

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

Burgundy Burgundy (; french: link=no, Bourgogne ) 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. The c ...

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

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

. Different grape varieties tend to have differing levels, with Muscadines and the Pinot family having high levels while the

Cabernet Cabernet can refer to several different things: Wine grape varieties * Cabernet Sauvignon, a hybrid of Cabernet Franc and Sauvignon blanc, and one of the most popular wine grapes in the world * Cabernet Franc, a parent of Cabernet Sauvignon and ...

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 The French paradox is an apparently paradoxical epidemiological observation that French people have a relatively low incidence of coronary heart disease (CHD), while having a diet relatively rich in saturated fats, in apparent contradicti ...

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

Phenolic acids

Vanillin is a phenolic aldehyde 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 rigidity ...

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 vanillin and hydrolysable tannins ( ellagitannins). The hydrolyzable tannins 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 Ethylphenol (4-EP) is an organic compound with the formula C2H5C6H4OH. It is one of three isomeric ethylphenols. A white solid, it occurs as an impurity in xylenols and as such is used in the production of some commercial phenolic resins. It is ...

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 Ferulic acid is a hydroxycinnamic acid, an organic compound with the formula (CH3O)HOC6H3CH=CHCO2H. The name is derived from the genus ''Ferula'', referring to the giant fennel (''Ferula communis''). Classified as a phenolic phytochemical, feruli ...

, and ellagic acids; protocatechuic, vanillic, coniferyl, and sinapic aldehydes; the coumarins

aesculetin Aesculetin (also known as esculetin, 6,7-dihydroxycoumarin and cichorigenin) is a derivative of coumarin. It is a natural lactone that derives from the intramolecular cyclization of a cinnamic acid derivative. It is present in chicory and in many ...

and scopoletin; the ellagitannins are roburins A and E, grandinin, vescalagin and castalagin. Guaiacol is one of the molecules responsible for the cork taint wine fault.

Phenolic content in relation with wine making techniques

Extraction levels in relation with grape pressing techniques

Flash release Flash release (FR) is a technique used in wine pressing. The technique allows for a better extraction of phenolic compounds and wine polysaccharides. The treatment consists of heating the grapes at 95 °C (203 °F) for several minutes with vapour ...

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 inte ...

* Anthocyanidin-caftaric acid adducts *

Astilbin Astilbin is a flavanonol, a type of flavonoid. Astilbin is the (2R-trans)-isomer; neoisoastilbin is the (2S-cis)-isomer and isoastilbin is the (2R-cis)-isomer. Natural occurrences Astilbin can be found in St John's wort (''Hypericum perforatum'' ...

* Astringin *

B type proanthocyanidin dimer Proanthocyanidin dimers are a specific type of proanthocyanidin, which are a class of flavanoids. They are oligomers of flavan-3-ol Flavan-3-ols (sometimes referred to as flavanols) are a subgroup of flavonoids. They are derivatives of flavans ...

s *

B type proanthocyanidin trimer Proanthocyanidin dimers are a specific type of proanthocyanidin, which are a class of flavanoids. They are oligomers of flavan-3-ol Flavan-3-ols (sometimes referred to as flavanols) are a subgroup of flavonoids. They are derivatives of flavan ...

s * Caffeic acid * Caftaric acid * Castalagin *

Castavinol C1 Castavinols are natural phenolic compounds found in red wines.Castavinol, a new series of polyphenols from Bordeaux red wines. Chantal Castagnino and Joseph Vercauteren, Tetrahedron Letters, Volume 37, Issue 43, 21 October 1996, pp. 7739-7742, T ...

Castavinol C2 Castavinols are natural phenolic compounds found in red wines.Castavinol, a new series of polyphenols from Bordeaux red wines. Chantal Castagnino and Joseph Vercauteren, Tetrahedron Letters, Volume 37, Issue 43, 21 October 1996, pp. 7739-7742, The ...

Castavinol C3 Castavinol C3 is a castavinol, a natural phenolic compound found in red wines.Castavinol, a new series of polyphenols from Bordeaux red wines. Chantal Castagnino and Joseph Vercauteren, Tetrahedron Letters, Volume 37, Issue 43, 21 October 1996, p ...

Castavinol C4 Castavinols are natural phenolic compounds found in red wines.Castavinol, a new series of polyphenols from Bordeaux red wines. Chantal Castagnino and Joseph Vercauteren, Tetrahedron Letters, Volume 37, Issue 43, 21 October 1996, pp. 7739-7742, The ...

* Catechin * Catechin-(4,8)-malvidin-3-O-glucoside *

Compound NJ2 Compound NJ2 is a xanthylium yellowish pigment found in wine. In model solutions, colorless compounds, such as catechin, can give rise to new types of pigments. The first step is the formation of colorless dimeric compounds consisting of two flav ...

* Coniferyl aldehyde * Coumaric acid * Coutaric acid * Cyanidin * Cyanin (Cyanidin-3,5-O-diglucoside) *

Cyanidin 3O-glucoside Chrysanthemin is an anthocyanin. It is the 3-glucoside of cyanidin. Natural occurrences Chrysanthemin can be found in the Roselle (plant), roselle plant (''Hibiscus sabdariffa'', Malvaceae), different Japanese angiosperms, ''Rhaponticum'' (Aste ...

Cyanidin acetyl 3O glucoside 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 ...

Cyanidin coumaroyl 3O glucoside Cyanidin is a natural organic compound. It is a particular type of anthocyanidin (glycoside version called anthocyanins). It is a pigment found in many red berries including grapes, bilberry, blackberry, blueberry, cherry, chokeberry, cranberr ...

* Cyanidin-3-O-glucoside-pyruvic acid * Cyanidin-3-O-acetylglucoside-pyruvic acid * Cyanidin-coumaroylglucoside-pyruvic acid * Delphinidin *

Delphinidin 3O glucoside Myrtillin is an anthocyanin. It is the 3-glucoside of delphinidin. It can be found in all green plants, most abundantly in blackcurrant, blueberry, huckleberry, bilberry leaves and in various myrtles, roselle plants, and ''Centella asiatica'' pl ...

Delphinidin acetyl-3O glucoside 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 that produces ...

Delphinidin coumaroyl 3O glucoside Delphinidin 3-''O''-(6-''p''-coumaroyl)glucoside is a ''p''-coumaroylated anthocyanin. It can be found in some red ''Vitis vinifera'' grape cultivars (like Graciano) and in red wine. It is formed by the enzyme anthocyanin 3-''O''-glucoside 6� ...

* 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 δ-Viniferin is a resveratrol dehydrodimer. It is an isomer of epsilon-viniferin. It can be isolated from stressed grapevine (''Vitis vinifera'') leaves. It is also found in plant cell cultures and wine. It can also be found in ''Rheum maximowicz ...

* Dihydro-resveratrol * Ellagic acid *

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 The phenolic content in wine refers to the phenolic compounds—natural phenol a ...

* Epicatechin gallate * Epigallocatechin * Epsilon-viniferin *

Ethyl caffeate Ethyl caffeate is an ester of a hydroxycinnamic acid, a naturally occurring organic compound. Natural occurrences It can be found in ''Bidens pilosa'', in '' Polygonum amplexicaule var. sinense''. It is also found in Huáng bǎi, one of the fi ...

Ethyl gallate Ethyl gallate is a food additive with E number E313. It is the ethyl ester of gallic acid. Ethyl gallate is added to food as an antioxidant. Though found naturally in a variety of plant sources including walnuts ''Terminalia myriocarpa'' or c ...

Ethyl protocatechuate Ethyl protocatechuate is a phenolic compound. It can be found in the peanut seed testa. It is also present in wine. It is the ethylic ester of protocatechuic acid. The compound is a prolyl 4-hydroxylase inhibitor and can be used to protect the my ...

* 4-Ethylguaiacol *

Fertaric acid Fertaric acid is a hydroxycinnamic acid found in wine and grapes. It is an ester formed from ferulic acid bound to tartaric acid. It is a metabolite of caftaric acid Caftaric acid is a non-flavonoid phenolic compound. It is found in the juice ...

* Ferulic acid * Gallic acid *

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. Pro ...

* Grandinin * Grape reaction product (GRP) * Guaiacol *

Hopeaphenol Hopeaphenol is a stilbenoid. It is a resveratrol tetramer. It has been first isolated from Dipterocarpaceae like '' Shorea ovalis''. It has also been isolated from wines from North Africa. It shows an opposite effect to vitisin A on apoptosis of ...

* p-Hydroxybenzoic acid *

Isorhamnetol 3-glucoside Isorhamnetin is an O-methylated flavon-ol from the class of flavonoids. A common food source of this 3'-methoxylated derivative of quercetin and its glucoside conjugates are pungent yellow or red onions, in which it is a minor pigment, quercetin ...

* Kaempferol *

Kaempferol glucoside Astragalin is a chemical compound. It can be isolated from ''Phytolacca americana'' (the American pokeweed) or in the methanolic extract of fronds of the fern ''Phegopteris connectilis''.Phenolic constituents of the fernPhegopteris connectilis. Kl ...

(astragalin) *

Kaempferol glucuronide 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. Kaempferol is a yellow crystalline solid with a melt ...

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 of ...

Malvidin 3O-glucoside Oenin is an anthocyanin. It is the 3-glucoside of malvidin. It is one of the red pigments found in the skin of purple grapes and in wine. Color stabilization of malvidin 3-glucoside at a higher pH can be explained by self-aggregation of the flavy ...

(oenin) *

Malvidin acetyl-3O-glucoside 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 of ...

Malvidin cafeoyl-3O-glucoside 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 of ...

Malvidin coumaroyl-3Oglucoside Malvidin-3-''O''-(6-''p''-coumaroyl)glucoside is a ''p''-coumaroylated anthocyanin found in grape and wine. There are two forms with the ''cis'' and ''trans'' isomers of ''p''-coumaric acid. It is a cation. See also * Phenolic content in win ...

* Malvidin glucoside-ethyl-catechin * Malvidin-3-O-glucoside-pyruvic acid * Malvidin-3-O-acetylglucoside-pyruvic acid * Malvidin-3-O-coumaroylglucoside-pyruvic acid * Malvidin-3-O-glucoside-acetaldehyde * Malvidin-3-O-acetylglucoside-acetaldehyde * Malvidin-3-O-coumaroylglucoside-acetaldehyde * Malvidin-3-O-glucoside-4-vinylcatechol * Malvidin-3-O-acetylglucoside-4-vinylcatechol * Malvidin-3-O-coumaroylglucoside-4-vinylcatechol * Malvidin-3-O-glucoside-4-vinylphenol * Malvidin-3-O-acetylglucoside-4-vinylphenol * Malvidin-3-O-coumaroylglucoside-4-vinylphenol * Malvidin-3-O-caffeoylglucoside-4-vinylphenol * Malvidin-3-O-glucoside-4-vinylguaiacol * Malvidin-3-O-acetylglucoside-4-vinylguaiacol * Malvidin-3-O-coumaroylglucoside-vinylguaiacol * Malvidin-3-O-glucoside-4-vinyl(epi)catechin * Malvidin-3-O-acetylglucoside-4-vinyl(epi)catechin * Malvidin-3-O-coumaroylglucoside-4-vinyl(epi)catechin *

Methyl gallate Methyl gallate is a phenolic compound. It is the methyl ester of gallic acid. Natural occurrences It is found in ''Terminalia myriocarpa'', ''Bergenia ciliata'' (hairy Bergenia) and ''Geranium niveum''. It is found in the fruit extract of '' Pa ...

Myricetol 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 struct ...

Myricetol 3-glucoside 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 struct ...

Myricetol 3-glucuronide 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 struct ...

Oxovitisin A Oxovitisin A is an oxovitisin, a type of pyranoanthocyanin with a pyranone ( 2-pyrone) component. It is found in aged Port wines. It does not contain an oxonium ion component (flavylium cation), as anthocyanins do. Therefore, it does not have an a ...

Pallidol Pallidol is a resveratrol dimer. It can be found in ''red wine Red wine is a type of wine made from dark-colored grape varieties. The color of the wine can range from intense violet, typical of young wines, through to brick red for mature wine ...

Pelargonin Pelargonin is an anthocyanin. It is the 3,5-''O''-diglucoside of pelargonidin. Natural occurrences Pelargonin is a pigment, found in barberries, the petals of the scarlet pelargonium flower pomegranates, and red wine. See also * Phenolic cont ...

(Pelargonidin 3,5-O-diglucoside) *

Peonidin 3O-glucoside Peonidin-3-''O''-glucoside is anthocyanin. It is found in fruits and berries, in red ''Vitis vinifera'' grapes and red wine, in red onions and in purple corn.Anthocyanins isolated from purple corn (''Zea mays'' L.). Hiromitsu Aoki, Noriko Kuze ...

Peonidin acetyl-3O-glucoside Peonidin is an O-methylated anthocyanidin derived from Cyanidin, and a primary plant pigment. Peonidin gives purplish-red hues to flowers such as the peony, from which it takes its name, and roses. It is also present in some blue flowers, such as ...

* Peonidin-3-(6-p-caffeoyl)-glucoside *

Peonidin coumaroyl 3O-glucoside Peonidin is an O-methylated anthocyanidin derived from Cyanidin, and a primary plant pigment. Peonidin gives purplish-red hues to flowers such as the peony, from which it takes its name, and roses. It is also present in some blue flowers, such as ...

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

Petunidin 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 redberries including c ...

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 redberries 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 redberries including ...

* 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 Phloroglucinol carboxylic acid is a trihydroxybenzoic acid, a type of phenolic acid. It is produced by ''Pseudomonas fluorescens''. It is a catechin degradation product excreted by the bacterium ''Acinetobacter calcoaceticus'', a species of bacte ...

* Piceatannol * Piceids * Pinotin A * Oligomeric procyanidins : **

Procyanidin B1 Procyanidin B1 is a procyanidin dimer. It is a molecule with a 4→8 bond (epicatechin-(4β→8)-catechin). Proanthocyanidin-B1 can be found in ''Cinnamomum verum'' (Ceylon cinnamon, in the rind, bark or cortex), in ''Uncaria guianensis'' (cat's ...

Procyanidin B2 Procyanidin B2 is a B type proanthocyanidin. Its structure is (−)-Epicatechin-(4β→8)-(−)-epicatechin. Procyanidin B2 can be found in '' Cinchona pubescens'' (Chinchona: in the rind, bark, and cortex), in ''Cinnamomum verum'' (Ceylon cinnam ...

Procyanidin B3 Procyanidin B3 is a B type proanthocyanidin. Procyanidin B3 is a catechin dimer ( catechin-(4α→8)-catechin). Natural occurrences It can be found in red wine, in barley, in beer, in peach or in ''Jatropha macrantha'', the Huanarpo Macho. ...

Procyanidin B4 Procyanidin B4 is a B type proanthocyanidin. Procyanidin-B4 is a catechin-(4α→8)-epicatechin dimer. It is found in the litchi pericarp, in grape seeds, and, along with 4-cis-isomer of procyanidin B4, in beer.

** B1-3-O-gallate **

B2-3-O-gallate B, or b, is the second letter of the Latin-script 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 r ...

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

** procyanidin C1 (epicatechin-(4β→8)-epicatechin-(4β→8)-epicatechin) ** Procyanidin C2 (catechin-(4α→8)-catechin-(4α→8)-catechin) **

procyanidin T2 Procyanidins are members of the proanthocyanidin (or condensed tannins) class of flavonoids. They are oligomeric compounds, formed from catechin and epicatechin molecules. They yield cyanidin when depolymerized under oxidative conditions. See t ...

(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. Biolo ...

* protocatechuic aldehyde * Quercetin *

Quercetol glucoside Isoquercetin, isoquercitrin or isotrifoliin is a flavonoid, a type of chemical compound. It is the 3-''O''- glucoside of quercetin. Isoquercitrin can be isolated from various plant species including ''Mangifera indica'' ( mango) and ''Rheum nobile ...

* Quercetol glucuronide *

* Roburin A * Roburin E * Scopoletin * Sinapic aldehyde * Sinapinic acid * Syringic acid * Tyrosol * Vanillic acid * vanillin * Vescalagin * 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 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, enhance fibrinolysis, and increase HDL cholesterol, but high-quality clinical trials 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