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 ecol ...

and

polyphenol Polyphenols () are a large family of naturally occurring organic compounds characterized by multiples of phenol units. They are abundant in plants and structurally diverse. Polyphenols include flavonoids, tannic acid, and ellagitannin, some ...

s—in

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

, which 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 (flavor). Taste is the perception produced or stimulated when a substance in the mouth reacts chemically with taste receptor ...

color Color (American English) or colour (British English) is the visual perceptual property deriving from the spectrum of light interacting with the photoreceptor cells of the eyes. Color categories and physical specifications of color are associ ...

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 ...

of wine. These compounds include

phenolic acid Phenolic acids or phenolcarboxylic acids are 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 naturally occurring types of ph ...

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 chalcones. Most stilbenoids are prod ...

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 " ...

s, 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 com ...

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 compo ...

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 tanni ...

s) and

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

tannin Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' (from Anglo-Norman ''tanner'' ...

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, 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. Sourc ...

and

s 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

s in the skin, and other phenols (

s, proanthocyanidins and

s) in the skin and the seeds. During the growth cycle of the grapevine, 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 gr ...

will be richer in phenols abundant in the skin and seeds, such as anthocyanin, proanthocyanidins and flavonols, whereas the phenols in

white wine White wine is a wine that is Fermentation in winemaking, fermented without skin contact. The wine color, colour can be straw-yellow, yellow-green, or yellow-gold. It is produced by the alcoholic fermentation of the non-coloured Juice vesicles, ...

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 an ...

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 Winemaking 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. The science of wine and ...

, 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 Oak is used in winemaking to vary the color, flavor, tannin profile and texture of wine. It can be introduced in the form of a barrel during the fermentation or aging periods, or as free-floating chips or staves added to wine fermented in a vess ...

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 extract of the vanilla bean. Synthetic vanillin is now u ...

which adds

vanilla Vanilla is a spice derived from orchids of the genus '' Vanilla'', primarily obtained from pods of the Mexican species, flat-leaved vanilla ('' V. planifolia''). Pollination is required to make the plants produce the fruit from whic ...

aroma An odor (American English) or odour (Commonwealth English; see spelling differences) is caused by one or more volatilized chemical compounds that are generally found in low concentrations that humans and animals can perceive via their sens ...

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 Metabolism (, from el, μεταβολή ''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 ...

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 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 and fungal cells and some protist, animal, and bacterial cells. Vacuoles are essentially enclosed compartments which are filled with water containing inorganic and organic m ...

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 region, Central Europe, and southwestern Asia, from Morocco and Portugal north to southern Germany and east to northern Iran. There are cur ...

'' 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 pr ...

. 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 plan ...

, 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 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 lubrica ...

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

s, which includes the yellow

pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compou ...

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 A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechanis ...

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

s and

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

. 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 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 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 p ...

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 th ...

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 the phrase commonly refers to champagne, European Union countries legally reserve that term for products exclusively produced in the Champagne regi ...

s 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 words for ''pine'' and ''black.'' The word ''pine ...

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

teinturier Teinturier grapes are grapes whose flesh and juice is red in colour due to anthocyanin pigments accumulating within the pulp of the grape berry itself. In most cases, anthocyanin pigments are confined to the outer skin tissue only, and the squee ...

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.

Ampelographer Ampelography ( ἄμπελος, "vine" + γράφος, "writing") is the field of botany concerned with the identification and classification of grapevines, ''Vitis'' spp. Traditionally this has been done by comparing the shape and colour of the ...

s 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 simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, u ...

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 varieties are also known to not synthesize para-coumaroylated or

acetylated anthocyanin : In organic chemistry, acetylation is an organic esterification reaction with acetic acid. It introduces an acetyl group into a chemical compound. Such compounds are termed ''acetate esters'' or simply ''acetates''. Deacetylation is the oppo ...

s 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 charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged atom or molecul ...

of anthocyanin pigments caused by the

acidity In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a ...

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 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 ...

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 (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...

s that eventually exceed their

solubility 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 solubi ...

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 pyranoantho ...

are chemical compounds formed in red

s by

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

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 p ...

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 an ...

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 Tactile may refer to: * Tactile, related to the sense of touch * Haptics (disambiguation) * Tactile (device), a text-to-braille translation device See also * Tangibility, in law * Somatosensory system In physiology, the somatosensory system ...

drying sensation 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 residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

s, 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 ...

. 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 a ...

) 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 substrates, and the enzyme converts the substrates into different molecules known as products. ...

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 Nebbiolo (, ; pms, nebieul ) 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, Roero ...

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 An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably ''L ...

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 perhaps 8,000 years a ...

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 unrel ...

, 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 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 plants ...

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 l ...

. 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 the proteins of the albumin family are water- soluble, moderately soluble in concentrated salt solutions, and experience heat denaturation. Album ...

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

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 Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...

, which oxidize tannins to quinone-like compounds that are polymerization-prone. The winemaking technique of

micro-oxygenation Micro-oxygenation is a process used in winemaking to introduce oxygen into wine in a controlled manner. Developed in 1991 by Patrick DuCournau, working with the exceptionally tannic grape Tannat in Madiran, the process gained usage in modern win ...

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 ...

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

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 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 f ...

) 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 oc, Bordèu ; eu, Bordele; it, Bordò; es, Burdeos) is a port city on the river Garonne in the Gironde department, Southwestern France. It is the capital of the Nouvelle-Aquitaine region, as well as the prefectu ...

), 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 u ...

, 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 comp ...

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,, ''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 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 crucif ...

. 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 structu ...

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. Kaempferol is a yellow crystalline solid with a meltin ...

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 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 ...

, 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 structu ...

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 phytochemicals that can be found in food, there ...

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 bananas, tamarinds, and citrus. Its salt, potassium bitartrate, commonly known as cream of tartar, develops naturally i ...

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 acid 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, ferulic ...

s).

Stilbenoids

''V. vinifera'' also produces

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 Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...

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

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 California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

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

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

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 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 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 found i ...

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 extract of the vanilla bean. Synthetic vanillin is now used ...

is a phenolic

aldehyde In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl grou ...

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

and hydrolysable tannins (

ellagitannin The ellagitannins are a diverse class of hydrolyzable tannins, a type of polyphenol formed primarily from the oxidative linkage of galloyl groups in 1,2,3,4,6-pentagalloyl glucose. Ellagitannins differ from gallotannins, in that their galloyl group ...

s). The

hydrolyzable tannin A hydrolyzable 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 hydrolyzable tannin molecule, there is a carbohydrate (usually D-glucos ...

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 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 ''Brettanomyces'' is a non-spore forming genus of yeast in the family Saccharomycetaceae, and is often colloquially referred to as "Brett". The genus name ''Dekkera'' is used interchangeably with ''Brettanomyces'', as it describes the teleomorph ...

Natural phenols and polyphenols from cork stoppers

Low molecular weight polyphenols, as well as ellagitannins, are susceptible to be extracted from

cork stopper A stopper or cork is a cylindrical or conical closure used to seal a container, such as a bottle, tube or barrel. Unlike a lid or bottle cap, which encloses a container from the outside without displacing the inner volume, a bung is partially ...

s into the wine. The identified polyphenols are gallic, protocatechuic, vanillic, caffeic, ferulic, 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 Scopoletin is a coumarin. It found in the root of plants in the genus ''Scopolia'' such as ''Scopolia carniolica'' and ''Scopolia japonica'', in chicory, in '' Artemisia scoparia'', in the roots and leaves of stinging nettle (''Urtica dioica''), i ...

; the ellagitannins are roburins A and E,

grandinin Grandinin is an ellagitannin. It can be found in ''Melaleuca quinquenervia'' leavesPolyphenols of Melaleuca quinquenervia leaves - pharmacological studies of grandinin. Moharram F. A., Marzouk M. S., El-Toumy S. A. A., Ahmed A. A. E. and Aboutabl ...

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

and

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

Guaiacol Guaiacol () is an organic compound with the formula C6H4(OH)(OCH3). It is a phenolic compound containing an 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 a wine fault characterized by a set of undesirable smells or tastes found in a bottle of wine, especially spoilage that can only be detected after bottling, aging and opening. Though modern studies have sh ...

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

* B type proanthocyanidin dimers * B type proanthocyanidin trimers *

Caffeic acid Caffeic acid is an organic compound that is classified as a hydroxycinnamic acid. This yellow solid consists of both phenolic and acrylic functional groups. It is found in all plants because it is an intermediate in the biosynthesis of lignin, one ...

Caftaric acid Caftaric acid is a non-flavonoid phenolic compound. It is found in the juice of grapes (''Vitis vinifera'') and impacts the color of white wine. It is an esterified phenolic acid, composed of caffeic acid, a hydroxycinnamate produced by plants ...

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

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 *

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 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 Coniferyl aldehyde is an organic compound with the formula HO(CH3O)C6H3CH=CHCHO. It is a derivative of cinnamaldehyde, featuring 4-hydroxy and 3-methoxy substituents. It is a major precursor to lignin. Biosynthetic role In sweetgum (''Liquidamba ...

Coumaric acid Coumaric acid is a phenolic derivative of cinnamic acid having a hydroxy group In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In ...

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 anthocyanins). It is a pigment found in many red berries including grapes, bilberry, blackberry, blueberry, cherry, chokeberry, cranb ...

* 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 that produces ...

* 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 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 Dihydro-resveratrol is a dihydrostilbenoid found in wine. It is also a metabolite of trans-resveratrol formed in the intestine by the hydrogenation of the double bond by microflora. It is also a non-cannabinoid estrogenic compound found in canna ...

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 backwards because it can be ob ...

* Engeletin *

Epicatechin gallate Epicatechin gallate (ECG) is a flavan-3-ol, a type of flavonoid, present in green tea. It is also reported in buckwheat and in grape. The tea component epicatechin gallate is being researched because in vitro experiments showed it can reverse ...

Epigallocatechin Gallocatechol or gallocatechin (GC) is a flavan-3-ol, a type of chemical compound including catechin, with the gallate residue being in an isomeric trans position. This compound possesses two epimers. The most common, (+)-gallocatechin (GC), CAS ...

* Epsilon-viniferin * Ethyl caffeate * Ethyl gallate * Ethyl protocatechuate * 4-Ethylguaiacol *

* Fertaric acid *

Ferulic acid 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, ferulic ...

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 plants. It i ...

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 Grandinin is an ellagitannin. It can be found in ''Melaleuca quinquenervia'' leavesPolyphenols of Melaleuca quinquenervia leaves - pharmacological studies of grandinin. Moharram F. A., Marzouk M. S., El-Toumy S. A. A., Ahmed A. A. E. and Aboutabl ...

Grape reaction product The grape reaction product (GRP, GRP1 or 2-S- glutathionyl caftaric acid) is a phenolic compound explaining the disappearance of caftaric acid from grape must during processing. It is also found in aged red wines. Its enzymatic production by polyp ...

(GRP) *

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 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. Kaempferol is a yellow crystalline solid with a meltin ...

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) * Malvidin acetyl-3O-glucoside * Malvidin cafeoyl-3O-glucoside * Malvidin coumaroyl-3Oglucoside *

Malvidin glucoside-ethyl-catechin Malvidin glucoside-ethyl-catechin is a flavanol-anthocyanin adduct. Flavanol-anthocyanin adducts are formed during wine ageing through reactions between anthocyanins and tannins present in grape, with yeast metabolites such as acetaldehyde. Aceta ...

* 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 * Myricetol *

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 * Pelargonin (Pelargonidin 3,5-O-diglucoside) * Peonidin 3O-glucoside *

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-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 (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 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 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 *

Piceid Piceid is a stilbenoid glucoside and is a major resveratrol derivative in grape juices. It can be found in the bark of ''Picea sitchensis''. It can also be isolated from ''Reynoutria japonica'' ( syn. ''Fallopia japonica''), the Japanese knotweed ...

s *

Pinotin A Pinotins are a type of pyranoanthocyanins, a class of phenolic compounds found in red wine. One such compound is pinotin A.Variation of pyranoanthocyanins in red wines of different varieties and vintages and the impact of pinotin A addition on th ...

* 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. H ...

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 **

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. Chemical ...

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

Procyanidin C2 Procyanidin C2 is a B type proanthocyanidin 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 '' Betula spp.'', in '' ...

(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. Biolo ...

protocatechuic aldehyde Protocatechuic aldehyde is a phenolic aldehyde, a compound released from cork stoppers into wine. This molecule can be used as a precursor in the vanillin synthesis by biotransformation by cell cultures of ''Capsicum frutescens'', a type of Chili ...

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 a ...

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 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 ta ...

* Roburin E *

Scopoletin Scopoletin is a coumarin. It found in the root of plants in the genus ''Scopolia'' such as ''Scopolia carniolica'' and ''Scopolia japonica'', in chicory, in '' Artemisia scoparia'', in the roots and leaves of stinging nettle (''Urtica dioica''), i ...

Sinapic aldehyde Sinapaldehyde is an organic compound with the formula HO(CH3O)2C6H2CH=CHCHO. It is a derivative of cinnamaldehyde, featuring one hydroxy group and two methoxy groups as substituents. It is an intermediate in the formation of sinapyl alcohol, ...

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 mass ...

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 d ...

Tyrosol Tyrosol is an organic compound with the formula . Classified as a phenylethanoid, i.e. a derivative of phenethyl alcohol, It is found in a variety of natural sources. The compound is colorless solid. The principal source in the human diet is ol ...

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 natu ...

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

* 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 Volatiles are the group of chemical elements and chemical compounds that can be readily vaporized. In contrast with volatiles, elements and compounds that are not readily vaporized are known as refractory substances. On planet Earth, the term ' ...

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, also called thrombocytes (from Greek θρόμβος, "clot" and κύτος, "cell"), are a component of blood whose function (along with the coagulation factors) is to react to bleeding from blood vessel injury by clumping, thereby ini ...

, 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 High-density lipoprotein (HDL) is one of the five major groups of lipoproteins. Lipoproteins are complex particles composed of multiple proteins which transport all fat molecules (lipids) around the body within the water outside cells. They are t ...

, but high-quality

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

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