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 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, ...

. It is an esterified phenolic acid, composed of

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 ...

, a

hydroxycinnamate 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 ...

produced by plants, and

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 ...

, the principal organic acid found in grape berries. As such, caftaric acid is found in all grape juices and wines. During

alcoholic Alcoholism is, broadly, any drinking of alcohol that results in significant mental or physical health problems. Because there is disagreement on the definition of the word ''alcoholism'', it is not a recognized diagnostic entity. Predomin ...

and

malolactic fermentation Malolactic conversion (also known as malolactic fermentation or MLF) is a process in winemaking in which tart-tasting malic acid, naturally present in grape must, is converted to softer-tasting lactic acid. Malolactic fermentation is most often p ...

, the ester can be enzymatically hydrolysed, releasing the two constituents. Caffeic acid is susceptible to chemical oxidation, and subsequent redox reactions involving caffeic acid can contribute to wine browning over time, and the straw-gold color that can develop in some white wines after bottling. Aside from wine, it is abundantly present in

raisins A raisin is a dried grape. Raisins are produced in many regions of the world and may be eaten raw or used in cooking, baking, and brewing. In the United Kingdom, Ireland, New Zealand, and Australia, the word ''raisin'' is reserved for the da ...

. It also occurs in ''Cichorium intybus'' (common

chicory Common chicory ('' Cichorium intybus'') is a somewhat woody, perennial herbaceous plant of the family Asteraceae, usually with bright blue flowers, rarely white or pink. Native to the Old World, it has been introduced to North America and Austra ...

) and is one of the bioactive components of ''

Echinacea purpurea ''Echinacea purpurea'', the eastern purple coneflower, purple coneflower, hedgehog coneflower, or echinacea, is a North American species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as w ...

'' (Eastern purple coneflower). Caftaric acid has a good bioavailability when fed in rats. Intact trans-caftaric acid was detected in rat plasma along with its O-methylated derivative 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 ...

In wine

Winemaker A winemaker or vintner is a person engaged in winemaking. They are generally employed by wineries or wine companies, where their work includes: *Cooperating with viticulturists *Monitoring the maturity of grapes to ensure their quality and to deter ...

s measure caftaric acid levels as their primary method to estimate the

oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...

levels that a wine has undergone. For example, press wines, which undergo a high degree of oxidation, will have little to no caftaric acid.

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 ...

(2-S glutathionyl caftaric acid) is an oxidation compound produced from caftaric acid and found in wine. Malvidin 3-glucoside alone is not oxidized in the presence of grape

polyphenol oxidase Polyphenol oxidase (PPO; also polyphenol oxidase i, chloroplastic), an enzyme involved in fruit browning, is a tetramer that contains four atoms of copper per molecule. PPO may accept monophenols and/or ''o''-diphenols as substrates. The ...

(PPO), whereas it is degraded in the presence of a crude grape PPO extract and of caftaric acid, forming anthocyanidin-caftaric acid adducts.

References

{{Hydroxycinnamic acid Hydroxycinnamic acid esters Catechols Vinylogous carboxylic acids

In wine

See also

References