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 undergoing the process of Maceration (wine), maceration, which involves prolonged contact between the juice with the grape skins, seeds, and pulp. The wine color, colou ...

. It is an esterified phenolic acid, composed of

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

, a hydroxycinnamate 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 tamarinds, bananas, avocados, and citrus. Its salt (chemistry), salt, potassium bitartrate, commonly known as cream of ta ...

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

alcoholic Alcoholism is the continued drinking of alcohol despite it causing problems. Some definitions require evidence of dependence and withdrawal. Problematic use of alcohol has been mentioned in the earliest historical records. The World Hea ...

and

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

, 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, Australia and South Africa, the word ''raisin'' is reserv ...

. 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 Europe, it has been introduced to the Americas and Australia. M ...

) and is one of the bioactive components of '' Echinacea purpurea'' (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.

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 de ...

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

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

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 p ...

(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 (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

In wine

See also

References