Caftaric acid is a non-flavanoid that impacts the color of white wine. Many believe this molecule

Molecule

A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...

 is responsible for the yellowish-gold color seen in some whites wines. Aside from wine, it is abundantly present in raisins.

Caftaric acid and caffeic acid

Caffeic acid

Caffeic acid is a hydroxycinnamic acid, a naturally occurring organic compound. This yellow solid consists of both phenolic and acrylic functional groups...

 are in a class of chemicals known as cinnamates (hydroxycinnamic acid

Hydroxycinnamic acid

Hydroxycinnamic acids are a class of polyphenols 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 are :* Alpha-cyano-4-hydroxycinnamic acid...

s). Caftaric acid is formed when caffeic acid and tartaric acid

Tartaric acid

Tartaric acid is a white crystalline diprotic organic acid. It occurs naturally in many plants, particularly grapes, bananas, and tamarinds; is commonly combined with baking soda to function as a leavening agent in recipes, and is one of the main acids found in wine. It is added to other foods to...

 undergo esterification. But during fermentation

Fermentation (biochemistry)

Fermentation is the process of extracting energy from the oxidation of organic compounds, such as carbohydrates, using an endogenous electron acceptor, which is usually an organic compound. In contrast, respiration is where electrons are donated to an exogenous electron acceptor, such as oxygen,...

, caftaric acid is oxidized into its principal components.

In wine

Winemakers measure caftaric acid levels as their primary method to estimate the oxidation levels that a wine has undergone. For example, press wines, which undergo a high degree of oxidation, will have little to no caftaric acid.

See also

• Grape reaction product
  Grape reaction product
  The grape reaction product is a phenolic compound found in aged red wines. Its enzymatic production by polyphenol oxidase is important in limiting the browning of musts. The product can be recreated in model solutions...
  
  or 2-S glutathionyl caftaric acid, a phenolic compound found in wine