Cutaric acid

Precursors. Precursors for this reaction are anthocyanins and t -quinones of caf-feoyltartaric (caftaric acid) and p-coumaroyltartaric (cutaric acid) acids generated by enzymatic oxidation by grape polyphenoloxidase (PPO) (Singleton et al. 1985). PPO first adds an OH group to monophenols and then oxidizes the resulting o-diphenol to o-quinone. 

Grape musts and wines contain depsides of some phenolic acids with L-tartaric acid. Common esters are depsides of caffeic (8-89), 4-coumaric and vanillic acids. For example, the vanilloyltartaric acid content in musts and wines ranges from 1.4 to 11.7 mg/1, and of 4-coumaroyltartaric (cutaric) acid and calFeoyltartaric (caftaric) acid is 0.6-5.5 and 10.2-26.9 mg/1, respectively. In all these depsides, (E)-isomers dominate. 2,3-Di-O-caffeoyl-L-tartaric acid, known as cichoric acid (8-90), is an example of diesters of i-tartaric acid, which occur in plants of the Asteraceae family. Cichoric acid is situated in the root and leaves of chicory Cichorium intybus), endive (C. endivia) and lettuce Lactuca sativa). 

Hydroxycinnamic acids are found mainly in skin and, to a lesser extent, in leaves [101,102] and stems [97]. The most abundant acids (viz., caffeic, p-coumaric, and feralic) are present as tartaric esters (caftaric, cutaric, and fertaric acids Figure 4.7) or in acylated anthocyanins (basically, p-coumaric and caffeic acids). 

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