Grape reaction product
Encyclopedia
The grape reaction product (GRP, GRP1 or 2-S-glutathionyl
caftaric acid
) 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. Other related molecules are trans-caffeoyltartrate derivatives like GRP o-quinone and 2,5-di-S-glutathionyl cafteoyl tartrate
(GRP2) or adducts with anthocyanidin
s.
Glutathione
Glutathione is a tripeptide that contains an unusual peptide linkage between the amine group of cysteine and the carboxyl group of the glutamate side-chain...
caftaric acid
Caftaric acid
Caftaric acid is a non-flavanoid that impacts the color of white wine. Many believe this molecule is responsible for the yellowish-gold color seen in some whites wines. Aside from wine, it is abundantly present in raisins....
) is a phenolic compound found in aged red wines. Its enzymatic production by polyphenol oxidase
Polyphenol oxidase
Polyphenol oxidase is a tetramer which contains four atoms of copper per molecule, and binding sites for two aromatic compounds and oxygen...
is important in limiting the browning of musts. The product can be recreated in model solutions. Other related molecules are trans-caffeoyltartrate derivatives like GRP o-quinone and 2,5-di-S-glutathionyl cafteoyl tartrate
Tartrate
A tartrate is a salt or ester of the organic compound tartaric acid, a dicarboxylic acid. Its formula is O−OC-CH-CH-COO− or C4H4O62−.As food additives, tartrates are used as antioxidants, acidity regulators, and emulsifiers...
(GRP2) or adducts with anthocyanidin
Anthocyanidin
Anthocyanidins are common plant pigments. They are the sugar-free counterparts of anthocyanins based on the flavylium ion or 2-phenylchromenylium, which is a type of oxonium ion . They form a large group of polymethine dye. In particular anthocyanidins are salt derivatives of the...
s.