Grape reaction product

Grape reaction product

Names
Other names GRP GRP1 2-S-Glutathionyl caftaric acid
Identifiers
3D model (JSmol)	Interactive image
SMILES Oc1cc(cc(c1O)SCC(NC(=O)CCC(N)C(=O)O)C(=O)NCC(O)=O)\C=C\C(=O)OC(C(O)=O)C(O)C(O)=O
Properties
Chemical formula	C23H27N3O15S
Molar mass	617.54 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
Infobox references

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 polyphenol oxidase is important in limiting the browning of musts, especially in white wine production. The product can be recreated in model solutions.

It is possible to determine its concentration in wine by mass spectrometry.

S-Glutathionyl caftaric acid is itself oxidizable. It is not a substrate for grape polyphenol oxidase, but laccase from Botrytis cinerea can use it to form GRP2.

Other related molecules are trans-caffeoyltartrate derivatives like GRP o-quinone and 2,5-di-S-glutathionyl cafteoyl tartrate (GRP2) or adducts with anthocyanidins.