Hydroxycinnamic esters and browning potential in mature berries of some grape varieties

Concentrations of caffeoyl‐, p ‐coumaroyl‐ and feruloyl‐tartaric acid esters in 28 mature grape varieties were determined by high performance liquid chromatography. Caffeoyl tartrate concentrations were generally found to be the highest (average amount 0.12 μmol g −1 of fresh weight). p ‐Coumaroyl tartrate concentrations were lower (average amount 0.05ümolg −1 of fresh weight). Feruloyl tartrate concentrations were very low and often non‐existent. The differences between varieties were very large for all the esters. In connection with previously‐determined polyphenol oxidase activities and according to the results of multiple linear regression and principal component analysis, no correlation was found between browning potential and hydroxycinnamic ester contents when such a correlation occurred in red grape browning with polyphenol oxidase activity levels.