Characterisation and evolution of grape polyphenol profiles of Vitis vinifera L. cv. Tannat during ripening and vinification

Abstract

Background and Aims: Changes in different polyphenol families during grape ripening and vinification were determined in Tannat grapes. This was done to establish a polyphenol profile for Tannat grapes during ripening and for young wines. Methods and Results: We demonstrated, by high-performance liquid chromatography with diode array detection and mass spectrometry (HPLC-DAD-MS) analysis, that the content of flavan-3-ols in Tannat seeds was higher than that reported for a large number of other grape varieties analysed. Forty per cent of the total flavan-3-ols in seeds were galloylated compounds, whereas the flavan-3-ol profile in skins was characterised by the absence of galloylated forms. Prodelphinidins in skins ranged between 30 and 35% with very low values for epigallocatechin. Epicatechin gallate was not detected in Tannat wine and galloylated forms represented a low percentage of total flavan-3-ols. Tannat grapes had very high concentrations of anthocyanins in skins with levels increasing during ripening. Eleven phenolic acids were identified in Tannat grape skins and wines, but only gallic and protocatechuic acids were found in the seeds. Conclusions: Tannat wines were shown to have one of the highest levels of phenolic compounds reported for vinifera grape varieties. The profiles for different polyphenol families present in Tannat grapes (skins and seeds) and wines were determined. Significance of the Study: The results presented will help to better understand the phenolic winemaking potential of this variety and its functional properties within food chemistry.