PHENOLIC CHARACTERIZATION OF THIRTEEN RED GRAPE CULTIVARS FROM GALICIA BY ANTHOCYANIN PROFILE AND FLAVANOL COMPOSITION

Aims: Phenolic compounds, extractable from grape skins and seeds, have a notable influence on the quality of red wines. Therefore, in this work the phenolic composition of 13 red grape cultivars, grown in one of the most traditional Spanish vine zones, was studied in order to identify significant varietal differences. Methods and results: Anthocyanin concentration and profile, total proanthocyanidin and flavanol contents in berry skins and seeds were determined by spectrophotometric and HPLC methods. The highest concentrations of total anthocyanins was found in the Loureira Tinta, Sousón and Ferrol varieties, while Ferrol was rich in proanthocyanidins in berry skin and Caíño Bravo was rich in proanthocyanidins and flavanols in berry seeds. Malvidin-3-monoglucoside was usually the major anthocyanin. Nevertheless, the anthocyanin profile was characterized mainly of di-substituted molecules for Albarello, Brancellao and Caíño da Terra grapes. Ferrol, Loureira Tinta and Sousón grapes showed the highest values of primitive anthocyanins (delphinidin and petunidin derivatives). Conclusion: Many differences in the phenolic composition of the cultivars studied were found. The results of the phenolic characterization can be utilized in winery in order to apply the most appropriate maceration and winemaking techniques to the processed grapes. Significance and impact of study: Knowledge of the biodiversity of the grape varieties of Galicia (North-West Spain) is still scarce. This study, on phenolic composition, provides oenological information that can be useful to improve the quality of the wines produced.