Aim: 

The aim of work was to determine the Total Antioxidant Capacity (TAC) and Total Phenolic Content (TP) of two Sicilian red grapes varieties, Nero d'Avola and Petit Verdot, during ripening for two consecutive vintages.

Methods: 

Grapes, growing in neighbouring vineyards and subjected to the same agricultural practices, were picked during ripening at intervals of 7–10 days. After pressing, 19 grape must samples were analysed by the crocin bleaching and Folin-Ciocalteau assays to determine TAC and TP values, respectively. Results were expressed as means and standard deviation of three tests.

Results: 

In both vintages, statistically significant differences in TP values were found between the two varieties (p<0.01), Nero d'Avola grape musts showing higher values. Moreover, during 2008 and 2009 ripening, TP values increased, respectively, of 23.1% and 7.3% for Nero d'Avola, and 30.9% and 55.7% for Petit Verdot. All TP variations proved to be associated with climatic conditions. Significant positive correlations between TP and TAC were detected during the 2009 vintage only: indeed, Nero d'Avola grapes reached their TP and TAC peak values after 13 days from the beginning of ripening, while Petit Verdot grapes after 26 days.

Conclusion: 

Determination ofTP during grape ripening is critical to assess the best period of grape harvest. However, higher TP values do not always overlap with higher TAC values, which are indeed strictly related to nutraceutical properties.