Characterization of some Italian V. vinifera L. grape varieties on the basis of their flavonol profile

“Suspect screening metabolomics” is a mid-way approach between ‘targeted’ and ‘untargeted’ analysis. For this aim, a new database of putative grape and wine metabolites (GrapeMetabolomics) was expressly constructed. Currently, this database contains around 1,100 compounds. By performing UHPLC/QTOF high-resolution mass spectrometry analysis of grape extract in both positive and negative ionization mode, averaging 320-450 putative compounds are identified, depending on the variety. Most of the compounds identified are important grape metabolites: e.g., around 80 polyphenols were identified in Raboso Piave grape extract with an identification score 95-99%, including flavonols, anthocyanins, and stilbene derivatives. The profound knowledge of the grape chemistry provided by the method can be effectively applied for the study of grapevine diseases, effects of cultural practices and for monitoring of climate change effects. In the present study, suspect screening metabolomics was focalized on the characterization of flavonols of several important Italian grape varieties. The method was effective for the flavonol profiling of grape by providing the identification of around fifteen compounds. By performing statistical analysis (Principal Component Analysis and Cluster Analysis), the effect of the variety on the flavonol composition of grape was studied.