Study of grape metabolomics by suspect screening analysis.

Suspect screening analysis is a targeted metabolomics approach in which identification of compounds relies on specific information on their molecular formulae. This method was applied to the study of grape metabolomics by using UPLC coupled with high-resolution Q-TOF mass spectrometry. For identification of compounds, a new database was expressly constructed by using the information of potential metabolites of grape and wine available in the literature and other electronic databases. Currently, Grape Metabolomics contains about a thousand putative grape compounds. If untargeted data processing of a sample provides identification of a new compound with a sufficiently confident score, it is added to the database. Thus, by increasing the number of samples studied, Grape Metabolomics can be expanded. This method is effective for identification of the molecular formulae of several hundred metabolites in two runs (positive and negative ionization) with minimal sample preparation. It is effective also for study of single classes of compounds involved in cell and tissue metabolism. E.g., by this approach a total of 18 stilbene derivatives and 15 monoterpene glycosides (aroma precursors) were identified in different grape samples. This approach can also potentially be applied to the metabolomics of other plant cultivars.