Novel aspects of grape berry ripening and post-harvest withering revealed by untargeted LC-ESI-MS metabolomics analysis

We established a step-by-step, experimentguidedmetabolomics procedure, based on LC-ESI-MSanalysis, to generate a detailed picture of the changingmetabolic profiles during late berry development in theimportant Italian grapevine cultivar Corvina. We sampledberries from four developmental time points and three postharvesttime points during the withering process, and usedchromatograms of methanolic extracts to test the performanceof the MetAlign and MZmine data mining programs.MZmine achieved a better resolution and thereforegenerated a more useful data matrix. Then both the quantitativeperformance of the analytical platform and thematrix effect were assessed, and the final dataset wasinvestigated by multivariate data analysis. Our analysisconfirmed the results of previous studies but also revealedsome novel findings, including the prevalence of two specificflavonoids in unripe berries and important differencesbetween the developmental profiles of flavones and flavanones,suggesting that specific individual metabolites couldhave different functions, and that flavones and flavanonesprobably play quite distinct biological roles. Moreover, thehypothesis-free multivariate analysis of subsets of the widedata matrix evidentiated the relationships between thevarious classes of metabolites, such as those betweenanthocyanins and hydroxycinnamic acids and betweenflavan-3-ols and anthocyanins.