Non-targeted, suspect and targeted High Resolution Mass Spectrometry (HRMS) approaches for the profiling of oenological matrices and different food commodities

The increasing number of foodomics studies based on non-targeted methods shows that this approach is considered by scientists to be an efficient way of evaluating food safety and quality. In the last few years, high resolution mass spectrometry (HRMS) has indeed gained wider acceptance thanks to the high selectivity and sensitivity achievable during analysis. In contrast to the classic unit-mass-resolution MS/MS approach, HRMS provides more information on sample composition through collection of full-scan spectra and thanks to the possibility of performing retrospective data analysis. Consequently, even without defining compound-specific tuning, HRMS data can be used for identification of suspect compounds or for structural elucidation of unknowns. HRMS can only compete with classic MS/MS methods using the targeted approach, even if it allows the simultaneous detection of a higher number of compounds. In contrast, HRMS is a more promising approach when suspect and non-targeted screening analysis is performed, not only because full-scan and retrospective analysis is feasible, but also because the accurate mass of both precursor and product ions and their isotope patterns are provided. Furthermore, a non-targeted approach leads to specific profiling of biological systems through a wide selection of chemical descriptors, and provides the fingerprint of the system under investigation, useful for more easily identifying potential adulteration. The aim of this work was to extend comprehension of the three different HRMS approaches (nontargeted, suspect and targeted screening), examining both their potential and limitations in relation to the analysis of the compounds of interest in different matrices. Initially, the objectives concerned the possibility of developing new methods – one for each HRMS screening approach – for the analysis of glycosides and phenolic compounds, in order to furnish innovative and well-performing analytical tools for food safety and quality control at all stages of food production, processing and distribution. Furthermore, they regarded the possibility of investigating the nature and occurrence of glycosides and phenolic compounds in widely consumed beverage and food commodities, such as grape, wine, spirits, cocoa and honeys. The thesis, which includes both published and in litteris papers, describes newly developed analytical methods and their technological applications in the study of different matrices, focusing on: - Investigation of Neutral Loss experiments as an instrument for non-targeted screening analysis of glycosides, and performance evaluation of this analytical approach in relation to the glycosidic profiling of international monovarietal wines; - Investigation of the distribution of free and glycosylated low-molecular-weight phenolic compounds in skin and seeds of color-rich Vitis vinifera grapes cultivated in southern Uruguay, combining Neutral loss experiment and suspect screening analysis; - Investigation of the selectivity and sensitivity of the HRMS approach for targeted analysis of free and glycosylated low-molecular-weight phenolic compounds and suspect screening analysis of the latter, together with evaluation of the best sample clean-up procedure for reducing matrix interference; - Investigation of the distribution of free and glycosylated low-molecular-weight phenolic compounds in skin, pulp and seeds, focusing on both Vitis vinifera and hybrid grapes; - Investigation of the impact of alcoholic fermentation on the free and glycosylated phenolic profile of wines produced from grapes of hybrid varieties; - Study of the occurrence of glycosylated low-molecular-weight phenolic compounds in tannins of different botanical origin, in order to evaluate the alteration of the phenolic profile of wines after tannin addition; - Study of the free phenolic composition of wood barrels, in order to evaluate phenolic enrichment during ageing, and investigation of the possible impact of different barrel sanitation treatments on the phenolic transfer from wood to wine; - Study of the free and glycosylated low-molecular-weight phenolic profile in Primitivo di Manduria and Negroamaro wines of different vintages and evaluation of the effect of wine ageing; - Investigation of the possibility of considering free or glycosylated low-molecular-weight phenolic compounds as new markers for beverages and food characterization and their geographical traceability, focusing on wine, spirits, vinegar, food tannins, cocoa beans and honeys; - Implementation of investigative methods of suspect screening analysis using naturally rich matrices as available sources of compounds of interest. This approach was applied on plant products for alkaloid identification; - Investigation of the selectivity and sensitivity of the HRMS approach for suspect screening analysis of flavonoids in flowering plant (C. pareira) extracts.