USe of HR-NMR for functional properties estimation of balsamic vinegar of Modena

Over the past few years, many works based on proton NMR coupled with multivariate data analysis were been conducted concerning the study of the suitability of HR-NMR as fingerprint analysis tool in the study of vinegars. Classical studies on vinegars are normally based on composition data obtained by various analytical techniques, however, since the quality and characteristics of a product are not the simple sum of individual chemical characteristics, NMR analysis with chemometrics certainly is a useful tool in this regard. In this context, the aim of the present work was to select and optimize a NMR sequences to characterize the Balsamic vinegar of Modena and the Traditional Balsamic vinegar of Modena and to study the possibility to obtain by NMR spectra useful informations about the biologically active compounds and the functional properties. The application of HR-NMR techniques to the samples has generated very complicated spectra that needed to be previously processed and subsequently analyzed by chemometric methods. The NMR spectra will be correlated with some analytical parameters such as total polyphenols, total condensed tannins, total flavonoid and total antioxidant activity determined by several methods (ABTS, DPPH, photochemiluminescence). The different methods selected for the determination of the antioxidant activity allow the assessment of different aspects of the oxidation process: the DPPH and ABTS assays are based on both HAT (hydrogen-atom abstraction) and SET (electron transfer reaction) mechanisms; the photochemiluminescence (PCL) method is based on the photo induced autoxidation inhibition of luminol by antioxidants mediated from the radical superoxide. In this way, the measured antioxidant activity can be compared to antioxidant activity of the balsamic vinegar in biological systems