1D and 2D NMR application on balsamic and traditional balsamic vinegar of Modena

In recent years it has greatly increased the interest in analytical techniques able to certify the origin and authenticity of food along the production and distribution chains starting from raw materials to commercial products. The main difficulty in the foodstuff characterization is related to the complexity of the sample, which is often a complex mixture of several compounds present in concentration ratios very different from each other. The full characterization requires supplementary information from different techniques, therefore, non-separative analytical methods, that allow to obtain molecular fingerprints of complex mixtures can be particularly useful for the characterization and quality control and foodstuff authenticity and traceability. In this regard, in recent years has greatly increased the interest in the Nuclear Magnetic Resonance (NMR) and its use as a routine method for the analysis of complex mixtures as foods, balsamic vinegar among them, thanks to the availability of instruments at high magnetic fields and the consequent improvement of analytical sensitivity (Caligiani et al., 2007; Consonni et al., 2008). The aim of the present work was to select and optimize several 1D and 2D NMR sequences (1H-NMR, 1H-1H COSY, 1H-13C HMBC) to characterize the Balsamic vinegar of Modena and the Traditional Balsamic vinegar of Modena. 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. To reduce the inhomogeneous proton NMR chemical shift of signals along the spectra, due to small pH changes and intermolecular interactions, all spectra were aligned using the toolbox Icoshift 1.0 for Matlab (Mathworks Inc., Natick, MA) (Savorani et al., 2010). Besides, to achieve a reliable classification of the different samples, unsupervised and supervised pattern recognition procedures were applied to the NMR data obtained.