Sviluppo di un metodo rilassometrico per la valutazione delle proprietà antiossidanti nei vini

A new relaxometric method for for the determination of the antioxidant capacity in wines has been developed in this work. In the last decades wine has receiving increasing interest for its polyphenols content that it is supposed to prevent oxidative stress ROS-mediated. Infact epidemiological studies have suggested the existence of an association between the consumption of polyphenol-rich food or beverages and the prevention of diseas, such as coronary heart diseas, Alzhaimer and cancer. The method was applied to 12, high-quality, Italian red and white wines from different vintages (2009/2011), using AAPH as a radical initiator. They were tested also with an ORAC-type method, using carboxy-fluorescein and the same radical initiator. To evaluate the antioxidants properties of a liquid sample, the relaxometric probe has to be sensitive to changes of solvent proton longitudinal relaxation rates (R1obs) when radical species are present. Furthermore it has also to detect in which way the wine, itself vulnerable to a radical attack, could prevent the oxidation and influence the relaxation rate of water protons. This strategy can be successfully pursued by using nanosized supramolecular system, such as liposomes encapsulating Gd-HPDO3A, a clinically approved paramagnetic complex of Gd(III) Three basic liposomal formulation based on DPPC (dipalmitoyl-phosphatidylcoline), POPC (palmitoyl-oleoyl-phosphatidylcoline) and DPPC/DLPC (dilynoleoyl-phosphatidylcoline) phospholipids were selected and investigated for our purpose. The relaxometric method we set up allowed us to conclude that red wines contain much more antioxidant compounds than white wines, even if their properties are influenced by the winemaking processes they went through.