Copigmentazione e anti-copigmentazione: Interazione tra le molecule fenoliche della bacca

The phenomenon of copigmentation is due to molecular association between pigments and other organic molecules in solution, resulting in a hyperchromic shift and, with certain cofactors, in a bathochromic shift, providing a blue-purple tone in a otherwise red solution. Many studies demonstrated the possibility of tannins to interact with Malvidin providing a copigmentation effect. Anyway grape seeds seem to be not important for copigmentation in wine conditions. In this research work we tried to understand why some demonstrated cofactors (with particular attention to seed phenolics) are not able to make copigmentation in grape and wine conditions. Three different cultivars(Shiraz, Pinot noir and Sangiovese) cultivated in Australia were compared. Results obtained by spectrophotometric analysis were compared with data provided by HPLC, with different elution methods and UV-VIS, PDA, LC-MS, ELSD detectors, together with some Post Column Reaction experiments. In this work we suggest the existence of a copigmentation equilibrium in a complex solution that can provoke an anti-copigmentation effect. The importance of flavonols in copigmentation interactions were underlined.