Analysis and chemistry of migrants from wine fining polymers

Fining of wine is prerequisite for the long-term stability of wine. Methods used are based not only on natural products, for example, proteins, but also on synthetic polymers such as polyvinylpolypyrrolidone (PVPP). Recently, new materials have been developed to overcome the disadvantageous use of traditional bluefining. These include polyvinylimidazole-polyvinylpyrrolidone copolymers (PVI/PVP) to combine the benefits of PVPP with selective binding of metals such as copper or iron. This work developed a HPLC-MS(2) method to monitor the potential migration of monomers and respective degradation products N-vinylimidazole, N-vinyl-2-pyrrolidone, imidazole, and 2-pyrrolidone in wine. Use of 0.5 g/L PVPP led to <83 microg/L 2-pyrrolidone in a wine model solution within 30 min, whereas PVI/PVP resulted in nondetectable quantities of 2-pyrrolidone and 18 microg/L imidazole. Unexpectedly, the analysis of 140 wines revealed 2-pyrrolidone as a natural constituent. Independent model incubations verified 4-aminobutyramide and 4-aminobutyric acid as the immediate precursors.