Maria Navarro and Eglantine Chauffour*
*Enartis USA, 7795 Bell Road, Windsor, CA 95492
(eglantine.chauffour@enartisvinquiry.com)

The forces at work in wine oxidation and their effects on wine quality have long fascinated researchers. In non-enzymatic oxidation, oxygen does not react directly with phenolic compounds, but through a reaction catalyzed by transition metals (Cu+ and Fe+) that convert oxygen into a highly reactive radical, capable of oxidizing organic compounds. Oxidation of phenolic compounds in white wines causes premature aging, browning, and pinking, leading to wine deterioration and loss of quality. Adopting strategies that block these systems is an effective way to improve wine aging potential and shelf life. These strategies include removing metals (catalyzers of oxidation), reducing the concentrations of phenolic compounds in wines (precursors to oxidation), and controlling the redox potential (decreasing the risk of oxidation). Enological products containing PVI-PVP were evaluated during winemaking for their effect on wine oxidative potential. PVI-PVP is an adsorbent polymer (copolymers of vinylimidazole and vinylpyrrolidone) that is capable of removing from wine heavy metals such as copper (Cu), iron (Fe), and aluminum (Al). PVI-PVP can also bind to phenolic compounds that could otherwise enter into oxidative reactions. This double bonding ability makes this polymer useful in blocking the oxidative system. This study showed that PVI-PVP was effective at removing metals, although more copper was removed than iron. The efficiency of metal elimination directly correlated with dosage rate and contact time. Additional testing using an accelerated-aging protocol showed that wines treated with PVI-PVP had a lower oxidation potential and developed less brown hues.

Funding Support: ESSECO group