Oxidation of Wine: Central Role of Iron for Polyphenol Oxidation

We were able to find a quick and simple method to discriminate between the two species of iron in wine, using only a spectrometer and very simple reagents, so the method is accessible in winemaking. We applied the method to measure iron in about 10 wines, and evaluated how the iron species in those wines changed in response to oxygen exposure. The observed responses suggested that the level of iron species in response to oxygen exposure could be used to evaluate a wine’s capacity or reactivity to oxidation. Separately, we also showed the products of reacting caffeic acid quinone with a number of flavonoids, including catechin. The observations help explain the basis of browning in white wines. And looking at quinone reacting with wines, we were able to find specific oxidation products.