TY - JOUR T1 - Reaction of Oxygen and Sulfite in Wine JF - American Journal of Enology and Viticulture JO - Am. J. Enol. Vitic. DO - 10.5344/ajev.2015.15069 SP - ajev.2015.15069 AU - John C. Danilewicz Y1 - 2015/11/03 UR - http://www.ajevonline.org/content/early/2015/10/29/ajev.2015.15069.abstract N2 - When model wines containing polyphenols are oxidized, hydrogen peroxide and quinones are produced. Sulfur dioxide reacts with the hydrogen peroxide, preventing ethanol oxidation by way of the Fenton reaction and in the case of (+)-catechin sulfite reduces the quinone near quantitatively back to the catechol. Consequently, the O2:SO2 molar reaction ratio is close to 1: 2 in ideal experimental conditions. Eight wines were studied to see if this ratio might be similar in practice, so as to assess how effective SO2 might be as an antioxidant in real wine. The reaction ratio was found to be reduced down to 1:1.7 in most wines and so to see why this ratio was reduced, a white wine was treated with a large amount of benzesulfinic acid. This substance is known to react very efficiently with quinones, and so would prevent their interaction with sulfite. The molar reaction ratio was then reduced to 1:1, as previously found in model wine. This result is taken to indicate that sulfite is fully effective in removing hydrogen peroxide and that the reduction in the molar reaction ratio from the theoretical 1:2 ratio is due to limited interaction with polyphenol oxidation products. Two white wines, which were found to be rapidly oxidized with much reduced O2:SO2 molar reaction ratios, were found to contain ascorbic acid. The effect of adding ascorbic acid to a white wine on the reaction of oxygen was also examined. ER -