**1. Introduction**

Wine is an interesting chemical reaction system, in part due to its tartaric acid content. The oxidation of wine is known to be autoxidative [1], stimulated by Fe and Cu ions [2], and is thought to involve Fenton chemistry [3], but neither the rate nor the extent of oxygen consumption can be predicted from a knowledge of pH, metal, phenolic or organic component concentrations. Autoxidation is a spontaneous reaction in air and a radical chain reaction sequence [4, 5].

What is known is that the rate of oxygen consumption in wine is relatively slow in the natural pH range between 3.0 and 4.0. The underlying tartaric oxidation with Fe(II) and oxygen can describe the autocatalytic radical chain reaction sequence, with a distinct initiation stage, a faster, accelerating oxygen consumption propagation stage and a termination stage due to the complete consumption of oxygen and/or Fe(II). It appears that during the propagation stage, ferryl ion, hydroxyl radicals, and/or potentially tartaric acid radicals that are the origins of generating hydroxyethyl

radicals when ethanol is present. These hydroxyethyl radicals would lead to an array of selective downstream reactions leading to the collective aged composition of wine. The commonly accepted formation of acetaldehyde would only be one possible fate of this selective radical.
