Oxygen and SO₂ Consumption Rates in White and Rosé Wines: Relationship with and Effects on Wine Chemical Composition

This Article addresses the study of O₂ and SO₂ consumption rates of white and rosé wines, their relationship to the initial chemical composition, and their effects on the chemical changes experienced by wine during oxidation. Eight wines were subjected to five consecutive air-saturation cycles. O₂ was monitored periodically; SO₂, color, and antioxidant indexes were determined after each cycle, and the initial and final compositions of the wines were thoroughly determined. Wines consumed oxygen at progressively decreasing rates. In the last cycles, after a strong decrease, consistent increases of oxygen levels were seen. Oxygen consumption rates were satisfactorily modeled, being proportional to wine copper, quercetin, and kaempherol contents and negatively proportional to cinnamic acids. SO₂ consumption rates were highly diverse between wines and were positively related to free SO₂, Mn, and pH, among others. In the last saturations, SO₂ consumption took place regardless of O₂ consumption, implying that SO₂ should reduce chemical species oxidized in previous saturations. Some volatile phenols seem to be the end point of radical-mediated oxidation of polyphenols taking place preferably in the first saturation.