Revisiting sensory and GC-olfactometric changes occurring in Spanish red wines during oxidation

Abstract

Sixteen different Spanish commercial red wines were subjected to an accelerated oxidation procedure (35 mg/L O₂ plus the stoichiometric amount to oxidise their SO₂, 35 °C, 28 days) and then evaluated against their controls by sensory and GC-olfactometric analysis. Two major patterns of sensory change linked to grape variety emerged. In both, there is an increase in dried fruit and a decrease in “spiced”; one is characterised by an increase in “alcohol-spirit like”, and the other by an increase in “cooked vegetables” and a decrease in “red fruit”. The only wine made with Bobal grapes did not develop oxidation notes. Changes were not associated with panellists’ preference. Wines consuming O₂ fast, developed less oxidation-related notes. A thorough GC-O procedure confirmed that the odorants responsible for the sensory changes were Strecker aldehydes, two acetals (diethyl acetal and 2,4,5-trimethyl-1,3-dioxolane), and sotolon and ruled out any implication of 3-methyl-2,4-nonadione.