Sulfur dioxide and glutathione promote acetaldehyde accumulation under aerobic conditions in a model wine system: Impacts on hydroxyl radical formation.

The addition of antioxidants is essential in red wine aging, as it influences chemical oxidation processes. This study investigated the effects of free sulfur dioxide (SO2) and glutathione (GSH), both individually and combined, on oxidative changes in a model wine system. Dissolved oxygen (DO), acetaldehyde, hydroxyl radicals (HO·), ferrous ions (Fe2+), SO2, and GSH concentrations were monitored. Results showed that 30 mg/L SO2 treatments effectively inhibited the Fenton reaction and accumulation of HO· and acetaldehyde, while higher SO2 treatments (≥60 mg/L SO2) promoted the production of acetaldehyde. All the GSH treatments increased the accumulation of acetaldehyde and HO· (fluorescence intensity = 686). Addition of SO2: GSH treatment 30:20 and 30:80 further promoted HO· accumulation (fluorescence intensity = 2785). This study demonstrates the roles of SO2 in radical scavenging and autoxidation, and acetaldehyde accumulation during wine oxidation can be effectively controlled and regulated by adjusting the GSH-to-SO2 ratio.