Labo VinSO2
SO2 (sulphur dioxide) is a biting gas, denser than air and very water soluble. It is essential in winemaking. Giving it up significantly increases the risk of wine illness, appearance of disagreeable, and even toxic substances.
In excessive concentration (some commercial wines contain more than 400 mg/L); it modifies the wine savour and produces a dilation of the brain vessels (headaches, hangover).
In reasonable concentration, it has useful properties; up to now no means to replace it has been found.
- It is a disinfectant: bacteria and wild yeasts are very sensitive to it, while cultivated yeasts strains bear relatively high concentrations.
- It combines with several fragile compounds (aldehydes) whose breaking down is so restricted.
- It favours glycerol formation during fermentation.
- It facilitates the clarification ending the activity of residual yeasts.
- It is an antioxidant that preserves the wine from being altered by oxygen.
- It reduces the formation of acetic acid.
The SO2 supplied before fermentation is greatly eliminated by the CO2, flow; that is why some more SO2 must be added after fermentation (except for sprinkling wines). The SO2 content decreases after each racking.