South African wine exports bring in more than $650m per year from a little less than half of total local production of around 450 million litres per year.
An important and often maligned constituent of this wine is sulphur dioxide (SO2), which exists in very small quantities in all wines, even those labelled ‘no sulphur added’, which typically contain up to 10 mg/ℓ or 10 ppm (parts per million).
It was first used in winemaking by the Romans, who discovered burning sulphur candles inside empty wine vessels kept the wine free of the ‘vinegar smell’ for much longer.
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