Sulphur dioxide (SO2) is the most widely used and controversial additive in winemaking. It’s used as an antiseptic (to kill off unwanted moulds, bacteria and yeasts) and as an antioxidant (to inhibit oxygen spoiling the wine).
Sulphur derivatives or sulphites occur in 99.9% of all wines in varying amounts, and it’s now law to include a ‘contains sulphites’ advice on all wine labels where there’s over 10 parts per million in the wine. Up to this level and sometimes above, it’s produced naturally by yeasts as a by product of the fermentation process itself.
Sulphur certainly isn’t a bonus for us to ingest in wine, but it can be in most circumstances a ‘necessary evil’ so we can enjoy a relatively clean tasting product. However for an increasing number of people, it can cause allergic reactions, asthma attacks, headaches and a heightened groggy ‘morning after’ feeling.
The good news is that there are positive choices as all certified organic and biodynamic wines contain regulated low average levels of sulphites, compared to many conventional wines. Indeed, new EU laws as of August 2012, now allow ‘ORGANIC WINE’ to appear on the label (formerly it had to be ‘wine from organically grown grapes’) Under the new laws, various dubious winemaking techniques are banned, and maximum levels of sulphur addition for both red and white wine (above and below 2mg residual sugar) are set lower than levels allowed for conventional wine. This is a step in the right direction and helps give a guarantee to you, the consumer.