Sulphites. Sulphur Dioxide. SO2. Preservative 220. All of these terms refer to the same thing - the chemical compound made up of one sulphur molecule and two oxygen molecules. And it's been used as a preservative in wine since the ancient Romans discovered that burning a sulphur candle inside the empty barrels before filling them, resulted in better, longer-lasting wines.
So what's the fuss surrounding preservative-free wines all about?
In its simplest sense, the term 'Preservative Free,' when used in wine parlance, means that no sulphur dioxide has been added to the wine at any stage during its production. In today's increasing world of natural wines, many vignerons prefer to keep the wines as "pure" as possible, by not adding anything to the naturally fermenting grape must. It's important to note, however, that ALL wines will have some naturally occurring sulphites within them, because SO2 is a by-product of the fermentation process.
Why do winemakers use sulphites? Sulphur dioxide inhibits microbial activity in wine, and protects it from exposure to oxygen, particularly during the bottling process, when the wine can be at risk. But there are certain styles of wine that are naturally more stable, deliberately oxidised, or free from harmful bacteria that don't need any sort of protection from sulphites. These wines are labelled as preservative-free.
Confusingly, you might come across wines that say "minimal sulphites added", or "contains natural sulphites." This is to do with Australia's strict labelling laws surrounding potential allergens. "Minimal sulphites added," usually means that the winemaker has only added tiny amounts of sulphur dioxide (mostly less than 15 parts per million), to just give their wines a touch of protection. The phrase "contains natural sulphites," means that no sulphur has been added, and the only sulphites are naturally occurring. You can also find wines that have no added sulphites, that will still state "contains sulphites" on the label. It's a real mine field! If you're ever in doubt, though, just look for the "preservative free" labels and you can't go wrong!