Explainer: what is Preservative 220, & what’s the use of sulphur dioxide in drinks?

Mining sulphur dioxide.

What is is that preservatives do? Put simply, they prevent food and drink from turning bad. For millennia, humans have been involved in the effort to preserve whatever food and drink they can get. Being able to store food and drink is basically what gives us civilisation. If we all had to find and eat our food à la minute, when would we have time to invent the iPhone?


When it comes to preservatives used in drinks, the one that gets the attention — and the controversy — is preservative 220, otherwise known as sulphur dioxide, along with its sulphite cousins preservatives 221 to 228.

Sulphur dioxide and other sulphites are naturally occurring minerals — they are, for instance,  found in wine as a result of the fermentation process — and they have long been used to reserve food and drink.



The use of sulphur dioxide dates all the way back to Roman times, where they would use sulphur dioxide to help preserve wine. Sulphur dioxide is a gas that is formed when the element, sulphur, is burned, and humans have been burning sulphur for a long, long time. The Greeks and Romans would burn sulphur in order to fumigate houses, and in Homer’s The Odyssey, which was first told some 2,800 years ago or so, Odysseus — the bloke who put the Greeks inside the wooden horse to the surprise of the city of Troy — calls for sulphur to fumigate a room after he and his mates have had a particularly bloodthirsty evening:


As for Melanthius, they took him through the cloister into the inner court. There they cut off his nose and his ears; they drew out his vitals and gave them to the dogs raw, and then in their fury they cut off his hands and his feet. 

When they had done this they washed their hands and feet and went back into the house, for all was now over; and Ulysses said to the dear old nurse Euryclea, “Bring me sulphur, which cleanses all pollution, and fetch fire also that I may burn it, and purify the cloisters.

Oh, and somewhere along the way sulphur became associated with the stink of the devil. You know all that fire and brimstone stuff in the Bible? Well, brimstone is the old world for sulphur, and the Bible suggests that it is sulphur which fuels Satan’s lake of fire. 


Food Standards Australia New Zealand says that for most pf the population, consuming sulphites is perfectly safe. They do make exceptions, however, writing that “some sulphite-sensitive people, many of whom also have asthma, may react to sulphites with allergy-like symptoms.” 

The addition of sulphur dioxide and other sulphites must be labelled appropriately in Australia, when there is 10mg per kilogram or more of sulphites in the product. 

Wine, beer, RTDs — they will for the most part be over this threshold.


As we said earlier, sulphur dioxide and sulphites are naturally occurring compounds that form through the fermentation process in both wine and beer; whilst most of the sulphur dioxide in wine comes from the use of additives, a not insignificant proportion occurs naturally.

The maximum permitted limit of sulphur dioxide — as set out by Food Standards Australia New Zealand — is 400mg/kg for wines containing greater than 35 g/L residual sugars, and 250mg/kg for wines containing less than 35 g/L residual sugars.

For beer, the standard prescribes the maximum concentration of sulphur dioxide to be 25mg/kg. The difference is you’ve got to drink a greater volume of beer to achieve the equivalent alcohol intake of wine (there’s 10 standard drinks in every litre of red wine at 13% ABV, and 2.66 for standard beer).


Yeah look, the rules on preservative free wine vary depending on where you are, and the same goes for organic wine, too.

In Australia, the use of added sulphur dioxide in organic wines is more acceptable than other jurisdictions. The Australian Certified Organic standard for wine limits sulphur dioxide to 100 mg/L for red wines with a residual sugar level lower than 2 g/L, and 150 mg/L for white and rosé wines and with a residual sugar level lower than 2 g/L.

For the USDA Organic label to be applied, any additional sulphites are not permitted; instead, only naturally occurring sulphites, up to 10 parts per million, are allowed. If the label states that the wine is made with organic grapes, however, you can add up to 100 ppm (or put another way, 100 mg/L) of sulphur dioxide provided that the term ‘added sulphites’ is disclosed on the label.


Whisky writer Jim Murray is a lightning rod for controversy, no doubt in part because of his own strong opinions. And he has been a vociferous critic of what he sees as a major fault made by some distilleries: too much sulphur dioxide character ruining his drams.

But first, though, let’s establish some facts.

As mentioned before, sulphur dioxide can form as a result of the fermentation process for beer. Since whisky making is at its simplest the act of distilling beer, it follows there’s going to be some sulphur dioxide happening.

All well so far. It’s here where things get interesting, and it comes down to the role of copper. Copper is used to fashion the pot stills that make malt whisky, and it is copper that is believed to have a big role in reducing the level of sulphurs — and the associated aromas of rotten eggs and vegetables — in the final product of the whisky. However, you don’t necessarily want to completely remove all of the sulphur character, as some presence of it in low levels is much appreciated.

Now, back to Jim Murray. In 2012 he wrote about the rampant problem of sulphur taint in whisky, and he certainly kicked up a stink. “We are facing crisis time,” he wrote. “This is no longer an occasional problem, it’s rampant.”

Murray believes the cause of this ‘rampant’ whisky taint is the use of former sherry barrels that have been treated with sulphur dioxide. Some sherry producers will burn a sulphur candle — creating sulphur dioxide — inside the spent barrels to prevent microbial spoilage before the journey. That smoke gets into the wood, the thinking goes, and then into the whisky as it sits there ageing.

The implication here, though, is that sulphur compounds are unwanted. Which may or may not be the case — clearly Jim Murray ain’t a fan.

But some distilleries encourage that sulphurous character. Craigellachie, for instance, has a faint smokiness to it despite the fact that the barley they use isn’t peated at all — that smoke is coming from sulphur dioxide, and it’s not coming from the cask per se, but from the distillation process. Craigellachie is one of a few distilleries — Mortlach being another — that use worm tub condensers as opposed to shell and tube copper condensers; the chief difference being that there is less contact between spirit and copper using a worm tub condenser, which means there are fewer sulphur dioxide compounds removed, which means more of that sulphurous character in the final spirit — you get a richer texture on the palate and some of that smoky, meaty character along with it.