Sulfur Dioxide – Ian Hickinbotham

By Ian Hickinbotham
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Ian Hickinbotham, author of Australian Plonky

Ian Hickinbotham, author of Australian Plonky

Australian Plonky by Ian Hickinbotham
A cellar full of old wine


Sulfur dioxide has been added to wine for some 2,000 years. The assertion is based on the simple fact that Russian researchers found elemental sulphur, which is mined straight from the ground in some places, near amphora type fermenting vessels around Mesopotamia – where winegrowing began.

As any resident of the riverland (where apricots are dried after being impregnated with sulfur dioxide) knows, sulfur dioxide is simply produced when ordinary sulfur is burned. Thus (even with no school chemistry) readers can grasp:

S + O2 = SO2

The ‘S’ being sulfur, the ‘O2’ being oxygen (supplied by normal air) and SO2 is sulfur dioxide.

Sulfur dioxide ensures better retention of a wine’s colour and helps to protect it from unwanted bacterial attack. The reason it can be claimed that the sulfur was burned by the ancients and that the gas generated was the actual additive, is just based on logic. If ordinary elemental sulfur is added to wine, development of repulsive rotten egg smell is a consequence. And surely it is reasonable to assume our ancestors were repulsed by that revolting smell: in fact they would have been more accustomed to it given they had no refrigeration, dehydration or freezing techniques with which to preserve any food.

During our times, sulfur did gain entry to wines in cellars. It has been an old practice to burn sulfur inside empty casks before filling them with wine and they were thereby filled with sulfur dioxide gas – while neatly consuming some of the available oxygen from the air normally present in the container in order to burn. Unfortunately, we used to just suspend the sulfur (which was supplied in measured rings with a hole through their centre – like a donut) on a wire dangled down through the top 'bung-hole' of the cask. The simple arrangement filled the cask with sulfur dioxide gas that was 'collected' by the subsequent wine filled into the vessel. Unfortunately, molten elemental sulfur used to drip from the rings and fall to the floor, where it eventually caused rotten egg smell.

This hypothesis about the initial use of sulfur dioxide is not inconsistent with other historical aspects of wine. Thus, we still like the old grape varieties for the making of our wine: pinot noir has been documented since 600 AD (which fact serves to underline the extraordinary snippet that Australians have only had the variety during our lifetimes).

Change in my lifetime has been immense: thus in figures alone, where 400 parts per million was a sulfur dioxide addition rate from a cylinder of the gas in my apprenticeship days, modern oenologists would use about an eighth of that. It is still used at a higher rate in white than red wines, especially those that have some of the original grape sugar retained – which are the most popular ones.

If winegrowers did not add some sulfur dioxide, wines would look like 'sweet sherries' and taste something like them. That is a generality, as there is a push to sell wines that do not contain sulfur dioxide, but so far they are intended for early consumption soon after vintage. Being practical, winegrowers cannot risk enthusiasts keeping such wines as they will deteriorate in quality quickly and the winegrower will inevitably be blamed.

Importantly, you do not have to understand the pH measurement to grasp that to achieve the same benefit, wines of around 3 pH that are relatively tart, like riesling, need about a quarter as much sulfur dioxide as those of high pH like 4 – the type unfortunately often acclaimed by Robert Parker Jr, the world’s most influential wine critic.



Ian Hickinbotham, one of the most innovative and influential oenologists in Australia over his 50 year career, is the author of Australian Plonky (see related review below).


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March 10th, 2011
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