Time to take on another hot topic which seems to be the worst nightmare of many maltheads – sulphur.

How Does Sulphur Get Into the Whisky?

Notes of sulphur, often identified by descriptors like “flint, “burning matches”, or “firerackers” can sometimes be found in whiskies that were matured or finished in sherry or other wine casks. But how does it get there?

On first thought you might have the idea that it has somthing to do with the fact that most wines are treated with sulphur dioxide as antioxidant. But the sulphur notes in wine are not nearly as prominent as they can be in whisky, also keeping in mind that only a few litres of wine are left in the cask wood to be further “diluted” with whisky.

No, there is a different reason. Many sherry and wine producers burn a sulphur candle in the cask for sterilization to prevent the growth of bacteria. There can be an awful lot of sulphur in the smoke that settles down on the inner surface of the cask. Whisky filled into such a cask will pick up the sulphur immediately, so that even a short finishing period may result in strong sulphur notes.

Sometimes sulphur infuence can already be present in the newmake. But these notes are usually more on the “meaty” end of the taste spectrum, like in Mortlach. It is said that prolonged contact with the copper of the still during distillation reduceds the amount of sulphur in the spirit because of catalytic reactions. And if you look at some spirit safes in distilleries you will see blue copper sulfate crystals that prove this effect.

How to Cope With Sulphur?

Many whisky lovers are very sensitive to sulphur, some to an extent that they utterly detest malts that show only the slightest trace of it, Jim Murray being a prominent example. But there is also a small minority who can take quite a bit of sulphur and who may even appreciate those special aromas.

I admit that I belong to the latter group of people. Although there have been sulphured drams I wasn’t particularly fond of, I have immensely enjoyed heavily sherried whiskies that many others regarded as sulphur-infested. A prime example is a Duncan Taylor Glenesk 1981/2007 (Cask B933) that I had tasted before I started writing tasting notes. This bottle was particularly popular in Germany, and I have heard on various occasions that for some strange reason German whisky lovers tend to like sulphur more than others, myself being no exception.

A Suprising Parallel

Obviously, sulphur isn’t something that belongs in whisky in the first place. but if you think about it, there is another chemical component that can give whisky a very specific taste: the phenols from peat smoke.

Just like sulphur, peat wasn’t meant to be a flavouring agent for whisky. It was just the fuel used to fire the kilns to dry the malt. It turned out that many people found peated whisky to their liking, so nowadays peated whisky is made on purpose even though there is no necessity to use peat anymore in malting.

And just like sulphur, peat is not everybody’s favourite. There are quite a few whisky lovers who dislike peat, albeit the fraction will be smaller than those who dislike sulphur.

Why Not Mark Sulphured Whisky?

As of today, the occurence of sulphur in whisky is erratic. It may or may not be present, and it may even be different with varying batches of the same expression. Wouldn’t it be a nice idea for distilleries to take a little more care about sulphur?

Collect the sulphured casks to create sulphur spiced expressions for those who dig them, in the same time preventing those casks to end up tainting batches of standard expressions. This way you could serve both the sulphur lovers and the sulphur haters.

Photo by Matt Biddulph via Flickr