Sulfur (American English) or Sulphur (British English) is a commonly used preservative. Most frequently, it is added to wines, but it is also present in many whiskies. It is rare to see it in such high amounts as to be bothersome, but occasionally it can be present in quantities high enough to be distasteful.
Sulfur has an ash-like, rubbery, slightly bitter, chemical taste that is commonly viewed as unpleasant. In large quantities, as has been known to happen with certain batches , it can ruin the whisky. Some people, however, don’t mind a bit of sulfur in their whiskies. Like peat, it is an extra element that creates a more complex taste. Unlike peat, there is such a thing as too much (many non peat-heads will argue with me here, ha).
Some people have a sensitivity to sulfur that causes them to feel ill. Full-blown sulfur allergies also exist, but they are quite rare. It’s likely that you’d know by now if you had a sulfur allergy as it is present in many foods.
Additionally, some folk are better than others at smelling sulfur. This means that a light hint of sulfur might add depth to a nose for one person, but dominate and ruin a nose for another person. This may or may not relate to how ‘sensitive’ a person is to drinking sulfur as described in the above paragraph.
Some Whiskies That Are Occasionally Described As Having A Sulfur Flavor
- Macallan 12
- Glenfarclas 10
- Mortlach 15
Sulfur In The Distillation Process
Sulfur as an element is created during the fermentation process. During distillation, it is removed by varying amounts via the process of oxidization. Sulfur created at this time is often viewed as more tolerable and described as a ‘meaty’ flavor and rarely viewed as unpleasant except by people who have difficulty tolerating it in any form.
Sulfur In Whisky Barrels
The sulfur notes present in whisky are due to the whisky maturing in a cask that has been sterilized with a sulfur agent. The story goes that up until around the late 80s, old sherry casks being shipped over to Scotland would have a sulfur candle burned inside of them to eliminate and prevent bacteria from growing. This added a sulfur ‘flavor’ to the cask that affected the liquid placed in it.
I’m no industry insider, but I find it difficult to believe that casks are still sterilized in this fashion. Interestingly, sulfur is basically only present in sherried whiskies. It is possible that there may be some chemical reaction present with old sherried casks when they are exposed to air or cleaned that causes a sulfur flavor to be added to the liquid that is consequently placed in the cask. Whether or not this flavor is actually the element sulfur or is a complex chemical reaction to create the taste of sulfur that we associate with rotting eggs is hard to say.
If it is a complex chemical reaction that creates the flavor of sulfur rather than the element sulfur, it is unique to sherry casks. Perhaps the wine reacts with the whisky and the wood in a certain way that other types of barrels (such as bourbon) do not.
If sherried casks are still sterilized with a sulfur agent, then that would make obvious sense, but what is it about sherried casks that makes them benefit from being cleaned with a sulfur agent? Why aren’t bourbon casks sterilized in the same fashion? If it is the nature of sherry casks being more prone to infection then that would make sense.
I fully realize that I have raised more questions than I have answered in this sub-section, but working through it logically, I can’t seem to find the justification for the rampant fear-mongering that Jim Murray puts forth in his Whisky Bible. The problem seems to be that there is a great deal of speculation (like I have just done) with people coming to conclusions based upon heresay and rumor.
Personally, I don’t mind a bit of sulfur, but I sometimes swear I taste it when it’s not there and sometimes can’t taste it at all when someone else says they can. In the end, it’s each to their own.