“My wine smells funny!” Wine Faults Part II

When good sulphur goes bad

Sulphur – stinky stuff. For anyone who feels physically ill at the smell of over boiled eggs, or who finds it hard to travel through Rotorua without a strategically placed clothes peg, this is instantly recognisable (hydrogen sulphide that is). Fortunately, sulphur does come in other varieties and is actually quite helpful (who’d have thunk it).

­It turns out that sulphur (sulphur dioxide) is a key part of the winemaking process typically used to avoid oxidation (see Part I) and to inhibit bacterial growth. If you want to make wine that lasts for anything longer than a few months then sulphur dioxide is your friend. Problem is, if you add too much then malolactic fermentation stops too early…a very very bad thing if you want a full bodied wine (white or red).

That’s where the fun ends. Other forms of sulphur in wine are not nearly so helpful. Back to our old friend, hydrogen sulphide. A by-product of yeast fermentation with insufficient nitrogen. The result is a whiffy number that you’ll probably recognise quickly but wish you didn’t.

Ever noticed an onion, rubber and/or skunk smell? Sulphur again (mercaptans for the chemists out there). This time it’s the wine spending too much time in contact with lees (dead yeast). This is one reason why “racking” wine is definitely a good idea in the wine making process (racking is siphoning off the wine to a clean barrel as part of the winemaking process).

Finally, and this one brings back some not so pleasant memories, if you grew up before the eighties then chances are you’re more than familiar with the then popular style of cooking affectionately known as “boil the life out of any vegetable and only when the water has more colour than the vegetable do you take them out threaten the kids with spending an eternity in the seventh level of hell (ie. no dessert) unless they eat them all”. Personally, I’d prefer the second level of hell – apparently reserved for the lustful, with Helen of Troy as hostess. Back to the fault – if you’ve ever smelled over cooked cabbage you’ll know there’s not much worse than this. The sulphur this time is dimethyl sulfide or DMS.