Sulphur, still shapes, worm tubs and the chemistry behind one of whisky’s most misunderstood ingredients.
Walk into almost any malt whisky distillery and you’ll see those magnificent copper pot stills, often polished to perfection. They’re beautiful, traditional and essential to the character of the whisky. But not necessarily for the reasons you hear during a distillery tour.
Copper isn’t just a convenient material for making stills. It actively influences the chemistry of distillation, particularly the sulphur compounds responsible for aromas ranging from rotten eggs and cabbage to meaty and savoury notes. Without sufficient copper contact, whisky can taste very different.
But if copper removes undesirable sulphur compounds, why don’t distilleries simply maximise copper contact? Why do some deliberately produce heavier, more sulphury spirits? And why can copper sometimes contribute to the formation of sulphur compounds rather than removing them?
Welcome to the copper paradox.
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