Wine fault
Reduction
Rotten-egg, struck-match or drain-like aromas from a wine deprived of oxygen. Often blows off with air; sometimes it does not.
What you notice
Smell
- Smells of rotten eggs or drains
- Smells of struck matches, flint or gunpowder
- Smells of boiled cabbage, onion or garlic
- Smells of burnt rubber — also seen in Burnt rubber character
What it is
Reduction is the opposite of oxidation: too little oxygen rather than too much. The compounds involved are detectable at extremely low concentrations.
It is context-dependent. A mild struck-match note is fashionable in modern Chardonnay and is sought deliberately by some producers. Rotten eggs and drains are not fashionable anywhere.
The practical distinction that matters at home is whether it blows off. Hydrogen sulfide is volatile and frequently disperses with air; heavier mercaptans often do not.
It is more common under screwcap for a straightforward physical reason — less oxygen ingress — which is why closure choice is a genuine winemaking trade-off rather than a simple upgrade.
What causes it
- Yeast under nutritional stress during fermentation producing hydrogen sulfide.
- Extended lees contact without racking or aeration.
- Screwcap closures with a very low oxygen transmission rate, which give the wine no chance to resolve it in bottle.
- Deliberate low-oxygen handling, which some producers use to preserve freshness and which can tip into reduction.
Can I fix it?
Yes — air often fixes it
Often, yes — this is one of the few faults that genuinely responds to treatment.
What you can do
- Decant vigorously, or pour the wine back and forth between two jugs. This resolves mild reduction surprisingly often.
- Give it twenty minutes and re-taste before concluding anything.
- The widely repeated copper-coin trick works chemically — copper binds sulfides — but a modern coin may not be copper enough to do much, and it is not a hygienic approach.
- If it persists after aggressive aeration, the wine is faulty.
What does not work
Published because a reader holding a spoiled bottle has usually already been told to try one of these. Correcting the specific wrong advice is more use than stating the right answer beside it in silence.
- Opening the bottle an hour early
- Almost nothing. The wine’s surface area at the neck is about the size of a coin. If you want air, pour it into something wide.
- A modern copper coin
- The chemistry is real — copper binds hydrogen sulfide — and it is the reason the trick exists. Most current coinage is copper-plated steel with very little exposed copper, and dropping money into wine is not a clean way to treat it. Vigorous decanting is easier and works.
Is it safe to drink?
Not a safety problem
Unpleasant, not harmful. You can drink it; you may not want to.
Yes. The concentrations involved are minute and harmless, however unpleasant they smell.
Can I take it back?
Try decanting first — this is the one fault that frequently fixes itself. If it survives half an hour of vigorous aeration, return it.
Sources
Sources consulted
- The Australian Wine Research Institute — AWRI
- Wine flavours, faults and taints — The Australian Wine Research Institute
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