Wine fault
Mousiness
A distinctive stale-popcorn or mouse-cage aftertaste that appears only after swallowing — and which some people cannot detect at all.
What you notice
Taste
- A stale popcorn, puppy-breath or mouse-cage taste appearing seconds after swallowing
- The wine smells fine but the finish is unpleasant
What it is
Mousiness is unusual among faults in being undetectable on the nose. The compounds are not volatile at wine pH, and only become so when mixed with saliva — which is why it appears as a delayed aftertaste.
A significant proportion of people cannot perceive it at all, which makes it genuinely contentious in tasting rooms. Someone saying a wine is mousy and someone saying it is fine may both be reporting accurately.
It has become more discussed as low-sulfur winemaking has spread, since low SO₂ is one of the conditions that permits it.
Unlike Brett, essentially nobody defends mousiness as a positive characteristic.
What causes it
- Lactic acid bacteria or Brettanomyces producing tetrahydropyridines.
- Low sulfur dioxide and higher pH, which is why it appears disproportionately in low-intervention wine.
Can I fix it?
No — nothing will fix it
No, and aeration makes it more obvious rather than less.
What you can do
- Nothing. It cannot be removed.
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.
- Decanting
- Mousiness is pH-dependent and appears in the mouth rather than the nose. Air does not remove the amines responsible, and giving the wine time tends to make the aftertaste more pronounced.
- Smelling the glass to check
- You will not find it there. It shows up as a stale, savoury aftertaste seconds after swallowing, which is why it is so often noticed by only one person at a table.
Is it safe to drink?
Not a safety problem
Unpleasant, not harmful. You can drink it; you may not want to.
Yes. The compounds responsible are produced by ordinary spoilage organisms and are not harmful. They are, however, deeply unpleasant to anyone who can perceive them.
Can I take it back?
Yes, though be prepared for the possibility that whoever you return it to cannot taste it.
Sources
Sources consulted
- The Australian Wine Research Institute — AWRI
- Wine flavours, faults and taints — The Australian Wine Research Institute
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