Just like last year, I was at Haut les Mains , a very convivial wine salon in Burgundy. The very first wine we tasted, an Aligoté, was an immediate hit: mouse . That set the tone for the rest of the day and for a new podcast episode, in which we delve into this disgusting wine fault.
Listen to our podcast about mice >
What is mouse?
"Mouse" is a wine fault that mainly occurs in natural wines. It manifests itself not in the aroma of the wine in your glass, but in the aftertaste. You take a sip, swallow, and then a musty, gritty, unpleasant taste emerges. Similar to the smell of a mousetrap, sawdust, or a guinea pig cage.
It is striking that the error only becomes noticeable in your mouth : the fragrances only become volatile there through contact with saliva.
The role of pH and saliva
Saliva has a near-neutral pH (6.2–7.6) thanks to buffers like bicarbonate and phosphates . Wine is much more acidic: pH 3–3.6 for white and red wines, sometimes even lower in Riesling or Chenin Blanc. At this low pH, the "mouse compounds" remain odorless. Only in the mouth, where the pH is higher, do they become volatile and noticeable.
The connections responsible for mouse include:
- 2-acetyl-1-pyrroline (2-AP)
- 2-ethyltetrahydropyridine (2-ETHP)
- 2-acetyltetrahydropyridine (2-ATHP)
They are caused by lactic acid bacteria or by certain strains of Brettanomyces .
Why natural wine in particular?
Many natural winemakers use little or no sulfites. Sulfites act not only as an antioxidant but also as an antimicrobial. Without this protection, lactic acid bacteria have a greater chance of survival. If you don't use them at all or only infrequently, it's crucial to maintain excellent hygiene. Impeccable hygiene in your wine cellar is crucial.
Other risk factors:
- high pH in the wine
- spontaneous fermentation
- use of whole bunches
- semi-carbonic maceration
- lots of oxygen contact
Even a minimal addition of free SO₂ (even at around 10 mg/l) can significantly reduce the risk of mice. For more information, check out Simon Woolf's Complete Guide to Mouseiness .
Mouse comes in varying degrees. Sometimes a wine has a full load of mouse and you notice it almost immediately, while in other wines it's more subtle or only appears after a few seconds. The latter makes it especially tricky during a tasting: you might write off the wine as "not quite fruity" and move on to the next wine. A fine wine if it holds up well.
Mouse can also appear halfway through the bottle. I experienced this years ago with Radikon, an iconic natural wine from Italy. The first glass was amazing, but after that (an hour later?) it went downhill and there was nothing left of the wine. Sometimes you notice "the mouse is lurking." Then it's important to drink quickly!
Not everyone tastes mouse
Not everyone is equally sensitive to mouse.
I would say there are three groups of people:
- People who don't (yet) taste mouse
- People who taste mouse and find it very disgusting
- People who taste mouse but don't mind
Yes, that last category also exists. Those people find "mouse" to have a certain artisanal quality, something that fits into the broader picture of natural wine. At the same time, it's also possible to train yourself. The more you encounter it, the clearer it becomes. And if not, then don't: an old study tells us that 30% of people can't detect mice. Use that to your advantage.
Can you do anything about it?
Not much. Once a bottle has mice in it, there's no saving it. Or, as we concluded in the podcast: "The mouse never goes home." The experiment with lemon and vinegar to lower the mouth's pH seemed fun, but it turned out to be no solution. Both ingredients are such an assault on your palate that you can't taste anything at all. Mouse or not.
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