How to Think about Mouse

This is the week for turkey but I want to talk about mouse.

No. I’m not contemplating roast mouse for Thanksgiving. I’m talking about everyone’s favorite new wine fault—mouse taint.

Mousiness in wine is variously described as “hamster cage,” “puppy’s breath,” “corn nuts,” and “vomit.” Although it was identified in the early 20th Century, it emerged as a common problem with the increasing prominence of natural wine and the reduced use of sulfur in winemaking.

You can’t smell it by sniffing; it only becomes apparent after mixing with saliva so it is available only  via retronasal olfaction.The more we look into it, the more puzzling it becomes. It’s a moving target, as well described by John McCarroll at Punch.

But the more one investigates mouse, the clearer it becomes that the quality is more nuanced, and more transient, than originally understood. Instead of being an unfixable problem, it begins to appear more like a flaw in how the wine is understood and contextualized.

And it is no longer associated only with natural wine.

Pascaline Lepeltier, sommelier and author of Milles Vignes, reports encountering wines that had been doused with SO2 and still showed mouse. “[Since 2016] you started to see it more outside the perimeter of natural wine [and] since ’18 I’ve tasted it in more… I wouldn’t say conventional wines, but [in wines from] people who are using sulfur,” she says. This is corroborated by sommelier Amanda Smeltz, who told me that she’s tasted mouse in wines with 8 to 10 grams of SO2—which is enough to change the taste of the wine, but clearly not always enough to prevent microbial activity.

Many winemakers claim that if you wait a year or so before bottling, the problem resolves itself without adding sulfur. But that isn’t always an option for struggling winemakers who need product to sell immediately.

Another theory is that mouse taint is related to climate change.

The connection of mouse with disruption in winemaking and storage goes even further. Years ago, in Catalunya, a respected winemaker linked mouse in the glass with drought vintages, saying that the pH disturbances in the vineyard often resulted in wines that needed more time to resolve. Smeltz says that the vagaries of climate are more apparent in natural wines, leading to “less-stable wine because the agriculture itself is not stable… We don’t see that in industrial wine because it’s not transparent, but in natural wine you see the difficulty of climate.” In other words, natural wine’s monomania at presenting an unadulterated wine means that, over the last few decades, we’ve been tasting vineyards that are struggling to adapt to a climate that is veering off-kilter in seemingly new ways each vintage.

Given the uncertainties about its origin and the fact it seems to go away when wines are left alone to develop,  McCarroll argues we should re-think labeling it as a fault.

To be sure, there are wines made by unconfident winemakers in bad conditions that may never resolve, but there are less of those each vintage as winemakers gain skill and understanding of their terroir. More likely, mouse at the hands of skilled winemakers can be looked at as something the wine is going through—a journey, rather than a destination. I think an apt comparison is, say, incredibly abrasive tannins in nebbiolo or reduction in white Burgundy, or even just the wound-up feeling one gets in young, age-worthy wines in general—these are, oftentimes, incredibly unpleasant sensations, but not ones we dismiss out of hand as flaws.

It seems like winemakers are beginning to get a handle on the problem. Brett and VA are faults that in small doses can add interest and dimension to a wine. Perhaps mouse taint will find a similar place.

I must confess a mere intellectual interest in this topic. I can’t taste mouse taint. I have been drinking natural wines for years. I’ve tasted conventional wines that smell vaguely like cereal and natural wines teeming with brett and VA  but no natural wines that taste like “puppy breath” or “vomit.”

I am not alone. Apparently between 30%-50% of the population can’t taste it. As Jamie Goode reports in an interview with a French expert on mouse taint, Dr. Nicolas Richard:

There are variations in mouth pH, variations in sensitivity, and the wine varies with aeration. ‘The first problem comes from the mouth pH,’ he says. ‘The variability is high. The variation for each person can be as much as one pH unit from day to day. This alters the perception of the mousy flavour.’…Aside from this, is there different sensitivity among people in their ability to perceive mouse compounds? ‘Yes,’ says Richard, ‘and there are at least three molecules. You can be anosmic for one, and very sensitive to another, and have medium sensitivity for the third. There are as many combinations as there are humans.’ So the sensitivity to mouse taint varies for each of the compounds, and the sensitivity to one is independent to the sensitivity to another.

This is a dilemma for writers who review natural wines and one reason I no longer do so. An ability to identify flaws is fundamental for honest reviewing.