The Ghost in the Wine

Thursday, 18 July, 2013
Jeff Cox, Great Wine News
We read a lot about minerality in wine—the taste and aroma of minerals, flint, chalk, gravel, slate, stones, and such–but what is that, exactly?
Is it minerals mined from deep in the soil by a grapevine’s roots? Does it develop as grape juice turns to wine? Is it a specific compound or compounds that can be scientifically identified? Or is it something ineffable, more art than science, a ghost in the wine that can’t be explained but whose presence is subtly perceived?

Wine writers and critics seem very familiar with it. I can remember expressing my enthusiasm for a recent vintage of winemaker Richard Arrowood’s ‘Reserve Speciale’ Chardonnay from Sonoma County because of its huge core of minerality. But I realized, too, that I literally didn’t know what I was talking about.

Neither does Arrowood. “I don’t use ‘minerality’ in describing my wines,” he says. But he’s aware of it. “Minerality to me is like when you put stones in your mouth as a kid—there’s a subtle taste there…It’s a combination of clean earth and rock. You find it in Chablis and Meursault, but it’s not scientific. I have no idea where it comes from.”

Since it’s such a common term, I thought The Oxford Companion to Wine might have an entry on minerality. But no. It lists the minerals found in wine—sulfur, magnesium, potassium, calcium, manganese, iron, copper, zinc—but makes no mention of them in relation to the stony quality of minerality. Similarly, the Wine Aroma Wheel invented by Dr. Ann Noble at UC Davis makes no mention of this quality.

Maybe wine scientists have nailed it down. I called Dr. Hildegarde Heymann, Professor of Enology at the University of California, Davis, who specializes in the descriptive analysis of wine. She has some ideas: “I think minerality might come from a complex of sulfur compounds found naturally in the grapes—not the sulfites added as a preservative. But I have no scientific basis for saying this,” she said.

Dr. Heymann says she would like to research the nature of minerality, but that no one has stepped forward with money to fund the studies—yet. Because it exists in the realm of jargon rather than science, she says, “It’s not a word I use.” Despite the disclaimer, she describes how bottle age may affect minerality: “It seems that wine can lose some minerality over time. Sulfite compounds are very reactive in wines as they age,” she said, and as they react with other compounds in the wine, their contribution to minerality may lessen. She finished our discussion by repeating, “I have no scientific basis for saying this. Minerality is not a word I use.”

Mick Schroeter, winemaker at Geyser Peak Winery in Sonoma County, also begs off the word. “Minerality is not a term we use at Geyser Peak that often,” he says. “When we do use it, it’s usually a descriptor for Sauvignon Blanc. It would also be applicable to Pinot Gris and white Burgundies. I see it as a character on the nose or palate likened to the smell of wet stones, wet gravel, or wet pavement. It may also be likened to the soils the grapes are grown in and the impact those soils have on the character of the wine; for instance, the calcareous soils in Burgundy.”

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