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Molecules of Minerality

What in wine actually produces this desirable characteristic?
Photo by: David Yellen

Posted: Jan 5, 2016 3:37pm ET

The last time I wrote about it, I likened the minerality that some of us prize in wine to the flavors of mineral water. Then I wondered what exactly is present in the wine that reminds us of the aromas of wet rocks or rain on concrete and that adds depth to the mix of flavors.

A study from Spain published in March 2015 looked into exactly that question. Antonio Palacios García, director of Laboratorios Excell-Ibérica in Logroño, and David Molina, director of Outlook Wine, a wine school in Barcelona, selected 11 whites and six reds, most of which had shown minerality in previous tastings. A few, included as controls, had no mineral qualities. Then two panels, one of winemakers and one of critics, wine sellers and educators, blind-tasted the wines.

For whites, they agreed that the most minerality was in a Sauvignon Blanc from the Loire; a Riesling trocken and Riesling kabinett from the Mosel also showed minerality; a Ribolla from Slovenia showed none. Among reds, they zeroed in on a Tempranillo and a Garnacha-Syrah blend from Spain and Syrah from the Northern Rhône for minerality, and a Poulsard from the Jura—a soft, light-style red—for its lack of mineral notes.

Finally, they did extensive lab workups. And yes, they did find certain chemical components common to the minerally wines that were not present in the non-minerally wines.

One standout in both reds and whites was succinic acid, described in the report as having a salty taste rather than the usual sharpness of acidity. Salt is a mineral, of course, and "salinity" is one descriptor applied to minerally wines.

Chemicals in the minerally wines but not in the others included β-phenylethanol, an alcohol with rose and orange blossom character. So did γ-decalactone, which has a coconut character. Curiously, the minerally wines also had 4-ethylphenol and 4-ethylguaiacol, associated with "animal" notes (and, often, brettanomyces). Wines that are reduced, show high free sulfur dioxide and have a low pH and high total acidity "can be interpreted as mineral," if they have "low aromatic fruitiness," the report adds.

The summary also goes out of its way to note that rocky soils do not automatically produce wines with mineral character. Mineral characteristics, they conclude, derive from the chemical balance of the soil, treatments in the vineyards and processes in winemaking. High-acid wines, for example, are more likely to show minerality, but soft-textured, even flabby, wines can taste of tar and wet rocks, too.

The study sidesteps the critical issue of defining the term "minerality." It simply looks at wines that tasters had labeled as such and analyzes them in the lab to determine what the wines have in common. That's a useful step forward. Since we like to use the term so much, it might get us a bit closer to some agreement on just what minerality is.

David Glancy
www.sfwineschool.com —  January 8, 2016 3:29pm ET
The Spanish study and discussion in this article give further insight into the definition and understanding of terroir. It is my experience that high acid wines extend and accentuate flavors of all kinds. It is also typical that low alcohol, un-oaked wines display more terroir, even in the new world. Phrased differently alcohol & oak can hide terroir that may or may not be present in a wine. Kokumi and calcium receptors on the tongue should be part of the conversation as well as noted in these 2 articles. Calcareous soils are the easiest for me to identify in blind tastings personally.
There is also quite a bit of talk about the impact of soil microbes impacting terroir impression - http://news.ucdavis.edu/search/printable_news.lasso?id=10762&table=news .
All fascinating stuff.

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