While there is no doubting the rocky quality of this Pierre Morey vineyard in Burgundy’s Meursault commune, the debate continues among vintners and scientists as to the true impact that such soil components have on a resulting wine’s nose and palate.
Drinking in MineralityBy Jeff CoxMuch is written about the essence of minerality in wine, suggesting that the aromas and tastes of flint, chalk, gravel, slate, stone - and even wet stone - are concrete qualities. Indeed, three out of the four Tasters' Choice Selections in the recent August/September 2008 Buyline section cited "minerality" - a word coined by wine writers - in the flavor profiles. Eleven of 22 California Chardonnay and Sauvignon Blanc descriptions that followed did, as well.
New York Times wine writer Eric Asimov favors the characteristic, too, writing recently that the 2006 Pie Franco Rueda from Blanco Nieva "is a wine that I love. It's got floral and citrus aromas with great mineral flavors and it's alive in the mouth." Robert Parker, Jr., publisher of The Wine Advocate, reported in issue #156 that the 2001 Guigal Ermitage Ex Voto Rhône white emitted "stupendous aromas of a liqueur of stones." Across the pond, Britain's leading wine journal, Decanter magazine, recently noted that the 2005 Premier Cru Chablis from Domaine des Marronnières imparts a "wet stone nose" and "mineral-laden structure."
But what, precisely, is minerality and where does this very pleasant sensation come from? In deciding a case involving pornography in 1964, Supreme Court Justice Potter Stewart famously wrote in his short concurrence that "hard-core pornography" was difficult to define, but that "I know it when I see it." Similarly, minerality in a wine is difficult to define, yet most of us seem to recognize it when we taste it.
Not long ago, I found myself praising the huge core of minerality in Richard Arrowood's 2003 Reserve Speciale Sonoma County Chardonnay. Yet, it also occurred to me - almost like an epiphany - that I literally didn't have any idea what I was talking about, so I set out to find answers to questions like: Are minerals mined from deep in the soil by a grapevine's roots? Does minerality develop as grape juice turns to wine? Is minerality a specific compound or compounds that can be scientifically identified? Or is minerality something ineffable, more art than science - a ghost in the wine that can't be explained, but whose presence is subtly perceived?
My first call was to Arrowood, who says, "I don't use 'minerality' in describing my wines," yet he's keenly aware of it. "Minerality 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, but it's not scientific. I have no idea where it comes from."
Because it is such a common descriptor, I expected The Oxford Companion to Wine to have a minerality entry; it doesn't. Instead, it lists only the minerals that can be present in wine - sulfur, magnesium, potassium, calcium, manganese, iron, copper, zinc. Similarly, the Wine Aroma Wheel, developed in 1990 by Dr. Ann Noble at UC-Davis, makes no mention of this quality either.
I next reasoned that maybe wine scientists have nailed it down by now. A call to Dr. Hildegarde Heymann, a professor of enology at UC-Davis who specializes in the descriptive analysis of wine, yielded a hypothesis: "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 says. >
Heymann would like to research the nature of minerality, but says no one has stepped forward with money to fund such a study - 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 speculates on 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 proposes.
Mick Schroeter, winemaker at Geyser Peak Winery in Sonoma County, also hedges. "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."
Much of wine tasting is subjective, based on individual taste. Dr. Susan Ebeler, professor of viticulture and enology at UC-Davis, specializes in wine analysis and sensory chemistry. She believes that, "Minerality is a perception people have, but it may not be specific compounds that produce it. That is, people might not be talking about the same thing when they say minerality. Is it in the alcohol? In the salts? There's no clear answer. For it to be objective, we need a reference standard so that people can always say, 'That's minerality!' when they encounter it. But we're not there yet."
The French, however, seem to be there already. For many of the country's vignerons, minerality is at the core of their cherished concept of terroir.
Napa-born Olivier Portet, son of Clos du Val's founding winemaker Bernard Portet and director of European imports for Wilson Daniels Ltd., a Napa Valley-based wine sales and marketing company, asserts that "Minerality is the essence of terroir." His firm has assembled an impressive international portfolio that is positively rife with wines oozing terroir. "Minerality is more the core and essence of a wine than the fruit components," Portet elaborates. "The Loire Valley, Burgundy, Alsace and Chablis all show this quality. You can see the reflection of white chalk soils in the wines of Blagny [in the Côte d'Or]. Minerality is strong in white wines in France. In fact, more infertile soils show more terroir." While minerality is found in red wines, the stronger phenolics, tannins and other robust components of red wines tend to mask it more than in whites.
Jacques Lardière, cellarmaster at Maison Louis Jadot, one of Burgundy's premier négociants, says flatly, "All our wines carry minerality." He believes the acidic cell contents of the micro-organisms in the soil dissolve minerals from the bedrock, and the grapevines then absorb these minerals. "This minerality applies to both Chardonnays and Pinot Noirs because their fruit depends on the same bedrock. The minerals in Burgundian soils create coherence in the wines, from the least to the greatest cuvées. But there exist places that are able to reveal this mineralization with more dynamism," such as the minerally wines of Meursault; the Grands Crus of Le Montrachet and Batard-Montrachet, Le Musigny and Corton-Charlemagne, and Vaucoupin in Chablis.
While terroir shouldn't be conflated with minerality (the former is a concept that embodies all of the apsects of a particular vineyard, while minerality is a particular quality often evident in fine wines grown in regions around the world), Portet proffers an interesting connection: "More infertile soils show more terroir." And they may show more minerality, too.
That's also the theory of winemaker and wine educator John Buechsenstein, who has delved into this topic more than most. He is one of the principals of Sauvignon Republic, a brand that bottles minerally Sauvignon Blancs from the Russian River Valley, New Zealand, and South Africa. Among all of the noble varieties, sauvignon blanc is perhaps best known for its ability to reveal minerality. "Minerality is a new buzz-word in wine," Buechsenstein says, and "it would be great to come to a common meaning for it." He offers a litany of process-of-elimination theories on the elusive trait.
"I think I know what it isn't. It isn't old vines reaching deep in the earth and bringing up bits of earth and rocks. Those deep roots are after water. Most nutrients, including minerals, are taken up by feeder roots in the top layer of soil. For a long time I've thought that maybe the source is environmental. That is, low level moldiness or earthiness picked up in the winery - I'm thinking about the ancient wine cellars in Germany," he says. "But then, how do you explain minerality in wines from brand new wineries? I thought maybe it was moldy barrel staves that might be the source of minerality, but I don't know. I've discarded the environmental source idea, but it's still always in the back of my mind."
"It also might be caused by a reaction between strong acidity in a wine and compounds known as pyrazines," he says. Human beings can detect pyrazines in vanishingly small amounts, such as parts per trillion. "One drop in the Reflecting Pool in Washington, D.C., and you'd smell bell peppers all the way to the Beltway. [So] minerality could be really low levels of pyrazines." He points out that "grassiness" in Sauvignon Blancs is caused by pyrazines.
Buechsenstein lays out his most compelling theory, based on mercaptans (also called thiols) last. Simply put, mercaptans are molecules containing hydrogen and sulfur - hydrogen sulfide (H2S), for instance, is not uncommon in wine. When it's present in large enough amounts, it smells like rotten eggs. But in very small amounts? Buechsenstein observes that, "Wines with minerality often come from Old World, cool climate sites that have been farmed for centuries, even thousands of years. Their soils are thin and rocky - worn out from so many harvests."
He explains that sulfides (mercaptans) are created in wines via musts that are poor in nitrogen. Yeast needs a certain amount of nitrogen to grow. If a must is nitrogen poor, then the yeast will start cannibalizing amino acids. "At the core of amino acids is a nitrogen group," he continues. "So the yeast goes after the nitrogen in the aminos. They use the nitrogen to survive."
Two amino acids have sulfur in their molecules - methionine and cysteine. When the yeast deconstructs methionine and cysteine to get their nitrogen, this sulfur is released into the must, which then goes through a reduction process to form mercaptans. That's why winemakers treat a stinky must with yeast-assimilable nitrogen. The yeasts are given enough nitrogen to stop attacking the amino acids and liberating the sulfur."
Buechsenstein further notes that in the old days in Europe, grapes and olives were planted where nothing else would grow, such as on rocky hillsides. "These sites are naturally low in nitrogen, and that may be the cause of nitrogen scavenging by yeasts and the production of low amounts of mercaptans. So, minerality could be trace amounts of mercaptans in the wine," he sums up.
I've sniffed enough hydrogen sulfide in wine to know that it is a really unpleasant offense to the nose. That in very tiny amounts it might actually be the cause of minerality is an interesting thought.
Yet I could not help but wonder why a human being's olfactory sense would have evolved into such a heightened state as to detect mercaptans in parts per trillion in a glass of wine. Dr. David Rand, professor of biology at the department of ecology and evolutionary biology at Brown University offers a simple answer: "There is an evolutionary advantage to being able to detect vanishingly small amounts of any odors, and mercaptans happen to be one of them. Interestingly, humans have many more odor receptor genes than chimps. The connection to wine is a red herring. Rather, focus on the importance of detecting anything good or bad in the things ancient humans wanted to eat or chose to mate with."
It's true that many things that are bad for us in quantity are good for us in very tiny amounts - that's the basis of homeopathy. It might also be the basis for the fine minerality that so pleases our palates. We may never know for certain, but we can hope that a generous grant will be made to UC-Davis that enables doctors Heymann and Ebeler to better wrap their scientific minds and taste buds around minerality.
Sonoma-based Contributing Editor Jeff Cox is the author of From Vines to Wines, Cellaring Wine and the newly released Organic Cook's Bible.
Tasting BAR
The wines that follow were evaluated open for their mineral qualities by a five-person tasting panel that included the author. Scores are based on the magazine's BuyLine rating system.
Domaine Pierre Morey, 2006 Les Tessons, Meursault - $107: A soft and pretty nose of pears and almonds. Elegant, restrained and well-integrated fruit flavors of light citrus and apple wrapped around a core of balancing minerality. Score: 93
Gainey, 2006 Chardonnay, Santa Rita Hills - $20: Shy mineral nose displays an elegance that continues in the mouth with sleek, fresh citrus blossom flavors and pleasant mineral aspects. Score: 90
Kumeu River, 2007 Villages Chardonnay, New Zealand - $19: A flintiness characterizes the aromas even more than the fruit. On the palate, there are ripe peach flavors with crisp acidity that give the wine a clean, refreshing quality. Score: 91
Marc Kreydenweiss, 2006 Le Moine Pinot Gris, Moenchberg, Alsace Grand Cru - $53: Pure minerals in the nose and across the palate from entry to finish along with lovely apricot aromas. The definitive terroir of Alsace plus sweetness from residual sugar graces the broad palate. Score: 94
Ponzi Vineyards, 2006 Reserve Chardonnay, Willamette Valley - $30: Light aromas of pear and fig with underlying mineral scents. Leesy flavors of brioche, golden raspberry and hints of spice. Score: 90
Sauvignon Republic, 2007 Marlborough Sauvignon Blanc, New Zealand - $18: A grassy, floral nose. Mineral aspects emerge on the palate, along with lemon zest, pineapple and crushed meadow grass bolstered by crisp acidity. Score: 89
Sauvignon Republic, 2007 Sauvignon Blanc, Russian River Valley - $18: Prominent aromas of hot, sun-warmed slate after a summer rain graces the bouquet. Rich, deep flavors of green apple and citrus with secondary notes of ripe tropical fruit and spice framed by crisp acidity. Score: 91 - JC
