Issue link: https://digital.copcomm.com/i/391696
{ SOMMjournal.com } 93 "We initially screened a number of different rocks with bench trials and ultimately decided on a few for larger scale experi- mentation: granite, Noyo cobble stone, black slate and Pami pebbles," he recalls. Grahm saw major changes in the texture and mouthfeel of the wine, as well as dramatic differences in aro - matics, length and persistence of flavor. "In every case, low doses of minerals added far more complexity and greater persistence on the palate. It is my personal belief that wines richer in miner - als just present way differently." He adds, "They seem to have a certain sort of nucleus or density around their center; they are gathered, focused, cohered the way a laser coheres light. It is a different kind of density relative to tannic density, somehow deeper in the wine than the tannins." But what about the interface between roots and soil? Do roots modify the pH of their immediate environment, causing the release of minerals? If water itself were enough to release significant quantities of minerals, then the vineyard soils wouldn't be stable over centuries, as they have been observed to be. However, the action of bacteria and other soil organisms can lead to decomposition of rocks, releasing their mineral constitu - ents into the soil. Reduction as Minerality So now to the second definition of minerality. Some people use "mineral" to describe aromas of wine; it's something they get on the nose. In this case, it could be that tasters are ascribing minerality to what is in reality the presence of certain volatile sulfur compounds in the wine, also known by the term "reduc - tion." In its rawest state, reduction is caused by hydrogen sulfide, and smells of rotten eggs and sewers. This is rare in a finished wine, and wouldn't be classed as mineral. Far more common is the presence of complex sulfides and mercaptans (also known as thiols). These sulfur compounds, like hydrogen sulfide, are pro - duced largely by yeasts during fermentation. Their expression depends on their concentration and the context of the wine, but in some cases they can give a flinty or struck-match aroma that can be quite "mineral." There is good reason to suggest that flintiness in white wines is a result of some low-level reduction. Great white Burgundies fre - quently show a little of this good reduction: a matchstick element to the nose adds complexity and even New World Chardonnay producers are now beginning to work out how to achieve this through their winemaking. There's also a link here with terroir: Some sites naturally have nutrient deficiencies that can stress the yeasts a bit and cause them to produce volatile sulfur compounds. Paul Draper of Ridge in California is a winegrower who believes in minerality from the soil, even in the face of questioning from scientists. "Though I am well aware of what soil scientists say about minerals or other elements in the soil and the impossibility of their traveling through the vine and into the wine, the roots deep enough into those minerals are affected and the wine shows that effect," he states. "I think of minerality as a wet stone quality in a wine. Our subsoils at Monte Bello are limestone and at times are at the surface or a meter below. In other places our backhoe pits find them several meters down. Perhaps 70 percent of our vine roots are deep in the limestone. I have seen minerality in some shales as well, so I don't think the effect is nec - essarily limited to limestone. We see the most marked minerality (crushed rock, perhaps flint are other descriptors) is in our more eroded blocks, where the limestone is closer to the surface. In the youngest blocks, where pits have shown considerable lime - stone, we don't see the minerality as yet but expect to when the roots are deeper." Minerality remains enigmatic. As we begin to understand more about it, the picture seems multifactorial, with different mecha - nistic underpinnings for what wine tasters describe as mineral in their tasting notes. I'm increasingly drawn to the idea that minerals in wine, derived from the soil, could be affecting wine flavor in interesting ways—and, in particular, helping to create long-lived compelling white wines. It's a subject that deserves more attention. Randall Grahm of Bonny Doon Vineyard: "It is my personal belief that wines richer in minerals just present way differently." "The anecdotal evidence suggesting that some terroirs create wines with much more 'mineral' characters is pretty strong."