Minerality in wines… what is it?

Though I’ve talked a lot about science and art coexisting quite harmoniously in the wine world, I knew this wouldn’t be the case in every scenario.  And indeed, I have found an issue where science and nonscience butt heads.  This just happens to be the issue I have set out to study with Dr. Chris Oze at the University of Canterbury.  Dr. Oze is interested in the concept of ‘minerality’ in wine.  Geologic references, including minerality and others such as ‘slate,’ ‘quartz,’ and ‘wet stones’ are pervasive in tasting notes (including my own), but while many wine aromas and flavors can be traced to specific compounds in the wines, the story is not so simple with minerality.  The scientific community remains largely unconvinced that it is possible to taste the soils in any direct way, as they (rightly) point out that whole minerals cannot be taken up by the roots and end up in the grapes, and then somehow manage to stick around during months or even years of processing and maturation until they reach your glass.  Metal ions are surely taken up from the soil, but the mechanisms for this aren’t well understood and contributions of metals from exogenous sources, such as pesticides, metal tanks, and bentonite clays used for fining, complicate source allocation.

So it seems like the science here is at odds with what many people commonly believe about the taste of their wine (remember the importance of the soil to winemakers in Priorat??), and the importance of vineyard geology and soil composition on the quasi-mystical concept of ‘terroir.’  But then, after reading upwards of 50 scientific articles on the subject, it has started to seem like maybe the problem is that no one actually knows either way.  My latest conclusion is that there simply hasn’t been enough work done on this issue to know whether or not you really can taste some version, albeit highly modified and likely indirect, of the soil in your glass.  Amazing how scientists are so good at using a lack of conclusive evidence to support arguments on both sides (though in defense of all the scientists who have looked at this issue, it is ridiculously complex and very possible that we may just not be able to get a conclusive answer because controlling the variables enough to produce a valid study may render the results completely inapplicable to real winemaking – but there are always different ways of thinking about problems, so perhaps all we need is a novel approach…)!  So it is not necessarily that science and winemaking/tasting lore are at odds here, but we just don’t yet know enough to say.