A discussion of soil and geology with Earth Sciences professor Alex Maltman, Alsace producers Olivier Humbrecht and Phillipe Blanc and Master Sommelier and former geologist Wayne Belding.
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Here are a few previous feature articles that provide some background on the topic:
Part 1: Soil PrinciplesPart 2: Vineyard Geology
Nicely done, Geoff!
More of my opinions below:
@ Keegan: then rocks & minerals do have a taste? or no taste? If you lick a rock maybe one is tasting dirt on the rock.
@Stefan: Minerality is not just a smell descriptor - it also can be used to describe a wine's flavor and texture. I grit my teeth on high acid wines. Mineral water has more taste/flavor than distilled water. The latter has zero dissolved solids. The former has more taste proportional to its concentration of dissolved minerals, i.e. dissolved solids or inorganic compounds & ions.
@Theodore: Agreed, but the question is not whether wine taste comes from different soils and rocks and minerals but whether we are tasting the actual soil, the rocks, or the minerals. Consensus is no - we are not tasting bits of rock - but probably dissolved elements/atoms/molecules from the minerals and rocks - which have a different taste than when they are not disassociated. e.g. pure sodium tastes different than sodium chloride (a fact from 11th grade chemistry lab). A wine might have traces of iron that give it a taste, but we are not tasting hematite, magnetite, shale or sandstone.
Regarding Dry Extract - this is usually measured in grams per liter without counting the sugars (or volatile organic compounds). So dry extract is just the dissolved inorganic salts, acids, carbonates, metals, cations, and anions in the wine. In other industries total dissolved solids (TDS) in water, anyway, are closely approximated with a conductivity meter (in millivolts).
If the acid in wine is mostly tartaric, and the wine was evaporated, you would have a pinhead of powder that was mostly cream of tartar (Potassium bitartrate) and a dash of other trace elements.
High acid wines seem to evoke the minerality descriptor more than warm climate wines. More tartaric acid = more minerality in the mouth and more dry extract in the lab. Therefore, more minerality in a wine literally = more dry extract.
When it comes to wine, minerality has a literal sense (dry extract), and a neboulous sensory sense or descriptive use.
Port Ewen, NY
This podcast has been a great relief to me. Recently my little brother showed me this set of rocks he had for his science class. I thought "Oh this is great! I get to taste all these different rocks side by side." So I proceeded to try all twelve types of rock. Guess what I discovered. They all taste the same. I could detect no difference between flint and limestone or any other combination. They all taste like rock. At the time I thought there was something wrong with me. Like I lacked the physical ability to detect the subtle nuances between the rocks. Thank you for letting me relax a little.
Wayne Belding is great for cutting through all fluff and hyperbole. He was one of the two administrators of my 2nd level test in Tucson a couple of years ago. In talking to him after the certificate presentation and toast, he said something I have never forgotten: "Lou, in the end its just fermented grape juice". I think its important not to forget that. It's suppose to be fun, too. Thanks Wayne, for teaching me that.
While I agree the correlation between the soil and the flavors in the glass has been over-simplified, doesn't blind tasting show us that there is some flavor derived from rocks in the ground? When label-bias is taken away, we still pick up on a chalkiness in chablis, savennieres, and sancerre - but not in mosel riesling. Clearly the rocks are contributing something to wine's flavor, although in a much more complex way than chalky soil = chalky wine.
@Rick - I've been thinking a lot about the dry extract thing and how it relates to perceived minerality. I tasted my staff on Alsatian Riesling today after listening to the podcast last night and it was an eye-opener. Which flavors were from extract? Which from minerality?