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
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