Nutrients not the cause of minerality
Minerality in wine is most likely to stem from volatile thiols or esters and not directly from nutrients in the soil, according to this month’s edition of the drinks business.
In an article written by Sally Easton MW in db‘s April issue, she highlights research to show that it’s impossible to get minerality in a wine directly from the nutrients in the ground.
Having spoken to Professor Alex Maltman of the Institute of Geography and Earth Sciences at the University of Wales, she explains that mineral elements in a wine are not only minimal but also tasteless.
“Potassium rarely exceeds a few hundred parts per million (ppm) with a few tens of ppm for calcium and magnesium… these are tasteless anyway and their concentration in wine are below sensory thresholds measured in water,” says Maltman to Easton during a discussion on minerality.
However, Maltman is also quoted in the article as suggesting that minerality may stem from esters, which are created by the reaction of alcohol with an organic acid.
These he says can vaporize easily, and we can smell some of these aromatics in parts per trillion.
Meanwhile, Dr Wendy Parr, sensory scientist at Lincoln University in New Zealand suggests that tasters may be using the term “mineral” to describe characters produced by volatile thiols such as Benzenemethanethiol (BMT) in Sauvignon Blanc, which produces gunflint aromas.
Parr is studying descriptors of perceived minerality in Sauvignon Blancs, and although her research is yet to be published, she tells Easton that there’s a correlation between use of the term “mineral’ and screwcaps.
““The increased use of the term ‘mineral’ in relation to wine here in New Zealand parallels the increased use of screwcaps which some argue has produced many more wines exhibiting low levels of reductive notes,” she comments.
She also says, “The general pattern seems to be that wines judged lower in the fruity and green flavour notes are more likely to be judged mineral.”
Easton’s article also considers the use of the term “mineral” in tasting notes following research by Dr Jordi Ballester, who is oenology lecturer and researcher at the University of Bourgogne.
Although the descriptor is common today, Ballester points out that word minerality is absent from both Emile Peynaud’s The Taste of Wine (1983) and Ann Noble’s Wine Aroma Wheel (1984).
As Ballester concludes, “Wine has not changed that much; people have changed”.
For a full analysis of the term “minerality” over time and possible sources of aromas and flavours such as chalky, smoky and salty, see the April edition of the drinks business.