Wine and Minerals

I spotted a story in the wine press recently that I just had to voice an opinion on – according to Scientists who met in Portland for the annual Geological Society of America Conference the belief that minerals could influence the flavour of wine is flawed. They consider that the quantity of minerals in wine is so small that it can't be detected through human taste and smell. This seems ludicrous. The belief in terroir in the Old World (how soil, weather conditions, geology and other local circumstances define the character of wine) is a long standing one and makes perfect sense to me.

Wine critics often use the French phrase, "gout de terroir", which means "taste of the soil" but the Scientists say much of that taste may be imagined. The geologists say wines may vary in levels of dissolved minerals, but those variations aren't related to the levels in vineyard soil. And they say the concentration of minerals in wine is below the threshold of human taste and smell.

"I am not saying that chemistry and geology have no effect on the wine. It may have effects that we don't understand,"

said geologist Alex Maltman.

"But whatever 'minerality' in wine is, it is not the taste of vineyard minerals," he said.

The fact that soils do affect the taste of the wine is self evident as the same grapes grown on different combinations of soils produce wines with marked differences when it comes to taste. Take Chateau La Fleur Morange for example – the 100 year old vines lie on a unique patch of soil. It is the only complex mixture known to exist in Saint Emilion and is a combination of sand, clay and chalk over an iron oxide sub soil (crasse de fer) which is 15.7 inches (40 cm) below the surface. This subsoil rests on top of limestone bedrock. Jean-François Julien, the wine maker, is convinced that this unique soil contributes to the finesse of the tannins.

The point of the argument seems to be that the minerally, flinty or earthy notes in the wine – according to the Scientists – do not come from the soil that the grapes were grown on but from some other undetermined factor.

I find it quite strange that there is little research into the way that soil affects the taste of the wine – maybe it is such a foregone conclusion that people have not bothered to look into it. Just because no relationship has been demonstrated between natural soil chemistry, as derived from different rocks, and wine type or quality doesn't mean that there isn't one. Any gardener – let alone grape grower or farmer – will tell you that soil type can affect the taste of your fruit and veg! Have you ever compared the taste of a tomato grown by hydroponics to one from your well manured vegetable plot?

Taste is such a subjective thing – one man's meat is another man's poison. If I can taste a certain minerality in my glass of wine it doesn't necessarily mean that the person standing next to me can. Can Science answer that?

Back in May European researchers discovered that even 10 years after bottling, wine still holds the chemical signature of the forest from which the barrel used to age it was made – would this be reflected in the taste I wonder? To me its all part of the magical mystery of wine and even if Science managed to unravel the “whys” and the “wherefores” I would still like to think that the wine I am enjoying holds the essence of the soil, sun and rain that went into its making.