Jamie Goode discusses the concept of minerality
in wine, and its relationship to terroir
is a written version of the talk I gave at the Wine & Culinary forum
in Barcelona, October 2014)
In this article, I'd like to explore one of the most interesting and
controversial topics in the world of wine, that of minerality. But
before we get to discuss this topic directly, let's take a side step
and look more broadly at the concept of terroir, which lies at the
heart of the world of fine wine. There are four elements or
definitions of terroir, each of which overlaps with the others.
The main definition of terroir can be summed up as the way the
vineyard environment shapes the quality of the wine. Physical
factors such as soil chemistry, aspect, drainage, average climate
and slope have a strong influence on which varieties grow where and
what the wines they produce taste like. Climate is obviously a huge
factor, but the differences seen over short distances where there is
a change in vineyard soil show that climate isn't everything.
A second definition would be terroir as local flavour: the
possession by a wine of a sense of place. This brings the human
factor into play, as local traditional practices will influence wine
A third is summed up by the French term goût de terroir. This
is the assertion that you can taste the terroir in the wine.
Traditionally, this expression was used to describe rustic or earthy
wines, and wasn't a term used for fine wines.
Finally, terroir can be used to refer to the physical vineyard site
itself, independent of the wine, as in 'this is a good terroir', or
'the terroir is clay and limestone here.'
Terroir can operate at different scales. On the one hand we have the
micro-scale: grapes harvested from different parts of the same
vineyard can result in different wines even when the winemaking is
the same. On the other, we have the macro-scale, with shared
characteristics held in common by wines made from larger geographic
regions (for example, 'this is a typical example of Central Otago
What about the human factor? Some definitions of terroir rule out
human influence, but interventions – including viticultural and
winemaking practices – may also confer a shared sense of place to
It's possible that winegrowers could also be adapting their
techniques to best exhibit regional differences in their wines. They
may have in mind what a typical wine from a certain site is like,
and seek to demonstrate this quality more clearly in the wine. They
may have the character of a site in mind when they blend a single
vineyard bottling, choosing to include lots of wine that exhibit its
sense of place and blending away those that lack this personality.
This ‘typicity’, which is influenced by human factors as well as the
physical characteristics of the vineyard site, helps maintain the
sort of stylistic regional diversity that makes wine so interesting.
It is worth pointing out here that terroir can be fragile, and poor
winemaking or picking grapes too late can interfere with terroir
expression. Conversely, good winemaking and viticulture can maximize
So what are the mechanisms underlying terroir? Here we need to look
at the biology of the grapevine. Plants are chemical factories. They
use light, water, air, and trace elements to synthesize all they
Grapes—the starting place for wine production—are made entirely
through the process of photosynthesis and subsequent plant
biochemistry. Chemically speaking, the soil supplies water and
dissolved mineral ions, which may or may not have any influence on
the flavour of wine (we'll come back to this later). The plant makes
The current scientific consensus is that the way that soils have
their influence on wine quality is through their effects on water
availability. An ideal terroir gives vines enough to drink, but not
too much, and – at the right time – gives the vine a bit of water
stress. According to this view, soil chemistry is not important.
But the experience of many winegrowers testifies that soil chemistry
actually matters quite a bit, and that soil effects are not just
about water availability. Certainly, there's a lot of discussion in
the wine world about soil type and its influence: more than you'd
expect if soil chemistry were irrelevant.
So this is where we need to look at soil chemistry, and in
particular the mineral composition of soils. Plant science shows us
that these could be having both a direct effect and also an indirect
effect on wine flavour. The direct effect is through the minerals
being taken up by the vine roots, ending up in the grapes, and thus
ending up in the wine. It's not likely to be a strong effect, as
most mineral ions have no smell and relatively little taste, but it
could be having some effect. The indirect effect is through minerals
(or their deficiency) altering plant gene expression, thus leading
to differential production of flavour compounds or their precursors
in the grapes. The chemical composition of grape must can also have
an important effect on the way that yeasts and bacteria carry out
fermentation, altering fermentation dynamics and causing microbes to
produce different levels of flavour compounds.
The bulk of soil mineral content comes from decaying organic
material, not decomposed rock, and it is microbial activity in the
soil that affects the ability of soil to break down organic matter
into mineral ions that can be used by the plant. This microbial
activity is influenced by the availability of water, food, and
oxygen. Soil texture is important: oxygen is more available in a
loose uncompacted soil.
Various factors influence soil life, and as we examine them it soon
becomes clear that farming grapevines involves compromises. There
are things you absolutely need to do in the vineyard that might
negatively affect soil microlife. You have to choose which
compromises to make.
Fungicides, which are routinely used in viticulture, kill off not
just fungi but also a high proportion of bacteria and actinomycetes.
Herbicides and insecticides also kill off microbes and restrict the
growth of others. But the worst culprit in terms of damaging soil
life is copper sulfate (which is permitted as a fungicide in organic
viticulture), which reduces microbial activity the most. But it
simply isn't possible to grow vines without any chemical inputs.
So this is where we get to introduce the concept of minerality. It's
a new tasting term: one that didn't exist until the 1980s, according
to experts Steven Spurrier and Michel Bettane, who have been writing
about wine for long enough to see this change. It has now become
The literalist view of minerality is probably best summed up by soil
scientist Lydia Bourguignon, who states that “minerality is the
perception of the rocks in the soil, by the palate.” Thus we have
those who can detect chalk and flint in their Chablis, and those who
find slate in their Mosel Riesling. But this literalist viewpoint
isn't supported by science: the rocks don't dissolve and then get
taken up by the vine. Besides, rocks don't taste of anything.
Jordi Ballester, a researcher from the Centre des Sciences du Gout
in Dijon, in Burgundy, has studied the use of the term minerality by
lexical analysis. He finds that it is a term being increasingly
used, but without a clear definition. In his studies, he compared
ratings of 34 wine experts and a trained panel, looking at the sorts
of tastes and smells that people describe as “mineral.” What he
found was that there were widespread differences among the tasters.
However, some of the subgroups used the term in similar ways,
suggesting that there is a cultural basis for its use.
So what are the different uses of 'mineral'? The first is
minerality as an aroma. Wines that smell 'mineral' tend to be
white wines, and the source of this matchstick/mineral character is
most likely a volatile sulfur compound produced during fermentation
by yeasts. The classic matchstick/struck flint character on the nose
of some white Burgundies is really attractive, and it's now being
deliberately sought by Chardonnay makers the world over. Volatile
sulfur compounds are responsible for the wine fault known as
'reduction', and what we have here is a classic example of a
compound that at one level is complexing, and another is a fault.
The boundary between the two conditions is quite hard to pin down.
The other two uses of the term involve minerality as a taste.
The first, and least justifiable of these, is the minerality
associated with high acidity in white wines. It's very easy to reach
for 'mineral' as a descriptor when we come across bright, acidic
whites, when really we should just say high acid. A related
condition is when a wine tastes 'stony', again likely due to the
acids. The second of these mineral tastes is, I think, the best use
of the term, and it's a sort of salty minerality as you might find
in some mineral waters, albeit usually at a low level. Here are some
definitions of this sort of minerality:
“A wine marked by salty and mineral undertones balancing (and not
hiding) the fruit, more often a white wine rich in calcium and
magnesium as many mineral waters are.”
“It is the fraction on the palate that makes the wine taste more
saline or salty. High acids or high tannins do not mean that the
wine has lots of minerality. High salt contents make the acidity
more ‘savoury’ and therefore less aggressive. Good minerality
makes one salivate and want to have another sip or glass or
“For me, there are two forms of minerality that influence a wine’s
qualities and characteristics. Firstly, the wine’s mineral
content, which is about taste and texture when tasting a wine.
It’s much like when drinking mineral water of a high mineral/salt
content, there is a flavour/taste and an almost ‘osmotic’
experience, perhaps similar to drinking seawater, just much less
concentrated and less salty.”
Could this be caused my mineral salts in wine, absorbed by vine
roots? The mineral content of wines fluctuates between 1.5 g/litre
and 4 g/litre, which may be enough to confer some flavour on the
wine. This would be very interesting indeed.
“It seems the soil’s exchange capacity of ions correlates with the
mineral concentration of a wine,” says Stepp. “Also, a
cold-stabilized wine has lower potassium content than the same wine
unstabilized, and it tastes different and has less flavour, perhaps
even less complexity.”
There is some evidence that soil type will influence the mineral
composition of wine. In 2000, a plant researcher
from Germany, Andreas Peuke, grew Riesling vines in pots containing
three different soils from Franconian vineyards: loess, muschelkalk
(seashell lime), and keuper. He collected sap from the vines and
analyzed its chemical composition, and found differences among the
different soil types.
In a more direct experiment, Randall Grahm famously put rocks into
tanks of wine. “We were able to discern significant differences
between the various types,” he reports. “There were major changes in
the texture and mouthfeel of the wine, as well as dramatic
differences in aromatics, length, and persistence of flavour.”
So this brings us back to soil biology. We discussed earlier about
how important soil life is for making minerals available to plants.
This could be why organic/biodynamic viticulture is often
beneficial to wine quality, because it
encourages the soil microlife to develop. Root exudates from
plants are important in encouraging growth of soil microlife, and
the vine is more likely to produce these if its nutritional needs
aren't being easily met by fertilizer application. The vine age
effect on wine quality may in part be to the expanded root system
encouraging better soil microlife-vine interactions.
It follows that increased soil microlife could lead to more mineral
wines. Finally, there's a question I'd like to throw out: is there a
connection with minerality and ageability of the wine? I can't think
of a scientific mechanism to explain this, but some wines that I'd
describe as more mineral seem to age much better than their less
Have I succeeded in rescuing minerality? I'm not sure. But it is
surely too soon to dismiss this concept, and I for one will carry on
using the term in my tasting notes.
Central Otago, New Zealand (series)
Martinborough, New Zealand (series)
Find these wines with wine-searcher.com