On Wine and Minerals

 Every wine lover has certainly heard of mineral wines or – at least – of the minerality of wines, possibly remaining completely confused or, perhaps, imagining that they will somehow find in the glass pebbles or solid substances in the form of fascinating crystals. Perhaps imagining – maybe for having heard it saying – those particular and elegant minerals are nothing more than the unequivocal sign of the soil in which the vine is grown, which generously donates its bunches to make that wine. Personally, I have been reading or hearing about the minerality of wines – or mineral wines – for over thirty years and, frankly speaking, I have heard the most disparate and imaginative definitions. Including the fairy tale of mineral substances – here intended as insoluble solid and crystalline inorganic compounds, therefore not the salts we define as “nutrients” – which, from the zealous root of the vine, magically reach the grape and, from here, give all their beauty to the wine that will be. Let's immediately clarify this point: the minerality of a wine has nothing to do with the soil or the territory, much less with the concept of terroir.

 In this regard, I need to make a necessary premise: when I taste a wine and I happen to perceive those sensations associated to the concept of minerality, I make use of this descriptor – and you can also find it in some detail forms of our Wine Guide – but I certainly never allude to or intend to support any olfactory or gustatory association referred to minerals in the strict sense. With this I am not excluding some mineral substances are characterized by a specific smell, which is actually subtle and light, after all, it is enough to pass your nose over them to be able to perceive it. Or in the case of the effect of a mechanical or thermal action: simply rub some types of minerals vigorously together and smell. Then there are more generous minerals in this sense, such as flint (especially after rubbing) or warm stone. In any case, it is never about the actual presence of that mineral in the wine. For the sake of completeness, neither those minerals nor any other type of mineral. Much less those that, with a lot of romantic and impossible imagination, are absorbed from the ground and are magically found in the glass, in all their sensorial splendor, at the end of vinification and aging.

 Around this sensorial descriptor, however, I notice a certain interest in wine enthusiasts, in particular the will – or better, the need – to have some kind of clarification and, last but not least, to know a precise definition. This is what I can see in the majority of tasting classes that I have been organizing and holding for decades: every time, punctually, at least one participant asks for an explanation on the concept of minerality of wines. I have already written in the past in the pages of DiWineTaste what is meant when the “mineral” descriptor is used, although there is no common or widely accepted definition, neither among tasters nor enthusiasts. The thing that can be said, without fear of contradiction, is that the concept of “minerality” is anything but the sensorial stimulus produced by substances belonging to the so-called “minerals”. Stating that a mineral character is perceived in a wine – at least and certainly for me – is not referred to the presence of any mineral substance or, even less, to any imaginative and extremely impossible probability of mineral substances absorbed by the vine directly from the ground.

 If mineral substances, even those which are sometimes used as descriptors are not found in a wine, why are they mentioned? After all, if there is no trace of flint, of any warm stone in a wine – and without any shadow of doubt, there aren't – why use them as a reference for the sensorial description of a wine? I could answer by saying that, in a wine – any wine – there is no trace of banana at all, yet this descriptor is widely accepted and used. However, isoamyl acetate is present, an ester whose smell is reminiscent of banana. This is to say that, in the sensorial description of a wine – as well as of many other foods and beverages – are used terms and descriptors which, by analogy, define an odor. Certainly, for the majority, the descriptor banana rather than isoamyl acetate is easier to understand and associate. The same is therefore true for most of the descriptors used in sensorial tasting, including minerality, that is we make use of description by analogy.

 Things are quite different, of course, for substances commonly known to anyone and actually found in wines, such as ethyl alcohol and acetic acid, therefore vinegar. In these cases it is not used a description by analogy and it is used its name instead. As for the minerality, however, a proper clarification should be made, noting that – in fact – there has also been a lot of confusion and the term has been used, and is still used, with careless superficiality and allusion. Above all, as already mentioned, with the intention of attributing supposed sensorial characteristics to the wine which are believed to be a direct expression of the soil where the vines which produced the bunches used to make that wine grew. Let's be clear: climate, environment, trend of the season, type of soil, cultivation practices and, last but not least, grape variety, are all factors influencing the sensorial qualities of a wine, although not being the only ones. To these must be added, undeniably, the operations performed by man at the time of the harvesting of bunches up to the moment the wine is poured into the glass. It is however and certainly excluded that the roots of the vine are capable of absorbing the solid mineral substances of the soil and making them reach the grape.

 So what is the minerality of a wine? Or better, what produces that sensation which is variously defined as “minerality” in a wine? In this regard, it must be said there is no exact and reliable description of the reasons determining this sensation in a wine. It must be said that, very often, this sensation is generally perceived in white wines characterized by a strong acidity, often produced – but not exclusively – in territories with a basically cold climate. Furthermore, the sensation of minerality is often found in wines from vineyards cultivated in basically alkaline soils, such as those with a high percentage of limestone or chalk. The most probable reason or, at least, the one that seems to have a quite accepted foundation, is that the sensation of minerality is produced by the reduction of certain sulfur compounds and which is mainly perceived by the nose. This condition – in fact – is conditioned by wine making factors and practices as well as by the ripening of the grapes at the time of harvesting, last but not least, by the type of closure used for the bottle and which directly influences the creation of a reduced environment, that is, it limits the exchange of oxygen.

 For some, minerality is an unmistakable sign of quality, as well as the expression of the territory through wine: in both cases, let me express my utmost and convinced perplexity. It should also be noted, in fact, that a wine defined as mineral, in case it is subjected for a sufficient time to the action of oxygen, this characteristic gradually tends to attenuate, thus making one think that it is – last but not least – a phenomenon linked to the reduction of sulfur compounds. Back to the olfactory analogy of isoamyl acetate and banana, it is certainly more understandable – even though nebulous – to define a wine as mineral rather than stating it is being perceived a smell of reduced sulfur compounds. Of the two, the former seems to me the lesser evil one and probably more understandable despite the difficulty of having and using a shared and reliable definition. There is no doubt the story and the fad for mineral wines have been well exploited by producers and “experts” for purely speculative as well as commercial and promotional purposes. However, the fact remains that mineral is an organoleptic descriptor widely used for over twenty years now, despite – it must be acknowledged – it has often been used inappropriately and carelessly. So, while waiting for a valid alternative descriptor to be found, and hopefully even the certainty of a rigorously scientific definition and explanation, we can continue to use the term “mineral”. Possibly, it seems appropriate to say, cum grano salis.