Minerality in wine: Where are we now?

It was over 15 years ago when I first published a article on the subject and I’ve been asked to write numerous pieces since then, along with numerous other writers. There are conferences, masterclasses and seminars on the mineral content of wine, and they continue to come. What is it that’s so fascinating about this topic that keeps attracting people?

Perhaps it’s the blending of the practical utility of the word that is evocative of the well-loved relationship between wine and soil – and the ongoing inconsistency on what the word really signifies.

The word “attractive” is apparent, and it’s not just with wine Minerality is reported from tea, beef watercress and maple sugar oysters, milk cannabis… So, where do we stand today, an understanding of the perception we get from certain wines we refer to as mineral?

Reporting and recognizing mineral content

The first question is what is the first way to detect it? It differs. According to a recent study, 20% of wine experts identified mineral content in Chablis wines by tasting and 16% through smell. The remaining utilized both senses. Incredibly, the three groups differed markedly in their evaluations of the strength of the minerality and expressed it in different ways.

In the scent-only state, around two-thirds of the minerality was correlated with scents like gunflint or reductive and absence of fruit, and (when you clip your nose) approximately the same percentage was correlated with bitterness and acidity. A different study concluded that French tasters were more dependent on smell than tasters of New Zealand, who tended to use both the nose and the palate.

Some studies have also found that when the sense of smell and taste are utilized, it is the level of acidity that the wine has to be significant in comparison to smell alone. the particular grape variety gets more attention. What grapes are most likely to have minerality?

The study conducted by the Spanish University of La Rioja of red wines made of Tempranillo, Syrah and Grenache have revealed weak responses and inconsistent patterns. Minerality is typically related to white wines, but there is some disagreement about the specific varietals.

In a study conducted at the Californian UC Davis, Riesling, Pinot Gris and Sauvignon Blanc wines were deemed to be more mineral-based as Chardonnay wines. (It’s important to note that the latter also included Chablis as well, which is the most iconic mineral wines.)

Of course the majority of vineyards are grafted and it’s it’s the rootstock instead of the cultivar that communicates to the earth. I’m not aware of any studies which examines the importance of rootstocks on mineralization.

The feeling of a thing you’ll refer to as minerality is only the beginning. How will you communicate to others what you’re referring to?

A number of studies have put the words used to describe minerality into different groups, such as acidity, tenseness, and freshness related to seashores, such as Iodine, saltiness, and shellfish; as well as stone-related experiences like hot or wet stones, flint, and chalk.

According to one study winemakers strongly preferred using phrases that evoked soil and location and perceived minerality as positive, in contrast to the negative and ambiguous meanings attributed to certain consumers.

Another example of the issue with communication is the numerous word-related associations uncovered by research teams located at Lincoln University in New Zealand and in Cali’s UC Davis. Both teams found positive relationships between minerality and other words like fresh, citrus as well as flinty, zingy and smoky, Lincoln researchers were different from those at Davis in that they found no connection with acidity or reductive notes.

One study revealed that minerality was a different concept in the eyes of Swiss as well as French wine drinkers as well as it was found that the Swiss group had a significantly more expansive vocabulary. Another study showed that the language used to communicate minerality depended on the level of education that was present, ranging from novice respondents who had never known about minerality, from comparisons to bottled water (especially loved, for no reason, among female tasters) as well as the importance for experts in acidity the earthy and terroir flavours.

What is minerality in wine due to?

Given the inconsistent results and the aforementioned inconsistencies, it’s no surprise that scientists continue to have difficult identifying what in wine could trigger the impression we call “minerality”. The majority of studies have focused on the potential roles played by acidity as well as reductive sulphur compounds, and the absence of fruit.

In relation to acidity, one of the first studies published that focused on Italian Rieslings as well as Gruner Veltliners, indicated the weak succinic acid that tasted slightly saline-like, however this claim has never been confirmed.

An additional study, by UC Davis, reported that professional tasters discovered minerality in wines that had higher tartaric and malic acidity, and in lesser amounts free and total sulfur dioxide. However an New Zealand study, while suggesting a role for sulfur dioxide, found no relationship between perceived minerality and acidity or notes that were reductive.

A number of studies have suggested a role for sulphur compounds like various methanethiols as well as polysulphanes. In their unselfish quest to greater comprehension of our world that surrounds us the Swiss team was looking into the smell of toilets – yes, it’s true: toilet malodours and they discovered the odour ‘like flint’ and found it was caused by hydrogen disulphane, also known as HSSH. They found that when they tasted blindly Swiss Chasselas wines the two wines with higher mineral content contained significant higher levels of HSSH than the other wines.

However, despite examining the vast array of possible compounds, the studies up to now haven’t established a definitive connection with minerality or reductive processes.

In the same way, while tasting data provide some evidence to the impression of minerality stemming from the absence of other wine flavors however, this has not been confirmed through chemical analysis. For instance, a lack of the key aroma components of Sauvignon Blanc wine (eg Isobutyl Methoxypyrazine and thiols) is not supported by higher levels of minerality.

Chablis Limestone Soil

But what happens to the winery?

Minerality may come and not through organic substances that are produced by vinification, but from soil, exactly like the name suggests. This could be in good accordance with it being connected to stones, earthiness, slate, flint and all the rest.

There is some research which links minerality to location like an analysis of Chablis wines that were sourced from the right and left bank of the Serein river. The wines that were from the left bank if analyzed solely by smell they showed more minerality. After analysis, they showed higher levels of methanethiol, a sulphur-containing compound (which has a sour shellfish scent) and less copper which is likely to be a result of the soil.

The authors speculated that on the right bank, the more abundant copper could be interacting with methanethiol, resulting in an unodourless chemical, consequently, decreasing perceived minerality. It is interesting to note that the top sites of Chablis (all located on one bank) offer less mineral-rich wines.

Many commentators accept the science-based arguments that minerality isn’t simply caused by vines collecting geological minerals from the soil and transferring them to the final wine we drink. However, for many, the term has significant geological meanings.

But, the earthy terms that are associated with minerality need to be metaphors, mental images and recollections from an earlier encounter with rocks, not the actual tasting of the geological substances that originated found in the vineyards. Here’s why.

The rocks have no taste. Every stone surface exposed the air is soon going to be coated with a variety of algae, bacteria molds, lipids, moulds and other such substances that are everywhere and that produce highly fragrant vapours when they are heated during a sunny day or when wetted by the rain.

Similar to tilled earth damp cellars, tilled earth and pebbles that have been struck emit familiar scents, but they are not part of the rock themselves. You can easily test this if can access a saw and various kinds of rocks. The smooth, freshly sawn surface will provide a cool feel on your tongue, however they not smell or taste. If you bite and smell the rocks with your eyes closed, you won’t be able tell the two rocks from one another. It appears to me that speaking of a “taste of slate’ or similar must involve imagination in a positive manner – imagining what it might be like in the event that slate were to have an odour.

Grey Slate Soil

The science of soil and wine taste

Vines take up dissolved chemical elements (with a positive electrical charge and hence properly called cations) from the soil, often called nutrients or just ‘minerals’. These elements are slowly unlocked from geological minerals by weathering, but in practice are largely derived from the organic material – the humus – in the top metre or less of the vineyard soil.

In the deepest parts the subsoils and the unweathered bedrock are not able to provide much nutritional value. Consequently, vines form deep roots to find water sources. Roots that are deep are a great factor for maintaining the water flow to the vine but they’re not accessing some kind of magic below.

In the same way, stony soils commonly believed to boost minerality, but the rocks exist because they’ve stood up to weathering and are therefore inert.

Wine critics often use phrases like ‘mineral rich soils’ and suggesting that this leads to more minerality in wine. This certainly sounds appealing however all soils and rocks comprise out of (geological) mineral substances, and not any more or less than the others.

If it’s high in nutrients it’s like calling it fertile. And it’s almost universally accepted in winemaking that fertile soils are not to be avoided since they cause higher vigor, lower quality of the grape and poor wine.

Chablis Fossils in Bedrock

The nutrients are vital for the growth of the vine, however their source isn’t important. The fossil oysters from Chablis for instance, are widely known and frequently believed to induce minerality however, the organisms are able to survive since they were replaced by a sturdy geological mineral, which is in this instance Calcite. Minerals that are nutrient-rich that vine roots acquire from these fossils are undistinguishable from those found in soils that host them, or, to be more precise the fertiliser.

Some of these minerals could make it in the final wine, along with the other nutrients introduced in the process of vinification. While most likely, they cannot be tasted as a group, they can affect our perception of taste. But these effects can be complex and a bit tangled, which is quite different from directly tasting minerals derived from the soil of the vineyard.

Sometimes, comparisons are drawn between the mineral content of wine and the flavor of certain water bottles. In spite of the fact (from time to time, gleefully published in tabloids) that blind tastings many people cannot tell the expensive bottled water from tap water and even differentiate the difference between bottled and tap water There are two things to consider.

The majority of bottled water comes directly from groundwater, and it’s remained for lengthy durations (the typical time for residence in the UK is over 100 years) directly in contact with the aquifer that hosts it. Anything that is water-soluble is absorbed from the ground by water. This is a far cry from the controlled uptake of cations from the vine’s roots. Therefore, the mineral levels in the water that is bottled are usually higher than those in wines, but most importantly unlike wine, they may contain numerous anion (negatively chargeable). These are the primary inorganic components that enhance flavour and mouthfeel.

There’s a saying in the beer industry that, while the cations in water control the processes, it’s the anions that create the flavor. The effects of dissolving anions in the taste of beer are apparent in beer.

In particular, traditional ales of England’s Burton-on-Trent are bursting with bicarbonate and sulphate content (the reason behind the sulphur-rich “Burton snatch” that is adored by beer lovers). The same is true for Tadcaster, England, when Samuel Smith’s brewery was contemplating bottling the delicious well-water that is used in their ales, it were forced to abandon the idea due to the amount of sulphate present exceeded the limit permitted in bottles of water.

However, the most striking way in which minerality is usually emphasized is beer that comes originated from that Czech city located in Plzen (Pilsen) is known to have extremely low mineral amount.

Minerality in wine

If the wine’s minerality was due to minerals It should be easy to boost it by adding more. However, for a variety of reasons, it isn’t working.

In one instance water tasters have reported that when the presence of these cations is more and more apparent, the flavor gets more unpleasant. Because water does not contain flavor compounds that compete with it and wine has no such flavour compounds, the thresholds of detection have to be significantly higher, and most likely, more unpleasant. This doesn’t seem like what we would call “minerality”!

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