Another article on mineralization… The time was over 15 years ago when I first published an article on the subject, and I’ve been asked for many more since then, just like many other writers. There are conferences, masterclasses, and seminars on the wine’s mineral content, and yet they keep in the pipeline. What is it about this topic that is still captivating?
It’s hard to say, but perhaps it’s an encapsulation of the practical utility of the term in evoking the cherished relationship between wine and soil – and the ongoing absence of consensus about what it really is.
The fact that the word “attractive” is used is evident and is not limited to wine only. Minerality is reported from tea, beef, watercress, 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 minerals?
Reporting and recognizing mineralization
The first question is how do we perceive it? It is different. A recent study found that 20% of wine experts observed minerality in Chablis wines by tasting and 16% via smell. The remainder utilized both senses. Incredibly, the three groups differed significantly in their evaluations of the strength of the mineral content and expressed it in different ways.
In the scent-only state, around two-thirds of minerality is correlated to scents like gunflint or reductive and the absence of fruit; however, (when you clip your nose), approximately the same percentage was associated with bitterness and acidity. Another study found that French tasters were more dependent on smell than tasters from New Zealand, who tended to use both their nose and the palate.
Another study has revealed that when both the sense of smell and taste are utilized, the wine’s acidity is crucial. In contrast, by relying on smell alone, the specific variety becomes more prominent. Which grapes are more likely to have minerality?
The study conducted by the Spanish University of La Rioja of red wines made of Tempranillo, Syrah, and Grenache has revealed weak responses and inconsistent patterns. Minerality is usually found in white wines, even though there is disagreement over the specific varieties.
In a research conducted by the Californian UC Davis, Riesling, Pinot Gris, and Sauvignon Blanc wines were found to be more mineral-based than Chardonnay wines. (It’s important to note that the latter wine was also Chablis, which is a classic mineral wine.)
Of course, most vines are grafted, and it’s that rootstock instead of the cultivar that communicates to the earth. I’m not aware of any studies which examine the importance of rootstocks on mineralization.
Being aware of something you’ll refer to as minerality is only the beginning. How will you communicate to others what you’re referring to?
Numerous studies have classified the words used to describe minerality into groups, such as acidity, freshness, and tension and seashore-related items like iodine, saltiness, and shellfish, as well as stone-related experiences such as hot or wet stones, flint, and chalk.
According to one study, winemakers strongly preferred using words that reference soil and location and also viewed minerality as positive, in contrast to the negative and ambiguous meanings attributed to certain consumers.
Another example of the problem with communication is the various words used by research teams from Lincoln University in New Zealand and in Cali’s UC Davis. Both teams found positive connections between minerals and terms such as fresh, citrus and zingy, flinty and smoky; Lincoln researchers differed from the ones at Davis in observing no correlation with acidity or notes that were reductive.
A study found that minerality was a different concept in the eyes of Swiss or French wine drinkers. It was found that the Swiss group had a significantly more expansive vocabulary. Another study revealed that the words used to describe minerality were based on the level of education that was present, ranging from ignorant respondents having never heard of minerality to comparisons to bottled water (especially loved, for no reason, among female tasters) and the significance for experts of acidity the earthy and terroir flavors.
What is minerality in wine due to?
Given the contradictions mentioned above and the inconsistencies above, it’s no surprise that scientists be unable to determine the factors that could cause the perception we call minerality. A majority of research has focused on the potential roles played by acidity and reductive sulfur compounds, as well as the absence of fruit.
In relation to acidity, one of the first studies published of Italian Rieslings along with Gruner Veltliners, suggested the weak succinic acid that tasted slightly saline-tasting however, this suggestion has not been confirmed.
Another study, conducted by UC Davis, reported that professional tasters discovered minerality in wines that had higher acidity in tartaric and malic acids and in lesser amounts free and total sulfur dioxide. However, a New Zealand study, while suggesting a role for sulfur dioxide, found no connection between perceived minerality and acidity or notes that were reductive.
Numerous studies have found a connection with sulfur compounds, including methanethiols, polysulphanes and other methanethio. In their unselfish quest for knowledge of what’s happening that surrounds us, the Swiss team was looking at the smell of toilets (yes, you read that right, toilet malodours when they accidentally identified ‘a like a flint odor’ and determined that it was caused by hydrogen disulphane, also known as HSSH. The team then discovered that, when they tasted blindly Swiss Chasselas wines The two that had higher mineral content contained significant amounts of HSSH than the other.
In addition, despite studying the vast array of possible compounds, the studies up to now haven’t established a definitive connection to mineral density and reduction processes.
Similar to the way that tasting statistics provide some evidence to the perception of minerality stemming from a deficiency of other wine-based flavors, however, this has not been verified by an analysis of the chemical composition. For instance, the absence of the well-known aromatic components in Sauvignon Blanc Wines (,e.g. Isobutyl Methoxypyrazine and thiols) is not supported by higher levels of minerality.
What about the winery?
It is possible that minerality originates is not from the organic compound that are produced by vinification but comes from soil – precisely as the name implies. This is in line with the notion that it’s connected to stones, earthiness, slate, flint, chalkiness and all the rest.
There are some studies that link minerality with place, like the study of Chablis wines that were sourced from the right and left banks of the Serein River. The wines that were from the left bank, when analyzed solely by smell showed more minerals. When analyzed, they revealed higher levels of methanethiol, a sulphur-containing compound (which has a sour shellfish scent) and less copper likely due to the soil.
The authors speculated that on the right bank, the greater amount of copper might be reacting with methanethiol, resulting in an unodourless substance, and thus reducing perceived minerality. It is interesting to note that the great crus of Chablis (all located on one bank) provide less mineral-rich wines.
