When drinking wine, there is an expression you will inevitably encounter somewhere along the way: "mineral character" or "minerality." Even those who haven't heard these terms yet will almost certainly encounter them in the relatively near future, as they are used with remarkable frequency.
This expression of mineral character is also a contentious one, having been the subject of various debates over the years. What exactly is this sensation we call "mineral character"?
The frequent use of mineral character as an expression is said to have begun around the year 2000. Despite being used regularly for over twenty years now, there is still no definitive answer to the question of what kind of sensation mineral character actually represents.
Wines with mineral character continue to remain simply wines that have "something of a mineral-like feel to them."
You could say that mineral character is an expression that, while vague in definition, is convenient to use. This article will summarize what we currently know about what mineral character ultimately is.
What Constitutes a Wine with Mineral Character
There is no clear definition of mineral character as an expression. Therefore, there is no correct answer to "this is what a wine with mineral character is." On the other hand, the image of what typical wines with mineral character are like is considered to be roughly established. The conditions thought to define such wines are as follows:
- Wines made from grapes grown in cool regions
- Early harvest to avoid over-ripening
- High acidity
- Reductive winemaking
- Addition of SO₂
Wines that meet these conditions are said to be judged as having minerality with very high probability.
Mineral Character is Perceived Through Taste
Have you ever tasted minerals when drinking mineral water? Probably not. Minerals are tasteless and odorless, except for a few compounds like chlorides. Minerals are not something we perceive through taste.
Among substances called minerals is one called silicon dioxide, which is used as a raw material for glass. If minerals had taste, then wine glasses made from minerals would also have taste. The bottles containing wine are also masses of minerals.
For wine enjoyment, it would be problematic if minerals had taste.
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The Scent of Wet Stone as Mineral Character
Of course not, I would like to say, but it cannot be dismissed as completely wrong.
The aroma perceived as wet stone is not the scent of minerals. Minerals themselves are odorless. If they had scent, mineral aromas would waft from wine glasses and from cheese plates placed nearby. When trying to capture aromas while drinking wine, the glass is closer to your nose than the wine itself. Mineral water doesn't smell either.
However, aromas reminiscent of wet stone are frequently described as "mineral character." The wet stone aroma is often attributed to sulfur dioxide, known in Japan as a preservative called SO₂. The inclusion of SO₂ addition among the typical conditions for wines with mineral character stems from this point.
"Mineral character" is not about perceiving minerals themselves.
Minerals Derive from Terroir
Terroir. This word might compete with mineral character for the top spot among frequently heard wine-related terms. Wine's mineral character is often said to derive from terroir.
Even among the typical conditions for wines with mineral character, those from cool regions are mentioned. However, this is incorrect. The mineral character perceived in wine does not reflect the nature of terroir.
The reason terroir and mineral character are discussed together is that the minerals (supposedly) responsible for mineral sensations were thought to derive from the soil of the vineyard where the grapes used for that wine were grown. Incidentally, this way of thinking is now gently dismissed as romantic fantasy.
There are two ways to explain why this seemingly plausible idea is actually fantasy.
First, minerals are tasteless and odorless. Mineral character is about sensing "something that gives a mineral-like impression," not sensing minerals themselves. Since minerals themselves are not the true nature of mineral character, the minerals contained in vineyard soil are also unrelated to mineral character.
Second is grape plant physiology. Grapevines do not absorb minerals from soil indefinitely through their roots. They only absorb the amount necessary for their growth. This means that no matter how mineral-rich the vineyard soil might be, the excess is simply carried over for future years' growth. The idea that grapes grown in mineral-rich soil accumulate abundant minerals in their fruit, which can then be sensed in wine, simply doesn't happen.
Moreover, it has recently been pointed out that an increasing number of low-priced, mass-produced wines exhibit mineral character. It is difficult to connect such wines with terroir.
Mineral Character is the Same in Both Red and White Wines
This is incorrect. While mineral character can be perceived in both red and white wines, recent research suggests their underlying nature is different.
To reiterate, mineral character is about imagining "something mineral-like" and expressing it in words. This "mineral-like something" is not minerals, nor is it any specific substance. If you sense something "mineral-like" in a wine you taste, that becomes a wine with mineral character.
The cause of this "mineral-like" sensation appears to derive from acidity and low pH in white wines, while in red wines it may stem from alcohol content and tannins. The key factor appears to be freshness from acidity and astringency.
It should also be noted that the elements contributing to mineral character perception vary according to the cultural background of the drinker. For example, reports suggest that for French consumers, total acidity and tartaric acid levels work negatively on mineral character perception.
Mineral Character is Determined by Grapes
This is incorrect. It is not determined by grapes.
Related to the terroir discussion above, there is a belief that since the minerals responsible for wine's mineral character are contained in grapes from the vineyard, subsequent winemaking processes cannot increase the wine's mineral character.
Since the cause of mineral character perceived in wine is not minerals, this reasoning is meaningless from the start. However, even setting that aside, the amount of minerals actually increases and decreases during winemaking processes. For example, in clarification using bentonite, bentonite itself is a rock composed mainly of montmorillonite, a clay mineral. Adding this to grape juice or wine causes minerals to leach out. The same occurs with diatomaceous earth filtration.
During winemaking processes, the amount of minerals contained in wine both increases and decreases.
Next, even when considering the cause of mineral character to be some non-mineral component, this also changes during winemaking processes. The addition of sulfur dioxide is a typical example of this.
The possibility that mineral character perceived in wine is created through winemaking processes cannot be denied.
Succinic Acid as the Causative Substance for Mineral Character
This is not incorrect, but it's not everything either.
Describing saltiness as mineral character is not uncommon. Succinic acid is said to become increasingly astringent at high concentrations, but at the low concentrations found in wine, it is perceived as saltiness. Additionally, reports show that succinic acid's influence on mineral character perception is greater in red wines than in white wines.
Incidentally, this succinic acid is known as an umami component abundant in shellfish. Correspondingly, in wine's mineral character, nuances reminiscent of shellfish, particularly oyster shells, have been identified as important factors.
Substances that give wine shellfish or oyster shell nuances include not only succinic acid but also yeast and methyl mercaptan (also known as methanethiol: MeSH). MeSH in particular is said to be a causative compound for shellfish odors and has been identified as having strong correlation with wine minerality.
Mineral Character is an Off-Flavor
In terms of expression, this differs, but in terms of causative substances, it cannot be completely dismissed.
"Mineral character" and "minerality" used in wine descriptions are fundamentally positive expressions. However, when exploring the causes of mineral character perception, many lead to off-flavors—so-called defective aromas.
Among the various elements identified as causes of mineral character perception, sulfur compounds play particularly important roles. These include thiol compounds containing the aforementioned MeSH, as well as SO₂—all sulfur-based compounds. 3-Mercapto hexanol (3-MH), known as the cause of characteristic aromas in Sauvignon Blanc and Koshu, is also a type of thiol compound. 3-MH has citrusy aromas and is said to be a factor contributing to mineral character perception.
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As indicated by reductive winemaking being among the typical conditions for wines with mineral character, reductive aromas perceived in wine are known to be one cause of mineral character perception. Both SO₂ and MeSH are causes of reductive aromas. MeSH in particular oxidizes to become disulfide, which causes the flint-like aroma that is one of the typical scents associated with mineral character perception. Furthermore, MeSH exhibits weak acidity, so increased concentrations lower wine pH. Low pH is also one of the causes of mineral character perception.
On the other hand, MeSH at high concentrations becomes the cause of rotten onion-like malodors. Even without this, the sulfurous odors and cabbage-like smells that thiol compounds possess are typically judged as off-flavors when present in wine. Even 3-MH, described as having passion fruit or grapefruit aromas, becomes the cause of malodors described as cat urine at high concentrations.
Additionally, oxidation, considered wine's great enemy, is said to be positive for mineral character when it occurs mildly.
While it's all a matter of degree, much of mineral character is perceived from substances similar to those causing off-flavors.
Summary | What Mineral Character Ultimately Is
Like the famous Chanel perfume anecdote, intentionally including trace amounts of components generally recognized as malodorous in fragrances intended as pleasant scents to add depth is now commonplace. From this perspective, there is nothing particularly surprising about off-flavor causative substances being responsible for mineral character. Anything becomes toxic in excess.
Multiple studies have demonstrated that mineral character (not minerals) can be perceived through both aroma and taste. In other words, mineral character is both taste and aroma.
The substances causing the tastes and aromas associated with mineral character perception are diverse. Compounds thought to contribute to mineral character perception include the aforementioned sulfur compounds, acids, and tannins, as well as isoamyl acetate (banana-like aroma), ethyl acetate (pineapple-like aroma), acetic acid, and γ-decalactone (osmanthus-like aroma, also famous as a causative substance for the sweet scent characteristic of young women).
What minerals people imagine and find "mineral-like" based on these aromas and tastes varies from person to person. Within current understanding, sulfurous aromas including shellfish odors have relatively strong influence as aromas, while acidity and tannins that provide freshness are important as tastes. However, even these do not work independently—mineral character is thought to result from combinations of multiple sensations.
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While the components responsible for mineral character perception in taste and aroma are being identified, there is also a school of thought that mineral character is neither taste nor aroma. Simply put, it's similar to astringency and puckering sensation. Astringency and puckering are felt in the mouth but not through taste buds on the tongue—they are tactile sensations felt when mucin, a protein in saliva and on the tongue surface, binds with tannins and is removed. In mineral character's case, mucin is not being affected, but the sensation might be perceived in similar tactile areas. This might be close to the difference felt when drinking mineral water compared to regular water.
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Is it smell, taste, or tactile sensation? Or is it a mixture of all these elements?
Ultimately, the expression "mineral character" seems to settle on being a versatile term for describing something hard and mineral-like that remains vague and somehow fits when we imagine minerals—even today.
