This article will provide an overview of the current research on minerality in wine, highlighting the factors that influence it and the need for further investigation to understand its true nature.
Wine is a complex beverage, and sensory experiences like minerality are often attributed to it, but the exact factors involved in creating such characteristics are not well understood. The term “minerality” is commonly used by wine critics and enthusiasts to describe a range of sensory experiences in wine, including earthy, flinty, stony, iodine, and salty flavours, among others. The scientific understanding of what causes these perceptions has been elusive.
Minerality in wine refers to a perceived taste or aroma reminiscent of minerals or rocks, such as slate, flint, or wet stones. It is often associated with wines from cool climates and certain grape varieties, such as Chardonnay, Riesling, and Sauvignon blanc. It is typically described as a positive quality that adds complexity and depth to the wine.
In the past, the most popular hypothesis for the origin of mineral character in wine was that it came directly from inorganic minerals in the vineyard soil. However, recent studies have shown that this is not the case.
So, what is causing the perception of minerality in wine? Researchers are still working to answer this question, but some promising findings have emerged.
Sulphur compounds
Research has indicated a link between minerality and low concentrations of sulphur-containing molecules. Some people, especially experts, perceive these low concentrations of reductive aromas as minerality. Studies have found a significant link between methanethiol and the chalky/shellfish aroma associated with minerality, often a characteristic of left-bank (of the Serein River) Chablis. Methanethiol also exerts a masking effect on fruity and floral notes, thereby enhancing the perception of minerality.
Another study found that benzene methanethiol, also known as benzyl mercaptan or BMT, elicits flinty/smoky aromas when present in Sauvignon blanc. A statistical link was also found between BMT and the presence of flint and wet stone notes in Australian Chardonnay. Hydrogen disulphanes and trisulphanes are also linked to flinty aromas in dry white wines. These sulphur-containing molecules can be derived from microbiological or chemical reactions during winemaking and even after bottling.
In contrast to all the findings from studies linking sulphur aromas to minerality, results from two studies could not find any relationship between volatile sulphur compounds associated with pungent aromas and perceived mineral intensity scores.
Positive relationships between perceived minerality and free, bound, and total SO2 were reported in some studies. Therefore, SO2 in wine is an important factor to consider in future research.
The absence of fruitiness
It has been hypothesised that minerality is merely the absence of fruitiness and wine flavour. However, a study found no significant relationship between the concentrations of key aroma compounds of Sauvignon blanc and perceived minerality.
Grapes from cooler areas are often less ripe when picked than grapes from warmer regions and are more often associated with mineral characteristics. Minerality is more often associated with the cooler left-bank Chablis than the right-bank Chablis. A study comparing left- and right-bank Chablis found the left-bank Chablis to have less fruity aroma compounds (norisoprenoids) and higher methanethiol concentrations. It seems that it is only when “the absence of fruitiness” is accompanied by methanethiol that a mineral perception becomes more likely.
Acidity and pH
Acidity is also often associated with minerality in wine, but the evidence on the topic is mixed. Some studies have reported a positive association between succinic acid and attributes related to mineral character, while others have associated malic acid with minerality. Some researchers also reported tartaric acid as a predictor of minerality, while in contrast, others reported that tartaric acid and titratable acidity were associated negatively with minerality in their study. This study also found no significant effect of pH or other organic acids measured on the mineral perception of a wine.
Compounds producing saltiness
Although wine typically contains little salt, some studies associate a salty taste with minerality. However, none of the sensory studies aimed at understanding the perception of minerality reported intensity judgements of saltiness in the wines evaluated.
Conclusions
Overall, the latest research on minerality in wine suggests that the topic is complex and multifaceted, with many factors influencing the perception of mineral character. While the precise chemical compounds responsible for this perception are still being identified, the popular notion that mineral character in wine comes directly from inorganic minerals in the vineyard ground is not scientifically plausible. As researchers continue to investigate this topic, we can expect to gain a deeper understanding of the mechanisms behind this intriguing aspect of wine.
References
Malfeito-Ferreira, M., 2022. Wine minerality and funkiness: Blending the two tales of the same story. Fermentation 8(12): 745.
Parr, W.V., Maltman, A.J., Easton, S. & Ballester, J., 2018. Minerality in wine: Towards the reality behind the myths. Beverages 4(4): 77.
Rodrigues, H., Sáenz-Navajas, M.P., Franco-Luesma, E., Valentin, D., Fernández-Zurbano, P., Ferreira, V., De La Fuente Blanco, A. & Ballester, J., 2017. Sensory and chemical drivers of wine minerality aroma: An application to Chablis wines. Food Chemistry 230: 553 – 562.
For more information, contact Karien O’Kennedy at karien@winetech.co.za.
Click here to get your copy of WineLand Magazine and here to subscribe to our newsletter.
