Why I am confused by wine-searcher.com's article "The Reality of Minerality"

Today I read a confusing (for me) and somewhat disingenuously titled article on wine-searcher.com called "The Reality of Minerality." Having written extensively on the topic on this blog, I was intensely interested and clicked through thinking that I had missed some grand development that had cleared up this abiding mystery once and for all. It was not what it appeared to be. As a matter of fact, I have some issues with the article and the report on which it is based; at least the elements of the report that are shared in this article.

The article was reporting on a study whose objective was to use trained sensory judges in New Zealand and France to investigate cultural differences in the perception of minerality," with the cultural differences arising around Sauvignon Blanc production processes and style. According to the wine-searcher article, the "results suggest that the concept is very real." Note that we have gone from the definitive "reality of minerality" in the title to the "concept" here. Further, a "concept" is defined as a "general idea or understanding" while "real" is defined as "being or occurring as fact" or "having verifiable existence." Is the author suggesting here that the idea of minerality is a verifiable fact? Because that is inaccurate. The traditional idea of minerality in wine revolves around the idea that minerals from the ground are somehow absorbed into the vine, transported into the fruit, and survives the rigors of fermentation to present "itself" unscathed to the taster's palate. And, being from the Maltman school, I do not buy that.

The lead author on the underlying study is quoted in the article as saying "Lack of perceived flavor was associated with the perception of minerality ... If there was nothing much else in the wine, people resort to calling it mineral by a process of elimination." This is not an argument for minerality; this is an argument against lack of flavor in wines and posits a fallback position for tasters: "If I cannot check any other box, let me check mineral." As a matter of fact, this is the headline here: "The perception of minerality results from an absence of detectable/describable flavors in wine." I can see the big-time tasters buying-in to that concept.

And maybe the issue here is the word minerality. We know that minerals cannot be smelled or tasted so why do we persist in acting as though we can taste and smell minerals in our wine. I am willing to concede that there is some sensation that I experience when I drink some white wines that is not adequately described by the available population of descriptors. But minerality is too loaded. Perminality anyone.

The article closes with the lead author stating "We are still not sure what minerality is." You probably should not be saying that in an article titled "The Reality of Minerality."

©Wine -- Mise en abyme

Part III of my review of Jamie Goode's "Rescuing Minerality"

This is the final installment of a three-part review of Jamie Goode's post titled "Rescuing Minerality." Where the first and second installments examined Jamie's discussions of terroir and the contribution of soils to wine quality, respectively, this post hones in on the elemental core of the article, minerality.

Jamie begins this section of his post by remarking on the relative youth of the term minerality in relation to wine. In this he is aligned with Alex Maltman (Minerality in Wine: A Geological Perspective, Journal of Wine Research, 2013) who, as I described in my post on the topic, sees minerality as "... a thoroughly modern invention which had received no mention in the works of the 'masters' (Peynaud 1987 and Vine 1997, for example) or the science-based tasting schemes (Jackson 2009 and Noble et al., Aroma Wheel 1987, for example).

Jamie takes issue with a "literal view" of minerality where it is characterized as "... the perception of the rocks in the soil, by the palate." In taking that position, he is aligned with the aforementioned Maltman. The two charts below (derived from Maltman) show (i) the differences between the types of minerals found in wine and geological minerals and (ii) an example of the path ("protracted, rocky, and time-variant") that a geologic mineral has to traverse in order to be usable to a vine.

The above shows some of the difficulty in tasting geologic rock in wine but, further, absorption and distribution of the cations by the vine plant, and cellar activities associated with winemaking, further dis-associate the minuscule amounts of minerals found in wine from the geologic minerals in the vineyard.

Jamie identifies aroma and taste as the areas in which minerality has been mentioned (I will add "texture" to that list.). In his discussion, Jamie specifically refers to a matchstick/mineral character in white wines and then dismisses it as a volatile sulfur compound created during alcoholic fermentation. I have not researched this particular area. I have, however, looked at the aroma described as "earthy minerality" and my research shows this to be an off-odor caused by geosmin, a secondary metabolite produced by the fungus species Penicillum expansum. The final nail in the aroma coffin is Maltman's assertion that aroma requires volatilization in order to register on the organs of the olfactory bulb. Neither rocks nor minerals possess this capability.

Before turning to Jamie's discussion on taste I would like to explore the category which I have contributed -- texture -- and relate it to the term "chalky minerality." Based on the work done by an Australian and French research team (S. Vidal et al., Use of an experimental design approach for evaluation of key wine components on mouth-feel perception, Food Quality and Preference 15, 2004) and reported on in Wine Business Monthly (Bibiana Guerra, Key Wine Components in Mouthfeel Perception, November 2011), we learn that chalkiness is an astringency categorization (along with pucker, adhesive, dry, medium-surface smoothness, and coarse-surface smoothness). According to sensorysociety.org (and Richard Gawel, Secret of the Spit Bucket Revealed, aromadictionary.com), astringency is a tactile sensation, rather than a taste, and is primarily caused by polyphenolic compounds contained in certain foods (including wine) but can also be caused by acids, metal salts (such as alum), and alcohols. A key characteristic of astringency is the fact that it is difficult to clear from the mouth and, as such, builds in intensity on repeated exposure to the source. The source of astringency in wines is tannins.

Jamie divides taste in minerality into two areas: those associated with high-acid whites and those having a taste of "salty minerality." The "mineral" taste associated with "high-acid" white wines is quickly dispatched with an admonition that they should be so described. The "salty minerality" is described by Jamie as being the "best use of the term" and he asks whether this could be "caused by mineral salts in wine, absorbed by vine roots." He posits that the minerality of wine fluctuates between 1.5 g/L and 4 g/L "which may be enough to confer some flavour on the wine." The Waterhouse Labs at UCDavis places that range at 0.2 to 2 g/l while winesofczechrepublic.cz places the range at 1.8 g/l to 2.8 g/l. Second, it seems (and please correct me if I am wrong) that there is an attempt here to equate mineral salts with saltiness but, according to Wikipedia: magnesium ions are sour to the taste; dilute solutions of potassium taste sweet; and calcium ions vary to human taste, being reported as mildly salty, sour, "mineral-like," and "soothing." Further, if there were to be a mineral taste imparted by these salts it would most likely be aligned with the potassium ion (sweet) as that ion comprises 50-70% of the mineral concentration in grape juice.

Jamie points to two cases as evidence that the soil type influences the mineral composition of the wine. He did not have to go that far. We know that different soils have differing CEC and will result in more or less minerals being available in the soil. But that does not prove that the wine tastes mineral. He shows where Anders Pueke grew Riesling in three different soils and then found chemical differences when the sap was analyzed. Notice here he said chemical differences. I am not sure if he meant mineral differences. Because chemical analysis does not advance the point. Further, was minerality (salty) found moreso or less so in the wines? He also mentioned Randall Grahm placing rocks into wines and getting a textural change. As Stephen Mense points out in his post (Rocks in our wine ... or just our heads? tableintime.com, 10/31/12), Grahm's intent was to "determine if minerally flavors and aromas would be communicated" from the rocks to the wines. Mission unaccomplished as "the alterations did not have the effect of making the wines taste more like rocks or gravel."

According to Jamie, "It follows that increased soil microlife could lead to more mineral wines." I am missing something. I can agree that increased soil microlife could be beneficial in a number of ways but I do not see how it leads to more mineral wines. I would be willing to say that increased soil microlife would eventually result in increased mineral levels in the soil but it is not clear that that automatically translates into increased mineral uptake by the vine plant. Nor does it show that these additional minerals would be delivered to the fruit versus other parts of the plant. And, why is this not a constant. Why are not all wines (red or white) that are subjected to organic/biodynamiic treatments exhibiting this salty minerality?

I am not sure but this looks like an awesome leap of faith to me.

©Wine -- Mise en abyme

Minerality in wine? Fuggedaboudit

Or so says Alex Maltman of the Institute of Geography and Earth Sciences, Aberystwyth University, Wales.

In a previous post, I outlined a battle revolving around the role of soils in wine quality/typicity. Alex Maltman (Role of Vineyard Geology in Wine Typicity, Journal of Wine Research 19 (1), 2008) noted that it had become de riguer, when describing a vineyard, to specify its geology and this, coupled with the geological indications common in tasting notes, has served to infer "... a direct link between the vineyard substrate and the resulting wine." According to Maltman:

Such perceptions bolster a valuable tactic for the wine trade, as, being one of the few aspects of wine production that cannot be translocated or easily replicated elsewhere, a vineyard's geology is something that can be invoked to promote a wine's typicity, to give it a marketable uniqueness.

In a follow-up article (Minerality in Wine: A geological perspective, Journal of Wine Research, 2013), Maltman has honed in on minerality, a thoroughly modern (according to him) invention which had received no mention in the works of the "masters" (Peynaud 1987, and Vine 1997, for example) or the science-based tasting schemes (Jackson 2009 and Noble et al., Aroma Wheel 1987, for example). Maltman's 2008 and 2013 articles are built around a similar core argument but in the 2013 article, in addition to focusing on minerality, he advances explanations as to what tasters could be confusing with minerality. The latter aspect of his research will be dealt with in a later post.

There is, in general, a lack of understanding of the differences between minerals in foodstuff (of which wine is a part) and geological minerals (Maltman).

While it is true that the vine plant needs a variety of mineral nutrients, and that weathered bedrock is the source of much of these nutrients, the path from geological mineral to nutrient mineral is a protracted, rocky, and time-variant road.



To illustrate the latter point, Maltman uses the example of feldspar, the most commen geological mineral resident in modern vineyards. Feldspar is a family of minerals containing various combinations of minerals that are "ionically and covalently bonded into a crystalline lattice that gives a grain of feldspar strength and rigidity." This feldspar particle is bound together with a number of other mineral grains to form the aggregate we call rock or, in its fractured form, stone. The minerals contained in feldspar are not directly accessible by the vine plant. To be accessible by the plant the minerals have to be ionic and in solution. The process of transformation from the geological mineral feldspar to vine-accessible mineral nutrients is illustrated below.

Source: geology.csupomona.edu

Source: letslearngeology.com

The gulf between the vineyard chemical profile and that of the wine is further widened as a result of vine activity. The amount of nutrient ions absorbed by the vine roots is not directly related to the amount of nutrient ions in the soil. Rather, it is dependent on the transportation proteins and cell wall hydrophobic deposits among other factors. Further, once in the xylem, differential amounts of ions are directed to the various components of the vine architecture. Even within the berries there is a differential allocation of ions between, skin, seeds, and juice (Maltman 2013).

The disconnect grows even wider once cellar activities commence (shown below) and, as a result, the "proportion of mineral nutrients in finished wine bears only a complex, indirect, and distant relationship with geological minerals in the vineyard" (Maltman 2013).

After establishing a less-than-tenuous relationship between vineyard minerals and the mineral-nutrient signature of the finished wine, Maltman goes on to argue that minerality, as such, cannot be tasted in a wine. First, he argues, the concentration of inorganic material, in general, and mineral elements, in particular, in wine is miniscule -- between 0.15 and 0.4% for inorganics and very low levels for the mineral elements. Of the minerals, potassium has the largest concentration at 577 ppm (.06%) while calcium ranges between 30 and 200 ppm and magnesium registers at .005 ppm. Of the 50 organic elements identified in wine, 25 are trace elements (1 - 100 ppm) while 20 are ultra-trace (parts/trillion).

Compounding their relative scarcity in wine, these mineral elements have no flavor, a situation that also holds for geological minerals which are both solid and insoluble. Flavor-detecting organs in the mouth can only deal with solutions thus only sodium chloride, of all the geological minerals, registers a flavor in the mouth (Maltman).

So mineral nutrients resident in wine occurs in small amounts and are lacking in flavor. Vineyard geological minerals are flavor-free and would not register a taste in the human mouth. Aroma, the other component of flavor, requires volatilization in order to register on the organs on the olfactory bulb but neither rocks nor minerals possess this capability. Minerality as a taste descriptor, then, requires a leap of faith on the part of the taster.

How about texture, you ask? The geological minerals that existed at the beginning of the journey have been transformed beyond recognition in that they now exist as ions, rather than compounds, and in extremely small quantities. Any minerality imbuing capability would have to survive the journey detailed above and still have enough "surviving energy" in order to "infect" the completed wine in such a way that it exhibits "minerality" in a uniform manner.

Does Maltman's analysis consign minerality to the scrap heap of taste descriptors? Let me know your thoughts.

©Wine -- Mise en abyme