Friday, October 24, 2014

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 (and Richard Gawel, Secret of the Spit Bucket Revealed,, 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 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?, 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

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