In this, the third in a series of posts about the white-wine-dyed-red study, we’ll explore what the students may have actually experienced. As I mentioned in my previous post, Morrot and his colleagues developed a vocabulary of descriptors for white and red wine, and analyzed these words to see how they grouped.* The results led to the conclusion that there was a set of specific words that were most often used to describe white wines, and another set that were most often used to describe red wines. We also noted that Jacques Dupont, wine commentator for La lettre de Gault & Millau, used 16 words exclusively for white wines and only 2 exclusively for red wines, suggesting that descriptors for red wines can also be used for white, but not so much vice versa.
The 54 oenology students who participated in the study were given the Dupont list of words, and were allowed to develop their own vocabulary, using Dupont’s words plus their own, in order to describe the two wines—a Sémillon and Sauvignon blend for the white wine, and a Cabernet-Sauvignon and Merlot blend for the red.
The students then came back at a later occasion to use these individual vocabularies to describe what they smelled in the white wine and the white-wine-dyed-red.**
Morrot and colleagues present a graph (Figure 2 in the paper—see below) with the descriptors the students chose for white-wine-dyed-red and the white wine, showing how many participants chose each word. Far and away the most commonly used word for the plain white wine was “floral:” 15 students assigned this word to the white wine and 2 assigned to the white-wine-dyed-red. Dupont used this descriptor for white wine 93% of the time, and for red 7%.
The popular press focused on the use of red fruit words to describe the white-wine-dyed-red, and indeed some participants did in fact use words for red fruits, such as raspberry (10 people), strawberry (6 people), and cherry (7 people). Further, the words the students used for the white-wine-dyed-red were a subset of the words they each had used to describe red wines in the true red wine experiment.
Here are my thoughts:
First, the experimenters made an interesting choice of wine for this experiment: both wines contained Sauvignon grapes. The white wine was a blend of Sauvignon with Sémillion, and the red wine a blend of Cabernet-Sauvignon and Merlot. Both wines therefore can be expected to have contained methoxypyrazines, the key flavor ingredient of Sauvignon wines, both white and red. Methoxypyrazines give the characteristic aroma of green peppers, and stands out in a mixture (a flavor I hate, as I have mentioned in the past). Most people in the US are used to experiencing this aroma in the context of a red wine, where Cabernet Sauvignon is more common than Sauvignon Blanc. I believe this is true in France as well, so the association of this flavor with red wine would be stronger than its association with white. When I saw the types of wine, then, I began to wonder in which direction were the students fooled: were they fooled into thinking the white-wine-dyed-red was actually red wine, or were they assuming the white wine was white because of its color and therefore assigned it white wine descriptors, and that the red wine was the “correct” color for its aroma?
Next, in line with the study of vision-odor detection described in Part 1 of this series, people will tend to detect the presence of odors when the image that they see is congruent with the odor, and fail to smell odors that are incongruent. The two wine blends are not all that different from each other with respect to their chemistry, so the participants would have preferentially detected odors that matched what they were seeing in the glass.
Or was there an effect of the addition of anthocyanins to the white wine that physically altered what the students could detect? The authors of the present study said no, but there are plenty of studies where the non-volatile matrix of a red wine (particularly the anthocyanins), when added to a white wine, make the wine's odor more red-wine-like. One recent study, in particular, combined non-volatile matrices from two white wines (M1 and M2) and two white wines (M3, M4, and M5) with the volatile fractions of these wines (A1 through A5), and had trained panelists sniff these combinations:
"...replacing the original nonvolatile matrix (M1A1) by a nonvolatile matrix from a second white wine (M2A1) has a small sensory effect, but that replacing it by a red wine nonvolatile matrix (M3A1, M4A1, or M5A1) has a deep effect on the sensory properties of the reconstituted wine, changing its aroma to terms related to the “red fruit” aroma family in detriment to the terms typical of white wines observed in the M1A1 and M2A1 samples." ***This effect was most pronounced for the red wine matrix (M5) that was particularly astringent, and therefore (presumably) contained more anthocyanins. The students in the white-wine-dyed-red study were not trained panelists, and they probably were not aware of the consequences of the addition of anthocyanins when smelling the wines "blind," but with the addition cue of color, they were able to pick out the very real differences in aroma.
What caught my attention even more strongly, however, was that the two most commonly used words for the white-wine-dyed-red were “spicy” (18 people and 2 people for the white wine) and “pepper”**** (16 people and 4 people for the white wine). Neither of these words applies to a specific red fruit; instead they apply to the sensations we get from activating TRPV1, the “hot” receptor, from alcohol. In the study combining matrices with volatiles, adding a red wine matrix to white wine volatiles also enhanced the spiciness and woodiness of the reconstituted wine.
Which raised the question in my mind (and one of my Aha! moments): is the major association of color with odor—in this experiment as well as more generally—not so much based on specific odors, but rather on the trigeminal sensations these odors elicit?
And is the reason these colors elicit these aromas that, in our day-to-day experience, red plant substances such as anthocyanins actually shift the available odor profile to one that activates the warm and hot receptors?
And is the reason these colors elicit these aromas that, in our day-to-day experience, red plant substances such as anthocyanins actually shift the available odor profile to one that activates the warm and hot receptors?
And if so, can we then develop a scheme for pairing that involves the use of colors to bring out certain flavors? More about answering this question on Friday, with my next post.
* Morrot G., Brochet F., Dubourdieu D. The Color of Odors. Brain and Language, doi:10.1006/brln.2001.2493.
** I may have mentioned this before…there is some confusion in the paper concerning whether the students tasted or only smelled the wines. After multiple rereadings, I believe that they only smelled the wines.
**** The French distinguish between poivre=pepper and poivron=the pepper fruit (green or red pepper). The word used here was “poivre.” (Incidentally, neither of these words occurred among the most commonly used for red wine in the Dupont list.)
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