Note: all photos in this post are courtesy of Yan Chen, Yan Chen, Professor, Louisiana State University Agricultural Center Hammond Research Station.
Such fun to give the talk “The Aromas of Wine and Tea: a Sensory Adventure!” with the help of Marzi Pecen. Here we are talking with attendees before the start—Marzi is standing on the right:
In the Sensory Theater of the Robert Mondavi Institute for Wine and Food Science we could have a true sensory adventure—we could experience directly how the aromas of wine and tea shift and change as we alternatively sniffed individual chemicals and the teas and wines.
Here’s a picture of the set-up:
In front of each participant were six cups (the wine glasses in the back were in place for Andrew Waterhouse’s talk about wine aging, that followed my talk).
The three cups in front held (left to right) a green, oolong, and black tea, all Ready-to-Drink from Ito-En—thank you so much Rona Tison of Ito-En for providing these. The three cups behind the tea cups held a Chardonnay, a Pinto Noir, and a Cabernet Sauvignon, all from Robert Mondavi — many thanks to Babette Orendain of the Institute for the wines, and to her and her UC Davis student helpers for setting out everything!
(fBTW, the green tea was very close in color to the oolong—it was pan-fired—but it was clearly green tea by its aroma).
Earlier in the day, Colloquium speaker Susan Eberle, Professor (Chemist) of Viticulture and Enology, and Associate Dean, Undergraduate Academic Programs, College of Agricultural and Environmental Sciences at University of California Davis, had described some of the aroma chemicals common to tea and wine. Here is a picture of one of her slides:
To my great delight, I had chosen compounds that corresponded to these categories for my demonstration. I was planning to touch on all of these categories, but time was running short (we had to start late) so I chose just three:
- 2-phenylethanol, a phenylpropanoid,
- β-damascenone, a C13-norisoprenoid,
- vanillin—note that vanillin is developed during the heating steps in tea and comes from the oak barrels for wine., so is not actually either in the grape or the fresh leaf to any extent.
We started by soaking perfume blotter paddles ("touches") then sniffing 2-phenylethanol and β-damascenone separately and then together. When we sniff them together our olfactory bulb joins them together as "odor objects" different from the two separate smells. For me and for many of the participants, the resulting odor object was "honey." However, people differ genetically in their ability to smell β-damascenone, so the "honey" effect was less pronounced for some. This observation allowed for a very short comment on the genetic ability to smell different aromas in teas and wines.
The next effect we experienced was masking. People first sniffed the Cabernet Sauvignon, then sniffed the 2-phenylethanol or the β-damascenone, then sniffed the wine again—the smell of the wine disappeared! The same held for the black tea. Neither the wine nor the tea has a significant amount of these compounds so, at the concentrations on the perfume paddles, these chemicals effectively masked the other aromas in the tea and wine.
By contrast, when we carried out the same experiment with the Pinot Noir and the Oolong, the aromas of each became richer and even more pleasant. This wine and this tea both have significant amounts of these chemicals; sniffing the paddles before sniffing the wine and tea brought out their aromas—an additive effect.
Vanillin is produced when oak barrels are fired, so oaked wines will have a lot of vanillin. The Chardonnay we had was only lightly oaked, so when sniffed alone if had a more fruity, less Chardonnay-like aroma that wasn't as pleasant as that of a more oaked wine would be—Andrew Waterhouse (Director of the Mondavi Institute) and I agreed that the wine had probably been treated with oak chips rather than been aged in a barrel. When you sniffed the wine after sniffing the vanillin, the aroma of the wine improved dramatically.
Black tea is heated and fully oxidized, so it too contains significant quantities of vanillin, from the breakdown of lignin in the leaf's veins. Just as we experienced with the Chardonnay, the aroma of the black tea became richer after we had sniffed the vanillin. Interestingly, the vanillin somehow incorporated itself into the overall tea aroma, rather than stand out as separate but compatible as it did with the Chardonnay—with the black tea we were again experiencing odor object formation, which could be described simply as "black tea."
By contrast none of these compounds are present in green tea, so sniffing them before sniffing the green tea made the green tea either smell awful (for me) or just loose character completely (for some other people).
BTW, you can carry out some of these experiments at home with household herbs and spices. Will be live streaming to show how these experiments work on my upcoming twitch.tv channel. Details and link to come!
Or you could get samples of the actual chemicals in a Scents of Tea kit at http://scentsoftea.com and carry out the experiments with all manner of scents, wines, and teas.
==>> Now available on Amazon: Tea: a Nerd's Eye View.
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