Sunday, May 29, 2016

Synesthesia - Part 2 - everyday associations of colors with tastes?

As discussed in my previous post, some people experience colors when they taste flavors. While most people don’t have vivid color impressions when experiencing flavors, we do tend to associate certain colors with flavors, as we discussed before (see blog post from ***).  

Just came across a paper from Taiwan where mathematics were used to quantify the appropriateness  of the colors  chosen for food packages—appropriateness in the sense that colors should reflect the tastes of the food inside the package.

In this study, 53 design students determined how closely they felt five tastes (acid, sweet, bitter, spicy, and salty) were associated with each sample in an array of 216 color samples identified by RGB codes.

The researchers then applied the mathematical formulae they developed to the colors in a couple packaging designs. The designer of the packaging shown below “intended this design [to feel] acid, sweet and a little spicy for the accordance with the real pickle inside.” Using the algorithm the researchers developed, the result suggested that the acid and sweet color representations were “medium,” but the “spicy” message was less intense. What do you think?

They researchers presented another image, this time packaging for durian. The designer intended this image to convey sweetness. According to the researchers’ algorithm, and also to me, this color palette hardly represents sweet, and in fact, at least for me, says nothing about durians except that they happen to be yellow. I can’t even say that the stink of a durian comes through. Again, what do you think?

* Tsai, Hung-Cheng; Chen, Chiao-Ying; Hsu, Yu-Chun. Color design based on color-to-flavor synesthesia using fuzzy computation. The 40th International Conference on Computers & Indutrial Engineering, 2010, ISBN 9781424472956, pp. 1 - 4.

Saturday, May 28, 2016

Synesthesia - Part 1

Was recently asked some tea-tasting questions that led me to consider synesthesia, specifically flavor/shape synesthesia.

Synesthesia is the brain capacity that allows some of us (about 1 in 27 or so) to experience one sensation in terms of another. For example, a common form of synesthesia is the perception of letters or numbers as having specific colors. Each synesthete has his or her own panoply of dual or triple perceptions  triggered by a stimulus reaching only a single sensory modality.

In my personal case, numbers have colors, and so do letters, though the latter associations have faded as I get older. Numbers, however, are a real problem, because I have to actively turn off the associations to do calculations. Some sums kinda work, like 5 (bubble gum pink) plus 2 (a rich dark blue) equals 7 (a hideous very dark poison green color)—I can sort of imagine mixing the color for 5 and the color for 2 to get that hideous color. But for most combinations, combining the colors is hard because I don’t get the right answer. Fact is, I don’t bother combining the colors, but instead have in my head a progression through space of numbers (with their individual colors turned off), and when I calculate, I have to go through the individual steps of the progression to go from one number to the other. Slooooooow….

These colors are all wrong to me, so I don't even see the written numbers without effort...

Fortunately, synesthesia can bring a lot of joy, too, and richness to everyday experience, especially to the rare person for whom flavors have shapes.  When the person who asked the question described a tea as having a “hooky” aroma, I knew exactly what he meant, as many teas have that quality for me too. But for me, a strange and more important characteristic of flavors is their location and movement through space and time. Hard to explain, but very real to me.

A couple of years back, NPR had an article about synesthetes and taste, that will give you a better idea of what this is all about:

More to come!

Sunday, May 22, 2016

Creaminess without cream...

Our season at World Tea Expo will be packed with experiences, so Donna Fellman and I won’t have time to discuss the creaminess of oolongs—for that issue we recommend attending Thomas Shu’s* session “Cupping and Grading Oolong,” at 8am on Thursday June 16.**

So I thought I might discuss here why oolongs come across as creamy, despite their lack of any actual cream. 

In 1993, Yuriko Nobumoto and her colleagues published a seminal paper*** on the aromatic components of pouchong, where they demonstrated that previously unidentified lactones were an essential component of the tea’s aroma. Previous to their work, Yamanishi and colleagues identified jasmine lactone, methyl jasmonate, linalool, linalool oxides, benzyl cyanide and indole as major aromas in oolong. However, these chemicals could not replicate the “characteristic sweet and milky aroma of pouchong tea.”

Via silica-gel chromatography, Nobumoto and her colleagues separated the tea’s components into 5 fractions and identified their aroma:
  • #1: grassy-greenish [this is a pouchong, so lightly oxidized]
  • #2: citrus-like
  • #3: most significant pouchong tea aroma
  • #4: sweet
  • #5: unpleasant [that’s the indole fraction!—see blog of 5/13/16]

They then proceeded to analyze fraction #3, and found that it contained–in addition to geraniol, benzyl alcohol, and phenylethyl alcohol, all of which have a flowery odor–a total of 12 lactones, all of which have a fatty odor and creamy quality in the mouth.
Jasmin(e) lactone—found in oolongs, in jasmine and honeysuckle, and in Sri Lankan teas, too. Image from a great site for flowers and flower chemistry:

It turns out that lactones contribute to the creaminess of cream as well.**** 

I’ve been trying to figure out why lactones have this quality…to no avail. Any thoughts?

* Thomas Shu is the Vice President & Marketing Director of JT & Tea Inc. See


*** Y. Nobumoto, K. Kubota,  A. Kobayashi.  Lactones newly identified in the volatiles of pouchong-type semi-fermented tea. Bioscience, biotechnology, and biochemistry. 57:79-81, 1993.

**** Schlutt B, Moran N, Schieberle P, Hofmann T.Sensory-directed identification of creaminess-enhancing volatiles and semivolatiles in full-fat cream. J Agric Food Chem. 2007 Nov 14;55(23):9634-45. Epub 2007 Oct 13.

Monday, May 16, 2016


The Daily Tea is promoting basil with watermelon and Assam-infused simple syrup, so I was interested in finding out more about watermelon. 

Turns out that the refreshing flavor of watermelon comes from aldehydes like (Z,Z)-3,6-nonadienal and (Z)-3-hexenal.* The former has a typical watermelon odor, while the latter is the smell of cut grass. Both of these chemicals activate the cool receptor TRPM8, hence the coolness of watermelon flavor. (By the way, these chemicals are prominent in green tea, so it may be worth trying the recipe offered by The Daily Tea with a sencha-infused syrup.)

Watermelons produce these chemicals from fatty acids when you cut through them—another example of damage-induced flavor production. The problem with watermelon is that, as it hangs out on the plate, there is further metabolism, so the flavorful chemicals transform into less aromatic congeners.

Ever slice through a watermelon, wait a second or two, then feel its aroma wafting up to you? then later, looking for refreshment at the end of a picnic, you’ll pick up a slice of the same watermelon, only to find that it tastes kinda flat? Now you know why. 

BTW, this is a great site for infographics and information about the chemistry of food. 

The photo that should be here (but Blogger seems to have a problem) is from the great site

Friday, May 13, 2016

Stinky stinky!

Indole is one of the stinkiest chemicals around. It is so stinky, in fact, that it has been used in at least one experiment comparing the effects of a pleasant versus an unpleasant odor on brain function.*…Yet you find it in so many perfumes…and in oolong tea!

I’m sniffing some now…how to describe the smell…well, to put it simply, it is present in high amounts in human feces…you get the idea…yet, at the same time its camphor-y warm aspect is fascinating, and makes me want to keep sniffing. Maybe this is really what perfumers mean when they say indole contributes to “narcotic” aromas.

Stinky it may be, but the fragrance of white flowers—jasmine, for example—is more powerful and rich because of indole's presence. And perfumes from these flowers get their staying power, in part, from the base note it provides—its longevity on the skin is estimated at 400 hours!

Jasmine flowers, from

As I may have mentioned before (and if not, I’m saying it now), oolongs share many volatiles with jasmine flowers, including indole. In fact, as you process tea leaves, the levels of indole increase then decrease as oxidation progresses, which is why levels are highest in oolongs that have intermediate levels of oxidation. 

We’ll have a variant of indole (not so stinky!) for you to smell at World Tea Expo, so you can get the idea of how it contributes to the depth of tea flavor.

* M. Bensafi*, C. Rouby, V. Farget, M. Vigouroux, A. Holley. Asymmetry of pleasant vs. unpleasant odor processing during affective judgment in humans. Neuroscience Letters 328 (2002) 309–313. 

Thursday, May 12, 2016

What Earl Grey does with chocolate...

Earl Grey tea is special case when it comes to pairings, because it combines black tea with bergamot. While black tea mainly activates the warm and “hot” receptors, the major chemical components in bergamot, a citrus fruit, activate the “cool” and “cold” receptors, just as do those in lemon.  This sets up a conflict for the person looking for interesting pairings—do you emphasize bergamot’s flavors, or do you favor the black tea’s?  Is there a way to give both equal billing when paired with some other food?

Interestingly, chocolate—pure unsweetened chocolate, that is—covers the same taste spectrum as Earl Grey tea, which is probably why many people have tried to create chocolates and chocolate cakes containing Earl Grey tea. However these confections also contain sugar, vanilla, and fat. The results have sometimes been good, but none are spectacular in my experience. You can taste the bergamot, or (sometimes) the chocolate, or the black tea, but usually not all the flavors together.

Bergamot fruit
Image by Flickr user: Xenocryst @ Antares Scorpii, from Wikipedia.

But sip Earl Grey tea and eat 86% cacao chocolate with low vanilla, or, even better, eat unsweetened chocolate that has not been alkalinized. Suddenly you have a burst of flavor that combines the best of all three: bergamot, black tea, and chocolate, without too much of the perfumey quality of the tea that can appear with chocolate containing less cacao and more vanilla.

The reason you need high cacao content, and as little cacao butter, vanilla, and sugar as possible, is that:
  • the cacao butter inhibits the “hot” receptor, so you can't taste the black tea's qualities or the chocolate's;
  • the vanilla activates the "warm" receptors, which in turn conflicts with both the "hot" receptors activated by the black tea, and the "cool" receptors activated by the bergamot;
  • finally, the sugar turns on the "warm" receptor as well, thus further muddying the flavor profile of the combination, and it also dampens the slight touch of bitterness that brightens the flavors of both the chocolate and the tea.

Wednesday, May 11, 2016

Nerolidol: white tea, green tea, and now oolong?

In a previous post entitled “Why is white tea so elusive?” (April 26, 2016), I mentioned that there is some disagreement in the literature concerning the presence of nerolidol in white tea—is it there, or isn’t it? At this point the best we can say is that it may be in there, depending on what tea leaves are used and how they are processed.

Whether it is in white tea or not, it certainly is present in oolongs, and is a marker for oolong quality.* In the graph below, you can see how sun withering of oolong leads to the development of this chemical in the tea:

To me nerolidol has a very sweet, slightly woody smell—it has been described as a “tea” smell, and I can kinda sense that. Nerolidol is a significant component of natural jasmine smell. Worth noting: oolongs have a large number of these jasmine-related compounds.

Nerolidol's aroma is on the cool, fresh side, so probably binds to TRPM8, the same receptor as for menthol, and also, because of its slight pungency, to TRPA1 as well. In addition to its presence in tea, it can also be found in other foods that primarily activate cool/cold receptors, such as ginger and lemon grass. Furthermore, according to perfumers, it goes well with other cool/cold binding compounds such as linalool. 

However, with benzyl alcohol, another compound in oolongs (see the graph above), but one with a “warm” aroma, the aroma of nerolidol disappears completely, or if not completely, then it simply modifies the benzyl alcohol aroma in a pleasant but indescribable way.

Donna Fellman and I will be talking about sun withering and its effects on the production of nerolidol and other compounds in our presentation at World Tea Expo, and I will have samples of nerolidol and other aromas for you to smell. 

* Ma C, Qu Y, Zhang Y, Qiu B, Wang Y, Chen X. Determination of nerolidol in teas using headspace solid phase microextraction-gas chromatography. Food Chem. 2014;152:285-90. doi: 10.1016/j.foodchem.2013.11.010. Epub 2013 Nov 28.

Sunday, May 8, 2016

A Mother’s Day Note about Garlic…

The delivery room reeked of garlic—the mom had eaten garlic bread and garlic-laced spaghetti sauce for dinner…and the aroma was not from her breath alone—her amniotic fluid spilled out the smell as well…

In a previous life I was a pediatrician and attended many a garlic-smelling delivery, which years ago had already clued me in to the possibility expressed in the paper by Hepper and colleagues entitled: “Long-term flavor recognition in humans with prenatal garlic experience.”*

A fetus begins swallowing amniotic fluid by 12 gestation, and develops a fully equipped tongue, complete with taste buds, by 16 weeks gestation. Small molecules like allicin, the flavor compound in garlic,** pass easily into the amniotic fluid, so the fetus can develop a taste for it, as Hepper and his colleagues found. 

In a study carried out in Northern Ireland, where garlic is not part of the daily cuisine, a group of moms-to-be were given garlic to add to their food, starting at 34 weeks gestation, and another group was not given garlic and served as controls. Later, when the children were 8 to 9 years old, the experimenters were able to recruit 17 of the non-exposed children and 16 of the exposed ones to enjoy two meals, a month apart, in which they were offered simultaneously a potato gratin with garlic and an equal portion of gratin without. Importantly, the experimenters were able to ascertain with reasonable certainty that, in the interim from birth to experiment, the children had little if any exposure to garlic.

The children who had been exposed to garlic prenatally ate significantly more of the garlic-containing gratin on two separate occasions, though on the second occasion their interest in the garlic-infused potatoes had waned somewhat. By contrast, the children who had not been exposed to garlic prenatally seemed to avoid the garlicky potato dish in favor of the plain potatoes.

A curious experiment, which supports the idea that we have a flavor memory that starts before we are born.

* Peter G. Hepper, Deborah L. Wells, James C. Dornan, and Catherine Lynch Long-term flavor recognition in humans with prenatal garlic experience. Developmental Psychobiology
Volume 55, Issue 5, pages 568–574, July 2013.

** To quote Wikipedia: “Allicin is produced in garlic cells when they are damaged, which is why garlic’s scent is most potent once it is being cut or cooked. It is believed that alliin [the allicin precursor] and alliinase [the enzyme that forms allicin from alliin] are kept in separate compartments of the cells and can only combine once these compartments have been ruptured.” Another example an aroma-rich compound produced when a plant is damaged!

Friday, May 6, 2016

Tea Transport

Today's must-read...,_Sichuan_Sheng,_China_1908_Ernest_H._Wilson_RESTORED.jpg. The detailed description below this photo on Wikimedia gives you some idea of the struggles of the people who brought tea west and east from remote regions of Yunnan. 

Here's a map of the Tea Horse Road, also from Wikipedia. Note the town of Pu'Er, the starting point for much of these teas.

The Tea-Horse-Route, c. 700 AD – 1960. Map from Wikipedia.

Thursday, May 5, 2016

Why is rancidity so unpleasant?

Friend of Pairteas and tea connoisseur Marzi Pecen has been directing my attention to olfactory training sets, and one suggestion in the literature is to include a sample for rancidity, which led me to wonder: why is rancidity so unpleasant?

Found a paper* about receptors for polyunsaturated fatty acids (PUFAs) in the mouth and gut, and saw that free PUFAs bind to TRPA1, one of the trigeminal receptors that causes disagreeable sensations including pain when activated.

Normally, PUFAs exist in foods primarily in the form of triglycerides. Such a triglyceride consists of three PUFA molecules bound to a glycerol backbone. When tied up in this way the PUFAs can’t activate TRPA1. 

As food rots (and this is true of fish in particular), the triglycerides break down, so that PUFAs are freed. Free PUFAs become oxidized, and both oxidized and unoxidized versions have a distinct odor.
In addition, now they can activate TRPA1.  Activation of TRPA1 associates the odor with a disagreeable sensation—the overall effect is unpleasant rancidity!

Not with this lot of fresh fish, though...

Image from Morguefile.

* Arianne L. Motter, Gerard P. Ahern. TRPA1 Is a Polyunsaturated Fatty Acid Sensor in Mammals. Published: June 19, 2012.

Tuesday, May 3, 2016

The Tearoom - Part 4 - Menus and Pairings

After musing about tearooms of my past in Parts 1 and 2 of this series, I should get down to the question of menus and pairings. 

A casual perusal of afternoon tea menus available on the web reveals some basic patterns for the traditional English afternoon tea.

The first is that black tea, for example a Ceylon tea, is traditional. So are finger sandwiches with cucumber or smoked salmon. If you eat one of these finger sandwiches, the flavor of the tea will be eclipsed, at least for a little while: cucumber and salmon activate the cool/cold receptors and the fat in them will inactivate the hot receptors— which the black tea activates, so something has to give. Usually it will be the tea—it will be like drinking so much hot water.

Another common accompaniment: scones with clotted cream and strawberry jam. Strawberry and oolong go well together because they activate the warm receptors, but not strawberry and black tea—one or the other will dominate. In the presence of clotted cream with its fat content, it will be the tea again that disappears. Now with raspberry jam, you have a very different situation: raspberry ketone activates both the warm and the hot receptors, so in the presence of a black tea (which also has raspberry ketone in it!), the overall effect will be delightful: the tea and fruit will stand out, while the fat will cut some of the astringency of the tea.

A proposal: if you serve an afternoon tea, serve it in courses, with different teas to go with each course, for example green tea with the cucumber sandwiches, an oolong with a scone with strawberry jam, and a black tea with brownies and raspberries. That way each tea will have a chance to shine, while your food will taste all the more delicious.

Pictured below (couldn't resist a little more musing): not the huge groaning table of five-o’clock high tea for maybe twenty plus people that I enjoyed as a child at my parent’s friends' home when we we lived in Uruguay…more intimate but pretty close and one you can get now in Punta del Este, at B Restaurant & Bar (

Sunday, May 1, 2016

The Tearoom - Part 2 - Café American - More art nouveau - More tea

Pictured below, the art nouveau Café Americain, meticulously restored, at the Hampshire Hotel in Amsterdam—formerly the Hotel American…

…where I spent many a tea-time as a child, after playing in the park and before going back to our not-nearly-so-luxurious pensioen.

What we had with our tea there: sprits cookies, that we ate squiggle by squiggle. The fat of in them bumped off the astringent polyphenols from TRPV1, so the tea and the cookie were both sweet and very filling. BTW, remember that fat inhibits TRPV1 activity, so you can use it to dampen burn, for example.

Did I mention that we also have specific receptors for fats in our taste buds? In addition the effects of fats on TRPV1, fats also activate taste bud cells through the CD36 receptor (not temperature related), so there are actually six basic tastes for which we have specific receptors: sweet, sour (which like fat also acts on TRPV1), salty (ditto with TRPV1—a lot of salt can give a burning feeling…nature wants us to know when we have too much salt!), bitter, umami, and fat.

Café American: