Oolong-hai and lychees

Came across this fascinating photo by Chinh Le Duc when searching for tea images on Unsplash.com. The title words read: "Drink, glass, cocktail, beverage and alcohol."  

Photo by China Le Duc, Unsplash.com

Alcohol? When my keyword search was "tea?" What is going on here? 

Come to find out that there is an iced alcoholic beverage called oolong-hai consisting of oolong tea combined with shōchū, a Japanese drink fermented and distilled from any one of a number of starches, including rice, barley, buckwheat, and interestingly, sweet potatoes. Apparently the choice of starch conveys a distinctive flavor to its shōchū. 

Here's what Sara Shacket of the blog Tea Happiness* has to say about the oolong-hai she savored:

"The drink was incredibly refreshing on a hot NYC summer evening. I tasted the slightly bitter earthiness of the Oolong, along with a subtle hint of something smoky that reminded me of whiskey. Shochu has a subtle flavor, and so my drink didn't have the overwhelming alcoholic taste that I usually expect from a cocktail. This makes the drink quite dangerous for me. I hardly even noticed that I was consuming any alcohol! It had a similar refreshing feel to the mugicha I recently tried.  I also love that it wasn't sweet. In fact, the server warned me that it wasn't a 'sweet cocktail'."

At another (commercial) website,** found a good photo of oolong-hai, along with a recipe:

Oolong-hai from https://umamimart.com/blogs/main/japanify-oolong-hai

Comparing this photo with the one by Chinh Le Duc, it looks very much the same: same color and cloudiness. 

Which led me to the next question, namely would lychees go well in this drink?

Looked up the chemistry of lychees in a paper by colleagues of mine from Cornell, Peter Ong and Terry Acree.*** Turns out that lychees share a number of flavor-significant compounds with oolongs. Some of these, such as linalool, are found in all teas, but the one that stood out for oolongs specifically is furaneol, aka strawberry ketone, which activates the warm receptor, TRPV3. Another important flavor compound in lychees, and perhaps in some oolongs, is vanillin, which also activates TRPV3.  But most striking is the presence in oolongs of cis-rose oxide, which has a characteristic lychee aroma.**** Put together, oolong and lychee will each expand the flavor of the other.

In case you are wondering, I haven't experienced the drink myself. I lack functional aldehyde dehydrogenase, so become quite sick with very little alcohol, and despite my love for oolongs, I really don't like lychees—and now I know why. Lychees have δ-decalactone, which has a strong flavor of coconut. Can't stand the flavor of coconut, and lychees come across as too coconutty to me. So I am not about to try this drink, no matter how hot it gets this summer. 

But you might enjoy it very much!

* http://www.tea-happiness.com/2011/08/oolong-shochu-yes-please.html
** https://umamimart.com/blogs/main/japanify-oolong-hai
*** Ong, P.K.C., and Acree, T.E.. Similarities in the Aroma Chemistry of Gewürztraminer Variety Wines and Lychee (Litchi chinesis Sonn.) Fruit. J. Agric. Food Chem., 1999, 47 (2), pp 665–670
DOI: 10.1021/jf980452j.
**** Sheibani, E., Duncan, S. E., Kuhn, D. D., Dietrich, A. M. and O'Keefe, S. F. (2016), SDE and SPME Analysis of Flavor Compounds in Jin Xuan Oolong Tea. Journal of Food Science, 81: C348–C358. doi:10.1111/1750-3841.13203

Fresh versus dried fruits

The other day a friend of Pairteas asked me why certain fruits—blueberries, kiwis, and apricots in particular—go better with oolongs when dried than when fresh.

The first point to make is that the chemicals in oolongs for the most part activate the warm to hot receptors. Consequently foods that activate the cool/cold receptors, such as blueberries and apricots, will cause the flavors of most oolongs to disappear.

The second point is that drying, whether of fruit or tea leaves, changes their chemistry. When they are fresh, fruits and tea leaves are still alive, so they respond to drying by making defense chemicals in response to the stress. 

For example, fresh ginger has two chemicals, zingerone and gingerol, that are slightly different in flavor. Zingerone activates the cold receptor (TRPA1) and gingerol activates the hot receptor (TRPV1). As ginger dries, these chemicals disappear or, to be more exact, are transformed into shogaols that collectively activate TRPA1. For those of you who were at our WTE about green tea way back in 2015, you might remember how a tiny bit of dried ginger dampened the bitterness of the tea and brought out its herbaceous qualities.

Apricots have compounds that hit the cold receptors, so can kill the flavor of an oolong.  As apricots dry phenyl ethyl alcohols and linalool oxides oxides appear—they hit the warm/hot receptors and make oolong happy.

As for blueberries, don't know what happens in them specifically. Fresh blueberries hit the cool/cold receptors, as does blueberry jam—the berries don't have a chance to make an abundance of stress chemicals before they are cooked and their enzymes denatured. My guess is that drying makes them create a panoply of chemicals similar to those in apricots.

And as for kiwis—will have to do some experiments once I get settled in my new home...

...and please do experiments yourselves to see what happens. Would love to hear from you!

Asparagus, coffee, and tea

Had a fascinating experience the other morning. Bought a lightly roasted coffee called Stargazer from our local specialty coffee roaster, Gimme!. Flavor description from the package: "dark chocolate, bourbon cherry, caramel, stone fruit sparkle."

Stargazer coffee beans—notice the light color and lack of oil, indicative of a light roast.

I got the chocolate and maybe the caramel, certainly the sweet, but was overwhelmed by the coffee's vegetal taste — clearly asparagus. It even had that sweetish asparagus after-taste, all of which led me on a hunt for understanding how these flavors came to be in the coffee...and in green and oolong tea, too.

As I said in my book, "Three Basic Teas & How to Enjoy Them:"*

"The strongest odorants, and perhaps the most numerous, in asparagus are sulfur-containing and nitrogen-containing compounds—these can be detected by the human nose at the level of parts per billion. They will dominate any aroma mixture you can imagine. 

Of these 20 or so typical compounds in asparagus, the most abundant is dimethyl sulfide. This compound can be present in green and oolong tea, where it contributes a “marine/seashore/oceanic” quality. But if you associate that smell with cooked asparagus, then you would say it’s an asparagus smell. You could also associate that smell with the odor of urine after eating asparagus—the people who have the gene for breaking down asparagusic acid excrete dimethyl sulfide among other compounds."

Dimethyl sulfide doesn't give the asparagus aftertaste, however. Another sulfur compound that could be a candidate: methionyl acetate. It's in both coffee and asparagus, and beer, too. But it doesn't give a sweet aftertaste as far as I can tell.**

Perhaps the sweet aspect comes from an entirely different set of compounds, the pyridines, which abound in coffee, especially with light roasting. Pyridines can be sweet, even too sweet, though many also have a grassy quality. Turns out that 2-ethyl pyridine gives a sweet yet green grassy quality to asparagus—in fact, some people consider it to be "the" asparagus scent. (Worth noting that it is in black tea as well.)

The conclusion I reached from this hunt (and so many others) is that foods from plant materials such as tea, coffee, and asparagus, share a host of basic chemicals—the resulting flavors may well simply depend on which chemical stands out in the mix. 

* You can get a copy of "Three Basic Teas & How to Enjoy Them" either from the printers:  https://www.createspace.com/6961595, and get a 10% discount using the code V97A7SQ3; or from Amazon—sorry, couldn't get a discount with them.

** Ulrich, D., et al. Contribution of volatile compounds to the flavor of cooked asparagus. Eur Food Res Technol (2001) 213: 200. doi:10.1007/s002170100349.