The calmness of sugar

Was reading an article about the effects of drinking tea with sugar versus tea with stevia, tea with sucralose (sold here in the US as Splenda, for example), and tea without sweetener, on stress reactions.* 

Fifty people of a wide range of ages participated in the experiment. On the test days the participants first filled out a questionnaire about their level of stress, then after either the no-stress or the stress condition drank teas. In the no-stress situation, participants simply filled out a questionnaire about their mood state; in  the stress situation they had 10 minutes in which to solve math and logic problems, which they were told was going to tell the researchers whether they had high, medium, or low IQ.  This test has been shown to reliably induce stress (no surprise there!)

Here is the tea-drinking methodology as described in the article:

“Participants were then seated in individual sensory booths to taste the tea samples. A total of four samples were presented in a sequential monadic fashion based on William Latin Square Design31. Approximately 90-mL of each sample was provided in a 112-mL cup with a three-digit code. Participants were asked to rate on a 9-point scale how calm (1: extremely stressed; 9: extremely calm) and pleasant (1: extremely unpleasant; 9: extremely pleasant) they felt before drinking the tea samples. Participants were then asked to drink the entire cup of tea and rate only its sweetness intensity on a 15-cm anchored line scale (0: extremely weak; 15: extremely strong). Participants also rated their overall liking of the tea sample on a 9-point hedonic scale (1: dislike extremely; 9: like extremely). Participants also rated how calm and pleasant they felt after drinking the tea sample similar to how they did before drinking the sample.”

The order in which they drank the teas varied from person to person. From reading the methodology, the authors did not take into account this order in the data analysis. I assume that they felt they didn’t need to do so, because they felt that the results clearly favored the calming effect of tea with sugar compared to tea with the other sweeteners. Here is the graph:

[BTW, wondering why the calmness was negative for both stevia and unsweetened, rather than neutral...no explanation for this in the paper, and of course we don't have any idea about the order of presentation of the teas and whether this order may have led to any outliers, not to mention whether there were people who were outliers to begin with.]

The authors speculate that the reason that the sugar was more calming was because it provided the brain with the calories it needed to deal with the stress. As they noted, the brain needs glucose to function—in fact it uses more glucose than any other organ of the body, and takes up about 3% of the calories we need each day. 

At the same time, they point to literature that suggests that sucrose activates many more brain pathways than do artificial sweeteners.** Therefore another possible explanation for the effect may be that the reward circuits in the brain are activated more readily by sucrose than by other sweeteners.

I would like to point to another possibility: that theanine and caffeine in tea crosses the blood-brain barrier and enters the brain more quickly and easily in the presence of sucrose. Theanine has a calming effect that is pretty well established, at least when taken by itself. When taken with caffeine, it may be even more effective.*** (See my blogpost http://virginiaspairteas.blogspot.com/2016/01/caffeine-l-theanine-and-egcg-and-timing.html).

When sugar is added, caffeine and theanine may go into effect more quickly. Here’s why:

There is a transport system for neutral amino acids into the brain that works when the system can also transport glucose (sucrose is made up of two molecules of glucose). Caffeine also enters the brain more easily with a dollop of sucrose. In this study, theanine and caffeine entered the participants’ bloodstreams throughout the tea drinking process, no matter what sweetener was. But when sucrose was available, theanine and caffeine could zip right into the brain. The result would be a focussing  effect!

You can try this experiment for yourself. Assign yourself something somewhat stressful to do — for me it was writing this blogpost. Then use either a sweetener or sucrose and see what the effect is. Repeat on some other occasion, with the other compound—if you started with the sweetener then sucrose, or vice versa. And let me know what happened.

For me the sucrose was indeed more effective…

But here is a catch: if you use artificial sweeteners regularly (I don’t), your brain will light up the reward circuits in the same way as sucrose…and maybe act as if you had taken sucrose with your theanine and caffeine.****

Let me know what results you get with the experiment I suggest, and when you do, let me know whether you take artificial sweeteners regularly.

* Samant, S. S. et al. Tea-induced calmness: Sugar-sweetened tea calms consumers exposed to acute stressor. Sci. Rep. 6, 36537; doi: 10.1038/srep36537 (2016).

** Guido K.W. Frank, Tyson A. Oberndorfer, Alan N. Simmons, Martin P. Paulus, Julie L. Fudge, Tony T. Yang, Walter H. Kaye. Sucrose activates human taste pathways differently from artificial sweetener. NeuroImage, Volume 39, Issue 4, 15 February 2008, Pages 1559–1569.

*** Camfield, David A; Stough, Con; Farrimond, Jonathon; Scholey, Andrew B. Acute effects of tea constituents L-theanine, caffeine, and epigallocatechin gallate on cognitive function and mood: a systematic review and meta-analysis. Nutrition Reviews, ISSN 0029-6643, 08/2014, Volume 72, Issue 8, pp. 507 - 522

**** Erin Green, Claire Murphy. Altered processing of sweet taste in the brain of diet soda drinkers. Physiology & Behavior, Volume 107, Issue 4, 5 November 2012, Pages 560–567

As an aside: remember Jolt, the cola drink “with all the sugar and twice the caffeine?” One afternoon many years ago was working on a project with a student when we both started to flag, and thinking had become absurdly difficult. I then remembered that another student had given me a bottle of Jolt, so I unearthed it and we each took a swig. About 10 minutes later we both looked up…the Jolt had jolted us! The caffeine was mainlined into our brains by the sugar, and we could finish the job. 

That said, I am not recommending Jolt, just present this story to illustrate how sugar can make caffeine move more quickly into the brain.

Beer Flavor Map!

The day before yesterday, at the last minute, I offered to give a class on the sensory perception of beer for my friend Scott Kerkmans, Instructor and Director of the Brewing Industry Operations Program at Metropolitan State University in Denver, Colorado (https://msudenver.edu/beer/faculty/). 

Two things fascinated me about teaching the class. 

The first was the opportunity to use Skype to bring me into a classroom 1700 miles away from home. I could run the Keynote presentation (that’s Mac’s Powerpoint) from my computer, and make comments on each slide as I presented them. I could hear the class as I did this, so I could answer questions and respond to their thoughts. It wasn’t as good as carrying out a class in person, where I can see the students’ reactions and clarify my statements as needed, but it worked! So you may see me doing this even more in the future…

The second was that, for the presentation, I looked into the question of the different flavors of beer, and how they engage the trigeminal system. This question led me to the Beer Flavor Map created in 2016 by Lindsay Barr, MS and Nicole Garneau, PhD to supersede the existing beer flavor wheels. Here they are holding up the map and celebrating its creation, from their twitter page (https://twitter.com/beerflavormap): 

The purpose of this map is to give people into beer a vocabulary to describe their experiences. This standardization of vocabulary was the purpose of the original flavor wheel, made by Ann C. Noble at UC Davis for wine. 

As with the wine wheel, I had to keep reminding myself that the Beer Flavor Map is not based on the biology underlying our ability to sense these flavors, but rather on an attempt to put similar flavors together and to give them names relating them to other flavors, for example “wheat” or “lemon.”

Yet what makes this map important, and different from all other maps and wheels that I have seen, is the inclusion of “mouthfeel” as a separate “place” (to continue the map analogy). By mouthfeel the mapmakers mean trigeminal sensations. Here is the “Mouthfeel” section of the map:

“Irritation” and “Afterfeel” are both functions of the temperature (TRP) receptors on the trigeminal nerve. “Effervescence” is primarily a function of the touch receptors on the nerve, though the relationship of “Effervescence” to “Carbonation” brings the temperature receptors into play as well—carbonation activates TRPV1, the “hot” receptors (note “Burning” under carbonation). “Body” is also a function of the touch receptors, but there can be confusion with the “Afterfeel” characteristics, which are a function of TRPV1, at least with respect to astringency and slipperiness.

So exciting to find a diagram for flavor descriptors that acknowledges the contribution of the trigeminal nerve to the overall flavor experience!

Amphithermic and freshly ground pepper

Coining a new term: amphithermic, to denote a food or beverage that activates both hot and cold receptors. 

Have been wondering for a while what I should call this phenomenon, when I had a discussion about pepper with friend of Pairteas Marzi Pecen, who pointed out to me that freshly ground black pepper can enhance the flavor of vanilla ice cream.

How can that be?

To answer this question, I first needed to look at the chemistry of peppercorns for freshly ground black pepper. Peppercorns are the dried unripe fruit of a vine called Piper nigrum. To prepare them, the fruits, called drupes, are cooked in hot water for a short while, then dried. The cooking process is short enough that cells walls are broken down, but enzymes are for the most part left intact and freed to act on the cell’s components to create an amazing array of aromatic components. The drupes are then dried, giving a shriveled wrinkled peppercorn.

Peppercorns, from Wikipedia

The seed inside the peppercorn contains the sharp “hot” piperine. White pepper is made from this seed. This is the pepper in shakers that I know from childhood, before freshly ground pepper was commonly available here in the US. I found it disagreeably hot and irritating, and I hated it. Still do! Oh, and it turns out that it contains indole as well. Indole is a stinky chemical that helps perfume when combined with pleasant floral aromas, but without floral compounds is pretty bad (fecal…).

Then, when I was older, I discovered freshly ground peppercorns—what a revelation! While the seed has most of the piperine, the dried flesh of the fruit has an altogether different quality. Its flavor is dominated by cool/cold receptor activating terpenes, such as limonene and pinene, and especially linalool. 

(Do these compounds sound familiar? Yes—you find them in tea!) 

And there’s one more chemical, rotundone, which is also found in herbs that activate the warm receptors, such as rosemary and basil. For you wine drinkers out there: it’s also in Syrah/Shiraz wines, and some other red wines as well, where it provides the peppery aroma.*

(Interestingly, about 20% of people can’t smell rotundone—so if people tell you a Shiraz or Côtes du Rhone has a peppery aroma and you don’t know what they are talking about, you may be in that 20%.)

(Another aside: all of these compounds are highly volatile, so disappear over time. Buy your peppercorns fresh and keep them away from sunlight and in an airtight container. Clear plastic pepper mills filled to the gills with peppercorns are not the answer for the best pepper.)

Back to amphithermic and why freshly ground black pepper might enhance the flavor of vanilla ice cream, and I might add, strawberries. Vanilla activates primarily the warm receptors, and an important flavor compound in strawberries, furaneol, does as well. What I think happens is that, in freshly ground black pepper, the activators of the cool/cold receptor activators and those of the hot ones cancel each other out, leaving the flavors that activate warm receptors, which then have a chance to shine.

If you add lemon to pepper, then the flavor shift is towards the cool/cold receptors, and if you put pepper on a steak the shift will be to the more roasty flavors, and also the warm meaty umami flavors. That’s what I mean when I say that freshly ground black pepper is amphithermic.

Now for an experiment. Don’t have any vanilla ice cream to carry it out, but do have some oolong—oolongs activate the warm receptors. What would adding some pepper to an oolong do?

I have a stuffy nose today, so not the best experimental conditions, but perhaps the pepper could overcome the aroma block? 

It did! The oolong tasted definitely more aromatic and, to put it simply, richer. At the same time I did sense the catch in the back of my throat that pepper gives, so I’m not totally sure that is the best thing to do with a beautiful oolong. Still, gives me some cuisine ideas. 

Any thoughts?

* Wood C, Siebert TE, Parker M, Capone DL, Elsey GM, Pollnitz AP, Eggers M, Meier M, Vössing T, Widder S, Krammer G, Sefton MA, Herderich MJ. From wine to pepper: rotundone, an obscure sesquiterpene, is a potent spicy aroma compound. J Agric Food Chem. 2008 May 28;56(10):3738-44. doi: 10.1021/jf800183k.

TEA = CHAMPAGNE?

[Note: this post is an edited repeat of a Pairteas Facebook post from the past—hope you enjoy it, and hope you and yours experience fulfillment and happiness throughout 2017 and beyond!]

...Of course not exactly! 

But for those of us who, like me, can't tolerate alcohol and are thus tea-totalers, is there a tasty tea-based alternative?

Think I may have found it—try it and let me know what you think!

• Started with the question: what is the flavor profile of champagne? According to winefolly.com, champagne has flavors of citrus fruits, white peach, white cherry, almond, and toast (yeasty).
• In addition it has (of course) alcohol, which comes across on the palate as "acid." How to get a similar profile?
• Amazingly, by using white tea: white tea actually has a number of chemicals it shares with peach, cherry, almond, and bready flavors, the latter thanks to its long withering. In addition, it has about half the catechins of green tea, so is decidedly less bitter.
• Next, we need the carbonation. At first was thinking about getting a sparkling alcohol-free apple cider—there are a couple of chemicals in white tea with an apple-like flavor—but champagne isn't apple-y to me, so I nixed that idea.
• So I took myself to our local gourmet store to find a fizzy drink that wouldn't be too sweet, and found Juniper Berry DRY. To find out more about this exquisite sparkling soda, which you can get on Amazon, go to: http://www.drysparkling.com/flavors/juniper-berry/
• Remembering that champagne also has a peach aspect, and that I wanted to cut sweetness a bit (and also because white tea has about half the catechins of green tea), I also got some Fee Brothers peach bitters (http://www.feebrothers.com/products/bitters/peach_bitters.php).

Here's the recipe:
• Bring 18 oz (half liter) of water to 170ºF (I checked with a food thermometer, but you can guess the temp because little bubbles start to appear). Add the water to 8 grams of white tea, brew for 60 seconds, and remove the leaves. This yields a rather dark tea (see photo below), but it will soon be diluted!

• Either let the tea cool down or be sure to put a metal spoon in your glass, then pour equal amounts of tea (first) and sparkling soda (second).
• For each 4 ounces of the tea/soda combo, add two dashes of peach bitters (or more, to taste). 

• Enjoy!!

=>> While you can still taste the tea very gently, the overall flavor and aftertaste is remarkably like champagne, and it feels so very festive!!! 

The picture below shows the result. Note that the tea soaked up some two ounces of the starting water! Sorry it's not in a champagne glass—am in down-sizing mode, and can't reach them right now!

Oh, and the bubbles don't show up in the picture, but the tiny bubbles are there...

Injury to a leaf and the chemicals it produces

In looking for discussions of the consequences of damage on leaf volatile production—the aromatic compounds produced when leaves are damaged, came across an experiment that detailed what the intact parts of a leaf does when the leaf sustains partial damage.*

Matsui and colleagues injured Arabidopsis leaves. Arabidopsis thaliana is a favorite research plant, because it grows quickly, and because it is the first plant for which the complete genome was sequenced.

Arabidopsis thaliana, from Wikipedia

The injured part of the leaf produced a chemical, (Z)-3-hexenal. The plant produces this chemical to decrease the chances of further attack, because it is insecticidal, bacteriocidal, and fungicidal. However, this chemical can also be toxic to the plant itself. 

The question is, then, what does the uninjured part of the leaf do with (Z)-3-hexenal that reaches it. It turns out that the leaf converts the chemical into non-toxic products, (Z)-3-hexenol and (Z)-3-hexenyl acetate. As shown in the diagram below (from the article), this conversion requires an enzyme, aldehyde reductase, and a chemical called NADPH (green oval). The production of NADPH for this reaction requires energy and intact cells, so can only be carried out by the uninjured part of the plant. 

Meanwhile, as you can see in the diagram (red oval), enzymes in the injured part of the plant spontaneously transform (Z)-3-hexenal into (E)-2-hexenal, and, with oxygen from the air (red circle), into at least three other compounds. No energy is needed for these steps, so they occur spontaneously when cell compartments are broken down and enzymes are released.

In the “You can’t win” department: the non-toxic products are released into the air and attract many different predatory insects that proceed to destroy the injured plant...

Why the interest in this question? (E)-2-hexenal is one of the chemicals one of the chemicals that gives the smell to new-mown grass, and one of the chemicals that are produced in the tea leaf after plucking and during withering, and one of the chemicals we humans appreciate in the flavor of green tea!

* Matsui K, Sugimoto K, Mano J, Ozawa R, Takabayashi J (2012) Differential Metabolisms of Green Leaf Volatiles in Injured and Intact Parts of a Wounded Leaf Meet Distinct Ecophysiological Requirements. PLoS ONE 7(4): e36433. doi:10.1371/journal.pone.0036433

’Tis the season…

…here in the US Northeast for sore throats, whether caused by infection, or simply too dry indoor air. Was thinking about the soothing aspect of hot toddies, and came across a recipe from Emeril Lagasse, in the Food Network website, here:

http://www.foodnetwork.com/recipes/emeril-lagasse/hot-tea-toddy-recipe.html#communityReviews

This recipe got five stars as a treat(meant) for sore throats. However, fact is for me, that I won’t ever try this recipe, because I don’t do alcohol, and I don’t even like the smell of whisk(e)y...

...so I searched some more, and came across this excellent blogpost: in it, Aparna travels to India and back, and finishes with the recipe for a non-alcoholic tea-based hot toddy for sore throats that is also good sipped cold:

https://www.mydiversekitchen.com/a-non-alcoholic-hot-tea-toddy-amp-a-photography-exercise-recipe

What these two recipes share (aside from tea) is the presence of spices that activate both TRPV1, the hot receptor and TRPA1, the cold receptor. For TRPV1, for example, it’s black pepper in Aparna’s alcohol-free version, and alcohol itself in Emeril’s version; and for TRPA1 it’s powdered dried ginger with its shogaols and lemon in Aparna’s recipe, and lemon juice in Emeril’s.

If you sip either of these two drinks, you will first feel a bite of pain, only to feel the pain quickly subside and the soreness in your throat with it. 

Why would activation of TRPV1 and TRPA1 together actually be soothing?

To untangle the answer, first a rather unusual experiment where the researchers passed cold dry air across the throats of forty-five healthy (and, I might add, somewhat foolhardy) volunteers to cause a sore throat—the kind of experience we have here in the US Northeast during these cold winter months.* 

This treatment led to inflammation. To quote the authors’ paper:

“This study shows that tonic stimulation of the pharyngeal mucosa with cold dry air causes pain, irritation, and discomfort whilst swallowing and an increase of inflammatory mediators, which is reversible.”

The inflammatory markers they measured included substance P. Its levels rose in the throat during cold air treatment, and vanished about 30 minutes after cold treatment was stopped. 

Substance P tells pain nerve endings to send pain messages to the brain, and is released with TRPA1 activation by the cold air. Release of substance P in turn leads to release of the other inflammatory mediators, which then leads to the release of more substance P, and so on in a vicious cycle.

When you activate either TRPA1 or TRPV1 alone, the associated nerve endings release substance P. However, when you activate both together, you first get a burst of substance P release, but then the two receptors mutually inhibit—to my simplistic thinking, nature made it difficult to sense both hot and cold at the same time. 

Not so simplistically, though, we do know for sure that both receptors can sit on the same cells, and that when both are stimulated simultaneously, they can cancel each other out. **

The ingredients in these hot toddies do just this—that’s why hot toddies can make your throat feel so good!

* Renner B, Ahne G, Grosan E, Kettenmann B, Kobal G, Shephard A. Tonic stimulation of the pharyngeal mucosa causes pain and a reversible increase of inflammatory mediators. Inflammation Research. 2013;62(12):1045-1051. doi:10.1007/s00011-013-0663-7.

** Barry G. Green, Betsy L. McAuliffe. Menthol desensitization of capsaicin irritation: Evidence of a short-term anti-nociceptive effect. Physiology & Behavior 68 (2000) 631–639.

 ** Takaishi, M., Uchida, K., Suzuki, Y. et al. Reciprocal effects of capsaicin and menthol on thermosensation through regulated activities of TRPV1 and TRPM8. J Physiol Sci (2016) 66: 143. doi:10.1007/s12576-015-0427-y. 

Note: menthol activates TRPA1 as well as the cool receptor TRPM8.

"The Sweet Wine Lovers' Manifesto"

Friend of Pairteas and wine genius Tim Hanni MW (= Master of Wine) is working on a new book, “The Sweet Wine Lovers' Manifesto,” and I’ve just read through a draft. It’s a bit embarrassing insofar as he mentions me a bit, but then I do prefer sweet wines, so the book does speak to my interests and preferences. 

What sweetness does, as I have mentioned before, is to cut the burn of alcohol to which I am genetically very sensitive. According to my 23andme results, I carry T at rs161364 in both of my copies of the TRPV1 gene, the hot receptor, on chromosome 17.  This means that I am exquisitely sensitive to the burn of alcohol.* This double T state is also relatively rare in people of European descent like me: while about 39% of people of European descent carry one T, only 10% carry two. The percentage of Asians and Native Americans with two T’s is even lower, between 4 and 5%, while the percentage of Sub-Saharan Africans is essentially zero.** In other words, the T is a gain-of-function genetic mutation that occurred after anatomically modern humans walked out of Africa to settle the rest of the world.

Interestingly, alcohol is also bitter. It activates at least two different bitter receptors: TAS2R13 and TAS2R38.* The latter receptor is also the one that responds to PROP (6-n-propylthiouracil) that researchers have used extensively to test for taste sensitivity. I happen to have the genetic markers that lead to high sensitivity to bitter for both of these receptors as well, but the burn I get from alcohol is so intense that bitterness takes a back seat.

Another genetic feature that I have: the most active version of a protein called gustin. This protein helps to govern the number and function of your taste papillae.*** A person can carry one or two copies of the most active (A) form of the gene for this protein, and I happen to carry two (I’m A/A at rs2274333), hence my tongue is a carpet of taste papillae and taste buds. Lest you think this is a great thing, you should know that being so sensitive means that I taste nasty stuff more strongly, too, and alcohol burns all the more.

This is my tongue, stained with blue food coloring. Taste papillae don't stain very much, which is why most of the tongue is pink, while the upper part, towards the back of the tongue, is blue. The fissures appear when there is a carpet of taste papillae, and you can also see some round papillae sticking up separately. Compare with the picture below, of a person with few papillae—most of the tongue is blue; the taste papillae are the pinkish dots that are scattered on the tongue surface.

Sweet activates TRPV5, which turns off TRPV1—that’s why I can tolerate Harvey’s Bristol Cream Sherry at 17.6% alcohol, while I cannot abide a Cabernet Sauvignon at 16% alcohol.

Though another confession is needed here, namely that I hate the taste of green peppers, which is characteristic of Cabs…but it’s the burn that gets to me first.

In any case, while genetics alters your degree of sweet wine liking (or to be more exact, your degree of high alcohol dry wine dislike), in fact more people enjoy sweet wines than really enjoy those high alcohol dry wines. According to Tim, if it weren’t for the snob appeal of the latter, people would be drinking sweet wines much more often, and not just with dessert. Keep an eye out for his book with more details!

* Alissa L. Allen, John E. McGeary, and John E. Hayes. Polymorphisms in TRPV1 and TAS2Rs associate with sensations from sampled ethanol. Alcohol Clin Exp Res. 2014 October ; 38(10): 2550–2560. doi:10.1111/acer.12527. 

** https://www.ncbi.nlm.nih.gov/SNP/snp_ref.cgi?rs=rs161364. Note I used the HAPmap data for these percentages. While some people quarrel with HAPmap data, those percentages seem to correspond to my experience.

*** Melis M, Atzori E, Cabras S, Zonza A, Calò C, et al. (2013). The Gustin (CA6) Gene Polymorphism, rs2274333 (A/G), as a Mechanistic Link between PROP Tasting and Fungiform Taste Papilla Density and Maintenance. PLoS ONE 8(9): e74151. doi:10.1371/journal.pone.0074151.