Thursday, January 26, 2017

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 ( 

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 ( 

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!

Wednesday, January 4, 2017

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.