Thursday, July 19, 2018

Smell survey at World Tea Expo 2018

Hello All! -- Here are the results of the Smell Survey we undertook at WTE 2018!

As you can see, each of us has a different take on the nature of the aromas present in tea, so when we each enjoy our favorite tea, no doubt we enjoy it for different reasons!

Thank you so much, Marzi PecenIndependent Tea Consultant, Educator and Writer Extraordinaire, for helping to administer the survey!

Copyright 2018 Virginia Utermohlen Lovelace MD
First of all I would like to thank all of you who participated! This was a pilot survey, so the findings listed here are provisional and await a much larger effort. However even with a small number of participants, some interesting observations emerged.
Rationale for the survey
I was inspired to carry out this survey by three papers I had read. Two discussed the genetics of our responses to ß-damascenone, a smell present in Damask roses, and ß-ionone, characteristic of violets. In the third, threshold responses to each of these aromas were examined.*
Barrels of Kentucky bourbon whiskey; ß-damascenone contributes to Kentucky bourbon's characteristic flavor. Image from Wikipedia.
Both aromas are present in teas: ß-damascenone primarily in black tea, and ß-ionone in all teas. Participants in the survey sniffed both aromas and rated their qualities.
There were 55 participants with usable surveys, of whom 53 indicated gender—29 females and 20 males. The ages ranged from 18 to 74. Ten females and 5 males considered themselves beginners or novices when it comes to tea kowledge, and 19 females and 15 males considered their knowledge to intermediate or expert.
Effect of age on intensity of the aromas
Age came into play, as Plotto and colleagues suggested (see reference below). For their paper they looked at thresholds, the lowest concentration at which people could detect ß-damascenone, and found that people who were 45 years and over had higher thresholds than did younger people. While we didn’t measure thresholds, we did measure the intensity of the sensation given by each aroma. A lower intensity may generally reflect a higher threshold. Therefore I wasn’t surprised to find that the older participants didn’t find the sample of ß-damascenone to be as intense as did younger people. Although Plotto and colleagues didn’t mention any effect of age for ß-ionone, in our study older participants also found ß-ionone to be less intense. 
We do know that age influences our ability to smell, though data I collected many years ago suggests that this decline varies from person to person, with some people retaining their sense of smell into old age. For me at age 75, ß-damascenone is quite intense. I consider myself lucky in this respect! Or perhaps not so lucky, if the smell is unpleasant.** 
Qualities of the aromas
For ß-damascenone, 29 of 53 (55%) who responded to the smell found it to be rose-like and/or floral, while 24 did not find any floral quality in it. In fact some people indicated that it smelled like paint to them! 
Because ß-damascenone is present in black tea, it would have been interesting to see how people whose favorite tea was black responded, but their were only 8 people who cited a black tea as their favorite, so statistical analysis was impossible to carry out. There is a slight suggestion that people who considered black tea their favorite thought ß-damascenone was not quite as strong smelling, but more research is clearly needed, as this may simply be  question of age—in other work I have done, black tea tends to be a favorite of older people.
For ß-ionone, 39 (71%) of 55 participants could not detect any floral quality in the aroma. Instead they found it to be woody and often pungent and sour, as has been reported in the studies cited. ß-ionone is present in all teas derived from Camellia sinensis, so this observation raises the question of whether these off-aromas may be involved in some people’s avoidance of tea. However, clearly people at WTE were not avoiders!
Interestingly, 19 (36%) of 53 participants could not sense the floral qualities of either odor.  Importantly, this phenomenon did not influence their choice of favorite tea.
Bulgarian Rose from the Rose Valley, Bulgaria near Rosino Village. ß-ionone and ß-damascenone both contribute significantly to the aroma of roses.
With apologies to Gertrude Stein and Will Shakespeare, a rose may be a rose, but your rose is not my rose...and a rose by any other name may not smell as sweet to you as it does to me...
Image from Wikipedia.
Favorite teas
As for favorite type of tea: 51 participants stated a favorite type; of these 10 (20%) preferred green, 29 (57%) chose oolong, white, or BaiHao (all floral teas), and only 8 (15%) picked black tea. Interestingly, those who chose oolong/white/BaiHao were signficantly more likely to state that they liked their favorite tea’s aftertaste. People who listed green tea as their favorite were significantly less likely to appreciate its aftertaste—was it because green tea aftertaste tends to be bitter/astringent, or because green tea tends to have relatively little aftertaste when compared with oolong? I cannot tell.
Bottom lines 
  1. What you experience in tea  and what I experience may be radically different, yet our tea preferences may not reflect these differences. 
  2. Oolong/white/BaiHao teas are particularly appreciated for their aftertaste. Can we use this information to spread interest in these teas among the general public? and if so, how?
Those are the results for now—so many unanswered questions!

Next year we’ll do a more extensive survey, so let me know what kinds of questions you would like to ask!
* Here are the articles:
  • Jeremy F. McRae et al. Identification of Regions Associated with Variation in Sensitivity to Food- Related Odors in the Human Genome. Current Biology 23, 1596–1600, August 19, 2013, 
  • Sara R. Jaeger et al. A Mendelian Trait for Olfactory Sensitivity Affects Odor Experience and Food Selection. Current Biology 23, 1601–1605, August 19, 2013. A. 
  • A. Plotto, K.W. Barnes, K.L. Goodner.   Specific Anosmia Observed for β-Ionone, but not for α-Ionone: Significance for Flavor Research. Journal of Food Science. Vol. 71,  401-406 Nr. 5, 2006. doi: 10.1111/j.1750-3841.2006.00047.x.

** On the other hand, one decline I have noticed in my sense of smell is a decline in my ability to smell sulfur compounds. In the cross-sectional study that we (Willemien Steengracht MD and I, for her medical thesis at the Vrije Universiteit, Amsterdam) carried out, the most notable decline in senstivity by age was in sensitivity to the smell of natural gas, i.e. mercaptans. Skunk smell consists of mercaptans—I have observed that I am slower than my daughters to perceive the aroma of skunk roadkill as we approach and pass over it. 

For those of us who are getting older: we probably shouldn't rely on our sense of smell to warn us of a gas leak...

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