In anticipation of our upcoming feature length Supertaster video documentary, we spoke with Food Scientist Barb Stuckey about the theory behind the use of PTC (Phenylthiocarbamide) testing strips in food development.
In case you missed our Supertaster Teaser from last week, PTC strips were exactly what we spent three years subjecting over 1,000 test subjects to… on camera.
Barb’s fascinating book Taste (previously published as Taste What You’re Missing) is without a doubt a must-read if you have any interest in the science behind taste.
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Good Food Revolution: Ah Barb, I have so many questions for you!
What exactly is PTC and how did it come to be used for such tests?
Barb Stuckey: PTC is a compound that’s used to test humans for taste sensitivity. It’s somewhat akin to an eye chart in that it tests the acuity of one of your senses. PTC tests your sense of taste; a letter chart tests your sense of sight.
We learned about PTC the same way many discoveries happen: by accident.
Dr. Arthur Fox, a chemist at DuPont, accidentally created a dust cloud from a powdered substance he was working with in a lab. One of his colleagues inhaled and tasted something bitter. Dr. Fox was right in the thick of the cloud and tasted nothing. Eureka! This was the beginning of our understanding of how humans have individual differences with regard to the way we experience the sense of taste.
GFR: Can you tell me exactly what the various reactions to the PTC actually mean?
Barb Stuckey: Technically PTC is a genetic test. It indicates whether or not you inherited the genes that allow you to taste PTC as bitter. However, PTC sensitivity also extends to other things, too, namely all tastes.
When someone has a violently intense reaction to PTC, we call them supertasters (a term I hate) or hypertasters (my term).
About 25% of the population is hypertasters. About half the population can taste PTC but not quite as intensely. In other words, they taste it as mildly bitter.
About 25% of the population can’t taste PTC at all. We call them non-tasters (a term I hate!) or tasters (my term). Tasters can taste all 5 tastes (with certain exceptions like PTC), just not as intensely as the other 75% of people.
It’s critical to understand that there are only 5 tastes. They’re called Basic Tastes and they include sweet, sour, bitter, salt, and umami (the taste of savoury). It’s critical to keep in mind that PTC tasting ability has no correlation whatsoever on the sense of smell! You can taste PTC and have little to no sense of smell. This seems to be really hard for people to get their head around. Supertasting refers to only 5 tastes!
Let me give you an example. Hypertasters with zero sense of smell would experience black coffee as extraordinarily bitter. But it would be really out of balance since they don’t experience it in concert with coffee’s lovely roasty, toasty, chocolately, peat-y, nutty aroma. A super smeller who can’t detect PTC would experience all those lovely aromas but without much bitterness. Two different senses, 2 different people, 2 vastly different experiences!
GFR: So there is usually a link between the reaction to PTC and the concentration of tastebuds on a subjects tongue?
Barb Stuckey: Yes, they are positively correlated.
GFR: So what your saying is that just because someone is less sensitive to PTC doesn’t make them a “bad” taster?
Barb Stuckey: There’s no such thing as being a “bad taster”! One of my pet peeves is when people assume that those labeled supertaster are “better” tasters. That’s like saying someone with good eyesight would be a great art critic. Or someone with good hearing would be a good musician.
The words good and bad assign judgment to tasting. I prefer not to judge. If you can’t taste PTC I just consider you tolerant of intense levels of tastes that many of us are overwhelmed by. It’s neither good nor bad.
GFR: And conversely someone who has a violent reaction to the PTC strip is not necessarily a “better” taster, right?
Barb Stuckey: Correct. In fact, some people are so sensitive to the basic tastes—especially bitter—that they eat very bland, familiar foods. This may mean they have fewer novel and less diverse tasting experiences. And that’s the key word about expanding your tasting skills: experience! The more experience you have tasting, the more you’ll be to detect subtle differences and nuances. In other words, the more of an expert taster you’ll be.
GFR: In what kind of situation would this kind of testing be useful? I’m guessing in packaged food development and focus group testing? In order to find out the core group of “median” tasters?
Barb Stuckey: In food development, we’re usually developing for the broadest palate we can, so that the product will have the broadest market potential. This means we’re developing to the centre of the bell curve.
In some situations—like when we’re trying to match a product—we get really, really detail oriented. In these cases we may screen out those who can’t detect differences in foods. However, they may or may not be able to taste PTC. Familiarity with a food is more important than PTC since only a small percentage of the flavour of food comes from its taste. Taste alone leaves out smell, texture, sight, and sound. It’s more important to us that you can tell the difference between Coke and Pepsi than whether you can taste PTC or not.
GFR: Very interesting!
Having looked at the science of taste for many years, have you discovered any other interesting correlations between sensitivity to PTC and sensitivity to other food/wine components? Spicy heat for example?
Barb Stuckey: People who are PTC tasters tend to be more sensitive to textures. This is because tastebuds are surrounded by fibres that detect texture. And since spicy heat is a textural experience (a painful one, but tactile nonetheless), those who are extremely sensitive to PTC tend to have the same reaction to heat.
GFR: And have you read anything that would point to such sensitivities being hereditary?
Barb Stuckey: PTC tasting is almost entirely hereditary. That’s what genetics are all about! (see above)
However, there is some data that show that smokers are less sensitive (as a group) to PTC. This would seem to indicate that you can override your tasting genes with certain types of behaviour, physical damage, or other phenomenon. We definitely don’t know everything there is to know about the sense of taste!
GFR: Thank you for joining us Barb. I think that will clear up a lot of the questions our readers have been asking.
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Edinburgh-born/Toronto-based Sommelier, consultant, writer, judge, and educator Jamie Drummond is the Director of Programs/Editor of Good Food Revolution… And it was great to get the true story behind those pesky strips.
