PTC Taste Test Strips: Let's Talk Science Outreach

PTC taste test strips have been used in biology genetics labs for years to demonstrate inheritance patterns. Their use has become popularized as a way to find “supertasters”; people with a heightened sense of taste. The Let’s Talk Science Outreach people at the University of British Columbia have kindly shared some of their experiences with us.

Dr. Tanja Voegel is a program coordinator at the Okanagan Campus of UBC. She tells us more about this project in her own words:

“One of Let’s Talk Science’s recent activities was: ‘Are you a supertaster?’ at the Winter Carnival at Watson Road Elementary in Kelowna. Students used Indigo Instruments PTC strips to find out if they could taste the chemical PTC and have the gene that codes for ‘supertaste’. The PTC model was used to explain how the compound binds to taste receptors on the tongue, with visualization through the SEM photos of taste buds on the tongue.

Seeing the face of a supertaster – priceless! We all know that “yuck” look; a dead giveaway for a supertaster identified with a PTC strip. Let’s Talk Science Outreach UBC Okanagan is looking forward to identifying more supertasters in the region.

Three student members of the Outreach team sitting at the activities desk. The test strips are in the cups in the middle of the table. Instructional material is front left with a model of PTC beside it. The SEM images of the tongue & taste buds are front right.

Let’s Talk Science is a national charitable organization that aims to engage youth through offering hands-on minds-on STEM education in the community. The Let’s Talk Science Outreach site at UBC, Okanagan Campus would like to thank Indigo Instruments for providing the PTC model and SEM photos to enhance the outcome of this project.

About Tanja Vogel

Tanja Voegel received her doctoral degree from Albrecht-Ludwigs-Universitaet Freiburg and the University of California, Davis in Plant Pathology. In her current position as a Research Associate at the University of British Columbia, she studies Crown Gall, a disease of grapevines caused by Agrobacterium vitis. Since September 2018 she has taken on the role of Outreach Coordinator for Let’s Talk Science.

The Let’s Talk Science Outreach team from the University of British Columbia, Okanagan, Campus. That’s Tanja Voegel on the far right who sent us these pictures.

Please feel free to connect with us if you are interested in learning about our program or how you can bring activities like the Supertaster Experiment into your classroom.”

Dr. Voegel, Research Associate
Let’s Talk Science Outreach Coordinator
Biology Department, University of British Columbia Okanagan
Kelowna, BC V1V 1V7, CANADA

Statistical Distribution Example?

The number of people who can taste PTC is predictable due to what is known as the Hardy Weinberg principle. The number of people who can taste it strongly or somewhat is in the range of 70%.

Dr. Voegel ordered 20 packs of 100 strips for her project. When she tested them on ~10 people she knew, to her surprise, no one could taste the PTC. Statistically speaking, at least 7 people should have had some response. Did she get a bad batch?

We tried some in our office and 1 person out of 7 tested did react strongly, 2 slightly. Still below the norm but it indicated the strips worked. So, we asked her if she had other people who could try. Sure enough, they worked. A great example of a statistical anomaly.

What is PTC?

PTC or phenylthiocarbamide is a chemical that closely resembles many naturally occurring alkaloids that are poisonous. A highly developed sense of taste for detecting such compounds in potential foods was very beneficial to early human ancestors. A strong response to a disgusting taste has a great selective advantage since it alerts the person to spit it out rather than swallow & and get very sick or die.

PTC, aka phenylthiocarbamide or phenylthiourea, resembles many toxic alkaloid compounds but is harmless in the trace quantities used in test strips. If you tried to eat enough test strips for a toxic dose, you’d die of constipation first.

Free SEM Images of the Human Tongue

We have posted some high-resolution images of the tongue & taste buds on our website. Any student or teacher is free to reproduce them for educational use.

This is a scanning electron micrograph (SEM) image of a human tongue. You can see several taste buds in the middle, slightly left. Click on the picture to go to a larger version you can download for free.

There is also an image of a single taste bud which you can use freely.