PTC Taste Test Paper

If you are experiencing different results (taste of bitterness, then no taste at all) with the PTC paper, there might be a few explanations.

Sensitivity to PTC is based on a genetic disposition, so it seems likely that a positive one time should give a positive the next time. There does appear to be evidence that results with the same individual can vary as much as 8 times.  This may be what you are experiencing.

It does make sense to limit intake of food or drink prior to the test, since it may be possible to offset or mask the effect. Have a supply of water available to rinse out your mouth (spit) to eliminate the bitter taste. There is also mention in some literature that smoking can diminish a person’s ability to detect PTC.

PTC paper is very stable, so it’s unlikely the paper is too old to work. A couple of other unlikely possibilities might be that the paper didn’t get proper soaking treatment during manufacturing or the paper was Control paper and not PTC. These situations are both very unlikely, and could be tested by trying a strip from another vial or batch.

The SDS for each taste test paper lists the ingredients. The concentration of ingredients is usually so small, it is less than what would be considered hazardous. Aside from these small quantities, the cellulose paper is the only other ingredient. In addition, the proper use of each taste test is to touch the strip to the tongue. These taste strips have been used safely in classrooms for decades.

The manufacturing facility where the PTC paper is produced (Cottonwood, AZ) is a typical manufacturing site. We don’t manufacture nuts or other products usually associated with allergy concerns. Please note, however, that the facility is not certified or considered an allergy-friendly manufacturing facility. In addition, the raw materials used in producing the taste test papers are not procured in any special fashion. We have no assurance that they were produced in an allergy-free environment.

Despite the above information, if you have a concern about a possible allergic reaction, perhaps it would be best to abstain from the activity.

The taste test strips exhibit a taste due to a dominant allele on chromosome number seven, and the ability to taste these compounds is present in about 70% of the U.S. population. The ability to taste is due to two different sets of alleles. These compounds are present in various naturally occurring foods, and are selected due to their similarity to bitter alkaloids and cardiac glycosides, used by the plant to reduce browsing by herbivores.

Thus, their presence is a result of natural selection both for the plants which produce them and the animal which benefits from the ability to sense them. It is a benefit to be able to detect them and avoid bitter tasting foods, some of which might be harmful if swallowed. Hence, it is a trait selected for in populations evolving in an area which had/has such plants.

Unlike PTC, which taste bitter if an individual can taste it at all, Sodium Benzoate might taste sweet, salty, or bitter. It would generally taste salty to an individual who can taste the bitterness of PTC.

YES. In the case of the genetics taste test strips, both PTC and Sodium Benzoate are salts of benzoic acid. Any possible toxicity would be in grams per kilogram of body weight, which is millions of times greater than anything which would be found in our taste test strips. Phenylthiocarbamide (PTC) is present at only 20 micrograms per strip. At this level, the compound is negligible and harmless.