The PTC and PROP taste strips can be used to determine whether someone can taste PTC or PROP. With these taste strips you can reliably identify tasters and non-tasters, the strips are ideal for research studies and for classroom demonstrations. The strips are made of paper and impregnated with the taste Phenylthiocarbamide PTC or PROP which can be described as a bitter taste. A significant number of people are PTC tasters or non-tasters, or whether someone can taste this taste is genetically determined by a dominant gene. The PTC strips are therefore widely used as a genetic test. Whether you experience Phenylthiocarbamide as bitter or not is determined by the so-called receptors, or protein receptors.
NB! If a person can’t taste the bitterness on the strips, it doesn’t mean the test person can’t taste at all. For the detection and quantification of taste disorders, we do not recommend the PROP/PTC taste strips, but to use the Burghart Taste Strips, which consist of multiple flavors and concentrations.
Here is a protocol that can help with the use of the PROP and PTC taste strips in a group:
• Depending on audience size, allow everyone to participate, or ask for 20-30 volunteers.
• One hour before the start of the test, the test person should not eat or drink anything except water (no coffee, cigarettes, chewing gum).
• Preferably use tweezers to remove the taste strips from the containers.
• After each strip, the patient rinses his/her mouth with water, so have a cup of water ready for the test person.
• Hand out the control strips. Have the test person label the strip in pencil with the number 1. Or have them hold it in their left hand if they don’t have a pencil.
• Distribute the PTC (or PROP) strips. Have the test subjects label the strip with the number 2. Or have them hold it in their right hand if they don’t have a pencil.
• Have the test persons place the control strip in the middle of their tongue. Instruct them to write down what it tastes like to them (or just remember). One may close the mouth and move the tongue back and forth.
• Have the subjects place the PTC (or PROP) strips in the middle of their tongue. Instruct them to write what it tastes like to them (or just remember). One may close the mouth and move the tongue back and forth.
• Ask the test subjects how many of them can taste the PTC strips. Write the number down (if possible, somewhere where everyone can see it).
• Then confirm that the rest of the test subjects were NOT able to taste the PTC (or PROP) paper. Write down the number (again, somewhere where everyone can see it if possible).
• Tell the test subjects that the second strip was impregnated with a chemical known as PTC (or PROP). Some people can taste it, others can’t. This is caused by a single gene. PTC (or PROP) will bind with the protein if it is present allowing this person to perceive the taste. If the protein is not present, PTC (or PROP) will not bind and a person will not be able to taste it.
• Ability to taste PTC (or PROP) is a dominant trait. About 2/3 to 3/4 of the group should be able to taste it, while 1/3 to 1/4 won’t.
• Ask the “PTC tasters/PROP tasters” how it tasted. They should all say “bitter” (or dirty or something like that). Ask if there were people who found it so bitter they just couldn’t stand it. Hopefully about 1/3 of the “tasters” (or about ¼ of the total participants) will say this was the case. These are the super tasters.
• It has long been believed that the ability to taste PTC/PROP relies on a single autosomal gene with two alleles. Non-tasters are homozygous for one allele, super tasters are homozygous for the other allele. Super tasters think PTC tastes very strong (and often very bad too). Someone with the heterozygous genotype can taste the substance, but does not taste it very strongly.