Phenylthiocarbamide, also known as PTC, or phenylthiourea, is an organic compound that either tastes very bitter, or is virtually tasteless, depending on the genetic makeup of the taster. The ability to taste PTC is a dominant genetic trait. The test to determine PTC sensitivity is one of the most common genetic tests on humans.
About 70% of people can taste PTC, varying from a low of 58% for Aboriginal people of Australia and New Guinea to 98% for Indigenous peoples of the Americas. One study has found that non-smokers and those not habituated to coffee or tea have a statistically higher percentage of tasting PTC than the general population. PTC does not occur in food, but related chemicals do, and food choice is related to a person's ability to taste PTC. There is conflicting evidence whether a higher percentage of women taste PTC versus men.
Sodium benzoate (E211), also called benzoate of soda, has the chemical formula NaC6H5CO2. It is the sodium salt of benzoic acid and exists in this form when dissolved in water. It can be produced by reacting sodium hydroxide with benzoic acid.
Thiourea is an organic compound of carbon, nitrogen, sulfur and hydrogen, with the formula CSN2H4 or (NH2)2CS. It is similar to urea, except that the oxygen atom is replaced by a sulfur atom. The properties of urea and thiourea differ significantly because of the relative electronegativities of sulfur and oxygen. Thiourea is a versatile reagent in organic synthesis. "Thioureas" refers to a broad class of compounds with the general structure (R1R2N)(R3R4N)C=S. Thioureas are related to thioamides, e.g. RC(S)NR2, where R is methyl, ethyl, etc.