Background
When we perceive the flavor of a food, we actually perceive the result of the brain's analysis of signals from the taste system in the mouth, coupled with signals from the olfactory system in the nose. Taste is not separated from smell as we eat -- we only perceive flavor through a complex process of sensor fusion. Individuals live in one of three very distinct flavor worlds, defined by their sensitivity to a compound called 6-n-propylthiouracil (PROP). PROP is a chemical which tastes unpleasant to those who can taste it, but has no odor. …
