Taste generally comprises the sensation categories of sweet, sour, salty, bitter, and umami that are experienced in the mouth. (Astringency has also been debated as a taste, but since gustatory as well as non-gustatory epithelia react to an astringent stimulus, it is not considered a taste.) Yet taste receptors are not only found on the tongue; scientists recently discovered the existence of taste receptors that reside in the gastrointestinal tract, internal organs, and central nervous system.
Despite the different locations, taste and aroma perception do not seem to be completely independent; they combine in the brain. Aroma, in fact, is the most important part of flavor. Research has disclosed that about 80% of that which makes up the perception of taste is olfactory. Aromas, complete with flavor molecules, are perceived on the olfactory epithelium in the nasal cavity.