The Science of Taste and Texture

What people casually call "taste" is actually a composite sense built from several distinct inputs. Taste proper is detected by taste buds on the tongue and elsewhere in the mouth; smell contributes through two separate pathways, orthonasal olfaction when aromas are sniffed in through the nose and, more importantly for flavor, retronasal olfaction when aromas released during chewing travel up from the back of the mouth to the same receptors; and the trigeminal nerve adds sensations like the heat of chili peppers, the cooling of menthol, or the fizz of carbonation. The dominant role of retronasal smell in flavor perception is easily demonstrated: when the nose is pinched shut, it becomes difficult to distinguish an apple from an onion by taste alone.