Originally Posted by munki

Olfaction, taste and trigeminal receptors together contribute to flavor. The human tongue can only distinguish among 7-8 distinct types of taste, while the nose can distinguish among hundreds of substances, even in minute quantities. Olfaction amplifies the sense of taste, as can be proved by a simple "kitchen" experiment. If peeled pieces of apple are placed in one bowl, and peeled pieces of potato in another, and then the nostrils are held completely closed while a piece from one bowl is sampled, the taste of apple and potato are indistinguishable. http://en.wikipedia.org/wiki/Olfaction