The Physiology and Biochemistry of Taste

The taste receptor cells are bundled together in onion-shaped taste buds in an arrangement that fits together much like the segments of an orange, forming a small pore at the surface of each papilla. Small hair-like structures (microvilli) extend from the cell membranes at the top of these taste receptor cells. Taste substances must pass through the pores in order to be detected, and they can do so only if they are dissolved in water or saliva.

The receptors that can identify the taste substances biochemically are located in the membranes of the taste cells. A receptor is a large protein that functions as a sort of antenna that normally can detect and identify only one type of taste. But in order to be detected by the receptor, the taste molecules generally have to be small. The majority of pure carbohydrates and proteins have absolutely no taste because their molecules are just too large.