Sweetness is one of the five basic tastes universally considered as a pleasurable experience. Foods rich in simple carbohydrates such as sugar, glucose and fructose are those most commonly associated with sweetness, although there are other natural and artificial compounds that are sweet at much lower concentrations, permitting their use as potential non-caloric sugar substitutes.

   The chemosensory basis for sensation of sweetness, which varies between both individuals and species, has only begun to be understood since the late 20th century. Responsiveness to sugars and sweetness has very ancient evolutionary beginnings, being manifest as chemotaxis even in motile bacteria such as E. coli. Even newborn human infants are inclined to high sugar concentrations and prefer solutions that are sweeter than lactose, the sugar in breast milk.

   Sweetness has been found to have the highest taste recognition threshold, being....