It is still believed that the four tastes (sweet, sour, salty, and bitter) that we can perceive with the tongue are attached to certain areas on the tongue. However, this is not the case, because the receptors on the tongue are capable of perceiving any taste. There is also a fifth taste: umami.
The four known flavors are:
In addition, there is a fifth taste perception:
The sweet taste has to do with sugars (sucrose is the known table sugar). However, there are also other sweet substances, such as aspartame, saccharin and stevioside (non-caloric sweeteners), polyols, proteins (for example thaumatin) and complex substances such as liquorice. Fructose (in fruit) is also a sweetener. Another sugar is milk sugar, better known as lactose.
The sour taste with the acidity is expressed in pH. The lower the pH, the stronger the acid. In addition, a pH of 7 is neutral, an apple has a value of 2 and stomach acid is 1 or 2 pH. Well-known acid products are citric acid (many in fruit and citrus fruits), vitamin C, lactic acid (in buttermilk, yogurt and crème fraîche), hydrochloric acid, which is also known as a component of stomach acid.
The salty taste is found in table salt (sodium chloride) and hydrochloric acid (aqueous solution of the gas hydrogen chloride).
The bitter taste is usually associated with an unpleasant taste, especially for children. Adults sometimes “learn” to appreciate the taste more and more. Sometimes you have to “learn how to eat or drink it”, like with beer. Bitter substances can be found in artichokes (cynarin), fennel, basil, and rosemary,
The umami flavor is associated with savory. It is a flavor that has to do with glutamate and can be found in salty snacks and, for example, bouillon cubes. It is also common in ready-made products, but also in meals with meat, matured cheese, and peas.
For a long time, it was believed that certain tastes had receptors in certain places on the tongue. You would taste sweet with the tip of your tongue, while bitter would lie on the back of the tongue. For a good salty taste, you had to taste with the sides of your tongue (front), and the same goes for the sour taste (back). This thought has been in the picture, and still hard to let go of.
However, it is not the case that certain tastes are associated with specific places on the tongue. In fact, flavors are unbound to areas: the different flavors can be tasted all over the tongue. There are of course always exceptions to the rule, but in general, this applies to all people.
So the map of the tongue is a misunderstanding, a misconception. There are no different areas on the tongue. This theory originated from an article written by Edwin G. Boring, in 1901. Each area of the tongue is said to be sensitive to a particular primary taste.
Research has now shown that the tongue contains receptors that recognize each primary taste (sweet, salty, sour, bitter, and umami). The intensity of the sensation does not differ, although the threshold at which sensitivity is noticed may differ. It was also announced in 1974 that all receptors on the tongue recognized all tastes. This research was conducted by Virginia Collings.