Understanding flavour

It’s one of the cornerstones of the restaurant business (along with employee problems and debt). Isn’t it time you got to know it a little better?

We describe our flavour world as being composed of four basic tastes: sweet, sour, salty and bitter. To these, Aristotle added astringent, pungent and harsh. At other times, qualities such as urinous, acrid and putrid were also hypothesized. Scientists continue to debate whether the modern four cover all experiences; a growing body of data suggests that the sweet/sour/salty/bitter paradigm may be an oversimplified model for a process so complex that we are only on the brink of understanding it.

Flavour is perceived by taste “buds”—groups of taste receptor cells that cluster together like the segments of an orange. The average adult has 10,000, although the number varies widely. Taste buds can be found not only on the tongue, but on the soft palate, pharynx, larynx and epiglottis as well.

From the 1940s through the ’90s, virtually every basic biology textbook perpetuated the myth that taste buds were grouped in the mouth according to the specialty. The tongue was “diagrammed” into separate areas where certain tastes were registered: sweetness at the tip; sourness on the sides; and bitterness at the back of the mouth.

In the ’80s and ’90s, research at Yale, Monell Chemical Senses Center, the University of Connecticut and elsewhere demonstrated that the “tongue diagram” explanation of how we taste was false. Instead, leading taste researchers such as Dr. Linda Bartoshuk of the Yale University School of Medicine found that taste buds are not specialized and do not congregate according to specialty. Sweetness, saltiness, bitterness and sourness can be tasted everywhere in the mouth, although they may be perceived at slightly different intensities at different sites on the tongue.

Though taste buds are not specialized, the taste receptor cells that make up taste buds are. A taste receptor cell, in other words, may be specialized for sweetness, another for saltiness and so on.

Taste buds that can sense all taste qualities and that are dispersed throughout the mouth, researchers say, make evolutionary sense. With a taste mechanism thus structured, an individual does not lose the capability to perceive one of the four basic tastes even if a part of the tongue is damaged. The French author and gastronome Brillat-Savarin made the same observation. In his “The Physiology of Taste,” he describes a man whose tongue had been partially amputated as punishment for attempting to escape from prison. In response to Brillat-Savarin’s inquiry, the man wrote that he could still taste fairly well and could, like other men, determine what was pleasant and what was unappetizing.

One of the most intriguing of recent findings is that the tongue is controlled by two major nerves that relay information to the brain ipsilaterally; that is, a taste perceived on one side of the tongue goes up and is interpreted on the same side of the brain. Most nerves work contralaterally, sending their messages to the opposite side of the brain. Why the taste system is wired in this manner is not fully understood, but scientists suspect a complex interdependent network by which one nerve can inhibit another, or take over should one of the nerves be damaged.

Another recent finding suggests that the intensity of bitterness is perceived differently at the front of the tongue than at the back. The front is most sensitive to bitterness; a small amount is readily picked up. Above a certain threshold, however, the back registers bitterness more intensely. This may be due to the way taste buds are arranged and the distance between them.

The fact that taste buds at the back of the tongue register bitterness more intensely helps to explain why tannin is perceived at the back of the throat.

Interestingly, although our sensitivity to sweetness does not decline as we get older, our sensitivity to bitterness may. Most bitter substances are pharmacologically active; they are poisonous in massive quantities. Some evidence suggests that people who expose themselves to large amounts of bitter substances such as coffee and cigarettes, for example, may develop a reduced sensitivity to bitterness as they age.

Defined
Flavour-n 1. the quality of something that affects the sense of taste, 2. the blend of taste and smell sensations evoked by a substance in the mouth, 3. characteristic or predominant quality.

Taste-n 1. one of the special senses which perceives and distinguishes the sweet, sour, bitter or salty quality of a dissolved substance and is mediated by taste buds on the tongue, 2. the objective sweet, sour, bitter or salty quality of a dissolved substance as perceived by the sense of taste, 3. a sensation produced by the stimulation of the sense of taste, in conjunction with that of touch and smell.

Source: Webster’s New Collegiate Dictionary

IN?FOOD, PEOPLE RESPOND TO…

Temperature
Texture
Taste
…in that order
The tastes
Sweet
Sour
Salty
Bitter
Umani (savory)

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