The sense of taste is much simpler than the sense of smell. Whereas we can distinguish thousands of different smells, there are only four (or six, as will be seen later) basic tastes. The four are sweet, sour, salty and bitter, each identified by a class of taste buds on the tongue and the roof of the mouth.
Sweetness is detected primarily near the tip of the tongue. Those taste buds can detect the shape of the hydroxyl groups found in sugar molecules. Sour receptors along the sides of the tongue respond to the acids in sour substances. Salt receptors, also along the edges, detect the metal ions, such as sodium, in salts. Complex nitrogen-containing compounds called alkaloids are detected as bitterness at the back of the tongue.
Sweetness tells us if the fruit or vegetable is ripe. Sourness might put us off unripe fruit or food that is going bad. Saltiness alerts us to the presence of chemicals that are essential to the proper functioning of our cells. Alkaloids are often poisonous. Their bitter taste is our warning. Basic survival depends on the four basic tastes.
There’s more to taste than that, though. There is the vast array of flavors we can identify when we combine tastes with smells. And there is actually a fifth category of taste called “umami.” Umami is the sensation stimulated by the presence of glutamate. Glutamate is the most common amino acid, accounting for almost half of the protein in plants and almost one fifth of animal protein. Proteins are made from amino acids. Although we can’t taste proteins themselves, we can taste their constituent amino acids as they start to break down in our mouths. Being able to detect the presence of such essential food elements is a pretty obvious benefit.
With the five basic tastes, alone or together, combined with thousands of smells into a huge catalog of flavors, we humans can have a very rich relationship with food. Throw in texture, or “mouth feel,” like smooth or creamy and so on, along with the recent discovery that we can taste fat, and a person could spend their whole life just trying new food sensations.
At this time of year it’s good to have good taste. We have turkey, shortbread, oranges, chocolate and so on in an endless stream of intoxicating seductions. Chewing a shortbread cookie sets off a burst of activity. The sugar activates the front of the tongue, where sweetness receptors abound. Salt stimulates the sides. Protein arouses umami. Vapors rise up the back of the nose where they engage the sense of smell. Along with the evolving chemical combinations in the mouth and nose, there exists the mechanical world of mouth feel. The crumbling and dissolving. The smoothness of fat. It all combines to make you want to swallow so you can take another bite.
The sense of taste is simply profound.