Ode to the Not-So-Simple Human Tongue
It is sometimes easy to forget that the gateway to a great food experience is the lowly human tongue.
In combination with our olfactory senses, however, it makes gustatory perception possible. Its thousands of taste buds (and those on our epiglottis) house hundreds of thousands of taste receptors. These, in turn, can sense at least five distinct classifications of flavors: bitter, salty, sweet, sour and umami (savory). This last type is not well understood and so the research continues. Scientists suspect that there may be more types of taste sensors; the search is on.
Even before you place a piece of chocolate on your tongue, pause and smell it first. Smell, like taste, is a form of chemoreception. You are experiencing the volatile chemicals (“odorants”) coming off the chocolate in very low concentrations. The roof of your nasal passage is where the odorants are detected. According to Wikipedia, “Odor receptor nerve cells function like a key-lock system: if the airborne molecules of a certain chemical can fit into the lock, the nerve cell will respond.”
As you inhale, you are simply smelling the chocolate, but as you exhale you are contributing to the act of tasting the chocolate.
Once you place the chocolate on your tongue, you naturally close your mouth and push the chocolate up against the roof of your mouth. The tongue is well evolved for this purpose. It is strong enough and tough enough to masticate food. This ability makes it possible for us to gain a deeper sense of the taste of food (and, by the way, it exposes more of the food to saliva to start the digestion process.) At this point we are experiencing the full flavor of the chocolate with all its particular notes.
And here is where the sensory meets the cerebral: in an amazing display of evolutionary adaptation, our tongues – combined with our over-sized brains – also evolved for speech, allowing us to express our opinions on said chocolate. In tasting food, our brains make sure that all eight muscles that allow the tongue to taste as well as tell work in perfect harmony.