Let’s say you lick a sheet of pure elemental copper. What makes it taste like copper? Is your tongue actually stripping copper atoms off the sheet and somehow analyzing them…?
Then, what if it’s an alloy, compound, or solution of some sort? Is your tongue individually analyzing each component and “summing” them up, or is the taste of a combined substance overall different from the sum of its individual parts?
Then what happens when you get into the actually complex things, like vegetables and meats and a hearty home-cooked meal made with all those things and sauces and carbs and such?
I know nothing about any of this, so please explain it like I’m five…
You have taste buds (which are small clusters of specialized receptor cells) on your tongue for five basic “true flavors”: salty, sweet, bitter, sour, and umami. Pretty much everything else is scent, which is why when you have a cold, foods can taste bland. When you chew, aroma compounds travel up the back of your throat to your nose. That’s “retronasal olfaction.”
The various dimensions of input have different pathways. The tastebuds go by way of cranial nerves to medulla to thalamus to gustatory cortex. Heat/cold (spicy hot/menthol) through a different cranial nerve. Olfactory information has a more direct route to the olfactory cortex. Those brain areas are then integrated at higher order cortical centers, send information to other brain areas, and receive information from each as well. All of which impacts the gestalt of what taste is experienced.
More information on the non-linear multimodal process than you likely want to know:
And it bears repeating: elementary school lied to you. There is no “zones” of the 5 different tastes mapped on your tongue. Certain types can cluster in an area, but they’re not elsewhere on the tongue too.
As said, your tongue detects which of the five basic tastes are in whatever you are tasting.
The scent component of taste is more complicated. As I understand it, the olfactory organs contain a large variety of different chemical sensors, and anything you scent (while tasting or otherwise) actives those sensors according to how sensitive that particular sensor is to it. Some are activated strongly, some weakly, some not at all. Your brain then interprets that pattern of activation as a scent.
Which is why wildly different things can share smells. They may be chemically different, but if they produce a close enough pattern of activation your brain will perceive it as the same scent.
Reality though is that the processing of taste perception is nowhere near as well studied as visual or even auditory processing.
Much is understood about the how visual cortical columns process information and the interplay between “bottom up” and “top down” processing - how the brain at multiple levels complete the perception filling in expected signal to make up for noise - sometimes falsely resulting in various perceptual illusions.
Taste perception? We don’t even know if it shares that columnar organization or not. How much top down occurs? (The literal bit of hunger being the best appetizer, of plating impact on flavor perception.) Are there taste perceptual illusions? (Yes BTW but not anywhere near as well studied as many other sensory illusions.)