How does taste work?

You forgot the fifth taste, umami.

” The taste buds are chemoreceptors, meaning that they transduce, or translate, chemical signals in food into electrical signals in the body. These electrical signals, called action potentials, travel to the brain via the nervous system, allowing us to experience the sensation of taste. Taste buds are known as direct chemoreceptors, meaning that they must make direct contact with the chemicals in food in order for us to taste. Distance chemoreceptors, on the other hand, such as those that sense smells, do not need to make direct contact with chemicals.”

Source

Some foods are combinations of any number of those qualities. The actual variance in flavor comes from the aromatics of the food, strength of the flavor, plus texture and other qualities. And I was going to write about sensory receptors, but I see that @marinelife has beat me to that. :) It’s all about the nervous system.

I think certain parts of your tongue will taste food differently…that could explain it a little bit.

Other than that I don’t know much on this subject.

“But it seems impossible for all the flavors of all the different kinds of food to be variations of just four tastes.”

I would think so too. Spices are the first thing that comes to mind. I don’t think spices are sour, salty or sweet, maybe bitter, but there seems to be so much flavour that can’t possibly be attributed to just these few things.

From what I know, the flavour of food is determined by the chemicals and gases it is made of and our taste buds recognise these different combinations of chemicals and sort them in our brain as a particular “taste”.

What many are forgetting (except @ubersiren, who only mentioned it), is that taste also takes into account the sense of smell. Smell is very important in taste, and has a much, much larger variability. Don’t you remember having to eat something you didn’t like as a kid, and someone told you to hold your nose? This doesn’t work great, as vapors still travel up your uvula to your nose, but if you’re able to close that (i can, not sure how common that is), you can seriously effect the flavor of what your eating, and it does actually reduce to just the four flavors, which tend to be easier to deal with then all the smells. Have to be careful with that, though, because if you open your uvula too soon, vapors in your mouth will travel up and make you taste it anyway >.<.

So, as far as mechanics, @marinelife had it good, but when it comes to variations in taste, most of that is due to the much larger variability of smell.

another side note. Have you ever smelled something, and said “that tastes great!” by accident? I think this may be a part of how closely linked the two senses are, but that’s probably just anecdotal

If you lose your taste of smell, you can’t taste as much. Your tongue tastes bitter at the back, sour down the sides and sweet and salty at the tip. It’s the smell of spices and food combined with this that makes taste. .

The classic demonstration of how olfaction accounts for most of taste is to have a blindfolded subject try to distinguish between a slice of apple and a slice of raw potato while holding ther nose. The textures are similar & neither stimulates the taste buds very much. It’s all about smell.

I recall reading somewhere recently that the left & right sides of the nose contains different sets of chemorecptors (sensitive to different odors) that project only to their side of the cerebral cortex.