I learned this today. Different things have different tastes because the taste buds in our mouths can react to different chemicals in different ways.
There are basically five tastes. Those are sweet, salty, bitter, sour, and umami. Umami is another word for “savory” and the fact that we can taste for it was discovered by a Japanese scientist in 1910, hence why we use the Japanese word for it.
There is a long-held myth that we can taste different flavors on different parts of our tongues, but this is not true. All flavors can be tasted on all parts of the tongue. The one exception is bitter. The back of the tongue has more receptors for bitter tastes than any other part. This is so we can avoid swallowing bitter foods, which are usually dangerous.
Avoiding dangerous foods is one of the reasons why we can taste. When we evolved to taste foods, it had a purpose and that purpose was to tell us what we could eat and couldn’t eat. If something tastes sweet or salty, it is usually a sign of a food rich in nutrients. If something tastes bitter, it is most likely a poisonous plant and should be avoided. If something tastes sour, the chances are high that it is rotten meat or food that has gone bad.
First, we need to look at how we taste. Our tongues have tastebuds. A tastebud is a tiny lump on the tongue that contains 50 to 150 taste receptor cells. The receptor cells are bundled together like a flower and contained within the surface of the tongue, in taste pores. These taste pores are like funnels that let fluid in to the taste receptors. There are extensions to the receptor cells that are called taste hairs, and these are inside the taste pores. At the other end of the taste bud, the taste receptor cells are connected to the nerves that carry information to the brain. The average human tongue has between 2,000 and 8,000 tastebuds. That means, between 100,000 and 1.2 million taste receptor cells. This difference is the reason why some people have a far better sense of taste than others. The taste receptors regrow every week.
When we put something in our mouths, chemicals on that thing attach themselves to proteins on the taste hairs and are guided to the taste receptors. That sends a signal to the brain and tells the brain what flavor it is. That also tells the brain whether to keep eating it or spit it out.
We also don’t taste with only our mouths. Your tastebuds can detect chemicals, but your brain needs extra information from your nose to put together a taste map. If you have a strawberry and a cherry jellybean and you hold your nose and put one in your mouth, you will not be able to tell if it was the strawberry one or the cherry one. The scent from the food is a vital part of the taste.
So, why do different things have different tastes. The sweet flavor is caused by sugars, such as sucrose, fructose or lactose. The sugar is detected by a protein coupled receptor. When sweetness is detected, the receptor starts a chain reaction that ends with an electrical signal being sent to the brain. We can taste sweetness to a level of 0.01ml in a liter.
Sour flavor is usually caused by acidity. It is detected by a group of cells called Type III taste receptor cells and they react to H+ ions that are abundant in sour foods.
Saltiness is caused by sodium chloride in food. It is detected by sodium ions coming into contact with the taste receptors.
Bitterness is also detected by a protein coupled receptor. Unlike the receptors that detect sweet flavor, there are up to 35 different proteins in our taste buds that respond to slightly different bitter substances. This is because bitter foods could be the most dangerous to our ancestors and being able to detect different kinds of bitterness was vital to survival. This is one reason why children don’t like bitter food and it tends to be a learned taste.
Umami is caused by an amino acid called glutamic acid or aspartic acid. Many different proteins found in foods contain these acids.
Each of these different tastes can be detected on an individual taste receptor at an intensity level of 0 to 10. That means a taste can vary across the tongue as different tastebuds are exposed to different intensities. It also means that combinations of flavors at different intensities are possible, giving more than 100,000 possible different flavors.
Different animals have different amounts of tastebuds. Some animals need to be able to taste more than others. Catfish have more tastebuds than any other animal and they clock in at 175,000. This enables them to detect a taste in the water from a long way away.
So, our tastebuds are collections of taste receptors that are bound together. Chemicals in the foods we eat attach to these receptors, sending an electrical signal to our brain, telling us what flavor we are eating. And that is what I learned today.
Photo by Karolina Grabowska: https://www.pexels.com/photo/a-close-up-shot-of-a-person-taking-a-medicine-5207309/
Sources:
https://en.wikipedia.org/wiki/Taste_bud
https://en.wikipedia.org/wiki/Taste_receptor
https://www.ncbi.nlm.nih.gov/books/NBK279408/