Illustration by Daria Krikunova
We all know we need a certain amount of nutrients and energy to live. However, while nourishment may be a necessity, the flavour is what makes food fun! But how does flavour work in the first place? What’s behind our ability to enjoy a slice of chocolate cake, or be repelled by a glass of sour milk?
Whether you want to improve the way you express yourself in the kitchen or are simply fond of trying out new foods, understanding the way flavour is perceived in our tongue will help you get the most out of the experience.
Most of us have seen that old “map of the tongue” in school or around the internet. At first glance, it looks pretty straightforward: sweet at the tip, salty at the sides, and bitter at the back. But if you have ever tested some lime juice with the tip of your tongue, you will probably have noticed that there is more to that story.
How is flavour detected?
Our perception of flavour consists of two senses: taste and smell. Both are first felt through receptors on your mouth and nose, which “read” the different components of your food and then send this information to your brain. Here, that information will be processed together and will confirm whether what you are eating is indeed your mom’s chicken soup.
The scent is detected through receptors located inside your nose. These don’t react to the food itself. Instead, they will be activated by the airborne molecules that come out of our food, especially when it’s hot – this is why cold lasagna can still taste good, but it doesn’t feel just as mouth-watering as the one that just came out of the oven.
Taste, on the other hand, is felt on your taste buds: small nerve endings located on your tongue, your palate and the roof of your mouth that can detect the chemicals contained in your food. Most of these taste buds are arranged in tiny clusters known as “papillae”, which you can see on your tongue’s surface (1).
Out of the two, the receptors on your nose provide the widest array of sensations. If you take scent out of the equation (such as when you have a cold), all you ever feel is different combinations of five basic tastes: sweet (like any type of candy), salty, bitter (like those Brussel sprouts), sour (such as pure lime juice), or savoury or umami (like meat).
But what about all the other flavours?
Two more mouth sensations are often considered flavours and alter the way you perceive food: spiciness and coolness. However, these are not actually “read” by your taste buds.
Spicy foods such as chilli pepper are actually causing a pain response on all the nerve receptors inside your mouth. However, we feel this “kick” at the same time as we feel all the other flavours of that hot sauce, so we don’t register it as outright pain.
Then there’s the cool sensation that you get from mint or toothpaste. This fresh feeling happens because one of the components of mint – menthol – can stimulate the cold receptors inside your mouth (2). Therefore, your brain gets the message that your tongue is cold.
Finally, two other factors influence whether we experience food as pleasant: the food’s texture (such as something being crunchy or soft) and our emotions. Most of us learn what kind of food we like early on. Also, certain flavour combinations or scents can remind us of happier times or stressful periods.
Is the tongue map accurate?
Most taste buds are located at the tip, to the sides, and the far-back end of the tongue, so all flavours will be more intense in these areas. Conversely, the middle section of the tongue doesn’t have as many taste receptors. This makes sense, as this part is far from your teeth, so food doesn’t usually linger there much.
The map is not completely off-track: there are indeed some areas where you can feel flavours at their strongest. For example, that rough section at the back is indeed best attuned to bitter flavours. It is also connected directly to your IX Cranial nerve, which is one of the main nerves that control your gag reflex (3). This is meant to force you to quickly spit out anything that tastes odd or spoilt – a safety feature that probably saved countless lives in prehistoric times.
Both our bodies and our tastes resist a simple explanation. After all, we have created entire industries behind the pleasure we get from a well-cooked and pleasant meal. Our tongues and their taste buds have an incredibly complex job, so they deserve some love during our oral health routines.
1. Janson-Cohen B, Taylor J. (2005). Special Sense Organs. In: Memmler’s Structure and Function of the Human Body. 8th Edition. Baltimore: Lippincott Williams & Wilkins. Pages 188-9.
2. McKemy D. (2007). TRPM8: The Cold and Menthol Receptor. In: Liedtke WB, Heller S, editors. TRP Ion Channel Function in Sensory Transduction and Cellular Signaling Cascades. Boca Raton (FL): CRC Press/Taylor & Francis; Chapter 13. Available online: https://www.ncbi.nlm.nih.gov/books/NBK5238/
3. Reeves A, Swenson R. (2008) Disorders of the Nervous System: A Primer. Chapter 7. Online Textbook for Dartmouth Medical School. Available online: https://www.dartmouth.edu/~dons/index.html