Taste & Smell: Do You Know How Do They Work?

Updated: Sep 28

Have you ever thought about how does your taste sense work? The word goes around about Confucius once having said: “Everyone eats & drinks, but very few can appreciate the taste." I wasn't born yet at the time the notorious philosopher existed along with other humans so I cannot tell you for certain if this is exactly what he said. However, I can understand what this

Enjoying a comforting cup of tea

sentence means. As a tea drinker with a highly developed palate since childhood, I often thought about this. Since everyone perceives taste & odours differently it made me wonder what's the reason behind it.

And as a self-proclaimed Japanese Tea Evangelist, I think it is truly important not only to know how do we taste teas but also to understand how the smell & taste senses work & how they both are interconnected. Let's dig it! What is the definition of taste?

Taste: the sensation of flavour perceived in the mouth and throat on contact with a substance. More than a simple action, the taste is a whole experience filled in with sensations. We do not only taste with our tongue or mouth but the aroma, texture & temperature are also part of the equation. The human sensory systems are so well developed that allow us to distinguish around 100.000 different flavours. I don't know about you but I am certain I have never distinguished as many flavours in my whole life & I don't think I will ever will. Taste is also strongly connected to human emotions. Depending on what we taste we can feel happy, sad, cold, warm, disgusted, nauseated... This is due to our taste, & smell, senses connection with the involuntary nervous system. Are flavour & taste the same?

Strictly speaking, they aren't the same. If your sense of smell becomes impaired, for example when you have a cold, & ingest a piece of dark chocolate, you will only be able to sense its sweetness or bitterness. However, once your sense of smell gets back to normal you are able to perceive more than just that. Taste is formed via the nose, once the aroma & taste combine flavour gets formed. Without a sense of smell, there is no flavour to be tasted.

How does the sense of taste work?

Taste buds encased inside fungiform papillae.

Until not long ago it was believed that different areas of the tongue were suited to specifically taste different flavours such as salty or sugary. However, this paper states otherwise. All the flavours can be sensed by the tongue as a whole even though its side areas are especially sensitive to taste. The back of the tongue is actually an exception, it is extremely sensitive to bitterness. This would allow us to spit without delay any poisonous or rotten food before they would enter our bodies via the throat. Bitter & sour tastes have been seen as an indication of danger & this information has been passed on through the generations. Our tongue is layered with multiple wart-like taste buds covered with micro taste receptors called fungiform papillae, they bind the molecules contained in the food we eat & help our brains to recognise the flavours. There are 4000 of them on average & there are also taste buds located in the mouth walls & the throat.

The taste buds are the only parts of our nervous system that regenerate. 10% of the taste cells in our taste buds are regenerated on a daily basis. These are the steps involved in the tasting process:

1. We smell the food or drink before & whole it enters the mouth

2. Saliva breaks down the food through chewing, liquids do not need any chewing

3. Nerve cells send signals to cranial nerves

4. These signals end in different parts of the brain, they can trigger cravings or memories & feelings

This is a very simplified process since there are a larger number of steps involved which can be very complex.

How many tastes are there?

There are five officially recognised basic tastes: sweet, sour, bitter, salty & savoury. Before savoury (umami) was discovered, there were only four recognised flavours.

Yeah baby, you are so sweet!

Sweet: sugar & all its derivates are part of the sweet flavours group in addition to certain types of amino acids & alcohols. It is a taste associated with feeling good & happiness, this is the reason why many people eat sweet treats when they are going through a rough patch in their lives. This is known as emotional eating, salty & savoury foods are also favoured when binge eating.

Sour: acidic juices such those coming from citruses or sour-tasting organic acids. Not everybody enjoys sour flavours, some people feel great discomfort. For many it is an acquired taste, it takes them time to get accustomed to it. Salty: salt crystals contained in the salt we use to season our dishes is what we perceive as salty. However, magnesium or potassium salts can also be perceived as such. Bitter: this taste can be found in a number of sources & it is deeply connected to our survival as a species. Since there are numerous plants & foods that taste bitter but only some are poisonous we had to learn which ones were safe to eat. I find this type of taste especially fascinating since my tongue/throat are extremely sensitive to bitterness. While I have learnt how to enjoy some types of bitter tastes, usually I don't feel really keen on them. One clear example is Brussel sprouts, I haven't been able to cope with them in all these years. In contrast, I love the slight pleasant bitterness of the tonic water.

The fifth recognized taste

Savoury: known as umami it wasn't discovered until 1910. It usually refers to brothy, flavour rich, caused by glutamic or aspartic acids contained in certain types of food.

First identified in 1908 by Kikunae Ikeda (池田 菊苗), a chemistry professor of the Tokyo Imperial University, he realised the flavour from kombu broth (dashi) was different from the other officially recognised flavours. This was due to its glutamate content. His disciple, Professor Shintaro Kodama, discovered another type of umami flavour source inosinic acid contained in dried bonito flakes (katsuobushi) in 1913. And in 1957, Akira Kuninaka discovered that the ribonucleotide contained in shiitake mushrooms could also be classified as part of the umami taste.

Miso soup with shiitake an umami rich experience.

Thanks to Kuninaka's discoveries we got to know that by combining foods that contain glutamate & ribonucleotides we obtain a much more powerful taste profile than when those ingredients are consumed separately. This helps to understand the classical food pairing choices in the cuisines of many countries, not only in Japan. There is one emerging word in use, also from Japan, to define a number of flavours, textures & sensations when consuming food. Kokumi can be translated as "rich taste", umami is used to describe brothiness or savouriness, kokumi refers to the richness, body & complexity of the food. However, it doesn't look like kokumi will become the sixth recognised flavour since it is referred to as a flavour modifier instead of a taste. More research & debates around this concept are needed, is worth noting that it only took 94 years for umami to be recognised as the fifth flavour. Let that sink in.

Are there any other recognised basic tastes?

Taste Science is a fascinating discipline. Scientists continue doing research on the matter in order to identify new types of taste & also to understand how our taste & smell receptors work.

Fatty is a serious contender to be considered as the sixth recognised basic taste. There are indications for the existence of specific fat receptors that can detect fatty acids, which might mean that the strong attraction we feel for high-fat content foods is more than just their texture.

What about hot or spicy?

Believe it or not, hot or spicy is not considered a basic taste & therefore it hasn't been recognized as such. I was actually surprised when I found this out since I have always thought this was a type of taste.

Hot is considered a pain signal sent by the nerves triggered by the capsaicin contained in spicy foods. This is why eating spicy food can feel uncomfortable for many people including me. If I observe the reaction of my own palate when eating some spicy food, I realize that I can no longer perceive any of the subtle flavours in the dish & all is left is a painful feeling plus a stomachache afterwards. While I am not really keen on consuming very spicy food, I like to use a bit of spice as an accent sometimes but it shouldn't dominate the flavour profile of the whole dish.

Is there any way to find out what type of taster am I?

According to NIDCD statistics, about 25% of the American population is classified as a non-taster, 50% fall in the Medium taster spectrum & the remaining 25% are considered supertasters. Non-tasters: usually consume really spicy & highly seasoned foods to compensate for the lack of perceived taste. They tend to favour fatty foods, sweet treats & alcoholic drinks more than other types of tasters.

Medium tasters: they tend to like pretty much all types of foods, including those that taste really bitter. They do not need high amounts of sauce, salt or seasonings to enjoy their food.

Supertasters: it might sound preposterous but this is actually the term in use. It might also sound like a great superpower however it can be a curse. Supertasters are more sensitive to flavours than other humans this is due to the presence of a greater number of papillae on their tongues. The degree of intensity they perceive smells & flavours is determined by the degree of sensitivity their taste buds have. Women are more likely to be supertasters than men. They tend to feel repelled by bitterness, spicy foods are painful to eat & they don't tend to crave as much sugar or fat. However, since saltiness aids masking bitterness they tend to consume higher amounts of salt.

Taste buds are located thorough the tongue's surface.

There are certain tests in the market aimed to find out if you are a supertaster since it is believed most supertasters have the gene TAS2R38. However, I am not sure if they are legit. I have provided you with the link as an example yet I haven't taken it myself. This is not an affiliated link & I get nothing from it. If you want to do it yourself at home, this page explains how to do it. However, this is not a scientific method & therefore it isn't as reliable. According to Professor Virginia Utermohlen, a reliable way to find out is by tasting propylthiouracil (PROP) if it tastes bitter to you it means you are a supertaster.

I would love to see more studies related to this subject but run in different countries since these numbers might defer from one country to the next.

How does all this apply to tea tasting?

Matcha drinking the ultimate tea tasting experience.

As with any other types of foods & drinks, the types of teas you like the most might be determined by the way you perceive taste.

Those who have more difficulty to perceive very subtle notes might prefer to drink stronger types of tea such as black tea or might need to make their brews stronger by using more leaves to water ratio. Whereas those who are supertasters might favour umami-rich teas such as gyokuro. Medium tasters, on the other hand, can enjoy a wide number of tea types, aromas & flavours

All the senses are used in tea tasting. We analyze the tea leaves visually, we smell them dry or wet, we smell & taste the resulting liquor, we feel the temperature when poured in a cup... all these steps are part of the tea tasting experience as a whole. How do you perceive taste?

In my case, I have had an enhanced sense of smell & taste since I was very little. I remember being a super picky eater, disliking bitter flavours & being unable to handle spicy foods. I only became familiar with the term supertaster four years ago. I would enter a room & would smell the most subtle scents around. Sometimes this wasn't very comfortable since I could detect unpleasant smells coming from the bathrooms located far away from my table. The most notable experience I remember is telling my mother that the fried eggs she just made tasted the same way the fridge smelled. I didn't know back then but the eggshell is porous & can absorb all the flavours around, this is why it is recommended to keep them stored separately.

What about you? How do you perceive smell & taste? Leave your comments below!

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