Four or five basic tastes?

Do you remember learning about different flavours as a kid? You probably did the time-honoured experiment of eating different kinds of food at school and seeing which tastes you perceived and where on your tongue you noticed them. With this experiment (besides amusing the teachers by having us make funny faces to do it), we were taught that the human tongue can detect 4 separate tastes, each in distinct regions of the tongue. If you’ve forgotten which part is which, take a look at our diagram! Sweet tastes are processed with the front/central part of the tongue, salty with the tip, sour along the sides, and bitter towards the back. This is a nice and simple way to perceive the information, and easy for kids to learn in school. But is everything really this simple when it comes to the human taste buds?

How does our sense of taste work?

Contrary to the title of the iconic 1999 horror film, The Sixth Sense, the human body has 5 senses of which taste is one. Around your mouth (though mainly clustered into the tongue) you have taste buds; these buds represent groupings of sensory cells clustered together. The notion that certain parts of the tongue respond to certain types of taste stimuli is a longstanding and widespread belief, with diagrams like the one we have above graced the pages of textbooks around the world. Where things get interesting here (drumroll please) is that though the experiment to test this model is incredibly simple, the experiment was not repeated and the information was taken as being accurate, so it took a long time for the error to be noticed. The first taste map of the tongue was published in 1901 by a German scientist, D. P. Hanig. Following this, a 1942 version was put forward by the Harvard physiologist, Edwin Boring, having a major impact on the spread of this misconception. The original images had highlighted areas displaying which regions of the tongue were slightly more sensitive to a particular sort of flavor. These images came to be misinterpreted as showing specific tastes as exclusively existing in those loci. In 1974, Virginia Collings tried to correct this mistake, however, her account was regarded and seen as not being sufficiently reputable (a sadly common theme through history for female scientists). Today, our knowledge has advanced, and we now know that the variation in sensitivity between parts of the tongue is in fact very small (even insignificant), and researchers are increasingly finding that there are in fact 5 sorts of taste rather than 4.

What is the fifth taste?

This is a case of modern science confirming existing folk knowledge. Though the fifth taste may be mind-blowing to those of us who were raised in the Western world, the Japanese have known of the existence of this 5th taste for a long time. Referred to as umami (う ま 味), which translates approximately to “pleasant savory taste,” this taste is traditionally associated with meats and soups. The modern term was first employed in 1908 by the Japanese chemist Kikunae Ikeda, though it would take 80 years from this point before science would come to agree with him. Now, as you may also remember from back in your school days, the taste isn’t really just perceived as taste. Think back to being a child and remember the foods you hated. What is the classic method of eating that gross food to make your parents happy but not having to taste it? Plugging your nose! This is because our perception of taste is actually importantly connected to our sense of smell. The volatile compounds enter our nasal cavity as we eat and provide us with more sensory information that our brain uses to fill in the information it gets from our taste buds. Not only does smelling your food do this, but when you chew you also release volatile compounds that go back through your throat and up into your nasal cavity thus stimulating your sense of smell that way as well. Umami, in contrast, is a “true” taste. In other words, it is actually processed entirely by your tongue. This taste can be stimulated by the consumption of glutamate; the taste is mild but lasting and is associated with the activation of our mucous membranes. Though not inherently pleasant, it becomes quite enjoyable when combined with other flavors. This fifth taste is especially important for elderly individuals. As we age (and with the use of various medicines) we lose our senses of taste and smell which can lead to decreased appetite and poor nutrition. Umami, however, is thought to increase appetite.

Now, back to the glutamate we mentioned. Glutamate is a glutamic acid salt (not to be confused with glutamine, which is another amino acid). Glutamic acid serves as an amino acid and thus a building block of proteins. When you eat, however, most glutamate is protein-bound and thus undetectable. That being said, some proteins do break down in every food, thus releasing amino acids, including glutamate. The current theory is that this pleasant taste was an incentive for our ancestors to search for nutritious, protein-rich foods. Foods where proteins break down become especially delicious when more and more types of proteins decompose, for example as in the ageing of cheese. Some plant foods also contain glutamate, which may be what gives them a fuller taste. Tomatoes, for example, increase their quantity of glutamate as much as ten times in their last few days of maturing. Take a look at our table to see some other foods that contain glutamate.

Free glutamate content in foods (mg / 100 g of food)















Grape juice


Tomato juice




Soya souce


Parmesan cheese


Roquefort cheese


Yeast spread (MarmiteVegemite)




Interestingly, a special source of glutamate has been used in East Asia for over 1200 years. This special source is a seaweed called kombu (Saccharina japonica) which contains so much glutamate that it can be seen on the surface of the seaweed as white crystals. Besides this being really cool, it’s also incredibly tasty when cooked in the appropriate spices (10/10 would recommend. You’ll thank us).Nowadays you can also buy pure glutamate as a spice. This is generally obtained by fermenting Micrococcus glutamicus after growing in in a nutrient medium. The bacteria releases glutamate into the growing medium and then purifies it at the end. You can also read a BBC article about umami HERE.

Have a gluta-great day!

The Hungry Pumpkin Team

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