May 28, 2024

I, Science

The science magazine of Imperial College

By Aaron Khemchandani

4th March 2022

It was getting dark and Dr. Kikunae Ikeda had promised his wife that he would be home by nightfall. An obsessive chemist, he was prone to letting the outside world melt away, focusing on nothing but test tubes. While this approach did have obvious downsides, it did also mean that he was thorough and inventive in his research. 

Ever since arriving at the Chemistry department at Tokyo Imperial University in 1901 (now the University of Tokyo), Dr Ikeda had been immersed in new and ground-breaking experiments. He had been in this department for six years now and had yet to lose any interest in his field. However, although Dr Ikeda desired nothing more than to continue working, his duties as a father were more important – he had to see his wife and children for dinner. He sighed, gathered his belongings and left.

Upon arriving home, Dr Ikeda spotted a large pot of yudofu (boiled tofu in broth) on the dining table. He had loved this dish ever since his youth and was excited to dig in. He joined his wife and children in sitting around the table and inhaled the familiar, nostalgic scent of his childhood. However, something was different about this yudofu. He couldn’t pinpoint it, but the scent was stronger somehow and his it made his nose twitch in excitement. With his curiosity piqued, Dr Ikeda gingerly brought the bowl up to his mouth, unsure of what to expect…

“Careful, it’s hot!” His wife warned, but Dr Ikeda was impatient. He needed to try a sip. As the first drops of broth slid onto his tongue,  he felt an unexplainable sensation. This broth had a unique flavour, but it wasn’t sweeter, saltier, sourer or bitterer than the yudofu broths he had tried before. No – this was a different taste altogether. This broth was deeper, with a more complex flavour which couldn’t be explained by previous conventions of taste. But what was it that separated this broth from everything else? What did it contain to send his taste receptors into overdrive? 

As he voluptuously licked up the last of his broth, exploring every inch of the bowl for even the slightest bit of residue, he noticed the difference. Green flecks dotted the sides of the bowl. His wife had added small amounts of kombu, a type of edible kelp, to this dish. Because kombu wasn’t present in the yudofu Dr Ikeda had eaten in the past, it could certainly have been the defining factor of this special sensation. The chemist decided to devote his immediate future to studying kelp to find this wonderful new-found taste that he had come across. 

Later that year, Dr Ikeda conducted an experiment wherein he simmered twelve kilograms of dried kelp in a large pot of boiling water. He then removed the kelp and conducted chemical analysis on the resulting liquid. Through this, he would discover that glutamic acid was the central component to which he could attribute the ‘fifth taste’ he had been so fascinated by, providing a strong and savoury flavour. 

Essentially, to obtain the glutamic acid, Dr Ikeda extracted it using the technique of ‘crystallisation’, whereby a liquid with compounds dissolved in it is heated such that the liquid evaporates, leaving solid crystals of the no-longer-dissolved compounds behind.

When we think of a savoury dish, we often note how sweet, sour, bitter or salty it is. But what about the nature of savoury itself? It seems that lay in the realm of this newly-discovered sensation. This led Dr Ikeda to name the new taste ‘umami’ – Japanese for ‘savouriness’. 

Following his ground-breaking discovery, Dr Ikeda realised the potential for glutamic acid to be used as a seasoning product. He found that, by combining glutamic acid with sodium, a substance  known as monosodium glutamate (MSG) was produced, ensuring a safe avenue through which to enhance the flavour of almost any savoury dish. Dr Ikeda patented the process for the manufacture of MSG and founded the company ‘Ajinomoto’ (meaning ‘the essence of flavour’), through which he sold this intuitive product to the masses. 

Today, MSG is widely used to impart umami into dishes around the world, and Ajinomoto employs over 30,000 people. Not bad, considering all of this stemmed from one heartily-cooked family meal.  

Aaron Khemchandani is a contributing writer for I, Science, and is currently a student on the Science Communication Masters here at Imperial College London. After graduating with an undergraduate degree in Biomedical Science from the University of Warwick, he developed a passion for writing and communicating science through various forms of media. He hopes to continue exploring and communicating this passion to a wide range of audiences in the future.