Umami, or the mysterious fifth taste, went undiscovered for thousands of years. Its presence makes food taste savoury, not just as the absence of sweetness, but as a particular taste in itself. (Think asparagus, Parmesan or cured meat.) It is a sensation triggered by most of the dishes that we eat. It is something that most of us will taste a few times a day, every day of our lives. So we might expect to be a little more familiar with the idea of umami. And yet, after thousands of years of exposure, it was only just over a century ago that someone noticed it.
In 1908, Kikunae Ikeda, a chemist at the University of Tokyo, became the first person to distinguish the subtle taste of umami from the clamour of the dominant tastes: sweetness, sourness, bitterness and saltiness. Ikeda was convinced that there was a quality to dashi, a popular seaweed broth used in Japanese cooking, that could not quite be captured by any of the four accepted fundamental tastes.
Ikeda faced a difficult task. It was hard enough that he had to try to persuade his fellow scientists that he could characterise and describe the properties of a previously elusive chemical. But he also had to convince people – all people, not just scientists – that he had something new to say about one of the most fundamental experiences in life: eating.
How could everyone have missed something so obvious as the essence of the savoury taste? Ikeda was not trying to describe a rare and exotic delicacy with a peculiar flavour all of its own. He was trying to reinterpret the human palate. Such a bold project would require some seriously convincing chemical proof if anyone was to pay any attention to Ikeda. So he set up a series of experiments in an attempt to distil the essence of this as yet indescribable quality. Ikeda put to use the scientific training he had received in a German laboratory, where he had been taught the tricks of the trade by the Nobel laureate Wilhelm Ostwald. Using a labyrinthine set of glassware, Ikeda began evaporating, condensing, isolating, purifying and characterising the thing that made dashi what it was.
Out of choice or perhaps more out of necessity, due to the peculiar nature of his project, Ikeda worked almost entirely alone, aided by a sole technical assistant. After putting more than 10 kilograms of seaweed through this elaborate chemical process, the product of his efforts was a sprinkling of white crystals. It may not have looked like a triumph, but the few grams he had produced in his initial experiments were the start of a culinary – and a commercial – explosion.
Ikeda dissolved a tiny amount of his crystals in a volume of pure water. Then, with the carefree confidence of an early-20th century chemist, Ikeda drank it. It tasted like dashi. Better still, he found that he could detect even the smallest trace of the crystals in water more easily than he could detect salt. He seemed to have been successful in distilling the essence of umami. Later that year, and with considerable business nous, Ikeda teamed up with entrepreneur Saburosuke Suzuki and successfully sought a patent for the crystals, which Ikeda foresaw would be enormously popular in cooking.
What Ikeda had isolated was glutamate – an amino acid, that when joined in a chain forms proteins – stabilised by its association with a single sodium ion. In other words, he had made monosodium glutamate, or MSG. Suzuki wasted no time in commercialising the discovery in the form of the first, and most famous, umami seasoning, Ajinomoto salt (a word which means, literally, the essence of taste). The company he founded with Ikeda was also named Ajinomoto after its famous product and it became one of Japan’s most successful food businesses. The science, on the other hand, stagnated. Ikeda’s initial paper on umami was published only in Japanese and scientists in the anglophone world were slow to catch on. While a presentation on umami occured at an international symposium in 1979, and an international symposium was dedicated to the subject in 1985, it was not until 2002, almost a full century after it had been written, that Ikeda’s original paper was translated into English.
The addition of umami to the four fundamental tastes of sweet, sour, bitter and salt was not an intuitive idea for many. After all, it is not hard to bring to mind the taste of sweetness, or to make your mouth water at the thought of lemons. Ikeda himself acknowledged the problem, but proposed that MSG was the answer to that, too:
Had we nothing sweeter than carrots or milk, our idea of the quality of ‘sweet’ would be just as indistinct as it is in the case of this peculiar quality. Just as honey and sugar gave us so clear a notion of what sweet is, the salts of glutamate are destined to give us an equally definite idea of this peculiar taste quality.
Not everyone was convinced. Why draw the line at five tastes? Who is to say that mint or even metallic tastes are not fundamentals, too?
It was not until the early 2000s that researchers in the US caught on to the idea of umami and started searching for a solid biochemical answer as to how we perceive of it. A group in Miami identified a receptor in rats’ taste buds that responded to glutamate. Another group, based in San Diego, discovered a few more receptors that responded to chemicals associated with umami, too. The latter receptors did not respond to glutamate, however, but to certain nucleosides, which are another kind of simple biochemical building blocks found in almost all foods. Closely related to nucleotides – the individual beads of the string that make up DNA – they explained another peculiar property of umami: synergy.
Glutamate by itself tastes of umami. Add in just a tiny amount of the nucleosides inosinate or guanylate, and the umami sensation goes through the roof. This is known as synergistic effect. Glutamate also has a synergistic effect when combined with salt, making even the tiniest traces of salt taste a great deal more powerful.
So glutamate held some promise as a way to make salt saltier, while reducing the amount of it used in seasoning. This could be great news for people with high blood pressure, who often try to bring down their blood pressure by cutting down on the amount of salt they consume in food. But glutamate’s future as the next big superfood was crushed in 1968 with a letter to the editor of the influential New England Journal of Medicine. A doctor, Robert Ho Man Kwok, wrote of a syndrome that he said he had often witnessed when dining in Chinese restaurants, in which patients reported sweating, palpitations, dizziness and nausea. This was linked to the liberal use of MSG and was the beginning of a profound health scare that, rightly or wrongly, permanently damaged the image of Ikeda’s discovery. Many studies did not back up the people who perceived themselves as MSG sensitive, but did not rule out that the consumption of very large amounts of MSG would be dangerous, as is the case when consuming very large amounts of salt, for instance.
More recent research, however, has linked umami with particular health benefits. A study in the journal Flavour in 2015, for example, showed links between the perception of umami and overall health, particularly in the elderly. The loss of taste is a common problem among older people and is associated with weight loss, dry mouth and other unpleasant problems. Researchers in Japan found that giving elderly patients a seaweed tea with a rich umami taste helped to tackle these symptoms. Taste and the workings of the salivary glands are closely tied together. Improving salivary flow improves the health of the mouth and the patients’ sense of taste. The umami-rich tea helped patients enjoy their food more and put on weight.
At the other end of the scale, some research suggests that umami could also help people who want to lose weight. A 2014 study in the American Journal of Clinical Nutrition suggested that eating umami-rich foods could have a role in appetite control. In the study, researchers claimed that eating a soup with added glutamate and synergistic nucleosides helped to decrease the amount of food that participants in the study ate later on in the day. It was proposed that a diet rich in umami – possibly thanks to added MSG – could help people feel fuller on the same amount of food. That study was funded by Ajinomoto, the very same company founded by Ikeda, and so its findings should be taken with a pinch of salt, if not MSG.
In some ways, it took us an age to realise what we had been tasting all along because umami is the backdrop to our palates, rather than one of the main players. Its interplay with salt and with other components in our diet can pull together a plate of disparate, otherwise hollow tastes into something that feels rounded, wholesome and somehow finished. After all, the word “umami”, coined by Ikeda more than a century before, simply translates to “deliciousness”. §
Photography assistant: Federico Brozzi
With thanks to Il Pozzo di San Patrizio, Mantua, Italy