The discovery of umami: how a pot of kombu named a taste

Sweet, sour, salty, bitter. For a long time that was the full list, the four basic tastes every schoolchild learned. Yet anyone who has sipped a good Japanese broth knows there's something else in there: a deep, mouth-filling savouriness that doesn't fit any of the four. Today we call it umami, and the story of how it got its name starts with a pot of seaweed broth in Tokyo.

A chemist and a pot of kombu

Kikunae Ikeda (池田菊苗) was a professor of chemistry at Tokyo Imperial University, today the University of Tokyo. The story usually told is that he was struck by the flavour of a simple dish at home, tofu simmered in kombu broth, and wondered what exactly in the seaweed made it so satisfying.

Kombu (昆布) is the thick, dried kelp at the heart of Japanese dashi. Ikeda set out to find its secret, working through a large quantity of kombu broth to isolate the substance responsible. What he found was glutamic acid, or more precisely its salt form, glutamate.

Glutamic acid itself wasn't new: chemists had known about it since the 1860s. Ikeda's insight was to connect it to taste, and to argue that the flavour it produced was distinct from sweet, sour, salty and bitter. In 1908 he published his findings and proposed a name for the taste: umami (うま味), from umai (うまい), meaning delicious.

From laboratory to kitchen shelf

Ikeda also saw a practical use. He patented a method of producing monosodium glutamate, or MSG, a stable, easy-to-use form of glutamate that could be sprinkled into food like salt. Working with the businessman Saburosuke Suzuki, he helped bring it to market, and it went on sale in 1909 under the name Ajinomoto (味の素), "the essence of taste".

MSG became a staple in kitchens and food factories across Asia and beyond. From the late 1960s it also attracted suspicion in some Western countries, where it was blamed for a cluster of symptoms after Chinese restaurant meals. Controlled studies have struggled to reproduce those effects, and food regulators such as the US Food and Drug Administration consider MSG safe to eat at normal levels. Glutamate is, after all, the same substance that occurs naturally in kombu, ripe tomatoes and aged cheese.

Kodama, Kuninaka and the power of pairs

Glutamate wasn't the end of the story. In 1913, Shintaro Kodama, a student of Ikeda's, is credited with identifying a second umami substance, inosinate, in katsuobushi, the smoked, dried skipjack tuna shaved into dashi. Decades later, in the 1950s, the researcher Akira Kuninaka is usually credited with identifying a third, guanylate, which is abundant in dried shiitake mushrooms.

Kuninaka is also credited with describing something cooks had known by instinct for centuries: these substances amplify each other. Glutamate combined with inosinate or guanylate tastes far more savoury than either one alone.

That synergy explains a great deal of Japanese cooking. Classic dashi pairs kombu, rich in glutamate, with katsuobushi, rich in inosinate, and the result is far fuller than you'd expect from two such light ingredients. Vegetarian Buddhist cooking pairs kombu with dried shiitake instead. Many ramen shops layer pork or chicken stock with kombu and dried fish for the same reason.

You can see the same logic far beyond Japan: tomatoes with Parmesan, anchovies melted into a meat sauce, a stock built from meat and vegetables simmered together. Cooks everywhere found umami long before anyone gave it a name.

From Japanese word to fifth taste

For most of the twentieth century, umami remained largely a Japanese idea. Many Western scientists treated it as a blend of other tastes rather than a taste in its own right. The turning point came in the early 2000s, when researchers identified taste receptors on the tongue that respond to glutamate. If the tongue had dedicated sensors for it, it was hard to argue that umami wasn't a basic taste.

Today umami is widely recognised as the fifth basic taste, and the Japanese word has made its way into English and many other languages.

You can taste it for yourself with a simple experiment. Soak a piece of kombu in water for a while and sip the liquid: it tastes faintly of the sea, pleasant but subtle. Add a tiny pinch of salt and taste again, and notice how the flavour opens up. Then steep a handful of katsuobushi in it and taste once more. That jump in depth is the synergy Kodama and Kuninaka helped explain, in a single cup.

I love that umami was found not in some rare, exotic ingredient but in a pot of seaweed broth that Japanese cooks had been making for centuries. The word was new in 1908. The taste is as old as cooking.