Kikunae Ikeda had been thinking a lot about soup.

The Japanese chemist had been studying a broth made from seaweed and dried fish flakes, called dashi. Dashi has a very specific flavour – warm, tasty, savoury – and through laborious, lengthy separations in a chemistry lab, Ikeda had been trying to isolate the molecules behind its distinctive taste. He felt sure that there was some connection between a molecule’s shape and the flavour perception it produced in humans.

But as it was just a few years past the turn of the 19th Century, there was not yet a great deal of evidence to support the idea.

Eventually, Ikeda did manage to isolate an important taste molecule from the seaweed in dashi: the amino acid glutamate, a key building block of proteins. In a 1909 paper, the Tokyo Imperial University professor suggested that the savoury sensation triggered by glutamate should be one of the basic tastes that give something flavour, on a par with sweet, sour, bitter, and salt. He called it “umami”, riffing on a Japanese word meaning “delicious”.

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It cannot be said that at the time his idea was met with thunderous applause from colleagues around the globe. For one thing, Ikeda’s paper remained in Japanese (it was eventually translated into English in 2002). Also, umami taste behaves a bit differently from the others. It does not get stronger linearly with higher levels of glutamate and other substances that trigger it, the way that sweetness does.

“The two are completely different types of tastes,” Ikeda notes in his paper. “If these substances can be likened to color, ‘umami’ would be yellow and sweetness red.” It was not exactly your standard scientific fare.