A Tokyo Chemist Tasted His Wife's Soup and Discovered the Fifth Taste

In 1907, Kikunae Ikeda, a chemistry professor at Tokyo Imperial University, was eating dinner when he noticed that his wife's dashi — Japanese soup stock made from kombu seaweed and bonito flakes — had a savory quality he could not place under any of the four classical tastes. Sweet, sour, salty, bitter were the European list. Whatever was making the kombu broth taste like that was none of them.

He took the problem back to his lab. Over the next year, Ikeda boiled down 38 kilograms of kombu, performed repeated crystallizations of the residue, and isolated a single compound he could match to the flavor. It turned out to be the sodium salt of glutamic acid — the amino acid found in most protein, here liberated from kombu's cell walls by drying and brewing. He published the result in 1908 in the Journal of the Chemical Society of Tokyo and coined a name for the taste: umami, from umai (delicious) and mi (taste).

Ikeda patented the production of monosodium glutamate the same year, partnered with Saburosuke Suzuki II, and the company they founded — Ajinomoto, 'essence of taste' — began selling MSG as a kitchen seasoning in 1909. It took Western taste science most of the 20th century to catch up. Glutamate was treated as a quirky Japanese condiment, not a primary taste, until 2000, when researchers at the University of Miami identified a specific receptor on tongue cells, mGluR4, tuned to glutamate. By 2002, a second receptor type, T1R1/T1R3, had been cloned. Umami had moved from culinary intuition to molecular biology.

Ikeda named four other 'pleasant' tastes he hoped to study. He died in 1936 with only the first one settled.