Kikunae Ikeda (Discoverer of "Umami")

Umami seasoning (component: monosodium L-glutamate), widely prevalent as the flavor enhancer "Ajinomoto" in many households in Japan, was discovered in 1907 by the late Prof. Kikunae Ikeda, who was a professor at the Department of Chemistry of Tokyo Imperial University (now the University of Tokyo). The bottle of the first sample of monosodium L-glutamate, extracted from dried kelp by Prof. Ikeda, has been handed down to successive professors in the Department of Chemistry as one of the historical materials of the Umami discovery.

Prof. Ikeda was born in 1864 in Kyoto as the second son of the head of the Kyoto branch of the feudal Satsuma clan. He enrolled in the Department of Chemistry of Tokyo Imperial University in 1885 and studied chemistry under Prof. Joji Sakurai, who also happened to be his brother-in-law. He graduated in 1889 and became an associate professor at the university. From 1899, Prof. Ikeda studied in Germany for two years at the laboratory of Prof. Friedrich Wilhelm Ostwald at the University of Leipzig, which was then the center of physical chemistry. Prof. Ostwald himself was a Nobel laureate in chemistry in 1909. After finishing his studies in Germany, Prof. Ikeda stayed for a while in London, where he lived in the same boarding house as the author Soseki Natsume. Soseki later wrote in a collection of his notes that Prof. Ikeda's philosophical insights had a great influence on his writing. After returning to Japan in 1901, Prof. Ikeda became a professor in the Department of Chemistry, Faculty of Science, Tokyo Imperial University. He introduced the field of physical chemistry to Japan and established its foundation.

While Prof. Ikeda was conducting research on various themes related to basic chemistry, he was also very interested in practical research. Kyoto-born Prof. Ikeda had been interested in seaweed broth since his childhood. In order to find out the components of this broth, he started research on the seaweed broth that is usually used for the dish yudofu (boiled tofu). In 1907, he took out the liquid used to simmer 38 kg of dried kelp, and finally succeeded in extracting 30 g of monosodium L-glutamate, the real identity of Umami. The big English-made evaporating dish, which was used to simmer the dried kelp, has been handed down from Prof. Ikeda to Professors Samejima, Akamatsu, Kuroda, Ohta, and Ohkoshi of the University of Tokyo, as one of the valuable scientific implements of that time. On April 24, 1908, Prof. Ikeda applied for a patent for "a manufacturing method for seasoning with glutamic acid as the key component," and on July 25 of the same year, his patent registration was accepted. This invention is now ranked as one of the "ten great inventions in Japan." Mr. Saburosuke Suzuki, then head of Suzuki Pharmaceutical Company, who was contracted by Prof. Ikeda to produce and market the seasoning, chose "Ajinomoto" — literally, "quintessence of flavor" — as the product name for the monosodium L-glutamate. He developed a production and distribution system, which evolved into the current Ajinomoto Co., Inc.

The existence of Umami, proposed by Prof. Ikeda as the fifth taste following sweetness, sourness, saltiness, and bitterness, was disputed in academic circles for a long time. However, glutamic acid receptors were subsequently found in the sensory cells in taste buds on the surface of the tongue, and nowadays, Umami has become an internationally-recognized word. In addition, a physiological theory has been proposed that receptors exist in digestive organs, and that Umami helps stimulate digestion when it enters the stomach. Based on these developments, Umami-related research is also expected to become academically prevalent in the fields of medicine and physiology from here on.

The room at the University of Tokyo that Prof. Ikeda was using at the time of his retirement is still being used as a professor's room. The oldest red brick wall building on the Hongo Campus (construction started in 1913 and completed in 1916), where the room is located and which is now designated as the Chemistry East Wing Bldg., was designed based on a basic concept developed by Prof. Ikeda. Thanks to the roof's being made of lead, as suggested by Prof. Ikeda, the building was able to endure the massive fires caused when the Great Kanto Earthquake occurred in 1923, and it still boasts its original appearance. In the last years of his life, Prof. Ikeda built a laboratory in the garden of his house and worked on various research subjects. I think that his scientific spirit, his constant curiosity about the universe, and his attempts to clarify the true nature of things resulted in the discovery of Umami.

Profile

• Born October 8, 1864 in Kyoto
• Died May 3, 1936 in Tokyo

Academic history and professional highlights

1889	Bachelor of science in chemistry, Department of Chemistry, Faculty of Science, Tokyo Imperial University (now the University of Tokyo)
1891	Professor, the Tokyo Higher Normal School
1896	Associate Professor, Department of Chemistry, Faculty of Science, Tokyo Imperial University
1899	Studied physical chemistry at the laboratory of Prof. Friedrich Wilhelm Ostwald at the University of Leipzig, Germany, for a year and a half
1901	Stayed in London from May through October Start of close friendship with Soseki Natsume after living in the same boarding house in London Professor, Tokyo Imperial University
1902	Doctor of Science, Tokyo Imperial University
1907	Started isolation study after naming "Umami" as an additional taste component to complement sourness, sweetness, saltiness, and bitterness Discovered monosodium L-glutamate as the main component of the delicious taste of dried kelp
1908	Invented a manufacturing method for producing seasoning with monosodium L-glutamate as the major component
1909	Launch of "Ajinomoto," a taste seasoning, by Suzuki Pharmaceutical Company (now Ajinomoto Co., Inc.)
1913	President of the Chemical Society of Japan
1917	One of the founding members of RIKEN (director of chemistry department)
1919	Member of the Imperial Academy
1923	Retirement from Tokyo Imperial University