The Discovery of Umami

Extract

Sweet, bitter, salty and sour are the four taste qualities upon which the human sense of taste is based. But is this really all? Is there room for more basic tastes on the human tongue? Well, there is. Strangely, though, while people tasted it daily, the fifth taste long remained unknown and unnamed. Its final discovery, made nearly a century ago, was due entirely to a single man, a chemistry professor at the Imperial University of Tokyo, Kikunae Ikeda.

It was Ikeda's insight and endurance alone which powered this early work. The tedious chemical isolation and identification of the new taste substance was done without the help from postdoctorates or students, as would be usual today, aided only by one technician. The investigation was based on an observation concerning the dominant taste of dashi, a Japanese soup base. The taste of dashi is mild but, according to Ikeda, clearly distinct from that of the four basic tastes. Ikeda proceeded to isolate the principal taste substance from a main ingredient of dashi, the seaweed Laminaria japonica. This was done with the procedures of classical chemistry, aqueous extraction, removal of large-scale contaminants (mannitol, NaCl, KCl) by crystallization, lead precipitation and numerous other steps of preparative chemistry. Finally, low-pressure evaporation resulted in the slow crystallization of a single substance with the mass formula C₅H₉NO₄: glutamic acid. Its taste was named umami, a word derived from the Japanese adjective umai (delicious). It has taken root as a scientific term internationally.