穀氨酸
Glutamic acid was discovered and identified in 1866 by the German chemist Karl Heinrich Ritthausen, who treated wheat gluten (for which it was named) with sulfuric acid. Kikunae Ikeda of Tokyo Imperial University isolated glutamic acid as a taste substance in 1908 from the seaweed "Laminaria japonica" ("kombu") by aqueous extraction and crystallization, calling its taste "umami" ("pleasant savory taste"). Ikeda noticed that "dashi", the Japanese broth of "katsuobushi" and "kombu", had a unique taste not yet scientifically described (not sweet, salty, sour, or bitter). To verify that ionized glutamate was responsible for "umami", he studied the taste properties of glutamate salts: calcium, potassium, ammonium, and magnesium glutamate. All these salts elicited "umami" and a metallic taste due to the other minerals. Of them, sodium glutamate was the most soluble, most palatable, and easiest to crystallize. Ikeda called his product "monosodium glutamate", and submitted a patent to produce MSG; the Suzuki brothers began commercial production of MSG in 1909 as Ajinomoto ("essence of taste").