Pleasant, savory taste; "umami" 旨味, うまみ
Umami is one of the five basic tastes (together with sweetness, sourness, bitterness, and saltiness). The term was devised by Professor Ikeda Kikunae of Tokyo University, who in 1908 identified glutamic acid (glutamate) as the component responsible for the tastiness of dashi stock made with konbu-kelp. As this fifth taste was first recognized in Japan and there was no word for it in other languages, the Japanese term UMAMI has come into general use.
After the scientific identification of glutamic acid in kelp by Professor Ikeda Kikunae in 1908, two more umami components were discovered by Japanese researchers. Professor Kodama Shintaro, a disciple of Ikeda, discovered in 1913 that katsuobushi (smoked and fermented bonito flakes) contain another umami substance, inosinic acid or inosine monophosphate (IMP). And in 1957, Kuninaka Akira realized that guanylic acid or guanosine monophosphate (GMP), present in shiitake mushrooms, also conferred the umami taste.
Another discovery of Kuninaka Akira was the synergistic effect between inosonic acid / guanylic acid (both ribonucleotides) and glutamate. When foods rich in glutamate are combined with ingredients that contain ribonucleotides, the resulting taste intensity becomes many times higher than that of the individual ingredients. That is the science behind dashi, where the glutamate-rich konbu is combined with ribonucleotide-rich katsuobushi or shiitake mushrooms.
People taste umami through receptors in taste buds specific to glutamate. Umami of course not only occurs in Japanese food - in fact, all humans first come across this taste in breast milk! In larger or smaller amounts, umami is present in fish, shellfish, cured meat, mushrooms, vegetables as ripe tomatoes, Chinese cabbage, spinach, celery, etc., and fermented and aged products involving bacterial or yeast cultures, such as cheeses and soy sauce. Rice also contains umami and umami is an important characteristic of sake as well.
Umami was especially important to the Japanese. Already 800 years ago the Japanese spoke of umami, and in writings from the Edo-period (17th-19th century) it is stated that umami forms the basis of all taste. It certainly is the basic principle of the Japanese cuisine, which doesn't use strong sauces or spices to give taste to food, but which aims to bring out the original taste of the ingredients themselves in a delicate way. That is exactly the function of umami.
By the way, nowadays umami components can also be artificially produced according to the methods of the fermentation industry. It was in fact Prof. Ikeda Kikunae who already in 1909 developed a process for mass-producing monosodium glutamate or MSG (he called it "Ajinomoto," "the basis of taste," and this is now the name of one of the largest food companies in Japan). In that case we speak about “flavor enhancers.” During the production of flavor enhancers, guanylic acid and inosinic acid are added to monosodium glutamate, making this another example of the synergistic umami effect.