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BioMed Research International
Volume 2015 (2015), Article ID 189402, 10 pages
http://dx.doi.org/10.1155/2015/189402
Review Article

Umami the Fifth Basic Taste: History of Studies on Receptor Mechanisms and Role as a Food Flavor

Aomori University, Aomori 030-0943, Japan

Received 23 March 2015; Accepted 16 June 2015

Academic Editor: Francesco Perticone

Copyright © 2015 Kenzo Kurihara. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Three umami substances (glutamate, 5′-inosinate, and 5′-guanylate) were found by Japanese scientists, but umami has not been recognized in Europe and America for a long time. In the late 1900s, umami was internationally recognized as the fifth basic taste based on psychophysical, electrophysiological, and biochemical studies. Three umami receptors (T1R1 + T1R3, mGluR4, and mGluR1) were identified. There is a synergism between glutamate and the 5′-nucleotides. Among the above receptors, only T1R1 + T1R3 receptor exhibits the synergism. In rats, the response to a mixture of glutamate and 5′-inosinate is about 1.7 times larger than that to glutamate alone. In human, the response to the mixture is about 8 times larger than that to glutamate alone. Since glutamate and 5′-inosinate are contained in various foods, we taste umami induced by the synergism in daily eating. Hence umami taste induced by the synergism is a main umami taste in human.