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Review
. 2015:2015:189402.
doi: 10.1155/2015/189402. Epub 2015 Jul 12.

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

Kenzo Kurihara  1
Affiliations
Review

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

Kenzo Kurihara. Biomed Res Int. 2015.

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.

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Figures

Figure 1
Figure 1
Structure of glutamic acid (a) and monosodium glutamate (b).
Figure 2
Figure 2
Effects of addition of  5′-inosinate to glutamate on strength of umami [4].
Figure 3
Figure 3
Amino acid composition of kombu dashi [5].
Figure 4
Figure 4
Canine taste nerve response to 100 mM glycine as a function of NaCl concentration [6].
Figure 5
Figure 5
Canine taste nerve response to 100 mM glutamate as a function of NaCl concentration [7].
Figure 6
Figure 6
Canine taste nerve response to monosodium glutamate (MSG) in the absence and presence of 0.5 mM 5′-guanylate (GMP) [8].
Figure 7
Figure 7
Canine taste nerve response to a mixture of 100 mM monosodium glutamate (MSG) and 0.5 mM 5′-guanylate (GMP) and 100 mM NaCl as a function of amiloride concentration [9].
Figure 8
Figure 8
Schematic structure of T1R1 + T1R3.
See this image and copyright information in PMC

References

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