Taste umami

In Foods. Each amino acid has its characteristic taste of sweetness, sourness, saltiness, bitterness, or "umami" as shown in Table 13. Umami taste, which is typically represented by L-glutamic acid salt (and some 5 -nucleotide salts), makes food more palatable and is recognized as a basic taste, independent of the four other classical basic tastes of sweet, sour, salty, and bitter (221). 

Sensory receptors expressed in particular in taste receptor cells of the taste buds that sense the five basic tastes salt, sour, sweet, bitter and umami (glutamate taste). Sodium type ion channels sense salty taste whereas sour taste is transduced by potassium type ion channels. The underlying cause of sweet, bitter, and umami tastes is the selective activation of different groups of G protein coupled receptors that discriminate between sweet, bitter, and umami tasting molecules. 

Mushrooms have been investigated with especial reference to shiitake, Lentinus edodes, the flavorful fungus widely used in Chinese and Japanese dishes. While the umami taste is attributed to guanylic acid, lentinic acid 14 (Scheme 6) is converted to lenthionine, 1,2,3,5,6-pentathiacycloheptane 15, a compound with the characteristic shiitake flavor. This complex reaction requires a C-S lyase enzyme.30 Other important flavor compounds are 1,2,4,6-tetrathiacycloheptane 16 (Scheme 6) and 1,2,3,4,5,6-hexathiacycloheptane (not shown). 

Sweet, bitter and umami taste involve receptor-coupled second-messenger pathways that are differentially expressed across the gustatory epithelium 827... 

In many cells, phosphoinositide signaling leads to an elevation in intracellular calcium levels through the release of calcium from intracellular stores in response to IP3-dependent gating of channels in the endoplasmic epithelium (Ch. 20). It is not known if IP3 plays a critical role in TRC transduction, but such a role would be consistent with recent findings that a Ca2+-activated cation channel, TRPM5, is essential for normal sweet, bitter and umami taste function [49,66-69],... 

Zhang, Y. et al. Coding of sweet, bitter, and umami tastes different receptor cells sharing similar signaling pathways. Cell 112 293-301,2003. 

He, W. et al. Umami taste responses are mediated by alpha-transducin and alpha-gustducin. /. Neurosci. 24 7674—7680, 2004. 

Damak, S. et al. Detection of sweet and umami taste in the absence of taste receptor Tlr3. Science 301 850-853, 2003. 

Straszewski L, Li X, Xu H, Durick K, Zoller M, Adler E, Human receptors for sweet and umami taste, Proc NatlAcd Sci USA 99 4692 696, 2002. 

Salt is the best known taste enhancer for a variety of foods. Monosodium glutamate (MSG) and nucleotides, such as inosine monophosphate (IMP) and guanosine monophosphate (GMP), are known to enhance flavor and are recognia as the "umami taste" in Oriental cuisine. They have longer aftertastes than the "basic... 

Sodium Ion. The excessive intake of sodium ion coming from other than NaCl should be noticed, though reduced intake of NaCl is now a matter of great concern. Monosodium glutamate (MSG), for instance, is a subject of discussion. Since MSG effectively provides umami taste, it has been very popular as a Japanese seasoning. In the United States, MSG has currently been mark as a cause of "Chinese restaurant syndrome". In addition, beef, liver, blood and their processed foods contains a large amount of sodium ion. Sine sodium ion combines with aspartic acid and glutamic acid residues in protein, study of affinity of acidic amino acids to sodium ion has to be set out first. 

Sensory analysis of mixed solutions of MSG and each of four dipeptides was carried out (Table VI). The umami taste of MSG was not changed when it was mixed with peptides containing aspartic acid. On the other hand, Glu-Glu, produced the... 

Taste of Orn-p-Ala Derivatives. We reported in the previous paper (5) that omithyl-p-alanine monohydrochloride produced the salty taste as omithyltaurine. We prepared two tetrapeptides composed of ornithine and p-alanine. Both tetrapeptides, however, produced mainly an astringent taste instead of the salty or the umami taste (Table Xffl). 

Other components described in the literature which are able to enhance saltiness or umami taste are umami-tasting glutamate glycoconjugates (e.g. 18 or 19) [42], (S)-malic acid 1-0-D-glucopyranoside (morelid 20) [43], theogalline (21) [44], M-lactoyl ethanolamine (22) [45] and JV-gluconyl ethanolamines (23) [46], a-keto acids derived from amino acids (e.g. 24) [47] and some N-succinoyl derivatives of aspartic acid or glutamic acid (e.g. 25 and 26) [48]. 

Some peptides enjoy the property of masking the bitter taste of foods. Ohyama et al. (24) conducted sensory analyses using synthetic peptides and found that neutralized peptides consisting of aspartic acid and glutamic acid had a taste similar to that of monosodium glutamate. They termed this umami taste or relish. ... 

On the other hand, L-alanine, glycine and L-threonine taste mainly sweet [26]. Only for these amino acids, the potentials of channels 1 and 2 decreased. L-Glutamic acid and L-histidine monohydrochloride, which taste mainly sour, increased each of the potentials of channels 1-5 to almost the same degree. Only monosodium L-aspartate elicits mainly umami taste in humans among amino acids used here the response pattern was different from those of the other amino acids. 

Zhang, Y., M. A. Hoon, J. Chandrashekar, K. L. Mueller, B. Cook, D. Wu, C. S. Zuker and N. J. Ryba, 2003, Coding of sweet, bitter, and umami tastes different receptor cells sharing similar signaling pathways, Cell, 112, (3), pp. 293-301... 

We have systematically investigated the umami taste using psychometric procedures. In this paper, a part of our studies will be outlined. 

Mathematical Consideration of the Synergistic Effect. Generalizing the above-mentioned results, we can introduce a concept of an umami taste space. The umami solution of any combination of the two groups of umami substances can be expressed as a point in a space of 2-dimensions, say, G, defined as follows ... 

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