Glutamic acid taste

From these criteria, we can deduce that the glutamic acid taste is a primary taste for the following reasons ... 

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). 

The a-carbon of glutamic acid is chiral. A convenient and effective means to determine the chemical purity of MSG is measurement of its specific rotation. The specific optical rotation of a solution of 10 g MSG in 100 mL of 2 A/HQ is +25.16. Besides L-glutamic acid [56-86-0] D-glutamic acid [6893-26-1] and the racemic mixture, DL-glutamic acid [617-65-2] are known. Unique taste modifying characteristics are possessed only by the L-form. 

L-Glutamic acid does not racemize in neutral solution, even at 100°C. Deviation of pH from neutral to greater than 8.5 results in thermal racemization with loss of taste characteristics. Racemization in neutral solution occurs at 190 °C after formation of the lactam, 5-oxo-L-proline, pyroglutamic acid [98-79-3]. 

In salt substitutes, the metallic or bitter taste of potassium chloride is often masked by other ingredients, such as the amino acid L-lysine, tricalcium phosphate, citric acid, and glutamic acid. 

Discoverer of glutamic acid in seaweeds. Production of a seasoning of Aji-no-Moto . Introduction oV Umamr into the classification of tastes Discoverer of Orizanin (vitamin B ). 

Agresti, C., Tu, Z., Ng, C., Yang, Y., and Liang, J. F. (2008). Specific interactions between diphenhydramine and a-helical poly(glutamic acid)—A new ion-pairing complex for taste masking and pH-controlled diphenhydramine release. Eur. J. Pharm. Biopharm. 70 (1), 226-233. 

Bitter taste can be masked by sweeteners, by salt or by dipeptides containing aspartic or glutamic acids (22,25,24,25). The bitter-masking potential of sugars wife quinine was recently assessed, and quinine-equivalent values were derived to predict masking ability of these substances. Attenq)ts to mask bitter taste may be successful only wife certain bitter substances. 

The role of aspartic acid and glutamic acid was investigated in BMP (Beefy Meaty peptide, Lys-Gly-Asp-Glu-Glu-Ser-Leu-Ala) isolated from enzymatic digests of beef soup. The taste of BMP was affected by the sequence of acidic fragment. Sodium ion uptake of acidic dipeptides and their taste, when mixed with sodium ion, were dependent on the component and/or sequence of dipeptides containing acicHc amino acids. 

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. 

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]. 

By market volume the most important flavour molecule is L-glutamic acid. In 2004, the worldwide annual MSG production was estimated to be amount 1,500,0001 [21]. The amino acid is extensively used as taste enhancer, frequently in conjunction with nucleotides, a flavour impression which is also referred to as umamf, a term derived from the Japanese meaning deliciousness or a savoury or palatable taste. MSG is manufactured by aerobic cultivation of Coryne-bacterium glutamicum on starch hydrolysates or molasses media in large-scale bioreactors (up to 500 m ). Production strains with modified metabolic flux profiles and highly permeable cell walls for an improved product secretion are... 

L-Glutamic acid 105 NONESSENTIAL AMINO ACIDS Fermentation (WS) Synthesis from acrylonitrile and resolution MSG. taste enhancer... 

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. 

Looking at compounds with direct taste effects, the significance of amino acids and nucleotides in the formation of potato taste has been described in several papers (3,4,5). The free amino acids and 5 -nucleotides are certainly an important fraction they contribute to taste due to their content of glutamic acid, aspartic acid, 5 -AMP, 5 -IMP and other compounds. From the vast literature two analytical examples which have also been tested in taste tests are presented in Table II. 

When glutamic acid was removed from the synthetic extract, umami decreased markedly, and the characteristic taste disappeared. 

From these results and from the free amino acid compositions of the extracts, they regarded amino acids, chiefly glutamic acid and glycine, as the main contributors to the taste of these crustaceans. 

The results showed that seven nitrogenous constituents, glycine, alanine, glutamic acid, arginine, AMP, GMP, and CMP, and four inorganic ions, Na+, K+, Cl-, and P0 , contribute more or less to produce the taste of crab. The opinions of the panelists regarding the taste of the test solutions are summarized as follows. 

Glutamic acid contributes greatly to umami. When it is removed, the characteristic taste of crab and the sweet sensation decrease considerably. 

From these results, we have depicted a model for the construction of the taste of crab meat. This is shown in Figure 7. The nucleus of the crab taste is produced by a limited number of compounds, such as glycine, glutamic acid, arginine, AMP, GMP, sodium ions, and chloride ions. The characteristic taste of crab meat thus formed is elaborated upon and enhanced by such components as alanine, glycine betaine, potassium ions, and phosphate ions, and possibly by CMP. The other components, though their individual contributions are slight, jointly also serve as taste enhancers. 

Just as positional isomers affect taste, so do different stereoisomers. There are eight amino acids that are practically tasteless. A group of three has varying tastes except for glutamic acid, these are probably derived from sulfur-containing decomposition prod-... 

A number of compounds have the ability to enhance or improve the flavor of foods. It has often been suggested that these compounds do not have a particular taste of their own. Evidence now suggests that there is a basic taste response to amino acids, especially glutamic acid. This taste is sometimes described by the word umami, derived from the Japanese for deliciousness (Kawamura and Kare 1987). It is suggested that a primary taste has the following characteristics ... 

Glutamic acid does not affect the taste of the four primary tastes. 

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