Amino taste threshold value

Table 1. Taste, Threshold Value and Discovery of Amino Acids...

Amino acid Taste Threshold value(mg/dl) Where found... 

Table 1.14. Taste threshold values of various peptides effect of configuration and amino acid sequence (tested ...

Fig. 3 demonstrates, on the basis of the sweet and bitter taste of the amino acids, that not only hydrophobicity, but also the shape of the side chains influences the threshold value. 

It was reported that q-glut amyl peptides, particularly peptides with hydrophilic amino acids, such as Glu—Asp, Glu-Thr, Glu-Ser, and Glu-Glu, elicited an umami flavor236 These peptides were isolated from the umami constituents in the enzymatically hydrolyzed products of soybean proteins. The same author also reported that tripeptides such as Glu-Gly-Ser also elicited the umami taste. The threshold value (0.15%) of these peptides is greater than that of MSG. The flavor of meat extract can be reproduced using these peptides with MSG and IMP. Recently,. Y-lacroyl glutamic acid, which is a condensation product of lactic acid with glutamic acid, was shown to elicit a weak umami taste, similar to MSG.237... 

Though amino acids can elicit any one of the primary tastes, the threshold value of taste of each amino acid is high. As the levels of some free amino acids in natural foods are lower than their threshold values, it may be thought that they may not contribute directly to food taste. However, they may have an Important role in making the food savory because of the synergistic effect. 

TASTE DESCRIPTOR AND THRESHOLD VALUES OF AMINO ACIDS (ADAPTED FROM O CALLAGHAN, 1994)... 

Heating of meat is accompanied by changes in appearance, taste, texture, smell and nutritional value (7). The sulfhydryl groups and disulfide bonds which are moieties of cysteine and cystine contribute to these qualities in meat. Sulfur-containing compounds including disulfides are often found in foodstuffs and usually contribute to the overall aroma of such food because of their low threshold values (2). Sulfur compounds are major contributors to the flavor of cooked products (J). Furthermore, destruction of labile amino acids during heat processing operations may have detrimental effects on nutritional value of such products. 

The taste intensity of a compound is reflected in its recognition threshold value. The recognition threshold value is the lowest concentration needed to recognize the compound reliably, as assessed by a taste panel. Table 1.12 shows that the taste intensity of amino acids is dependent on the hydrophobicity of the side chain. 

For example, intense proteolyses of muscle proteins, due to the action of endogenous proteolytic enzymes, have been reported to occur during the processing of dry-cured ham. This gives rise to the formation of free amino acids and short peptides (especially from actin through the action of cathepsin D in meat and from caseines as a result of plasmin and other proteases in cheeses) that contribute directly or indirectly to the flavour characteristics of the final product. In the case of octapeptide Lys-Gly-Asp-Glu-Glu-Ser-Leu-Ala, isolated from beef broth, this reportedly showed umami taste with a threshold value of about 500 mg/1. 

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