Taste of amino acids

In traditional cooking of proteinaceous foods, the fundamental difference between Western and Oriental cultures is that the former cooks proteins with unseasoned fats and the latter cooks with many kinds of traditional seasonings that have tastes of amino acids. Western cultures have some traditional foods with amino acid taste such as cheese. Protein hydrolysates are popular as seasonings (225). 

Taste of amino acids was studied using the taste sensor [23]. Taste of amino acids has had the large attention so far because each of them elicits complicated mixed taste itself, e.g., L-valine produces sweet and bitter tastes at the same time. Thus, there exist detailed data on taste intensity and taste quality of various amino acids by sensory panel tests [26]. The response of the sensor to amino acids was compared with the results of the panel tests, and response potentials from the eight membranes were transformed into five basic tastes by multiple linear regression. This expression of five basic tastes reproduced human taste sensation very well. 

Amino acids are generally classified into several groups which correspond to each characteristic taste. Since amino acids show mixed tastes as above, the taste interactions such as synergistic effect and repression effect are automatically included in their taste. The taste sensor should express this situation. The present study is the first trial to study the taste of amino acids using artificial sensing devices. 

Sweet taste of amino acids dependence on ammonium and carboxylate groups (9). 

Bitter taste of amino acids and related compounds dependence on the ammonium group (24)... 

Taste of amino acids derivatives of ammonium and carboxylic groups ( 9, 24) Amino acid/derivative Taste quality ct w ctbi (mmol/1) (mmol/1) ... 

Taste of amino acids dependence on the shape of the side chain (9, 23)... 

Suzuki, H., Kajimoto, Y., and Kumagai, H. 2002. Improvement of the bitter taste of amino acids through the transpeptidation reaction of bacterial y-glutamyltranspeptidase. J. Agric. Food Chem. 50, 313-318. 

Ever since Fischer, many chemists have focused their attention on the taste of amino acids. Generally, natural L-amino acids exert either no taste or a bitter taste while unnatural D-amino acids elicit a sweet taste almost without exception. Proteinogenic L-amino acids that exhibit a bitter taste include Trp (0.133%), Phe (0.069%), Tyr (0.017%), Leu (0.011%), Arg, Val, lie, and Pro, and the remaining amino acids exert either no taste or a sour taste. The values in parentheses show the caffeine concentration that provides the same bitterness as a 0.3% amino acid solution.165 However, different authors have reported different values for the strength of their... 

Brand JG, Teeter JH, Kumazawa T, Huque T, Bayley DL. 1991. Transduction mechanisms for the taste of amino acids. Physiol Behav 49 899-904. (Covers taste responses for AA in catfish, preliminary studies of similar mechanisms in mouse)... 

The amino acid, phenylalanine, with aromatic ring, although close at 10 M, falls slightly separate from the aliphatic amino acids. The complete separation of taurine from the other compounds is most probably related to the sulfur atom. This arrangement is similar to one derived for tastes of amino-acids (, , 27 ). For example, serine, alanine and glycine are sweet and cluster together in space while taurine is bitter and falls out in space. 

Table 1.12. Taste of amino acids in aqueous solution at pH 6-7 sw - sweet, bi -...

The existence of protein receptors in the tongues of mice and cows have been shown. Monosodium L-glutamate MSG [142-47-2] is utilized as a food flavor enhancer in various seasonings and processed foods. D-Glutamate is tasteless. L-Aspartic acid salt has a weaker taste of umami. Glycine and L-alanine are slightly sweet. The relationship between taste and amino acid stmcture has been discussed (222). 

The enzymatic hydrolysates of milk casein and soy protein sometimes have a strong bitter taste. The bitter taste is frequently developed by pepsin [9001 -75-6] chymotrypsin [9004-07-3] and some neutral proteases and accounted for by the existence of peptides that have a hydrophobic amino acid in the carboxyhc terminal (226). The relation between bitter taste and amino acid constitution has been discussed (227). 

For us to remain perfectly healthy, the protein in our diet must supply suffident quantities of amino acids. We prefer to eat our protein in particular forms, that is in foods having particular textures, tastes and smells (these are called organoleptic properties). Conventional sources of protein are plants, mainly as cereals and pulses, and animals, mainly as meat, eggs and milk. The proportions of such proteins eaten in various parts of the world differ widely (Figure 4.1). 

Different optical enantiomers of amino acids also have different properties. L-asparagine, for example, tastes bitter while D-asparagine tastes sweet (see Figure 8.3). L-Phenylalanine is a constituent of the artificial sweetener aspartame (Figure 8.3). When one uses D-phenylalanine the same compound tastes bitter. These examples clearly demonstrate the importance of the use of homochiral compounds. 

The role of these tastes has been nicely summarized Taste is in charge of evaluating the nutritious content of food and preventing the ingestion of toxic substances. Sweet taste permits the identification of energy-rich nutrients, umami allows the recognition of amino acids, salt taste ensures the proper dietary electrolyte balance, and sour and bitter warn against the intake of potentially noxious and/or poisonous chemicals. ... 

Table IV. Relation between Tastes of O-Aminoacyl Sugars and Side Chain Length of Amino Acid Moiety...

Otagiri et al. (22) used model peptides composed of arginine, proline, and phenylalanine to ascertain the relationship between bitter flavor and chemical structure. They reported that the presence of the hydrophobic amino acid at the C terminus and the basic amino acid at the N terminus brought about an increase in the bitterness of di- and tripeptides. They further noted a strong bitter taste when arginine was located next to proline and a synergistic effect in the peptides (Arg)r(Pro) ,-(Phe) (/ = 1,2 m, n = 1, 3) as the number of amino acids increased. Birch and Kemp (23) related the apparent specific volume of amino acids to taste. 

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