Taste recognition threshold concentration

Linssen, J., Janssens, A., Reitsma, H., Bredie, W., Roozen, J. 1993. Taste Recognition Threshold Concentrations of Styrene in Oil-In-Water Emulsions and Yogurts. J. Sci. Food Agric. 61 457-462. 

Clear, colorless, liquid with a sweet, fragrant odor. Sweetish taste. Odor threshold concentrations ranged from 42 ppmv (Nagata and Takeuchi, 1990) to 100 ppmv (Leonardos et al, 1969). Experimentally determined detection and recognition odor threshold concentrations were 48 mg/m (20 ppmv) and 78 mg/m (33 ppmv), respectively (Heilman and Small, 1974). 

Clear, colorless, watery liquid with a penetrating or pungent rubber-like odor. Becomes yellow to yellowish-brown on exposure to air. Experimentally determined odor threshold concentrations in air for inhibited and unhibited styrene were 0.1 and 0.047 ppmv, respectively (Leonardos et al., 1969). Experimentally determined detection and recognition odor threshold concentrations were 220-640 pg/m (52-150 ppbv) and 64 pg/m (15 ppbv), respectively (Heilman and Small, 1974). At 40 °C, the average odor threshold concentration and the lowest concentration at which an odor was detected were 65 and 37 pg/L, respectively. At 25 °C, the lowest concentration at which a taste was detected was 94 pg/L, respectively (Young et al., 1996). The average least detectable odor threshold concentrations in water at 60 °C and in air at 40 °C were 3.6 and 120 pg/L, respectively (Alexander et al., 1982). 

Structural analogy with alkaloid compounds. One of these compounds, named quinizolate (13), exhibits an intense bitter taste at an extraordinarily low detection threshold of0.00025 mmol/kg of water. This novel taste compound was found to have 2000- and 28-fold lower threshold concentrations than the standard bitter compounds caffeine and quinine hydrochloride, respectively, and, therefore, it is claimed to be one of the most intensely bitter compounds reported so far [46]. It is important to note that in sensory evaluation there is a difference between detection threshold and recognition threshold the first determines the concentration of a substance that makes one able to say this is not pure water the second means that the panelist is able to state this is bitter. Therefore these reported data on the taste of new compounds must to be taken carefully especially in comparison with others. 

Wiley (1945) reported for this oxazole the odor of pyridine and a similarity with that of 2,4-dimethylthiazole (M.9). According to Shibamoto (1977), this compound has a nutty and sweet flavor. After the analysis of volatile basic compounds derived from roasted barley, Harding et al. (1978) reported that the inclusion of 2,4-dimethyloxazole to ale resulted in a soapy after taste, presumably at levels above the recognition threshold. At a concentration of 5 ppm it has a green, fruity and blackcurrant flavor (Chemisis, 1987). 

Decarboxylation of glutamic acid yields y-amino-butyric acid. This compound, which also occurs in wine (cf. 20.2.6.9), tastes sour and produces a dry feeling in the mouth at concentrations above its recognition threshold (0.02 mmol/1). 

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. 

Threshold This is for the recognition of taste, odor, and flavor components. A series of solutions in order of physical concentration of the stimulus is used to determine the absolute threshold (ascending forced choice). 

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