Taste threshold, determination

The human taste threshold for PCP in drinking water is about 30 pg/L (USEPA 1980), a level far below the upper safe limit of 1.01 mg/L and near the no-observable-effect level of 21 pg/L (Table 23.7). Odor detection is not as sensitive as taste the odor threshold for PCP ranges from about 857 pg/L at 30°C, to 1600 pg/L at 20 to 22°C, to 12,000 pg/L at 60°C (USEPA 1980). It is not clear whether the determined organoleptic threshold values made the water undesirable or unfit for consumption (USEPA 1980). If fish and wildlife species of concern have PCP organoleptic thresholds that are similar to those of humans, or lower, will they too avoid contaminated habitats or diets ... 

Clear, colorless liquid with a pungent, suffocating odor. Burning taste. Experimentally determined odor threshold concentrations of 1.0 ppmv and 0.50 ppmv were reported by Leonardos et al. (1969) and Nagata and Takeuchi (1990), respectively. 

Colorless liquid with an aromatic odor. Experimentally determined detection and recognition odor threshold concentrations were 40 pg/m (8 ppbv) and 230 pg/m (47 ppbv), respectively (Heilman and Small, 1974). The taste threshold concentration in water is 60 ppb (Young et al, 1996). 

White, crystalline flakes, or powder with a strong aromatic odor resembling coal-tar or moth balls. At 40 °C, the average odor threhold concentration and the lowest concentration at which an odor was detected were 6 and 2.5 pg/L, respectively. Similarly, at 25 °C, the average taste threshold concentration and the lowest concentration at which a taste was detected were 50 and 25 pg/L, respectively (Young et ah, 1996). A detection odor threshold concentration of 200 pg/m (38 ppbv) was experimentally determined by Punter (1983). 

In tests to better define this mixture of components (and their proper proportions) necessary for good orange flavor, volatile components believed from prior analytical studies to be important to orange flavor were examined (5). Individual taste and aroma thresholds in water were determined on the compounds selected. Then, the influence of nonvolatile juice constituents on the taste threshold of certain of the volatile components was studied. Finally, selected individual compounds and mixtures containing from two to six components were evaluated in a bland juice medium for their contribution to orange flavor. 

Table II. Taste thresholds of octanal determined in aqueous solutions of selected 5 -nucleotides at 10 ppm (23)...

Taste thresholds of 1 ppm nootkatone in water and 5-6 ppm in grapefruit juice were determined by Berry et al. (34), who stated that grapefruit juice containing 0.005% oil contains an average level of less than 0.5 ppm nootkatone, which is considerably lower than the threshold level in juice. They considered only the nootkatone present in the oil, and any nootkatone present in the oil-free juice would have added to this value. 

Attention should be given when determining odor or taste threshold levels for a substance in a food or other testing medium, that during the taste test the compound studied can be detected in the gas headspace in contact with the food where the partition coefficient KG/F plays an important role. 

From experience it has been established that the sensory threshold for coffee creamer and condensed milk products is on the order of 0.1 mg/kg (ppm) of styrene in the product. This observation is only partly supported by threshold values from the literature in Table 14-2 where values range from 0.2 ppm for 3 % yogurt, 1.2 ppm for 3.8 % fat milk and 2-5 ppm for condensed milk. This points out two problems with threshold concentration values caused by the way they are determined (e.g. experimental methods) and the definition of the threshold value being the value at which the substance is correctly identified by 50 % of the panelists (versus other possible ways of measur-ing/defining the taste threshold). 

Quotient of concentration in wine and taste threshold of the compound in water. Taste values were determined according to Warmke et al. (26). 

Nature-identical and artificial flavouring substances are produced in order to evoke specific sensorial effects. The potency of the individual compounds is usually described by a set of parameters comprising the odour or taste threshold in the corresponding matrix, i.e. water or oil phase, as well as the dynamics of perception as determined by Steven s law [7]. For many compounds a shift of the specific sensorial properties is observed in different concentrations. 

A number of studies have been carried out to determine the levels at which odour can be detected in drinking water. These studies are normally carried out in a laboratory setting with trained panellists in order to maximise the sensitivity of the study. This is important because the number of panellists must be highly restricted, but there is a wide variation in the sensitivity within the population and it is not necessarily possible to cover the full range. Set against this is the fact that under normal circumstances of use individuals would not be routinely seeking to detect odour in water, much water is drunk cold, which reduces the potential for the volatilisation of odorous substances, while other water is boiled resulting in increased loss of such substances before consumers drink the water. In addition, while every effort is made to exclude extraneous odours in the laboratory, this is not the case when the consumer uses the water. Odour and taste are closely linked and in most circumstances both odour and taste thresholds are determined in laboratory studies. In many cases one is clearly lower than the other but with MTBE the data are mixed. This may reflect the volatility of MTBE and its release in the mouth. 

Dale MS, Moylan MS, Koch B, Davis MK (1997) MTBE taste and odor threshold determinations using the flavor profile method. Presented at the Water Quality Technology Conference, 9-13 November 1997, Denver, CO... 

In order to study the influence of the pH value on the sweetness enhancing effect of the novel Maillard reaction product, binary mixtures of the tasteless alapyridaine and the sweet tasting compounds glucose, saccharose, or L-alanine were sensorially evaluated in a triangle test using water with pH 5.0, 7.0 and 9.0, and the sweet detection thresholds determined were compared to the threshold concentrations of aqueous solutions containing the sweet tastants alone (Table I). 

The taste threshold concentrations were determined by a triangle test using tap water (pH 5.0, 7.0, 9.0) as the solvent. Factor by which the threshold of the sweet tastant was decreased in the presence of alapyridaine. 

Taste threshold screening. The saccharin taste threshold screening, performed without wearing a respirator, is intended to determine whetherthe individual being tested can detect the taste of saccharin. 

ASTM E 679-97. Standard practice for determination of odor and taste thresholds by forced-choice ascending concentration series method. 

TA directly mediates feeding threshold determination. In the blowfly Phormia regina, proboscis extension reflex was used as an indicator of behavioral sensitivity for taste. Acquired experiential effects of nonappetitive or appetitive odors were linked to TYR levels in the brain [36]. 

The main compounds in the potato tuber are a-solanine (Formula 17.23) and a-chaconine, which differs from the former compound only in the structure of the trisaccharide (substitution of galactose and glucose with glucose and rham-nose). a-Solanine and a-chaconine and their aglycone solanidine have a bitter/buming taste (Table 17.18) and these sensations last long. The taste thresholds have to be determined in the presence of lactic acid due to a lack of water... 

Substances influencing colour (such as dyes and pigments) are also important sensory-active substances present in foods. They determine not only the characteristic colour of the food, but also affect the taste threshold concentrations of substances and the ability to identify smells. Food that has a satisfactory nutritional and hygienic-toxicological quahty or excellent odour, taste and texture will still not be accepted by consumers unless the characteristic colour corresponds to the standard product. 

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