Sensation human taste

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. 

In Figure 14, the same letters indicate beer produced by the same company. The results were similar to those of human taste sensation of beer [28]. It is interesting that five kinds of beer from company K are aligned on a line at a 45 ° angle with the abscissa. 

For quantification of the taste of tomatoes, the taste sensor was applied to commercial canned tomato juice, to which four basic taste substances had been added. Data were analyzed by means of principal component analysis. The taste of several brands of tomatoes was expressed in terms of four basic taste qualities by projecting the data obtained from these tomatoes onto the principal axes. This expression agreed with the human taste sensation. 

Studies on human taste sensations confirm and extend our understanding of the types of chemical signals measured by these oral chemoreceptor systems. There are, for instance, several distinct sensations elicited by chemical stimulation of fungiform papillae innervated by the geniculate ganglion, indicating that a neural functional complexity similar to that described above for... 

Table II Partial Summary of some Human Taste Sensations...

Partial summary of some human taste sensations After BOUDREAU [7] ... 

Cat group III stimuli include nucleotides, phosphate compounds, various carbonyl compounds, phenolic compounds, o gen heterocycles and lactones. Many of these compounds are connion food substances and food additives. The human taste sensations elicited by these compounds are of an Indistinct variety and may be described with the terms pleasing, sweetish, creamy, etc. (22, 23). Nucleotides elicit a sensation which the Japanese term mami, or deliciousness (24). It is quite probable that small fiber systems similar to those seen in the cat are present in the human. 

In humans, sensors for taste are collected in structures known as taste buds. Your mouth contains about 10,000 taste buds the majority are located at various sites on your tongue. The remainder are found in the pharynx, epiglottis, and at the entrance to the esophagus. Each taste bud senses and reacts to all five primary taste sensations. I want to dispel an old, untrue but widely held belief that different parts of the tongue are devoted to different tastes. It just isn t so, regardless of what you might have been taught or otherwise have been led to believe. 

There are five primary taste sensations salty, sour, sweet, bitter, and umami (or savory). The receptors for these tastes are encoded in a few dozen genes in the human genome. These are expressed in taste buds. 

Sweetness is one of the most important taste sensations for humans. Sucrose has been widely used for its sweetness as well as for functional properties such as texture, mouthfeel, bulking agent, and preservative. However, the specialized dietary requirements of diabetics and health concerns about obesity and dental caries have prompted a considerable research effort into the development of alternative sweeteners (1-6). 

Table II summarizes some of the different types of taste sensations that can be elicited by chemical stimulation of the human oral cavity and the types of chemical compounds found to elicit them. In some cases It Is possible to assign a sensation to a particular ganglion because of the locus of elicitation.

Human taste response is modified by several plant-derived substances. The detergent sodium dodecyl sulfate, as well as triterpene saponins from the leaves of several plant species (most notably Gymnema sylvestre and Ziziphus jujuba) will temporarily inhibit the sweet taste sensation in man the duration of the effect being about one hour for G. sylvestre and about fifteen minutes for Z. jujuba. The mechanism of action seems to be related, in part, to the surfactant properties of the materials. Structures of the modifiers and possible mechanisms of action are discussed. 

Taste is a complex combination of sensations including gustation, olfaction, tactility, and responses to heat and cold. In humans the sensation of taste is confined primarily to the dorsal face of the tongue, the soft palate, the epiglottis, and parts of the gullet. In children, however, the taste receptors are distributed over larger areas of the mouth." Basically there are four so-called primary tastes sour, bitter, salty. 

No studies were located regarding neurological effects in humans after inhalation exposure to 2-butoxy-ethanol acetate. Male and female volunteers exposed to 98, 113, or 195 ppm 2-butoxyethanol for 4-8 hours experienced headache at 98 ppm and disturbed taste sensation at 113 and 195 ppm (Carpenter etal. 1956). 

Neurotoxicity. The only information on neurological effects in humans exposed to 2-butoxyethanol is that humans exposed experimentally by inhalation experienced headache and disturbed taste sensation (Carpenter et al. 1956), and that people who intentionally ingested household cleaning agents containing 2-butoxyethanol became comatose (Bauer et al. 1992 Gijsenbergh et al. 1989 Litovitz et al. 1991 Rambourg-Schepens et al. 1988). 

There are five primary taste sensations including sweet (carbohydrate based molecules), sour (acidic concentration), salty (sodium chloride), bitter (quinine and other basic functionalities) and umami (salts of glutamic acid). The human tongue does not discriminate every chemical substance composing a flavor it decomposes the taste of foodstuffs into the five basic taste qualities, instead. A single taste bud contains 50-100 taste cells representing all 5 taste sensation. An adult has about 9000 taste buds. 

Flavor is a combination of taste, sensation, and odor transmitted by receptors in the mouth (taste buds) and nose (olfactory receptors). The stereochemical theory of odor is discussed in the essay that precedes Experiment 16. The four basic tastes (sweet, sour, salty, and bitter) are perceived in specific areas of the tongue. The sides of the tongue perceive sour and salty tastes, the tip is most sensitive to sweet tastes, and the back of the tongue detects bitter tastes. The perception of flavor, however, is not so simple. If it were, it would require only the formulation of various combinations of four basic substances—a bitter substance (a base), a sour substance (an acid), a salty substance (sodium chloride), and a sweet substance (sugar)—to duplicate any flavor In fact, we cannot duplicate flavors in this way. The human possesses 9,000 taste buds. The combined response of these taste buds is what allows perception of a particular flavor. 

Oral ingestion of food and other substances in humans and higher animals are inseparable from the subjective taste sensations. The stimulae for irritation of taste receptors localised in the mouth, especially on the tongue, are taste-active substances. They are usually polar, water-soluble and non-volatile compounds. The resulting sensation is usually a combination of fundamental and other tastes ... 

This is a chemical sense detected by receptors—the taste buds in the mouth, primarily on the tongue. Upon entering the mouth, certain dissolved chemicals create nervous impulses in the taste buds. These impulses travel to the brain where they are interpreted eis (1) salty, (2) sweet, (3) bitter, or (4) sour. Humans have about 12,000 taste buds, and each taste bud possesses a greater degree of sensitivity to 1 or 2 of the taste sensations. In general, the tip of the tongue is the most sensitive to sweet, the sides to sour, the back to bitter, while salt sensitivity is distributed over most of the tongue. 

This brief listing of compounds for which humans report one of the four basic taste sensations supports the notion that these compounds have great ecological relevance for many species. This does not mean that each has equal relevance for all species, or that other stimuli do not have relevance for some species (c.f., 23). Indeed, within one taxonomic group, the responses of individual species to various chemical stimuli may differ considerably. The degree to which these differences represent adaptations to the unique ecological conditions encountered by each species has not been thoroughly studied in mammals. 

The taste signals identified for the carnivore in Table III can in part be related to human taste signals (Table IV). This comparison can be made largely on the basis of the similarities in chemical stimuli active in the two species. Especially valuable in cross species comparison, have been the L-amino acids which in part selectively elicit different sensations just as they selectively activate different neural groups (Figure 12). 

Whatever the physiology of odor perception may be, the sense of smell is keener than that of taste (22). If flavors are classed into odors and tastes as is common practice in science, it can be calculated that there are probably more than 10 possible sensations of odor and only a few, perhaps five, sensations of taste (13,21,35—37). Just as a hereditary or genetic factor may cause taste variations between individuals toward phenylthiourea, a similar factor may be in operation with odor. The odor of the steroid androsterone, found in many foods and human sweat, may eflcit different responses from different individuals. Some are very sensitive to it and find it unpleasant. To others, who are less sensitive to it, it has a musk or sandalwood-like smell. Approximately 50% of the adults tested cannot detect any odor even at extremely high concentrations. It is befleved that this abiUty is genetically determined (38). 

The direct transformation from the output pattern to the taste quality was performed here as one trial of expressing the actual human sensation using the output electrical pattern. A similar trial was done for evaluation of the strengths of sourness and saltiness, which will be mentioned later. These two trials depend on the utilization of simple transformation equations by extracting typical properties of output patterns. This method is effective if some data on sensory tests, using humans as a standard, can be obtained to compare with the sensor outputs. However, the expressions for the tastes of beer are obscure because they are not described by the five basic taste qualities. The purpose of the application of the taste sensor is also to express these kinds of obscure terms of human sense in scientific terms. 

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