Salty sensations

The salty taste is primarily due to sodium ions acting directly on ion channels. Amiloride specifically blocks sodium channels however, it does not block all responses to salt, in cating more than one mechanism for salty sensation. A different compound, 4-aminopyridine, blocks potassium channels but not sodium. This suggests that receptor proteins and second messengers are not uired, and that these stimuli act directly on ion membrane channels. The physiology of the response of cells to salt has been reviewed (7). 

Redistribution of sodium in a food product (especially between liquid and solid compartments) so as to increase the amount of sodium that reaches the receptors on the tongue. In order to elicit a saltiness sensation, the sodium ions must reach the taste buds. Hence what matters for the saltiness impression is the fraction of accessible sodium ions in contrast to the sodium that one swallows without ever being perceived. This can be influenced by the way the sodium is distributed over the different constituents of the food products. 

Sensory perception is both quaUtative and quantitative. The taste of sucrose and the smell of linalool are two different kinds of sensory perceptions and each of these sensations can have different intensities. Sweet, bitter, salty, fmity, floral, etc, are different flavor quaUties produced by different chemical compounds the intensity of a particular sensory quaUty is deterrnined by the amount of the stimulus present. The saltiness of a sodium chloride solution becomes more intense if more of the salt is added, but its quaUty does not change. However, if hydrochloric acid is substituted for sodium chloride, the flavor quahty is sour not salty. For this reason, quaUty is substitutive, and quantity, intensity, or magnitude is additive (13). The sensory properties of food are generally compHcated, consisting of many different flavor quaUties at different intensities. The first task of sensory analysis is to identify the component quahties and then to determine their various intensities. 

Simultaneous stimulation of the tongue with the appHcation of different taste stimuli produces an interaction, modification, or blending of the stimuli in some instances but not in others. Warm and cold sensations are reported to act similarly on the tongue in two groups bitter, warm, and sweet and sour, cold, and salty (24). The theory of the specificity of the taste buds may be subject to modification (25). 

A century ago, Fick proposed the concept of four primary tastes, namely, sweet, salty, sour, and bitter. It has since been found that taste sensations are not describable by a single collection of discrete primaries. Electrophysiological studies of afierent taste-units in the chorda tympani and glossophyrangeal nerves have revealed that a continuous spectrum of gustation may be based on these four taste elements. Furthermore, the intensities of the tastes that we commonly experience are due not only to gustatory sensations but also to tactile, hot and cold, and, above all, olfactory sensations. The complexities of taste studies are such that, unless one of the taste modalities is singled out for study, there is very little hope of success. 

There is controversy about the nature of the salt receptor. In one theory, Na" " ions enter the sensory cells through a sodium channel (this is distinct from the sodium channels of nerve andmuscle cells), causing membrane depolarization, entry of Ca " ", and generation of an action potential. We sense salty. Acids create the sensation of sour think about lemon juice or vinegar. In one mechanism, and there may be more than one, the H+ ions derived from acids block K+ channels. Blockage of these channels, basically responsible for maintaining the membrane potential, leads to membrane depolarization, Ca + entry, and so on. We sense sour. 

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. 

After the saliva has carried the tastants into the taste bud, they interact with the taste receptors on the surface of the cells, or with ion channels, which are pore-like proteins. Salty and sour tastants act through ion channels, and sweet and bitter sensations are mediated by surface receptors. The different taste submodalities rely on specific mechanisms Na+ flux through Na+... 

Reviews of taste sensations normally concentrate on four basic tastes - sweet, salty, sour and bitter (7,2) however, other oral sensations can contribute important information to the perceived flavor (3), Examples of stimulants evoking these very different sensory sensations are shown in TABLE I. Studies on the mechaiusms of perception are usually restricted to sensation-specific stimuli however, food flavors represent an interaction among the various sensations. This chapter describes recent... 

Sour and salty. Within the membrane of the taste cell are ion channels which control the movement of ions, such as sodium, potassium and calcium, into and out of the cell. Sour taste sensations are in part due to the effect of hydrogen ions however, some taste is also a function of the hydrophobicity of the organic acid, such as citric acid (18). Acids can produce a decrease in potassium ion conductance (depolarization) in the membrane. 

Xuan Shen is bitter, cold and salty, and enters the Kidney meridian. It can clear heat and reduce fire. Unlike Sheng Di Huang, it is not sweet and has no function in generating Yin, but it can lift the Kidney-water (Yin) upwards to reduce the excess fire of the Heart. It is often used with Sheng Di Huang to treat excess heat and empty-heat in the Heart. It can relieve thirst, dry throat, warm sensations in the chest and irritability. However, if a patient has a Yin deficiency, especially Kidney-Yin deficiency, Xuan Shen should not be used for too long. 

There are four basic sensations salty, bitter, sweet, and sour. A combination of efforts is required to mask these tastes. For example, menthol and chloroform act as desensitizing agents a large number of natural and artificial flavors and their combinations are available to mask the bitterness most often found in organic compounds. Most formulators refer the selection of compatible flavors to companies manufacturing these flavors, as they may allow use of their drug master file... 

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. 

Cocaine and other local anesthetics abolish not only the sensation of pain, but other special sensations, if they are suitably applied. Here also there is some selection. In the skin, they paralyze first the vasoconstrictor reaction, then progressively the sensations of cold, warmth, touch, tickling, pressure, pain, and joint sense. In the nose, they abolish the olfactory sense. On the tongue, they destroy the taste for bitter substances but have less effect on sweet and sour taste and none on salty taste. When cocaine is applied to the appropriate nerves, it is found that the centrifugal vagus fibers are paralyzed before the centripetal, vasoconstrictor fibers before vasodilator, bronchial constrictors before the dilators, etc. (Sollmann, 1944). 

Wine is one of the most complex and interesting matrices for a number of reasons. It is composed of volatile compounds, some of them responsible for the odor, and nonvolatile compounds which cause taste sensations, such as sweetness (sugars), sourness (organic acids), bitterness (polyphenols), and saltiness (mineral substances Rapp and Mandary, 1986). With a few exceptions, those compounds need to be present in levels of 1%, or even more, to influence taste. Generally, the volatile components can be perceived in much lower concentrations, since our organs are extremely sensitive to certain aroma substances (Rapp et ah, 1986). Carbohydrates (monosaccharides, disaccharides, and polysaccharides), peptides, proteins, vitamins, and mineral substances are among the other wine constituents. 

As indicated elsewhere, there is evidence for a possible correlate of a pleasant sensation in a cat unit group, but this system has been little investigated in either the cat or in other species. Although the goat has a system that responds maximally to Na and Li salts, this system has not been seen in the carnivore. The chemical stimuli eliciting the human sensation of salty are salts in relatively high concentration, concentrations that in other species may stimulate more than one group. 

A complete different mechanism seems to be present in the bitterness of salts, as two bitter sensations are differentiated (90) bitter I as elicited by stimuli like 1-tryptophan, this would correspond to our "hydrophobic bitterness" and bitter II, elicited e.g. by MgSO. This bitter II seems to be triggered by ions. Kionka and Stratz (91) comparing 1 n solutions of the different alkali halo-genides made a separation in three groups as shown in Table XXIII salty, salty + bitter, bitter. 

The basic sensations—sweet, sour, salty, and bitter—account for the major part of the taste response. However, it is generally agreed that these basic tastes alone cannot completely describe taste. In addition to the four individual tastes, there are important interrelationships among them. One of the most important in foods is the interrelationship between sweet and sour. The sugar-acid... 

In the evaluation of contribution to taste, amino acids and peptides are being studied as to sweet, salty, bitter, sour and umaml [brothy mouth-feel, see (19)] sensations. In the production of gravies and soups, proteins are hydrolyzed to smaller molecules which evoke... 

Taste consists of four primary sensations sweet, sour, bitter, and salty. Correspondingly, there are four... 

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