Salty taste perception

Salty tastants act directly on Na+ channels in the PM of cells on the tongue surface. Direct passage of Na+ through these channels causes depolarization and thence signalling to the CNS. Much (but not all) salt taste perception is inhibited by the voltage-sensitive Na+ channel inhibitor amiloride (see Chapter 4) and evidently some salt perception also occurs via amiloride-insensitive channels. 

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Confusion of the taste perception mechanism by the competition of sweet, salty, sour, and bitter factors may seem to be hopelessly complicated. In the author experience this is merely a part of the normal phenomenon of flavor blending. A better understanding will be reached when more studies such as those of Fabian and Blum (5) are carried out in actual food and beverage media. 

Flavour enhancers and suppressers are used in low concentrations to enhance or suppress other flavours. Examples include maltol and ethylmaltol, which have a low caramel taste and enhance the sugary feeling of products furaneol, which is used with red fruits or wild fruit flavours and vanillin, which softens bitter chocolate and fruit flavours and can also enhance the perception of sweetness. In general, sucrose suppresses bitter, sour and salty tastes, for example in chocolate, and enhances fruit flavours. A further important point for ice cream is that the perception of flavour is affected by temperature flavours are less intense at low temperatures. For this reason, ice cream and water ices are generally more strongly flavoured than products consumed at warmer temperatures, such as soft drinks (Experiment 17 in Chapter 8 demonstrates this). 

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. 

While table salt is generally classified as a flavoring agent (basic taste), it clearly functions as a flavor potentiator as well. There is little question that to most individuals, foods without salt are very bland and lack flavor. Salt contributes much more to sensory perception than simply adding a salty taste. Interestingly, this taste for salt is acquired. 

Like MSG, salt has a generally unfavorable status with the consumer. Salt is associated with hypertension in some individuals, which contributes to stroke and some types of cardiovascular disease. There has been substantial research effort directed at finding salt substitutes, but other than K+ chloride, little has been found that elicits a true salty taste. Unfortunately, K+ is bitter and thus not well received. Some research has shown that the addition of MSG and/or 5 -nucleotides reduces the need for salt. There are other reports of L-lysine and L-arginine [39], L-omithine-P-alanine [40,41], and trehalose [42] enhancing salt perception (thereby reducing usage level). 

Salty substances exhibit a variety of pharmacological effects, whose character depends on the type of cation and anion. Some substances are toxic at higher concentrations. The compound consumed in the largest amount is sodium chloride. The daily intake of salt in developed countries is estimated at 8 15g. Sodium chloride supports the perception of taste of foods at the required intensity and fullness, stimulates not only receptors for salty taste, but significantly increases the perception of the sweet taste of sucrose and some other sweet substances, as well as sour taste perception, and suppresses the sensation of metaUic taste and some other... 

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. 

A persistent idea is that there is a very small number of flavor quaUties or characteristics, called primaries, each detected by a different kind of receptor site in the sensory organ. It is thought that each of these primary sites can be excited independently but that some chemicals can react with more than one site producing the perception of several flavor quaUties simultaneously (12). Sweet, sour, salty, bitter, and umami quaUties are generally accepted as five of the primaries for taste sucrose, hydrochloric acid, sodium chloride, quinine, and glutamate, respectively, are compounds that have these primary tastes. Sucrose is only sweet, quinine is only bitter, etc saccharin, however, is slightly bitter as well as sweet and its Stevens law exponent is 0.8, between that for purely sweet (1.5) and purely bitter (0.6) compounds (34). There is evidence that all compounds with the same primary taste characteristic have the same psychophysical exponent even though they may have different threshold values (24). The flavor of a complex food can be described as a combination of a smaller number of flavor primaries, each with an associated intensity. A flavor may be described as a vector in which the primaries make up the coordinates of the flavor space. 

Multiple senses, including taste, contribute to our total perception of food. Our perception of the flavor of food is a complex experience based upon multiple senses taste per se, which includes sweet, sour, salty and bitter olfaction, which includes aromas touch, also termed mouth feel , that is, texture and fat content and thermoreception and nociception caused by pungent spices and irritants. Taste proper is commonly divided into four categories of primary stimuli sweet, sour, salty and bitter. One other primary taste quality, termed umami (the taste of L-glutamate), is still somewhat controversial. Mixtures of these primaries can mimic the tastes of more complex foods. 

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... 

Very broadly, tastes can be divided into three, possibly four, categories—sw eet, saur (or ULid I, and bitter (alkaline) and salty. Salty, w hich for practical purposes is a major componeni of laste perception, involves physiological differences in some ways it may be classified as a flavor potentiator. 

Taste transduaion is initiated when taste stimuli interact with exposed cells in the apical microvilli of the tongue. The receptor-ligand interaction leads to membrane depolarization and to activation of afferent gustatory neurons. The perception of the common human taste qualities— sweet, bitter, salty, and sour—has been assigned to groups of taste neurons. But a characteristic property of taste transduction is that the taste cells can also be stimulated directly without the intervention of receptors. 

Moskowitz and Arabic (1970) found that the taste intensity (sweetness, sourness, saltiness, and bitterness) was related to the apparent viscosity of carboxymethylcel-lulose solutions by a power function with a negative slope. Pangbom et al. (1973) observed that the influence of different hydrocolloids on the perception of some basic taste intensities (saltiness, bitterness, sourness) appeared to be more dependent on the nature of the hydrocolloid and the taste of the substance than on the viscosity level. In contrast, sweetness imparted by sucrose was found to be highly dependent on viscosity, that is, the hydrocolloid concentration above a certain viscosity threshold, it was shown that the sweetness intensity of sucrose was significantly depressed. Saltiness was the taste attribute less affected, sourness, imparted by citric acid, was significantly reduced by all hydrocolloids tested, and for the other taste substances, the presence of a hydrocolloid generally enhanced the taste intensity of saccharin and depressed that of sucrose and caffeine (bitterness). 

In taste studies, sucrose is usually taken as a reference standard in the sensory evaluation of sweetness and caffeine is generally used as the reference material for bitterness. However, sour and salty tastants modulate taste-receptor function by direct effect on specific ion channels in the membrane, while sweet and bitter tasting compounds seem to bind to closely located receptors which are coupled to a guanidine-nucleotide binding protein (G-protein). The perception of their tastes proceeds through a transduction mechanism involving G-protein and a second messenger system (Kinnamon, 1988). 

Taste. Taste Is the human perception of chemicals In the mouth due to their Interaction with receptors on the tongue. Taste consists of four dimensions sweet, salty, sour and bitter. Taste Is affected by odor and texture, which makes it a complicated, subjective quality attribute, difficult to measure objectively (22). In fruits and vegetables, taste Is mostly determined by the types and amounts of carbohydrates, organic acids, amino acids, lipids and phenolics (5.71). CA combinations, to the degree that they modify changes in these constituents, can affect the taste of stored fruits and vegetables. Usually, extremely low O2 or high CO2 will result In off-flavors and reduced quality due to anaerobic respiration. The specific effect of CA on flavor depends on the crop Involved (2). 

The flavor of food is the most important sensory attribnte affecting the acceptance and preference of consumers. Standards organizations in many countries define flavor as a total impression of taste, odor, tactile, kinesthetic, temperature, and pain sensations perceived through tasting [1]. It is widely accepted that flavor includes the aromatics, such as olfactory perceptions caused by volatile substances the tastes, such as gustatory perceptions (salty, sweet, sour, and bitter) caused by soluble... 

Flavor compounds (aroma compounds). Term for volatile compounds in food that are perceived by osmoreceptors (see aroma chemicals) either directly in the nose (smelling, nasal perception) or in the pharyngeal space on eating or drinking (retronasal perception). Together with the generally non-volatile taste compounds (sour, sweet, bitter, salty, or spicy tasting compounds). F. c. make a decisive contribution to the taste of a food, the consistency of the food also contributes to the complete sensory impression. 

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