Physicists have long psychiatry that the existence of four, known as basic tastes: sweet, bitter, sour and salty. Although first described in 1908, only recently recognized new umami taste is fundamental since Thursday have cloned a receptor of an amino acid receptors in 2002. The illustrated umami by salty feeling evoked by some free amino acids such as monosodium glutamate (seasoning). Another suggestion, which has shown a certain fatty acids in as linoleic acid. Some researchers still argue against the concept of basic tastes and instead said that a taste receptors continuously similar visual perception of color. All your feelings arising from all areas of the oral cavity, and misconceptions but quite popular on a "tongue map" in which the perception of different positions corresponding to the concept of luoi.Quan this due to a mistranslation from German texts, and exists in schools in North America since the early twentieth century there was little difference in the perception of the compound of the different areas of the tongue. The taste alone (containing approximately 100 taste receptor cells), in fact, often reminiscent of one of the five basic tastes. Human taste perception through sensory organs called "taste", focusing on the upper surface of the tongue, but a small number are also found in the mouth, furthering the feeling that they're I can feel. The scientists describe five basic tastes: salty, bitter, sour, sweet and umami. The basic position is just one component contributing to the feeling of food in the mouth, other factors including smell (olfactory sense), structure (detected by mechanical receptors) and feeling temperature (detected by thermal receptors). Smell and taste are often lumped together as "flavors".
The basic tastes
For a long time, it is thought that there are a finite number of small and the "basic position". As with the primary colors, the "basic position" is derived mainly from self perception of people, in this case, the position of the tongue different people can identify. To the 2000s, the number of "basic position" is considered to be four. Recently, a fifth taste, umami, has been proposed by various agencies related to this field. 2015, the fat is also recognized as the "basic position" Friday
The bitter taste is the most sensitive in the position, and is perceived by many feeling quite uncomfortable and clear. Food and beverages are often bitter coffee, unsweetened cocoa, bitter melon, beer, olives, lemon zest, many plants in their Reform and lemon. Kinin (quinine or sign security) is also famous for its bitter taste. The stimulation threshold of the bitter taste of quinine average 0.000008 mol / l. Taste perception threshold of different bitter compounds were compared relative to quinine (bitterness of quinine considered equal to 1).
For example, Brucine index is 11, bitter than quinine, and was discovered at a much lower threshold. The most bitter compounds known as synthetic chemical denatonium bitter index is 1.000.
Salty is created primarily by the presence of sodium ions. Other ions of alkali metals group also taste salty, but less sense by sodium. The size of the lithium ion and potassium ion nearly similar to that of sodium and salty so very similar. Conversely rubidium and cesium ions is much larger so their salty taste differs. The salinity of the substances are evaluated relative to sodium chloride (NaCl) (NaCl salinity considered equal to 1). As potassium chloride (KCl), is a major component of salt substitutes salt index of 0.6. Monovalent cations such as ammonium (NH4 +) and divalent cations of alkaline earth metal group such as calcium (Ca2 +) is often reminiscent of a bitter taste is salty.
Sour taste is the smell from the acidity. The acidity of the substance is evaluated relative to dilute hydrochloric acid (acidity by 1). 0.7 acidity tartaric acid, citric acid and carbonic acid is 0.46 to 0.06. Detection mechanism similar to sour detect salty taste, based on hydroni ion concentration and acid forming water.
Sweetness, often regarded as a positive feeling, sense of sugars, proteins and other compounds. Sweetness and often involves aldehyde ketone, containing a carbonyl group. Sweetness is detected by a series of G protein receptors associated with G protein gustducin found on the taste buds. At least two different variations of "sweet receptor" should be activated for the brain to "register" the sweetness.
Detection thresholds for sweet substances are evaluated relative to saccharose. The average level of detection by humans for saccharose of 10 millimol / liter. For lactose level of detection of 30 millimol / liter, and the sweetness index of 0.3  and 5-nitro-2-propoxyanilin is 0.002 millimol / liter.
Umami is the taste sensation name created from amino acids such as glutamate. These compounds often produce umami in food fermentation and composting storing food. It is also described as "the