Whenever we eat food it touches our tongue which is studded with numerous taste buds. These taste buds, as soon as come in contact with food, get stimulated and immediately send a signal to the brain through nerves which join them to the brain. The lower portion of the brain called the brain stem after receiving the taste sensation immediately send the signal to the main part of the brain called Cerebral cortex. Thus we can feel the taste of the food within a fraction of second.
The taste system consists of 3 types of taste papillae, on which taste buds are located which is an onion-shaped structure. Fungiform papillae, which are mushroom-shaped structures, are located towards the front of the tongue. Each fungiform papillae usually contains 3-5 taste buds. Circumvallate papillae are located towards the back of the tongue, and unlike fungiform papilla, they each contain more than 100 taste buds. The ridges and grooves located along the sides of the tongue are foliate papillae. Like circumvallate papillae, foliate papillae also contain more than 100 taste buds each.
To taste the different tastes there are different taste buds in a different area of the tongue.
1.) Sweet: Sweetness of the food is produced by the sugar present in it. The area of the tongue which is sensitive to sweetness or which have concentrated taste buds for sweet taste gets activated as soon as the food mixes with the saliva when it is placed in the mouth. This sweet sensation is then carried to the brain via nerves and thus we experience the sweet taste. The sweet foods include sweets, sugar, fruits (like mango, grapes etc.), cold drinks, ice cream etc.
2.) Salty: The food contains ion of metals such as Sodium (Na⁺) and Chloride (Cl⁻) but the saltiness of the food depends on the ion with positive (+) charge like Na⁺, K⁺ or Li⁺. There is an area on the tongue that reacts as soon as, these positive ions, comes in their contact when the food mixes with the saliva when placed in the mouth. The signal of saltiness is then transferred through the nerves to the brain and within a fraction of second, we feel a salty taste. the salty food includes common salt, chips, cooked food containing salt like Dalia, soup, vegetables, khichri etc.
3.) Sour: Sourness is the taste that detects the acidity of the food. Sour taste is detected by a small set of cells that is present across all the taste buds in the tongue. Those foods which contain acids like tartaric acid, citric acid etc. , when placed in the mouth, these cells immediately detects the acid in the food and send the sour signal to the brain through the nerves and we can experience sour taste of the food. The most common food group that contains naturally sour taste is fruit such as lemon, grape, orange, tamarind and sometimes melon.
4.) Bitter: Bitter taste is generally related to toxicity and acts as a protective function. Bitterness is the most sensitive of the tastes, and many perceive it as unpleasant, sharp, or disagreeable, but it is sometimes desirable and intentionally added via various bittering agents. Common bitter foods and beverages include coffee, unsweetened cocoa, South American mate, marmalade, bitter gourd, beer, olives, citrus peel, many plants in the Brassicaceae family, dandelion greens, wild chicory, and escarole.
5.) Umami: Umami is an appetitive taste and is described as a savoury or meaty taste. It can be tasted in cheese and soy sauce and while also found in many other fermented and aged foods, this taste is also present in tomatoes, grains, and beans. Monosodium glutamate (MSG) which was developed as a food additive in 1908 by Kikunae Ikeda produces a strong umami taste and it is being frequently used for Chinese preparation in India.