tastants

Tastants are chemical compounds that stimulate taste receptor cells in the gustatory system to produce the sensation of taste. Most tastants are ingested and interact with taste buds located on the tongue and, to a lesser extent, in the palate and pharynx. Each taste bud contains sensory cells that respond to tastants and transmit signals through cranial nerves to the brain.

Humans commonly recognize five basic tastes: sweet, sour, salty, bitter, and umami. Sweet and umami stimuli are detected by specific G protein-coupled receptors in the T1R family (sweet is T1R2+T1R3; umami is T1R1+T1R3). Bitter tastants are detected by a large family of T2R GPCRs. Salty taste arises primarily from sodium ions entering through amiloride-sensitive sodium channels, while sour taste is associated with protons affecting ion channels on acid-exposed cells.

Beyond these basic tastes, researchers have proposed additional taste qualities. Some scientists recognize fat as a possible sixth taste, sometimes called oleogustus, based on the detection of long-chain fatty acids, though this remains debated. Other tastant-related phenomena include kokumi, a modulation that can enhance sweetness and mouthfeel without a distinct taste of its own.

Common tastants include sugars such as sucrose, glucose, and fructose (sweet); citric and malic acids (sour); sodium chloride (salty); quinine, caffeine, and certain alkaloids (bitter); and monosodium glutamate and other amino acids (umami). Understanding tastants is important in food science, nutrition, and pharmacology, influencing flavor optimization, taste masking, and product development.