A sixth basic flavor may have been discovered. The five established basic flavors are salt, sweet, bitter, sour, and umami, a Japanese word meaning “a pleasant savory taste.” They relate to simple chemicals: For instance, sweetness is produced by sugars; saltiness by metal ions such as those in table salt; sourness by acidity. Glutamate, an amino acid, creates umami. Now scientists at the University of Southern California think they have found that taste-bud receptors also respond to ammonium chloride, a chemical found in many waste products which could signal toxicity. That said, some humans may like it: Ammonium chloride is a key ingredient in salt licorice, a popular candy in Scandinavia. |