bittering

Bittering is the sensory perception of bitterness, one of the basic tastes detected by taste receptor cells on the tongue. It arises when a wide range of chemically diverse compounds bind to bitter taste receptors, particularly the T2R family, triggering signaling pathways that inform the brain. Bitter substances include alkaloids such as quinine and caffeine, as well as a variety of terpenoids, polyphenols, and glycosides. Individual sensitivity to bitterness varies, influenced by genetics, age, and training or exposure.

Biology and ecology underpinning bitterness are linked to protection against potential toxins. Many bitter compounds occur in plants and herbs, aiding deterrence of herbivores. In humans, heightened bitter sensitivity can influence dietary preferences and the acceptance of certain medicines, while some individuals (super-tasters) perceive bitterness more intensely due to variations in taste receptor genes.

In culinary and beverage contexts, bitterness is a deliberate characteristic. In beer and other brewed beverages, bitterness is often introduced by hopping, with alpha acids isomerizing during boiling to produce iso-alpha acids that contribute bitterness. The level is commonly quantified in International Bitterness Units (IBU). Brewers balance bitterness with malt sweetness, aroma, and mouthfeel, and may adjust through timing of bittering additions or by using alternative bittering agents.

Bittering agents are also used outside food contexts to deter ingestion of hazardous products. Denatonium benzoate, for example, is added to antifreeze, pesticides, and cleaning products to impart an extremely bitter taste and discourage accidental ingestion.