FLAVOUR

also spelled Flavor, in particle physics, property that distinguishes different members in the two groups of basic building blocks of matter, the quarks and the leptons. There are six flavours of subatomic particle within each of these two groups: six leptons (the electron, the muon, the tau, the electron-neutrino, the muon-neutrino, and the tau-neutrino); and six quarks (dubbed up, down, charm, strange, top, and bottom; a particle containing the top quark has yet to be observed). Flavour can change in particle reactions only through the agency of the weak nuclear force, as when, for example, a muon changes into an electron, or a neutron (containing two down quarks and one up quark) transmutes into a proton (made from two up quarks and one down quark). Christine Sutton also spelled Flavor, in sensory perception, attribute of a substance (apart from its texture and temperature) that is produced by the senses of smell, taste, and touch and is perceived within the mouth. These sensations help to identify substances and are sources of enjoyment when eating and drinking. Tasting occurs in the mouth, chiefly on the tongue through the taste buds. The taste buds are stimulated by four fundamental taste sensationssweet, salty, sour, and bitter. Examples of substances that induce the four basic tastes are sugar (sweet), salt (salty), lemon juice (sour), and quinine (bitter). Substances can be tasted only when they are in water solutions, and if a substance is not in solution when taken into the mouth, it must be dissolved in saliva before it can be detected by the taste buds. The taste buds most sensitive to salty flavours are dispersed along the sides and front of the tongue. Taste buds sensitive to sweet flavours are concentrated on the tip of the tongue. Bitter flavours are detected at the rear of the tongue and sour flavours on the sides. Smelling involves the olfactory nerve endings in the upper part of the interior of the nose. Aromas can reach these nerves either directly through the nostrils as in breathing or indirectly up the back passageway from the mouth. Because of their remote location, the olfactory nerve endings are best stimulated by sniffing through the nose or swallowing if food is in the mouth. Odours are smelled only when the material is in gaseous formi.e., a dispersion of molecules in air. Touch sensations that contribute to taste originate in the nose, lips, and throughout the entire mouth and throat. The touch sensations relating solely to taste are based on the chemical properties of the substance. Reactions induced by chemical properties include the coolness of peppermint, the bite of mustard and pepper, the warmth of cloves, and the astringency of spinach. When a person consumes food, the simultaneous stimulation of the senses of taste, smell, and touch create an immediate impression that causes him to accept the food and continue eating it or to reject and discard it. Many foods such as bananas, berries, and other fruits, nuts, milk, and a few vegetables have flavours that make them highly acceptable in their natural, uncooked state. Other foods derive their flavour through cooking, seasoning, and flavouring or combinations of these. Psychologists have demonstrated that preference for or avoidance of a particular flavour is a learned behaviour. Flavour evaluation tests are used by the food-processing industry to determine acceptability of new food products and to assure uniform quality of established products. Many tests rely on panels composed of trained tasters. Flavour tests include ranking and scoring, with panel members ranking samples according to intensity of the flavour characteristic being judged; profile methods, in which trained participants describe sensations produced by food samples; difference tests, with participants reporting differences detected in samples; and consumer acceptance testing, in which trained workers evaluate surveys of reactions of potential consumers to product samples. In the late 20th century, scientists working with foods were developing objective methods for isolating and measuring the chemicals contributing to flavours. Knowledge of the chemicals involved and the conditions affecting them can lead to improvements in raw materials; quality evaluation and control; processing, storage, and preparation methods; and new-product development.