![]() About six years ago, explains Zuker, who previously worked on other sensory systems in flies, ‘there was a disconnect between our understanding of sensations in the case of photoreception, mechanoreception, touch, and so on and what we knew about taste’. The olfaction results also enticed researchers from other disciplines into the taste field, including collaborators Charles Zuker (University of California, San Diego, La Jolla, California, United States) and Nick Ryba (National Institute of Dental and Craniofacial Research, Bethesda, Maryland, United States). This landmark discovery, in part, encouraged many established taste researchers to investigate the molecular aspects of taste. These proteins, which are exposed on the surface of cells in the nose, bind to volatile chemicals and allow us to detect smells. Then, in 1991, the first olfactory receptors were described. During the 20th century, electrophysiologists and other researchers worked hard to understand this seemingly simple sense system. Taste has been actively researched for many decades. It's an extremely important decision, but it can be made based on a few taste qualities’. We just have to decide whether to swallow or spit it out. Our sense of taste has a simple goal, explains Lindemann: ‘Food is already in the mouth. And umami (the taste of the amino acid glutamate) may flag up protein-rich foods. The quality sweet provides a guide to calorie-rich foods. ![]() Bitter detection warns of foods containing poisons-many of the poisonous compounds produced by plants for defence are bitter. Salty and sour detection is needed to control salt and acid balance. The five qualities that Lindemann refers to are salty, sour, bitter, sweet, and umami, the last being the Japanese term for a savoury sensation. ‘We are now settling at around five, though I would not be surprised if some additional qualities pop up’. ‘The number of taste qualities has varied over the years’, says Lindemann. Large numbers of people describe different tastants and then statistical analyses are used to define the important tastes. Quality or ‘basic taste’, explains Bernd Lindemann, now retired but an active taste researcher in Germany for many years, is a psychophysical term. Taste is the sense by which the chemical qualities of food in the mouth are distinguished by the brain, based on information provided by the taste buds. (Photograph courtesy of Sami Damak, Mount Sinai School of Medicine, New York, New York, United States.) This taste bud was taken from a transgenic mouse in which the marker green fluorescent protein is being driven by the T1R3 promoter 20%–30% of the cells in the taste bud are expressing T1R3.
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