Yukon Cornelius isn’t the only one with a taste for metals. While most people probably can’t find silver and gold by nibbling snow, as Cornelius seems to do in the Rudolph movie*, new research shows that taste buds can detect iron, zinc, copper, magnesium and other metals.
The source of metallic taste has long been elusive, but a study in the Feb. 25 Journal of Neuroscience traces the sensation to a combination of proteins used in detecting sweetness and the pain of red-hot chili peppers, and other as-of-yet unidentified proteins.
Scientists used to believe that there were only a handful of tastes the tongue could register — sweet, sour, bitter, salty and umami, a delicious, meaty taste found in monosodium glutamate, Parmesan cheese and portobello mushrooms. Scientists define a taste as something that is detected by a specific combination of proteins in taste buds, as distinct from a flavor that results from a combination of tastes and odors.
But it would be impossible to describe all the differences between chicken soup and lobster bisque using only the known tastes, says Johannes le Coutre of the Nestlé Research Center in Lausanne, Switzerland. So researchers think there are many other taste sensations. Le Coutre, Céline Riera and colleagues conducted the new study to find out if they could explain just one of them — metallic taste.