Taste Buds
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Is it sweet, bitter — or umami?
College research lights up taste
By Eva Emerson
Put a caramel in your mouth and your taste buds detect the sugary
substance and instantly send a message to the brain, which interprets
the signal—sweet!
Trying to figure out what happens in the split-second between eating
something and recognizing its sweet or bitter flavor, or more precisely
between the initial detection of a taste and a signal reaching the
brain, led neuroscientist Emily Liman to take a closer look inside the
cells in the taste buds. What she found reveals new details about how
the sense of taste works.
The research by Liman, an assistant professor of biological sciences in
USC College, and graduate student Dan Liu indicates that calcium plays
a key role in the detection of tastes by taste cells in the tongue.
Published in December in the Proceedings of the National Academy of
Sciences, the paper also offers a molecular model of how taste cells
reset so they are ready to detect new tastes.
Until recently, scientists have known little about how taste works on a
cellular or molecular level. Just four years ago scientists officially
added a unique taste, called umami, to the list of better known ones:
sweet, bitter, salty and sour. Umami receptors are sensitive to the
amino acid glutamate, which most think serve as a marker for
protein-rich foods. Glutamate is also the main ingredient in the
commonly used flavor additive MSG (monosodium glutamate), which may
explain the additive’s appeal.
Taste research has attracted the attention of basic researchers like
Liman interested in unraveling how cellular signaling works. Food and
drug industry scientists are also very interested in understanding the
molecular details of taste, especially bitter and sweet, Liman says.
“It’s important to know how taste works and to identify the molecules
involved. These molecules can be targets for designing chemicals that
activate taste—for example, a better artificial sweetener—or that block
taste, such as an additive that could be used to block bitter tastes,”
she says.
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