"We lump a whole bunch of things into that one word," said Suslick, whose study appeared August 1 in the journal Analytical Chemistry. "It just isn't clear yet what the bitterness receptors [in the tongue] are and what they respond to."
Still, Suslick and colleagues' past research has helped California-based company iSense to develop technology that can sense noxious gases for emergency first responders and military personnel.
Other applications down the road, Suslick said, include a kind of breathalyzer that could detect harmful bacteria, and biomolecules, which could provide people with an early warning of diseases such as pneumonia and lung cancer. (Learn more about human diseases.)
Eric Anslyn, a chemistry professor at the University of Texas at Austin, said in an email that an artificial tongue that sensed just these five flavors would still miss a lot.
Much of what we experience as taste is really smell, said Anslyn, who was not involved in the new research.
"You plug your nose and hold your breath to eat food you don't like—we all know this," he said.
"Hence, we are missing the vast majority of taste when not including the dimensionality that smell brings."
The sweetness sensor, said study leader Suslick, is "only one small part of a much broader program to create a new technology to imitate both our sense of taste and of smell."
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