Electronic tongue

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Researchers have developed an electronic tongue. (Don't start.) The device is something like a litmus test for taste that, according to chemists at the University of Illinois at Urbana-Champaign, is incredibly accurate at measuring sweet things. The system consists of a paper dotted with an array of color-changing gels that react to a variety of different sweeteners. The electronic device scans the color of the dots after the paper is exposed to a sample. The combination of the gels' reactions, represented by their color, reveals the "taste." There are already chemical or electronic methods to test for other flavors detected by human tongues: saltiness, sourness, and savoriness. From National Geographic:
Sourness is just another word for acidity, Suslick said, which any high school chemistry student can test for using litmus paper.

Savoriness - also called "umami" - and saltiness can already be measured by handheld devices sensitive to protein levels and sodium and potassium ions.

The final dimension of taste that remains to be cracked is bitterness, which is still somewhat of an unknown.

"We lump a whole bunch of things into that one word," said (UIUC professor Kenneth) 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."
"Electronic Tongue" Mimics Human Taste Organ