Electronic Tongues Sense MSG

Electronic tongues can now discern the fundamental, savory taste quality known as umami using carbon nanotubes and protein receptors borrowed from honeybees (ACS Nano 2015, DOI: 10.1021/acsnano.5b03031). Researchers led by Seunghun Hong and Hyung Wook Kwon of Seoul National University developed these devices to detect compounds responsible for the umami taste, including l-monosodium glutamate, the notorious MSG. But the team’s approach could be expanded to detect a range of analytes, researchers say. The devices rely on natural receptors coupled to gold electrodes resting on carbon nanotube beds. The electrode atop the nanotubes is floating, meaning it’s not connected to a device regulating its voltage. The electrode, however, is connected to vesicles containing umami-sensing protein receptors from honeybees. When a receptor binds an umami tastant, such as MSG, calcium ions flood into the vesicles and the sensor generates an electrical signal. The Seoul team says these are the first such devices to employ floating electrodes and that their electronic palates are more refined than those of human tongues, able to detect umami tastants in picomolar concentrations.