Effect of bitter substances on transducer membranes of taste sensor

A recently-developed taste sensor with global selectivity is composed of several kinds of lipid/polymer membranes for transforming information of taste substances into electric signals, which are treated with a computer. In the present study, effect of bitter substance, quinine, on the lipid/polymer membranes and a base membrane, which is made of polyvinyl chloride and plasticizer, were studied using measurements of membrane potential and impedance. As a result, a peak of the membrane potential in both the membranes was found several hours after they were put into quinine solution. It was shown that this phenomenon was brought about by adsorption of quinine ions onto the membrane surface and then into the membrane. Its effect was larger in the base membrane than the negatively-charged lipid/polymer membrane. This result may help quantification of bitterness and also fabrication of receptor membrane of the taste sensor.