A sweetness sensor with lipid/polymer membranes has been developed for evaluating

the sweetness of sugars and sugar alcohols. Among the constituents of lipid/polymer

membranes, gallic acid has been used as the main substance involved in sucrose response

in our group. In this study, as a step toward understanding the response mechanism of

the sweetness sensor, functional groups of gallic acid, namely, carboxyl and hydroxyl

groups, were focused on. The results demonstrated that the carboxyl group is essential

for the sweetness sensor, whereas the hydroxyl group is not always necessary for the

sucrose response. It was also revealed that the phosphate group may be a substitute

for the carboxyl group. Then, for one of the sensors with the highest response to a 300

mM sucrose solution, named the sweetness sensor GL1, the basic characteristics such

as selectivity and correlation with sweetness were investigated. The behavior of GL1

sensor outputs was relatively similar to the sweetness perception in humans.