l -Glutamate biosensor for estimation of the taste of tomato specimens

Abstract An amperometric biosensor has been developed for measurement of Umami, or the taste based on the amount of l-glutamate, in tomato foods. The biosensor is based on an enzyme-mediator system in which l-glutamate oxidase is used for biochemical oxidation of l-glutamate and a tetrafulvalene-tetracyanoquinodimethane (TTF-TCNQ) paste, prepared from the mixture of TTF-TCNQ salt, graphite powder, and silicone oil, serves as the mediator. The limit of detection, calculated by use of a four-parameter logistic model, was 0.05 mmol L-1, and the limit of quantification was 0.15 mmol L-1. The correlation coefficient (R 2) was 0.990 and the relative standard deviation was no more than 1% (n=5). The response time (t 95) was 20–50 s, depending on concentration. The repeatability of the sensor was better than 5% (n=10). The sensor developed was stable for more than ten days