Adsorptive-Stripping Voltammetry at PEDOT-Modified Electrodes. Determination of Epicatechin

The food industry has a direct interest to bitter-tasting substances, either for the identification of negative off-flavors or for the monitoring of organoleptic quality. Polyphenols (such as catechins and epicathechins) are among the main molecular components responsible for the bitter taste of coffee/cocoa/chocolate-based products. The electrochemical detection of epicatechin through adsorptive stripping voltammetry on poly(3,4-ethylenedioxythiophene)-modified Pt electrodes has been investigated. The accumulation conditions were defined in order to record repeatable and reproducible electrochemical signals. Calibration plots were built in the 0.2-2.5 ppm concentration range of epicatechin in phosphate buffer solutions, pH 7. Preliminary tests in aqueous extraction solutions of biscuits containing different percentages of cocoa were performed; they confirmed, in principle, the effectiveness of the device and of the procedure proposed for the epicatechin determination by simple extraction from complex food matrices.