Array of voltammetric sensors for the discrimination of bitter solutions

Novel voltammetric sensors based on electrodes chemically modified with electroactive substances (conducting polymers and on phthalocyanine complexes), with improved cross-selectivity have been developed. Polymeric sensors have been obtained by electrodeposition of the corresponding monomer (pyrrole) in the presence of different doping agents. Phthalocyanine electrodes have been prepared using the carbon paste electrode technique. The performance and the capability of discrimination of the sensors has been evaluated by testing model solutions of bitterness including MgCl2, quinine, and four phenolic compounds (monoaldehydic and dialdehydic forms of the oleuropein and of ligstroside), which are the main responsible of the bitterness detected in some foods and beverages such as olive oils. The features observed in the voltammograms reflect the redox processes related both to the electroactive material itself and to the studied solutions. In consequence, each sensor shows a rich and characteristic electrochemical response when exposed to the model solutions of bitterness improving the cross-selectivity. A multichannel taste sensor has been constructed using those sensors with the best stabilities, and cross-selectivities. The principal component analysis (PCA) of the obtained signals has allowed the clear discrimination of the bitter solutions. (C) 2004 Elsevier B.V. All rights reserved.