Fish Freshness Monitoring Using an E-Tongue Based on Polypyrrole Modified Screen-Printed Electrodes

In this paper, a novel e-tongue for evaluating biogenic amine compounds is reported. The method uses an array of voltammetric electrodes chemically modified based on screen-printed electrodes. The electrochemical signals toward amines consist in complex voltammetric curves. Cyclic voltammograms show redox processes related to the electrochemical activity of the amine under study, and redox peaks associated with the electrochemical activity of the electroactive material. Additionally, the electroactivity and basic character of amines influences considerably the electrochemical behavior of the electrodic material. The viability of the method is tested for the fish freshness monitoring. The samples are Pontic shad (Alosa Pontica), a fish living in the northwestern part of the Black Sea. Pontic shad migrates in the Danube River for spawning. The pattern of responses provided by the array can be used to discriminate and evaluate the fish freshness state. Principal component analysis confirmed the capability of the sensors array to fish freshness monitoring. Partial least squares–discriminant analysis showed that this method could be used for the analysis and determination of fish freshness as well as determination the postmortem time elapsed.