A New Approach for the Determination of Fish Freshness by Electrochemical Impedance Spectroscopy

Changes in several dielectric parameters of carp, herring and sea bass during their storage after death at 4 °C, 15 °C and 25 °C were examined by electrochemical impedance spectroscopy (EIS) in the frequency range of 0.1 Hz to 100 kHz. This method offers a simple, rapid and in situ measurement of the onset of spoilage. The phase angle and admittance changes are the best freshness indicators, from which four classifications of freshness may be defined for all of the tested fish species. Warburg‐type impedance and CE (chemical reaction preceding an electrochemical reaction) processes were observed in the relaxation process during storage and a proposed equivalent circuit satisfactorily described the overall electrochemical behavior.