Bioelectrical impedance analysis of frozen sea bass (Dicentrarchus labrax)

The potential of bioelectrical impedance analysis was investigated to differentiate sea bass samples (Dicentrarchus labrax) subjected to different freezing methods and numbers of freezing cycles. The resistance (R) and reactance (X) spectra recorded at 19 frequencies (1 Hz–1 MHz) were analyzed by principal component analysis (PCA). Discriminant analysis (DA) was applied to the first three principal components obtained by PCA, physical and chemical variables. The classification was found to be correct for 78% of the samples. It was observed that reactance (X) measured at frequencies higher than 500 kHz can be used to distinguish sea bass samples with different freezing histories. It was concluded that the most important electrical properties of frozen/thawed fish are extracted at frequencies 500 kHz–1 MHz, so that future studies should focus on the electrical properties measured at these frequencies. Additional statistical analysis (ANOVA) showed that differentiation between once-frozen and twice-frozen samples was more successful than differentiation between fast-frozen and slow-frozen samples.