Front face fluorescence spectroscopy enables rapid differentiation of fresh and frozen-thawed sea bass (Dicentrarchus labrax) fillets

- Discrimination between fresh and frozen-thawed sea bass fillets.
- High correlation between fluorescence spectra and reference methods.
- CCSWA allowed to study the spectral patterns at the molecular level.

The aim of this study was to evaluate the potential of using front face fluorescence spectroscopy (FFFS) to discriminate fresh refrigerated (up to 13 days at 4 °C) sea bass (Dicentrarchus labrax) fillets (F group) from: i) frozen-thawed (3 months at −18 °C), then refrigerated up to 9 days fillets at 4 °C (F-T R group), and ii) refrigerated (up to 9 days at 4 °C), then frozen-thawed (3 months at −18 °C) fillets (R F-T group). The evolution of emission fluorescence spectra after excitation set at 290, 340, and 380 nm, and excitation spectra after emission set at 410 nm were acquired throughout storage. Some traditional measurements based on color, textural, and chemical parameters were performed on the same fillets. Canonical correlation analysis (CCA), applied to the traditional and fluorescence data sets, showed high correlations between the two data sets, since squared canonical coefficients were found higher than 0.8 for canonical variates 1 and 2. This was confirmed by the factorial discriminant analysis (FDA) applied to the concatenated emission spectra recorded after excitation sets at 340 and 380 nm since 72 out of 78 samples were correctly classified. Finally, a multi-block analysis method based on common components and specific weights analysis (CCSWA) was applied to the whole data sets. A reliable discrimination between fresh from frozen/thawed fish was found suggesting that FFFS could be used as a promising tool in routine inspection for differentiating between fresh and frozen-thawed fish.