Front-face fluorescence spectroscopy coupled with chemometric tools for monitoring fish freshness stored under different refrigerated conditions

- Monitoring fish freshness/oxidation by front face fluorescence spectroscopy.
- Fish to fish differentiation as a function of storage condition and time.
- High correlation between 460/395 nm fluorescence intensity ratio and TBARS values for Whiting fish samples exposed to light.

Front-face fluorescence spectroscopy was used as a rapid tool for assessing freshness of whiting fish (Merlangius merlangus) fillets stored at 4 ± 1 °C for up to 12 days under different conditions. Some physicochemical analysis [i.e., water content, pH, peroxide value, thiobarbituric acid reactive substances (TBARS)] were performed. With increasing storage time, the TBARS and pH values increased progressively in all whiting fish fillets, in particular for those exposed to light. Principal component analysis and factorial discriminant analysis applied separately to the tryptophan (excitation: 290 nm, emission: 305-450 nm) and nicotinamide adenine dinucleotide (NADH) (excitation: 340 nm, emission: 360-600 nm) spectra gave only a slight discrimination between the investigated whiting fish fillets. These results were improved when data from all the fluorescence spectra were analyzed jointly, since nearly three-quarters of samples were correctly classified. The best results were obtained by concatenating the fluorescence and physicochemical data sets, giving more than 90% of correct classification.