Development of a rapid method based on front-face fluorescence spectroscopy for the monitoring of fish freshness

The intrinsic fluorescence of fish muscle was evaluated as a possible rapid and non-destructive method for the monitoring of fish freshness. The fluorescence emission spectra of aromatic-amino-acids + nucleic-acids (excitation: 250 nm, emission: 280-480 nm), tryptophan residues (excitation: 290 nm, emission: 305-400 nm) of proteins and NADH (excitation: 336 nm, emission: 360-600 nm) were recorded on cod, mackerel, salmon and whiting fillets at 1, 5, 8 and 13 days of storage. Principal component analysis and Mahalanobis distance method were applied to the spectral data sets. Considering the mackerel, the similarity map defined by the principal components 1 and 2 showed a discrimination of the aromatic-amino-acids + nucleic-acids spectra recorded after 1 day of storage versus the ones recorded after 5 and 8 days of storage according to the principal component 1. Similar trends were observed for all the fish species and all the fluorophores investigated. It appears that the intrinsic fluorescence spectra could be considered as fingerprints that may. allow the discrimination between fresh and aged fish fillets. (C) 2003 Elsevier Science Ltd. All rights reserved.