Classification of sea bream (Sparus aurata) fillets subjected to freeze-thaw cycles by using front-face fluorescence spectroscopy
Abstract
The most common frauds carried out in different points of fish and fish product supply chain concern the selling of freeze-thaw fish as fresh fish. Moreover, fluctuation of temperature during the storage process, transportation, and sale modified the fish quality and increased the frozen-thawed cycles. In this study, front face fluorescence spectroscopy (FFFS) was used to determine the effect of freeze-thaw cycles on the quality of sea bream fillets. The application of factorial discriminant analysis (FDA) to the concatenated fluorescence spectra allowed to distinguish clearly between the numbers of freeze-thaw cycles applied to sea bream fillets since correct classification rate amounting to 91.67% was observed, regardless of the initial raw quality. This could be explained by changes in the tertiary structure of tryptophan and the oxidation state of NADH. The obtained result was confirmed following the application of partial least square regression (PLSR) since an excellent prediction of the number of freeze-thaw cycles was obtained (R-2 = 0.99; RPD = 7.13). Therefore, FFFS could be used as a rapid screening technique to detect with high accuracy between fresh, once and twice freeze-thaw sea bream fillets.