Identification and quantification of tuna species in canned tunas with sunflower medium by means of a technique based on front face fluorescence spectroscopy (FFFS)

Abstract

The authenticity of tuna is now of great importance in the multi-step food chain, from on farm production to consumer consumption. A technique based on the use of front face fluorescence spectroscopy (FFFS) was employed to authenticate tuna species in canned tuna produced at the pilot scale with sunflower oil medium: skipjack tuna (Katsuwonus pelamis), yellowfin tuna (Thunnus albacares) and bigeye tuna (Thunnus obesus). Tryptophan residues, aromatic amino acids and nucleic acids (AAA + NA), riboflavin, nicotinamide adenine dinucleotide (NADH) and vitamin A spectra were recorded on 232 canned tunas. When Factorial Discriminant Analysis (FDA) was applied to the different intrinsic probes, the classification rates were not satisfactory. Therefore, the first five principal components (PCs) of the PCA extracted from each intrinsic probe was pooled into a single matrix and analysed again by FDA. Correct classification amounting to 74.6% was observed on the calibration data sets. The established models tested on 30 unknown commercial canned tunas illustrated 40% rate of mislabeling. The tuna cans labelled as skipjack species were 100% correctly classified, while those labelled as yellowfin and bigeye tunas seemed to be adulterated since for: i) tuna cans labelled as bigeye, skipjack species were detected; and ii) tuna labelled as yellowfin, bigeye, skipjack and mixtures of yellowfin and skipjack and yellowfin and bigeye were found.