Study of the oxidative degradation of farmed salmon lipids by means of Fourier transform infrared spectroscopy. Influence of salting

Farmed salmon fillets were dry‐salted for 24 h. Both salted and unsalted samples were submitted to oxidative conditions at 50 °C in an oven with circulating air. Lipids of both samples were extracted daily from aliquots and studied by Fourier transform infrared spectroscopy. The infrared spectra of salmon lipids are similar to those of vegetable edible oils, with differences in the frequency and absorbance of some bands due to their different acyl group compositions. The infrared spectra of salted and unsalted fish lipid samples remain unchanged during a period of time, which is shorter for the salted salmon. After this period, changes in the frequency and absorbance of some bands of the spectrum are observed owing to the presence of oxidation products. Therefore the reduction in the oxidative stability of farmed salmon lipids caused by the dry‐salting process is proved and the usefulness of this technique for studying the oxidative stability of fish lipid samples as well as their oxidation degree is shown.