Effect of Storage and Extraction Protocols on the Lipid and Fatty Acid Profiles of Dicentrarchus labrax Brain

Fish brain might represent an interesting raw material since it is particularly enriched in lipids (e.g., phosphatidylcholines (PCs)) that are valuable food additives and nutraceuticals. A chloroform-free solvent extraction protocol based on 2-methoxy-2-methylpropane also known as methyl tert-butyl ether (MTBE) was evaluated and compared with CHCl3:MeOH mixtures of the classical Bligh-Dyer method. Phospholipids (PLs) and sphingolipids (SPs) occurring in the brain extracts of farmed European sea bass fish (Dicentrarchus labrax) were identified/analyzed by flow injection-electrospray ionization-mass spectrometry (FI-ESI-MS), whereas the content and identity of fatty acids (FA) were obtained by gas chromatography-MS upon derivatization as FA methyl esters. On the basis of these preliminary results, the total contents of PL and SP, as well as their relative abundances, were not significantly affected by the extraction protocol used. The most abundant lipid class was the PC with a mean ± SD content (expressed as nmol/mg protein) of 507 ± 89, followed by phosphoethanolamines (195 ± 41), ceramides (35 ± 9), sphingomyelins (9 ± 4), lyso-phosphatidylcholines (8 ± 2), and phosphatidylglycerols (1.8 ± 0.8). In terms of pre-processing strategy of fish brain samples, two preservation methods, i.e., freezing and freeze-drying, were also compared. Lyophilization led to a partial degradation of PC to their corresponding lyso-form, most likely as a result of endogenous phospholipase activity.