One-step microwave-assisted extraction and derivatization for the evaluation of fatty acid methyl esters composition in marine organisms and their nutritional value

Lipid fraction of marine organisms primarily contain polyunsaturated fatty acids (FAs), followed by monounsaturated and saturated FAs. Among polyunsaturated FAs eicosapentaenoic and docosahexaenoic acid play crucial roles in various human metabolic processes, safeguarding the circulatory system, and preventing inflammatory and cardiovascular diseases. This work aims to characterize the FAs profile of seven different marine species, collected from the coastal shoreline of the Po Delta Park in the Emilia Romagna Region (Italy), and determine their nutritional values. The species examined were: two types of oysters, two varieties of clams, one species of mussel, one species of spiny dogfish, and one species of macroalgae. A recently developed one-step microwave-assisted extraction and derivatization (MAED) method was employed to simultaneously extract and derivatize the marine organism lipid fractions in FA methyl esters (MEs), followed by two-dimensional comprehensive gas chromatography – flame ionization detector (GC×GC-FID) analysis. Eighty-two FAMEs were tentatively identified through standard, literature data, and the 2D-GC plot. The FAMEs profile obtained by this methodology showed no appreciable variations when compared to literature data and reference method (AOCS Ce 2b-11). Furthermore, from the FAME profile, the most common nutritional indices were calculated: atherogenicity and thrombogenicity indices, hypocholesterolemic/hypercholesterolemic ratio, health-promoting index, unsaturation index, and fish lipid quality. The high GC×GC separation power made it possible to produce extremely precise nutritional indicators based on the distribution of FA in the samples investigated. The spiny dogfish had the best nutritional score of all the samples examined, whereas one of the clam species had the lowest scores in 4 out of 6 indices.