Nutritional indexes, fatty acids profile, and regiodistribution of oil extracted from four discarded species of the Alboran Sea: Seasonal effects

Abstract

The new EU fisheries regulations state that all catches from pelagic fisheries must be landed from the January 1, 2015 on. Consequently, the development of new techniques for the up‐grading of these discards is required. The aim of this work was to study the variations of the lipid profile and nutritional value of the oil extracted from four discarded species: axillary seabream (Pagellus acarne), sardine (Sardina pilchardus), horse mackerel (Trachurus mediterraneus), and blue whiting (Micromesistius poutassou). To that end, the proximate composition, the lipid profile, the regiospecific distribution of fatty acids within the glycerol backbone, the nutritional parameters (thrombogenic and atherogenicity indexes and hypocholesterolemic/hypercholesterolemic ratio), and the peroxidability index were determined in each season. All species presented polyunsaturated fatty acids (PUFA) as the major fraction in both the global and the sn‐2 profile. DHA presented highly regiospecifity to position sn‐2 whereas the tendency of EPA was to occupy sn‐1(3) positions. The relative concentration of PUFA occupying sn‐2 position varied from 30 to 60% (molar basis).Practical applications: This work proposes an up‐grading strategy for the fish oils extracted from four discarded pelagic species. In the last decades, fish oils have been widely employed as source for the production of structured lipids or PUFA concentrates. The choice between both applications depends on the fatty acids regiodistribution within the glycerol backbone. Oils with high PUFA content at the central bond may be selected for the production of structured lipids by using sn1‐3 lipases. In this case, the central position remains unmodified. To obtain concentrates it is necessary to release the free fatty acids and subsequently re‐esterified them. Consequently, oils with lower PUFA content in the central position are preferred for the production of concentrates by urea complexation or winterization.Seasonal variation of the percentage of DHA located at the sn‐2 position of four discarded species (axillary seabream, sardine, horse mackerel, and blue whiting).