Five discarded fish species in the Alboran Sea, namely axillary seabream (Pagellus acarne), small-spotted catshark (Scyliorhinus canicula), sardine (Sardina pilchardus), horse mackerel (Trachurus mediterraneus), and bogue (Boops boops) were evaluated as novel sources for the production of omega-3 polyunsaturated fatty acids (PUFAs). The lipid content of the five species varied significantly within the different seasons, being maximum in spring for axillary seabream, small-spotted catshark, and bogue (5.1, 2.7, 2.5%, respectively) and in summer for sardine and horse mackerel (13.6 and 6.2%, respectively). Sardine and horse mackerel presented also the maximum amount of eicosapentaenoic acid (EPA) + docosohexaenoic acid (DHA), 3000 and 1300 mg/100 g fish, respectively. Their oils exhibited a composition of EPA + DHA higher than 23% and they were mainly composed by triacylglycerols. Axillary seabream, small-spotted catshark, and bogue presented a lower amount of EPA + DHA, 960, 650, and 157 mg/100 g fish, respectively, but their oils also exhibited a composition of EPA + DHA higher than 20%. Particularly important was the composition of DHA, 23%, of the oil extracted from small-spotted catshark. Therefore, the five discarded species studied were found to be valuable raw material for the production of fish oil presenting a high content in EPA and DHA.
Practical applications: This work is in line with ongoing EU regulations avoiding fish discards. This has boosted research on the potential of these raw materials for the production of high added-value products such as omega-3 PUFAs, which are experiencing a growing commercial demand. This study provides a complete characterization of five discarded species in the Alboran Sea, with special focus on the availability of their omega-3 content throughout the year. Despite their different lipid content, all the species were good sources for the production of omega-3. The oils extracted from these species presented a maximum composition of EPA + DHA higher than 20%. Interestingly, small-spotted catshark's oil was relatively rich in DHA (up to 23%), which makes this oil an excellent functional ingredient for brain and children's health applications. The results obtained provide valuable information for food scientists interested in the production of omega-3 PUFAs from traditional and alternative fish species.