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This study investigates the stabilization of fish oil‐loaded electrosprayed capsules with different natural antioxidants: i) an ethanol extract from the brown alga Fucus vesiculosus; or ii) a combination of δ‐tocopherol and rosemary extract. The seaweed extract enhances the oxidative stability of fish oil‐loaded capsules with dextran as the main biopolymer wall material, but shows a prooxidant effect in fish oil‐loaded capsules having glucose syrup as the main biopolymer. These results can mainly be explained by the higher encapsulation efficiency of dextran capsules when compared to glucose capsules (90 vs. 83–85%), which prevents interaction of metal ions present in the extract with non‐encapsulated oil. On the contrary, the addition of a lipophilic radical scavenger such as δ‐tocopherol in combination with synergistic antioxidants such as carnosic acid and carnosol present in rosemary extract improves the oxidative stability of glucose syrup capsules during 21 day storage, but not when the capsules are added to mayonnaise. Moreover, the capsule‐containing mayonnaise presents a larger droplet size and higher apparent viscosity than mayonnaise enriched with neat fish oil. Both findings indicate that the structure of capsules may have been lost when added to a water‐based food matrix (e.g., mayonnaise) and this requires further investigation. Practical Applications: Novel omega‐3 delivery systems that are more easily dispersed and still maintain their oxidative stability are needed by the food industry. Electrosprayed capsules with a reduced size when compared to spray‐dried capsules, and which are produced without the need of heat for drying emulsions are promising omega‐3 powdered encapsulates. Moreover, the addition of natural antioxidants, commonly used by the industry to further stabilize omega‐3 encapsulates, deserves scientific attention. This study reveals the effect of seaweed antioxidants (e.g., phlorotannins) and commercial natural antioxidants (e.g., δ‐tocopherol and rosemary extract) on the oxidative stability of electrosprayed capsules loaded with fish oil. In addition, the effect of adding the capsules to a food matrix such as mayonnaise has been investigated. Although further development is necessary, these results will open up new strategies to enrich food products with omega‐3 polyunsaturated fatty acids. Fish oil‐loaded electrosprayed capsules stabilized with antioxidants. This study investigates the stabilization of fish oil‐loaded electrosprayed capsules with different natural antioxidants: i) an ethanol extract from the brown alga Fucus vesiculosus; or ii) a combination of δ‐tocopherol and rosemary extract.

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.

The influence of the carbohydrate-based wall matrix (glucose syrup, GS, and maltodextrin, MD21) and the storage temperature (4 °C or 25 °C) on the oxidative stability of microencapsulated fish oil was studied. The microcapsules (ca. 13 wt% oil load) were produced by spray-drying emulsions stabilized with whey protein hydrolysate (WPH), achieving high encapsulation efficiencies (>97%). Both encapsulating materials showed an increase in the oxidation rate with the storage temperature. The GS-based microcapsules presented the highest oxidative stability regardless of the storage temperature with a peroxide value (PV) of 3.49 ± 0.25 meq O2/kg oil and a content of 1-penten-3-ol of 48.06 ± 9.57 ng/g oil after six weeks of storage at 4 °C. Moreover, low-fat mayonnaise enriched with GS-based microcapsules loaded with fish oil and containing WPH as a film-forming material (M-GS) presented higher oxidative stability after one month of storage when compared to low-fat mayonnaise enriched with either a 5 wt% fish oil-in-water emulsion stabilized with WPH or neat fish oil. This was attributed to a higher protective effect of the carbohydrate wall once the microcapsules were incorporated into the mayonnaise matrix.