Evaluating sustainable techniques for the extraction of oils from processed sea bass and sea bream aquaculture side streams

Abstract

Global fish production has risen significantly to meet the growing demand for protein- and oil-rich food sources, yet this expansion has also led to increased waste generation, raising environmental concerns. Within the Horizon2020 EcoeFISHent project, this study investigates the valorization of unsorted, dehydrated side-streams from the filleting of farmed sea bream and sea bass. At laboratory scale, three environmentally sustainable methods for crude oil extraction were compared: green solvent extraction, Microwave-Assisted Extraction coupled to green solvents, and Enzyme-Assisted Extraction. All approaches yielded satisfactory oil recovery (33–42%) and maintained lipid oxidation parameters within the acceptable limits defined by regulatory standards (Codex Alimentarius, CXS 329-2017), confirming the oxidative stability of the extracted oils under the tested conditions. Fatty acid methyl ester profiling revealed consistent lipid composition across methods, with all oils exhibiting a beneficial omega-6/omega-3 ratio (1.7–2.6), supporting their potential for nutraceutical applications. Enzyme-assisted extraction emerged as a particularly efficient and scalable approach enabling the simultaneous recovery of oil and protein hydrolysates. This method was selected for semi-pilot scale-up in a 30 L reactor, achieving yields of 25% (w/w) for oil and 16.5% (w/w) for protein hydrolysates, whose protein content is 84.6 ± 1.44% (w/w). These findings highlight the feasibility of recovering two high-value fractions suitable for use in nutraceuticals, cosmetics, and biomaterials, contributing to the sustainable valorization of fishery side-streams.