Fish Oil Recovery From Gilthead Sea Bream (<i>Sparus aurata</i><scp>L.</scp>) Waste Using Ultrasound‐Assisted Enzymatic Extraction: Process Optimization and Oil Characterization

ABSTRACT This study investigates the optimization of fish oil extraction from gilthead sea bream ( Sparus aurata L.) waste using ultrasound‐assisted enzymatic extraction (UAEE), which is a sustainable and effective technique for extraction. Addressing the problems of fish processing waste, which accounts for 20%–80% of the total fish mass, ultrasonic waves and enzymatic hydrolysis in UAEE improve extraction efficiency while minimizing environmental effects. The fish oil extraction process was optimized by following a response surface methodology. The optimum conditions for the highest yield (31.0%, g/g) included an ultrasound time of 10.3 min, an enzyme concentration of 0.60% (g/g), and a hydrolysis time of 5 h, obtaining 72.0% extraction efficiency compared to classic Soxhlet extraction. The oil quality and stability were assessed by analyzing its physicochemical properties, fatty acid analysis with GC‐FID, and analyzing the oxidation induction temperature using DSC. The extracted oil was characterized by its favorable fatty acid profile, including its high levels of docosahexaenoic (22:6n‐3, 4.40%, g/g) and eicosapentaenoic acid (20:5n‐3, 2.20%, g/g). The saponification and iodine values of the extracted oils fall within an acceptable range reported for fish oils. Despite a slightly lower oxidation stability compared to Soxhlet extraction, UAEE demonstrates significant potential for producing high‐quality fish oil while using less energy and no hazardous solvents. This study promotes sustainable practices by using underutilized fish waste and reduces dependence on dangerous chemicals, which is in line with the worldwide effort to adopt environmentally friendly technologies.