This study aimed to extract oil from skipjack tuna belly (Katsuwonus pelamis) using thermomechanical extraction and supercritical CO2 extraction (SFE-CO2). The SFE-CO2 process was conducted at 25 MPa and 40 °C for 30 min, 1 h, and 3 h. Thermomechanical extraction yielded 88.1% crude oil, with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) contents of 7.6% and 19.2%, respectively. In the SFE-CO2 process, the shortest extraction time (25 MPa, 40 °C, 30 min) resulted in the highest DHA (12.6%) concentration, as well as a total polyunsaturated fatty acid (PUFA) content of 22.4%. This behavior is attributed to the shorter CO2–matrix contact time, which favored the selective extraction of target compounds. Conversely, extending the extraction time to 3 h under the same pressure and temperature led to the highest overall yield (26.4%). These findings demonstrate that SFE-CO2 is a promising green technology for the valorization of fish processing by-products, enabling selective recovery of high-value omega-3 fatty acids while promoting more sustainable production practices.
Silva et al. (Sun,) studied this question.