Properties of Oils and Hydrolysates Obtained from Tilapia (Oreochromis niloticus) By- Products Using Pressurized Fluid Technologies

In the fisheries industry, the consumption of residue and fish waste allows effective uses of the potential fish wastes as food additives, such as omega-3 fatty acids. Oil extraction from tilapia wastes and by-products were carried out by supercritical carbon dioxide (SC-CO ₂ ) at 45 °C, 250 bar, for 3 h and n -hexane at 45 °C, 250 rpm, for 16 h. Hydrolysis of de-oiled tilapia residues was done by subcritical water at 160 °C and 190 °C. The overall oil yield obtained through SC-CO ₂ was 34.3% ± 1.12% and through n -hexane was 63.5% ±0. 69%. Tilapia by-products were observed to have a higher proportion of total saturated fatty acids (SFAs) than monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs). The acid content of SC-CO ₂ for the skin, head and viscera was 5.46 ± 0.25, 3.35 ± 0.28, and 7.19 ± 1.06 mg KOH/g, respectively, and the peroxide values (PVs) were 1.77 ± 0.43, 1.34 ± 0.46, and 4.48 ± 0.17 meq/kg, respectively. The free fatty acid (FFA) obtained via SC-CO ₂ yields 3.62% ± 0.10% (skin), 1.79% ± 0.09% (head), and 4.29% ± 0.41% (viscera), and that via n -hexane yields 3.19% ± 0.35% (skin), 1.69% ± 0.02% (head), and 4.44% ± 0.55% (viscera) within a reasonable value range 1%–7%. Hydrolysate values ranged from 2.04% ± 0.01% to 7.44% ± 0.01% of samples. The maximum and minimum values of protein were 40.42 ± 0.79 and 31.28 ± 0.92 mg BSA/g and that of total sugar were 30.06 ± 4.07 and 28.51 ± 0.83 mg Glu/g, respectively. SC-CO ₂ and n -hexane are the favored techniques in the valorization of tilapia waste containing substantial bioactive compounds that are essential for human and animal health.