In the fishery 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 SC-CO₂ at 45℃, 250bar for 3h and n-hexane at 45℃, 250rpm for 16h. Hydrolyzing of deoiled tilapia residues were done by subcritical water at 160℃ and 190℃. The overall oil yield from SC-CO₂ was 34% and 63.5% from n-hexane extraction. A higher proportion of total saturated fatty acids (SFAs) than monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) was found in tilapia by-products. The acid content of SC-CO₂ for the skin, head and viscera was 5.46, 3.35, 7.19 mgKOH/g and the peroxide value were 1.77, 1.34 and 4.48 meq/kg. The FFA SC-CO₂ yields 3.62% skin, 1.79% head, and 4.29% viscera, from n-hexane 3.19% skin, 1.69% head, and 4.44% viscera within a reasonable 1-7%. Hydrolysate values ranged from 2.04±0.01 to 7.44±0.01% of samples. The highest and lowest protein and total sugar content were, 4.42±0.79, 31.28±0.92mg/g and 30.06±4.07, 28.51±0.83mg/g respectively. SC-CO₂ 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.