Fish oil from pangasius catfish by-products: composition, quality, and bioactive fatty acid Profile

Abstract

Fish oil was extracted from pangasius catfish (Pangasius hypophthalmus) by-products (skin, bones, and residual flesh adhering to bones) using wet rendering method. Subsequently, the physicochemical properties, fatty acid composition, and heavy metal content of the extracted oil were evaluated. Quality indices were determined by standard assays, fatty acid composition was analyzed using gas chromatography–flame ionization detection (GC-FID), and heavy metals were assessed by atomic absorption spectrophotometry. Among the three fractions, namely fish oil from meat (FOM), fish oil from bone (FOB), and fish oil from skin (FOS), FOM produced the highest yield (19.49 ± 0.71%, dry basis), compared to FOB and FOS (7.71 ± 0.55 and 1.57 ± 0.39%, respectively). All quality parameters complied with required standards, with FOM presenting the lowest values of free fatty acids (0.70 ± 0.23%), peroxide value (3.78 ± 0.65 mEq/kg), and saponification value (206.01 ± 19.41 mg KOH/g). In contrast, FOS exhibited a substantially higher p-anisidine value (5.92 ± 0.93 mEq/kg) and a significantly lower iodine value (54.83 ± 0.27 mg/100 g) compared with both FOB and FOM. It is noteworthy that all pangasius by-product oils exhibited significantly higher proportions of omega-6 and omega-9 fatty acids compared to commercial fish oil. These findings establish pangasius by-products as a promising and nutritionally valuable source of fish oil.