Comprehensive lipidomics analysis of Cape hake (Merluccius capensis) by-products: Screening key features for added value applications

• Lipid profiles of hake by-products were characterized using GC–MS and LC-MS techniques. • "Sawdust" and trimmings show distinct fatty acid and lipidome compositions. • "Sawdust" is richer in triglycerides, while trimmings have more phospholipids. • Both by-products contain omega-3-rich marine phospholipids with bioactive potential. • Valorization of hake by-products promotes sustainability in the fish processing industry. Fish processing generates substantial amounts of waste and by-products, which remain largely untapped resources, particularly regarding their lipid content. This study presents a comprehensive lipid characterization of two Cape hake ( Merluccius capensis ) by-products, “sawdust” and trimmings, using gas-chromatography and liquid chromatography coupled with mass spectrometry, aiming at disclosing the potential of these resources for added-value applications. Moreover, the bioactive properties of the lipid extracts of both by-products were explored using in chemico assays. It was revealed that “sawdust” contains higher levels of ash, proteins, and lipids compared to trimmings. The two by-products presented distinct fatty acid profiles, with “sawdust” displaying higher abundance of palmitic and oleic acids. The lipidome analysis enabled the statistical discrimination between the by-products, mainly driven by higher abundances of acylglycerol species, particularly triglycerides (TGs), in “sawdust.” Conversely, trimmings revealed a higher content of phospholipid species, notably phosphatidylcholines (PCs). Despite these differences, both by-products showed comparable levels of marine phospholipids and ether phospholipids bearing omega 3 fatty acids. Notably, lipid extracts from both by-products exhibited significant anti-inflammatory activity. These findings highlight the potential for valorization held by hake by-products by demonstrating their distinct and valuable lipid profiles. Leveraging these by-products as sources of healthy lipids, the fish processing industry can enhance sustainability and profitability, reducing waste and promoting efficient use of all parts of the fish. Moreover, the bioactive lipids in these by-products may be used in nutraceutical, pharmaceutical, and cosmeceutical applications. This study underscores the importance of valorizing fish by-products, contributing to a circular economy and supporting environmental and economic benefits in the fishery sector.