Comparative lipid analysis and valorization strategies for processed gilthead seabream and European pilchard secondary raw materials

The valorization of fish processing by-products enhances industry sustainability and profitability. This study analyzed the lipid composition of by-products from farmed gilthead seabream ( Sparus aurata , Sa) and wild European pilchard ( Sardina pilchardus , Sp). Total lipid content was high: 43.94±6.46 g/hg in Sa and 34.00±1.25 g/hg in Sp, with low phospholipid levels, indicating neutral lipid dominance. Sa was rich in oleic and linoleic acids, whereas Sp contained higher levels of EPA and DHA, leading to a more favorable n-6/n-3 ratio. Lipidomic analysis identified 154 lipid species (142 in Sa; 153 in Sp), mainly triglycerides (109 species), along with diglycerides, phospholipids, ceramides, and a cholesterol derivative. Triglyceride profiles enabled clear statistical discrimination between species. Despite limited antioxidant activity, the lipid extracts from the raw products showed strong anti-inflammatory properties. Sp by-products, with their superior omega-3 content, are suitable for food and feed applications. Sa by-products, though less nutritionally favorable, are valuable due to their high lipid content for non-food uses such as biofuels and cosmeceuticals. Lipidomic profiling supports optimized by-product utilization, adding value and promoting sustainability without affecting the availability of edible portions. • Lipids of S. aurata and sardine by-products were compared • Sardine by-products, rich in EPA/DHA, ideal for food/feed use • Lipid-rich S. aurata by-products, suited to non-food valorization • 154 total lipid species identified, mostly triglycerides • By-product valorization enhances sustainability in fish industry