Diet-dependent chemical fingerprinting in Tenebrio molitor larvae reared on tuna by-products

Diet composition significantly influences the chemical quality of edible insect ingredients. This study compared Tenebrio molitor larvae reared on wheat bran (WB) and tuna by-products (TB) using proximate analysis and metabolomics. On a dry matter basis, crude protein was similar at about 45 g per 100 g, whereas TB showed higher lipid and lower carbohydrate contents. Fatty acid methyl ester analysis revealed higher oleic and linoleic acids and a shift toward C18 unsaturated fatty acids in TB. Total hydrolyzable amino acids and essential amino acid proportion were conserved, although proline was higher in TB. Untargeted mass spectrometry of ethanol extracts identified 26 diet responsive metabolites, with WB enriched in polar metabolites and TB enriched in lipid derived components. TB extracts showed stronger antioxidant activity and no apparent cytotoxicity. Overall, tuna by-products remodeled lipid chemistry and metabolomic signatures while maintaining protein adequacy, supporting lipid enriched insect ingredients. • Tuna byproduct diet raised larval lipids while maintaining protein levels. • Metabolomics revealed diet-dependent shifts in larval lipid and polar metabolites. • Twenty-six metabolites differentiated tuna-fed from bran-fed larvae. • Tuna-fed larval extracts exhibited greater antioxidant capacity. • Results support tuna byproducts for producing distinct mealworm feed ingredients.