Bioconversion of Seasonal Vegetable By-Products into Nutrient-Rich Biomass Using Black Soldier Fly Larvae

Agro-industrial processes generate large volumes of by-products rich in proteins, lipids, and bioactives, yet their valorization remains limited. Black soldier fly larvae (BSFLs) offer a sustainable route to convert these residues into nutrient-rich biomass. We evaluated six seasonal by-product diets (pea–chickpea, chickpea–green bean, wheat–green bean, spinach–chickpea, tomato–chickpea, tomato–wheat) and profiled diets and larvae for tocopherols, carotenoids, fatty acids, and amino acids; principal component analysis assessed assimilation patterns. Larvae did not mirror diets but clustered into two compositional regimes, indicating selective metabolism. Tomato-based diets enhanced larval α-tocopherol (22.54 mg/kg dw) and lycopene (6.87 mg/kg dw), while spinach-based diets contributed higher lutein and other xanthophylls. Significant diet–larvae correlations were observed for lycopene (r = 0.6719) and β-cryptoxanthin (r = 0.5845). Across treatments, lauric (C12:0) and palmitic (C16:0) acids remained dominant, confirming the conserved BSFL lipid hierarchy (SFA > MUFA > PUFA). Amino acid profiles were relatively stable, with lysine and glutamic acid prevailing among essential and non-essential classes. Overall, BSFLs enriched with tocopherols and provitamin A carotenoids offer functional benefits for oxidative stability and micronutrient restoration, underscoring their dual role in waste valorization and nutritional enhancement within circular food and feed systems.