Supercritical Defatting, Composition and Digestibility of Meals from Black Soldier Fly (Hermetia illucens) Larvae Fed Olive Leaves, Olive Pomace or Quinoa Husk By-Products

The nutritional composition of insect-derived meals is strongly influenced by insect diet, while defatting can further modulate nutritional quality. However, some defatting methods, such as supercritical CO2 extraction, depend on sample properties, including density and macromolecule distribution. Therefore, diet-induced changes may affect lipid extraction efficiency and kinetics, a relationship that remains unexplored. This study evaluated the impact of feeding Hermetia illucens larvae with by-products from olive oil industry (olive leaves, OL, at 15, 30 or 50%; dry full-fat olive pomace, OP, at 30, 50, 70, 90%) or quinoa processing (husk, QH, at 15, 30 or 50%) on supercritical CO2 defatting performance, meal composition, amino acid profile and digestibility. Despite diet-induced variations in lipid accumulation, defatted kinetics mainly depended on the content and solubility of extractable material, while differences in packed bed microstructure had a minor effect. Protein-rich meals were obtained (25–35%), although most diets reduced protein content, except OP50. QH15 and OP30 worsened essential amino acids in meals, whereas OP50 improved them. Chitin content increased, especially for OP-based meals. Digestibility slightly improved with OP30, OP70, QH15, and QH50. These results show the potential of olive oil and quinoa by-products to be up-cycled by H. illucens into high-value insect meals, without compromising the processing by supercritical CO2 defatting, supporting sustainable insect-based food and feed production.