Influence of Agro-Industrial By-Products on Tenebrio molitor Biomass and Its Bench-Scale Fractionation by Supercritical CO2

The integration of sustainable insect rearing with green downstream processing is essential for the development of circular biorefineries. This study investigated the fractionation of Tenebrio molitor biomass obtained from larvae reared on diets containing agro-industrial by-products by bench-scale supercritical CO2 (SC-CO2) extraction. Larvae were reared on diets containing brewer’s spent grain (BSG), cocoa bean shell (CBS), or banana peel (BP). A preliminary process screening identified 40 °C and 200 bar as the most suitable extraction conditions, providing efficient fractionation under mild operating conditions. Lipid extraction yield depended on the initial composition of the insect meals, ranging from 6.47 ± 0.26% for BSG-derived biomass to 23.02 ± 1.52% for CBS-derived biomass. SC-CO2 extraction simultaneously produced protein-enriched meals, increasing protein content up to 69.4 ± 0.7%, with protein enrichment ranging from 14.9% to 33.4%. The recovered oils exhibited a favorable fatty acid profile, with more than 72% unsaturated fatty acids, predominantly oleic and linoleic acids. These findings show that differences in the composition of insect biomass obtained under different rearing conditions are reflected in the yield and characteristics of the fractions recovered under identical extraction conditions. Integrating rearing substrate selection with SC-CO2 extraction represents an effective strategy to produce high-value protein-enriched meals and oils from agro-industrial by-products, supporting the development of sustainable insect biorefineries.