Supercritical-CO2 for defatting and production of bioactive extracts from black soldier fly (Hermetia illucens) larvae

Abstract

Edible insects are gaining attention as a source of bioactive compounds of great interest for health. To produce bioactive extracts from insects with a high concentration of bioactive compounds, defatting seems to be relevant for those fat-rich forms of insects as larvae. Supercritical fluid extraction (SFE) might be useful for both the defatting and subsequent extraction of the defatted sample to obtain bioactive extracts from edible insects. Different samples of black soldier fly (Hermetia illucens) larvae were defatted using SFE as an alternative to conventional defatting methods, and the optimal defatted flour was sequentially extracted by SFE employing different levels of ethanol as co-solvent. The resulting extracts were characterised by GC-MS-FID and their bioactivity was then assayed in terms of their antioxidant and pancreatic lipase inhibitory activities. The maximum fat yield by SFE (around 43%) was achieved at 450 bar, 60 °C and 100 g/min of CO2 flow, not being significantly different from conventional defatting with hexane. Extraction yield of SFE extracts increased along with the proportion of co-solvent. The composition of the extracts widely varied depending on the insect sample and the amount of co-solvent used, free amino acids and fatty acids being the two major chemical families among the different extracts. In terms of their bioactivity, a lipase inhibitory activity closer to 50% was exhibited by most extracts, which was favoured by the amount of co-solvent in one of the insect samples. Regardless of the significant differences observed between the insect samples, the exhibited DPPH radical inhibitory activity was weak. It is concluded that SFE is an interesting alternative to the conventional defatting of H. illucens, as well as an integrative and sequential process that allows producing bioactive extracts from this insect, especially towards the inhibition of the pancreatic lipase.