A Pipeline for Green and Ultra-Fast Chitin Extraction from Black Soldier Fly Larvae

Insect larvae, such as the ones from Hermetia illucens (black soldier fly, BSF), are used as bioreactors for the upcycling of urban organic waste into high value-added compounds, such as fatty acids, proteins and chitin. A major issue is related to the extraction processes of the main components which are frequently based on high environmentally impacting conditions and substances. On this side, research focused on the use of deep eutectic solvents (DES), made up of natural, biodegradable and affordable compounds. In particular, hydrophobic DES have been reported to have promising properties in the dissolution of lipids and for the extraction of hydrophobic compounds from aqueous matrices. Here, we used two DES for chitin isolation, namely menthol:lactic acid 8:1 (MeLac, hydrophobic) and choline chloride:lactic acid 1:2 (ChLac, hydrophilic), and alternative extraction procedures on both BSF and defatted BSF (skimmed BSF, SBSF) samples: The use of ChLac combined to microwaves on SBSF allowed the highest recovery of highly homogeneous chitin (3.8% of the starting material). Furthermore, the 1-min microwave-assisted extraction process was also the most energy saving process. Next, proteins were recovered from the DES supernatant, reaching a 7.4% recovery yield for the microwave-assisted extraction. Importantly, about 80% of the originally used ChLac was recovered and could be reused for chitin isolation with no changes in chitin recovery yield. Overall, this report provides a first reference for the design of the sustainable preparation of chitin from insect biomass.