The integration of insect-derived extracts in feed and food products has become a field of growing interest in recent years. In this review, we collect different studies carried out on edible insects’ transformation processes and focus on the various treatment operations, extraction technologies, and solvents used in different processing steps. We include an overview of current insights into the different steps of the transformation process: insect reception, killing methods, pretreatments, storage, delipidation, protein extraction, as well as chitin and chitosan extraction. Finally, we reflect on the most important future challenges of this sector.

Insects are gaining interest as a sustainable and highly nutritious source of proteins and lipids for food and feed production sectors. Insect bio-refinery includes lipid extraction by pressing, dewatering, microbiological decontamination, and protein fractionation. The present study is experimenting the use of instant controlled pressure-drop (DIC), an emerging technology, for treating yellow mealworms and evaluating its combined effects on insect bio-refinery steps. A preliminary study allowed identifying the optimal hydraulic pressing conditions forTenebrio molitor larvae. Then, establishing an experimental design with DIC operative parameters of the saturated dry steam absolute pressure and treatment time ranging between (0.15 and 0.45 MPa) and (15 and 35 s), respectively, allowed identifying the DIC impact as a pretreatment on different larvae properties. It was possible to identify the optimal pressing parameters at 6 MPa, 60 °C, 2 cm of thickness, and 0.15 mm/s as initial piston speed. Moreover, DIC performed at 0.15 MPa for 25 seconds stood as an efficient killing method. Thanks to the changes in the membrane’s structure it provokes, DIC treatment modified larvae properties, ensured a partial expulsion of the matter (up to 0.47 g/g dry basis (db)), and resulted in larval expansion (up to 67%) which resulted in a decrease in the apparent density. As for the chemical properties, the larvae and larvae juice colours were found to become lighter as we increased the treatment conditions, which might be caused by the inactivation of oxidative enzymes. Moreover, severe DIC operative parameters decreased the pressing yields from 68 to 55%, possibly caused by protein aggregation and denaturation phenomena that prevent molecules from coming out by pressing. However, the water activity and moisture, lipid, and protein contents remained unaffected.

Insects are increasingly being evaluated as promising protein sources for the food and feed sectors. However, to be accepted as a viable food source, insects must undergo proper processing. Drying is a crucial step in insect processing, as it inhibits the growth of harmful microorganisms, improves their stability and extends their shelf life. After drying, insects can be further processed into various forms, to make them more socially acceptable as food and feed. During drying, biological materials are prone to shrinking, which usually affects their quality. Shrinkage of dried biological material results in a compact structure and causes a significant reduction in water diffusivity. It is typically escorted with unsatisfactory organoleptic quality and problems with grinding. Therefore, including retexturing and structure-expanding techniques in regular drying procedures is becoming essential. The instant controlled pressure drop (DIC) technique was suggested as a texturing technique for yellow mealworms. DIC treatment successfully overcame shrinkage at treatment conditions of 0.194 MPa/32 s and above, resulting in enhanced water diffusivity of 1,833 and 682% for DIC-treated larvae at 0.45 MPa/25 s, dried at 50 and 60 °C, respectively, as compared to blanched larvae. Furthermore, DIC caused a 125% increase in the specific surface area of the dried meal, and a more uniform particle size distribution, both of which reflect the influence of this pretreatment on grinding and, consequently, the end product’s quality. Finally, experimental data of sorption isotherms at 20, 30, and 40 °C were fitted with Brunauer-Emmett-Teller (BET), Guggenheim-Anderson-de Boer (GAB), and Oswin models to represent the sorption behaviour.