Characterization of all life stages of Tenebrio molitor: Envisioning innovative applications for this edible insect

The human food security is unavoidably dependent on exploring novel nutritional sources, such as edible insects. However, insects farming needs to improve their rearing practices, such as extracting value from all growing stages, from larvae until adults. In this work, a full characterization of larvae, pupae and adults of Tenebrio molitor was carried out. Higher protein and ash contents were observed in pupae, while higher lipids (mainly polyunsaturated fatty acids, PUFA) were observed in larvae, decreasing until reaching the adult stage. Chitin content was 6-fold higher in adults than larvae and pupae. Also, it was possible to quantify the chitin resorting to computed 3D tomography, achieving similar values as the traditional and chemically based method. Lower mineral content was found in larvae, while high iron, zinc and copper levels were found in beetles. Phenolic compounds content was similar among larvae, pupae and beetles. FTIR analysis was a valuable, easy, and fast method to assess the nutritional composition of T. molitor, detecting vibrations characteristic of protein, lipids and chitin fractions. This study provides a full characterization of all life stages of T. molitor, highlighting the possible valorisation chains that can be adopted to obtain highly nutritive and/or functional compounds.