Valorisation of Tenebrio molitor beetles: enzymes-based bioprocessing to obtain a highly digestible protein hydrolysate

Abstract The biological valorisation of edible insects is an eco-saving approach that may increase their use for food and feeding purposes. Beetles of T. molitor are a direct waste of insect farms since their protein have a low digestibility. Currently, the degree of hydrolysis achieved with biological treatments are much lower than with chemical treatments. This work focused on the enzymatic hydrolysis of protein from T. molitor beetles using proteases. The obtained protein hydrolysate was evaluated regarding the digestibility and functional properties. Higher hydrolysis degree (HD; 47%) was obtained using a protease from Aspergillus oryzae , which efficiently separated protein from chitin. A full factorial design determined that a liquid:solid ratio (LSR) of 15 and an enzyme load of 3200 U/g increase HD up to 78%. The protein hydrolysate showed higher digestibility (77.3%) compared to beetles’ meal before (17.8%) and after defatting (25.7%). The protein hydrolysate showed a high antioxidant activity (462.1 ± 7.48 μmol TE/g DW), it was highly soluble at pH ranging between 3 and 9 and showed an emulsification activity and stability of 53.6% and 82.2%, respectively. Therefore, this bioprocess improved the use of beetles, obtaining protein with greater digestibility to be used as food.