Unleashing the antioxidant potential of adult insects: combining physical and biological treatments in the valorization of Tenebrio molitor

Despite the top advantages of using edible insects for food and feeding purposes, adults are often disposed of, constituting a direct waste of the insect industry. However, adult insects' nutritional and functional value may be explored through the synergetic application of sustainable treatments and enzymes. This work focuses on using 4 different treatments – microwaves-assisted extraction (MAE), ultrasounds-assisted extraction (UAE), CO₂-assisted extraction, and temperature-assisted extraction (TAE) – in T. molitor adults to obtain protein-rich biomass and phenolic compounds. Treatments were performed using a 1 g solid: 10 mL solvent ratio. Water, ethanol and a mixture of water and ethanol 50% v/v were used in each treatment. Higher phenolic compounds (up to 116.9 µM Trolox equivalents/dry solid) and antioxidant activity (up to 8.98 mg gallic acid equivalents/dry solid) were attained after MAE in the three solvents, while the CO₂-assisted extraction was inefficient in extracting these molecules.

After, the wet and treated solids were submitted to enzymatic hydrolysis (EH) with 3% v/w of a commercial protease from Aspergillus oryzae (Sigma, Germany), at 50 °C, for 6 h, pH 8. The total amino acids release was higher after EH of MAE- and TAE-treated insects, which also resulted in higher solid yields at the end of EH. The protein was concentrated after the EH, reaching up to 64% w/w.

The synergetic use of physical and biological procedures is a cost-effective and sustainable approach that upgrades the nutritional value of adult insects, obtaining functional molecules with increased applicability in varied industries.