Bioactive and Functional Properties of Protein Isolates and Hydrolysates from Edible Insects

This study investigated the isolation and bioactive characterization of proteins obtained from insect flours of Tenebrio molitor, Zophobas morio, and Acheta domesticus. Protein isolates were produced from defatted insect flours using a modified alkaline extraction procedure, including extraction at pH 11, isoelectric precipitation at pH 4, and an additional purification step aimed at improving protein purity and isolate quality. The obtained protein isolates were characterized in terms of chemical composition, electrophoretic profile, solubility, water- and oil-holding capacities, amino acid composition, and antioxidant activity. All isolates exhibited notable antioxidant potential in the 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assay, indicating their ability to act as natural radical-scavenging compounds. In order to further evaluate their bioactive potential, the protein isolates were subjected to enzymatic hydrolysis using Alcalase. The obtained protein hydrolysates exhibited antimicrobial activity against both Escherichia coli and Staphylococcus epidermidis, whereas the corresponding protein isolates showed no antimicrobial activity under the applied conditions. Among the investigated samples, Zophobas morio hydrolysate showed the highest antioxidant potential and degree of hydrolysis, whereas Acheta domesticus hydrolysate demonstrated the strongest antibacterial activity. These findings highlight the potential of edible insect-derived proteins as sustainable sources of natural antioxidant and antimicrobial ingredients for future applications in the food, feed, pharmaceutical, and cosmetic industries.