Improvement of techno-functional properties of edible insect protein from migratory locust by enzymatic hydrolysis

Enzymatic hydrolysis of migratory locust (Locusta migratoria L.) protein flour (MLPF) was investigated as a method to improve the techno-functional properties. Experiments were conducted under variation of the applied proteases (Alcalase, Neutrase, Flavourzyme, Papain) or combinations thereof, enzyme–substrate ratio (0.05–1.0% w/w), heat pre-treatment (60–80 °C; 15–60 min), and hydrolysis time (0–24 h). Protein degradation was monitored in terms of degree of hydrolysis (DH) and SDS-PAGE. Solubility, emulsifying, foaming and water/oil binding properties of the hydrolysates were determined. In comparison to the control (DH = 5%), hydrolysis resulted in considerably higher DH values up to 42%. SDS-PAGE profiles revealed a steady decrease of bands between 25 and 75 kDa and an increase of low molecular weight bands (10–15 kDa). However, different heat pre-treatments resulted in impaired hydrolytic cleavage as evidenced by lower DH values. Protein solubility of MLPF hydrolysates was improved over a broad pH range from initially 10–22% up to 55% at alkaline conditions. Furthermore, hydrolysis resulted in enhanced emulsifying activity (54%) at pH 7, improved foamability (326%) at pH 3 and advanced oil binding capacity. The results of this study have clearly demonstrated the potential of targeted enzymatic degradation to improve the techno-functionality of migratory locust protein in order to produce tailored insect-based ingredients for the use in food applications.