Processing improves physical and oxidative stability of cricket protein emulsions

Cricket protein isolate (CPI) prepared through isoelectric precipitation was physically treated by heat (H), high pressure (HP), or ultrasound (US). The effect of the three treatments on the structural and functional property (emulsifying capacity, EC) of CPI was evaluated. Four oil-in-water (O/W) emulsions, control (C-), H-, HP-, and US-, were prepared by mixing 1% (w/v) CPI with purified rapeseed oil and Milli-Q water. The emulsions were monitored for physical and oxidative stability at 4°C for 21 days. Both HP- and US-treatments resulted in breakdown of larger proteins into smaller fractions as well as increased solubility, negative surface charge, and hydrophobicity of CPIs, which positively affected the EC. In comparison to C- and H-, both HP- and US-treatments resulted in emulsions with reduced oil droplet size on day 0, with better physical stability during 21-day storage indicated by changes of droplet surface mean diameter, and morphology. Both P- and US-treatments slowed down the lipid oxidation in emulsions, however with accelerating protein oxidation. In conclusion, HP- and US-treatments of CPIs resulted in improved physical stability and protection against lipid oxidation in O/W emulsion.